Document in Scrap - CORE · 2013. 7. 15. · THE SAURASHTRA UNIVERSITY FOR THE DEGREE OF Doctor of...

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Pathak, Chetna P., 2011, “A Study of Ecology of the Piscivorous Birds at Thol

Bird Sanctury”, thesis PhD, Saurashtra University

http://etheses.saurashtrauniversity.edu/id/eprint/559 Copyright and moral rights for this thesis are retained by the author A copy can be downloaded for personal non-commercial research or study, without prior permission or charge. This thesis cannot be reproduced or quoted extensively from without first obtaining permission in writing from the Author. The content must not be changed in any way or sold commercially in any format or medium without the formal permission of the Author When referring to this work, full bibliographic details including the author, title, awarding institution and date of the thesis must be given.

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JUNE-2011

Dedicated to:

My Father-in-law – Late Mr. T. B. Shah

My Sister-in-law – Late Mrs. Rupal K. Pathak

My Niece – Late Chi. Madhvi K. Pathak

My Nephew – Late Chi. Shrinivas K. Pathak

ACKNOWLEDGEMENT

Working as a Ph.D. student in Ecology background was a

magnificent experience for me. In all these years, many personalities

were instrumental directly or indirectly in shaping up my academic

career. It was not possible for me to thrive in my doctoral work without

the precious support of these personalities. Here is a small tribute to

all these personalit ies.

At the outset, I wish to express gratitude to my guide Prof.

(Dr.) V.C. Soni for his valuable guidance, invaluable advice, cheerful

enthusiasm and constant encouragement, without which, it was

difficult, rather impossible for me to complete my research work in a

respectable manner. I am grateful to him for allowing me some extra

time to finish my experimental work.

My special thanks to the Head of the Bioscience Department

Prof. S.P. Singh for providing necessary facili ties at the Department.

I express my sincere thanks to Mr. Pradeep Khanna, IFS,

Principal Chief Conservator of Forests, Dept. of Forests &

Environment, Gandhinagar for giving me permission to work in Thol

Sanctuary.

I am also grateful to Dr. C.N. Pandey, the former Director of

GEER Foundation for providing me required facilities and I would also

like to thanks to the Pollution Control Board and Data

Center,Gandhinagar for their help.

It gives me pleasure to acknowledge with profound gratitude and

indebtedness to Mr. Sanat Sothan and Mr. Aaditya Roy for their

vigilant guidance in photography.

I express my gratitude to Mr. Jayeshbhai for helping in some

statistical calculations.

My special thanks to Mr. Prakash Parmar, Mr. Pathik Shah,

Mr. Kandarp Bhatt for helping me in my computer work.

My sincere thanks to the Department of Forests & Environment

for providing some tools for my work and as a Field Co-operative

Mr. Lilabhai, who was always ready to extend his kind help during my

field work.

I express my sincere thanks to Ms. P.A. Vadher, Incharge

Principal of Govt. Science College, Gandhinagar for her moral support.

It is my privilege to have my Head of the Dept. Dr. S.K. Patel, my

colleagues Dr. Dilip Odedra, Prof. Shital Vyas, Dr. Tarak Thakker,

Dr. Rajkumari Parwani, Dr. Pragna Prajapati, Prof R. N. Maru, Mrs.

Dipikaben, Mrs. Bindu, who have provided great enthusiasm and

company during my work.

I also express thanks to my colleagues Dr. Suresh Patel, Dr.

Rajan Jadav in Dept. of Bioscience, Rajkot.

I am highly obliged and express my deep sense of gratitude to

my Father - Mr. P.J. Pathak & Mother - Smt. Kusumben Pathak for

their constant support and encouragement in all my work.

My special thanks to my elder brother Mr. Kashyap Pathak, who

always provided me moral support throughout two years and in early

morning in heavy winter during my toughest days of field work.I also

thank my younger brother Mayur Pathak for his helping hand and

taking care of things when good help was in demand.

I express my gratitude to my sister Prof. Nita Joshi and her

daughter Chi. Siniva Joshi for giving me company in my field work and

sometimes for taking care of the household during my busy schedule.

Last but not the least, I wish to express my gratitude from the

bottom of my heart for my father-in-law Mr. T.B.Shah & mother-in-law

Mrs. Savitaben Shah for always extending their constant support

though they are facing many physical odds.

I express my deep sense and gratitude to my husband – Mr.

Virendra Shah for his continuous noble moral support.

Lastly, I express my sincere thanks to all other known / unknown

persons whom I have come across during my field & thesis work, who

have directly or indirectly become instrumental in completing my

work.

____________

(Chetna Pathak)

CONTENTS

INTRODUCTION :-

CHAPTER-1 STUDY AREA 4

CHAPTER-2 POPULATION OF THE

PISCIVOROUS BIRDS 33

CHAPTER-3 HABITAT UTILIZATION BY THE


CHAPTER-4 FOOD AND FEEDING HABITS OF

THE PISCIVOROUS BIRDS 120

CHAPTER-5 BREEDING BIOLOGY OF THE


SUMMARY 163

REFERENCES 181

CERTIFICATE

This is to cert i fy that the data embodied in this thesis ent i t led

“A STUDY OF ECOLOGY OF THE PISCIVOROUS BIRDS AT

THOL BIRD SANCTURY” is an original piece of research work

carr ied out and interpreted by Mrs. Chetna P. Palhak under my

guidance.

It is further cert i f i ed that she has put in more than eleven

terms of research work and that this work has not been submit ted to

any other Univers i ty/ inst i tution for award of Ph.D. degree.

(Dr.V.C. Soni)

Proessor ,

Department of Biosciences ,

Saurashtra University,

Rajkot.

Forwarded through’

Head,

Department of Biosciences,

Saurashtra University,

Rajkot.

1

INTRODUCTION

Piscivorous birds are essential ecological components of wetland ecosystem,

capable of transporting nutrients in a single season, and because of their numbers and

mobility, these birds play an important role in energy movement in the wetlands (Kahl

1964, Kushlan 1976b, 1977 and Christy et al. 1981).

Piscivorous birds occupy a relatively high position in the food of predatory

niches (Kushlan 1978b).

In the present study, birds of the families Pelecanidae (Pelicans),

Phalcrocoracidae (Cormorants and Darters), Ardeidae (Herons and Egrets),

Ciconiidae (Stroks), Threskiornithidae (Ibises and Spoonbill), Laridae (Terns) and

Alcedinidae (Kingfishers) have been selected. The piscivorous, according to their

feeding habits, are divided into three groups, namely : 1) Swimming Birds : Large

cormorant Phalacrocorax carbo, Indian shag Phalacrocorax fuscicollis, little

cormorant Phalacrocorax niger, Darter Anhinga rufa and Pelecans (Pelicanus spp.),

2) Wading Birds : Grey Heron Ardea cinerea, Purpul Heron Ardea purpurea, Cattle

Egret Bubulcus ibis, Pond Heron Ardeola grayii, Large Egret Ardea alba, Median

Egret Egretta intermedia, Little Egret Egretta garzetta, Night Heron Nycticorax

nycticorax, Painted Stork Mycteria leucocephala, Openbill Stork Anastomus

oscitans, White ibis Threskiornis aethiopica and Spoonbill Platalea leucorodia and 3)

Diving Birds : Common Kingfisher Alcedo atthis, Whitebrested kingfisher Halcyon

smyrnensis and River Tern Sterna aurantia.

2

A number of publications on the ecological isolation of congeneric sympatric

species are available in ornithological literature (Lack 1971, Rowley et al. 1973, Cody

1974, Houston 1976, Nudds 1982, 1983, Poysa 1984, 1986). A few cases of

competition among sympatric herons and ibises have already been reported (Carrick

1959, Meyerriecks 1962, Jenni 1969, Kahl 1972, Kushlan 1976 b, Willard 1977,

Custer and Osborn 1978, Thompson 1978, Hoffman 1978).

In India such studies are linked to a few groups of birds such as vultures

(Grubh 1974), Bulbuls (Vijayan 1975), drongos (Vijayan 1984), Aquilla sp. (Prakash

1988) resident ducks (Sridharan 1989) and migratory ducks (Bhupathy 1991). In the

present study, an attempt was made to find out the methods of ecological isolation

among the fish eating birds. Feeding location, water depth, and feeding behavior

among the fish-eating birds were studied in detail. The degree of overlap in the

utilization of these resources and the ways in which they minimize competition were

also analyzed.

In India, Dave (2002), Sivasubramanian (1992) studied the biology of

piscivorous birds. Other information is generalized and scattered (Mukhopadhyay

1980, Johnson and Rao 1988, Nagalingam 1989, Parasharya 1989, Urfi 1989,

Prabhakarachari et al. (1990). However, breeding biology of some of the species have

been well studied i.e., Painted Stork by Desai et al. (1971), Pond Heron by Lamba

(1963), Reef Heron by Parashrya (1984) and Cattle Egret by Singh et al. (1988).

Information on food and feeding habits are scattered (Abdulali 1967, Kahl 1971,

1973, Mukherjee 1971, 1975, Pandey 1974, Newton 1986, Johnson 1988,

Sivasubramanian 1988, Grimwood and Brockleshut 1984, Pal and Bala 1989, Johnson

3

et al. 1990, Navroji 1989 and Sivakumar et al. (1990) Status and conservation

(Rahmani 1989 and Rahmani, Narayan and Rosalind 1990, Hancock 1990, Saikia and

Bhattacharya 1990) and general behavior have also been studied (Kahl 1971a, 1972a

and 1972b, Sodhi and Khera 1984, Kumar 1981, Mahadevan et al. 1990 and Saxena

1989).

Taxonomy of most of these birds is known (Baker 1928, Whistler 1935, Kahl

1971c, Ali and Repley 1983 and Hancock and Kushlan 1980). Biology of the

piscivorous birds has been widely investigated in different parts of the world. Most

works concentrate on their feeding behavior and food requirements (Bowmaker 1963,

Junor 1972a, Begg 1973, Whitefield 1978, Whitefield and Balber 1973, 1979a and b,

Cambary 1985, Donnelly and Huster 1986, Arkell 1979). Other ecological aspects of

the pisicivorous birds have also been well studied (Kahl 1966, Krebs 1974 and Burger

1978).

OBJECTIVES OF THE STUDY

1. To know the status of various bird species by population assessment,

2. To assess the habitat availability to various groups of birds,

3. To assess the feeding methods adopted by birds to adjust to the environment,

4. To assess breeding requirement and availability of resources in the area,

5. To know the ecological factors like water level, pH, salt contents, aquatic

plants, fishes etc.

CHAPTER-1

STUDY AREA

4

CHAPTER – 1

STUDY AREA

The study was conducted in Thol Bird Sanctuary (TS) famous for its wintering

congregation of waterfowl migrating from the Palearctic realm.

LOCATION:

TS is located about 25 km northwest of Ahmedabad between 23o 15' to 23o 30'

N. and 72o 30’ to 72 45’ E. It is 22 km away from the town of Kadi and district in

Mehsana.

5

Fig: 1.1 LOCATIONMAP

6

Fig: - 1.2 LOCATION MAP OF THOL SANCTUARY

7

TOPOGRAPHY:

Thol water body has a total area of 699 ha (6.99 sq. km). Its periphery is 5.62 km. It is a

manmade wetland spread on west to east line. There is a continuous earthen bund on its western,

southern and eastern periphery, which helps in collection of water that flows into it during the

monsoon. The wetland has a variable depth over its entire basin. Even in exceptionally good rainfall,

the entire water body is not inundated. Less than half of its basin area holds water on a regular basis by

August - September. By November, only a small part along its South - Western periphery holds water.

As water starts drying up from eastern and northern sides, agriculture takes over these dry areas of the

water body. There is a continuous ditch located along the Western and Southern bund besides the

approach road. This ditch has varying width and depth of 10 to 25 metres and 0.50 to 0.90 metres

respectively.

BOUNDARY:

A masonry wall around the border separates the TS from the surrounding agricultural fields.

There are four villages, Bhimasan, Hajipur, Karoli and Jethalaj in the immediate vicinity of the

sanctuary.

SOIL:

The soil is of thick alluvium, and on dry grounded in summer.

8

HYDROLOGY:

The catchment area of the waterbody is located to its north and north – east. Water finds its

way through a number of canals draining into the feeder canal located on the north - northeastern sides

of the water body. Water is received through the following canals at Thol water body (Vaghela 1993),

(1) Eastern canal (2) Saij - Hajipur canal (3) Irana - Indrad - Wamaj Canal (4) Hajipur - Pivaj canal (5)

Eastern feeder at Saghan drain (6) Jaspur canal.

In addition to the feeder canal, the water body receives run-off water directly from the

catchment area. Before the feeder canal reaches the manmade wetland, there is a diversion which is

known as waste weir and is employed to control the volume of water in the water body. If the level of

water reaches beyond 2.75metres the water is diverted to waste weir. Waste weir drains into a canal

which runs along the eastern boundary of the Thol pond to reach Nalsarovar Bird Sanctuary located

south of TS. TS and Nalsarovar are thus connected with each other.

Thol waterbody supports a well-developed canal based irrigation system. There are four head

regulators at the waterbody to control the flow of water. The canals and their distributaries / sub-

distributaries are about 19.97 km long. The villages of Thol, Jhaloda, Adhana and Vayana receive

water from these canals.

9

Table-1.1: Details of Thol waterbody

Particulars Measure

1. Fill Supply Level (FSL) 49.68m

2. High Flood Level (HFL) 40.90m

3. Top of the bank 52.42m

4. By - Pass Level 50.29m

5. Sill Level 46.63m

6. Catchments area 155.34 sq. km.

7. Storage Capacity 907.37cubic m.

8. Total Command Area 3,37S0 acres

9. Irrigation Command Area 1,835 acres

10. Area of the tank 1,728.31 acres

11. Area under submergence at FSL 1780 acres

10

Table-1.2: Details of irrigation canals of Thol water body

No. Canal No./ Distributory Length (km) Command

Area (Acres)

Discharge

(cusecs)

1. Canal 2 2.56 360 09.00

2. Canal 3 4.10 435 11.00

3. Canal 4 6.70 300 26.00

4. Distributory 1 of Canal 4 0.80 100 02.80

5. Sub-Distri of Distri 1 0.65 100 02.80

6. Distri 2 of canal 4 2.52 200 10.00

7. Distri 3 of canal 4 2.64 285 12.00

11

CLIMATE:

TS experiences three distinct seasons namely winter (Nov. to Feb.), summer (April to May)

and monsoon (June to Sept.). Months of October and March mark the transition period from monsoon

to winter and winter to summer respectively. The lake receives rainfall from July to September

through the southwest monsoon. Old records for Mehsana district in general (Rajyagor 1975), as well

as rainfall data of previous years at TS (Table – 1.6) indicate that the rainfall is highly erratic and

ranges from 100 to 900 mm. The overall climate of the area is sub humid to semi arid.

Meteorological variables, rainfall, temperature (maximum and minimum), humidity,

photoperiod in hours and evaporation were also recorded.

12

Table-1.3: Monthly Climatic Data Source: (Station name –Gandhinagar, Station

Code: Gandhinagar, Local River / Basin –Sabarmati, Year: 2005)

Month Average

Min.Temp.

(oC)

Average

Max.Temp.

(oC)

Relative

Humidity

(%)

Rainfall

(mm)

Pan

Evapo.

Photoperiod

( hours)

January 14.7 26.9 56.6 0 90.5 10.55

February 16.8 31.2 45.4 0 96.4 11.25

March 20.9 34.6 50.6 0 125.3 12.04

April 25.1 37.9 46.3 0 181.9 12.47

May 28.5 39.8 52.4 0 210.2 13.14

June 28.3 35.4 65.2 35.5 158.5 13.33

July 26.8 30.9 86.7 230.4 96.5 13.21

August 25.6 29.6 87.6 565.7 62.3 12.55

September 26 31.7 74.4 65.9 92.8 12.17

October 24.4 34.5 62.5 0 102.6 11.36

November 20 32.8 59.2 0 84.4 11.01

December 15.9 28.8 56.1 0 89.1 10.48

13

Fig. 1.3 - Climatic data – 2005

14



Month Average

Min.Temp.

(oC)

Average

Max.Temp.

(oC)

Relative

Humidity

(%)

Rainfall

(mm)

Pan

Evapo.

Photoperiod

( hours)

January 14.9 27.1 48 0 92.1 10.55

February 19.5 33.3 47.1 0 95.2 11.23

March 21 33.5 44.2 1.5 104.7 12.02

April 25.1 37.6 43.4 0 153.2 12.46

May 29 40.4 44 0 203.7 13.14

June 28 36.5 64.7 100.5 146.1 13.34

July 26.4 30.8 80 259.9 76.8 13.23

August 25.4 28.6 85.6 554.5 60.6 12.56

September 26.4 32.3 71.5 148.5 95.3 12.18

October 24.7 33.7 63.6 0 105.3 11.35

November 22.5 32.1 61.5 0 89.3 10.58

December 15.5 28.5 55.5 0 90.6 10.47

15

Fig. 1.4 - Climatic data - 2006

16



Month Average

Min.Temp.

(oC)

Average

Max.Temp.

(oC)

Relative

Humidity

(%)

Rainfall

(mm)

Pan

Evapo.

Photoperiod

(hours)

January 15 26.7 60.6 0 89.7 10.54

February 17.8 29.8 61.4 0 97.3 11.25

March 20.3 33.6 51 0 155.5 12.05

April 25.5 38.7 50.3 0.8 213.3 12.45

May 28 39.2 57.9 3 211.9 13.13

June 29.1 36.7 66.6 61.5 158 13.3

July 26.9 30.8 76.5 647.5 84.5 13.22

August 26.2 30.5 80.9 415 64.8 12.54

September 26.6 32.3 74.4 52.5 92 12.17

October 22.7 33.1 61.3 0 111.1 11.37

November 16.5 32.3 54.1 0 85.6 11

December 15.5 27.6 47.5 0 88.2 10.48

17

Fig. 1.5 - Climatic data – 2007

18

TEMPERATURE:

The lowest monthly average temperature was 14.7 oC in Jan. 2005 while the highest monthly

average temperature was 40.4 oC in May 2006. (Table -1.3 & 1.4).

Table-1.6 Yearly average raninfal of Kadi Taluka

Year Rainfall (mm)

1980 644

1981 1032

1982 511

1983 955

1984 709

1985 542

1986 302

1987 207

1988 806

1989 440

1990 946

1991 796

1992 517

1993 785

1994 943

1995 262

1996 403

1997 680

19

1998 756

1999 452

2000 216

2001 623

2002 278

2003 720

2004 636

2005 895

2006 1250

Table-1.7: Average pH (mean) recorded at T.S.

Month pH-2005 pH-2006

January 9.0 9.0

February 9.0 10.0

March 10.0 11.0

April 10.0 11.0

May 12.0 12.0

June 12.0 12.0

July 8.5 8.5

August 8.5 8.5

September 8.5 8.0

October 8.0 8.0

November 7.0 7.0

December 7.5 7.5

20

Fig.-1.7 Average pH (mean) recorded at T.S.

21

Table-1.8: Average total hardness in ppm recorded at T.S.

Month Total Hardness-2005 Total Hardness-2006

January 187.20 203.38

February 194.05 171.35

March 155.15 164.05

April 142.95 140.90

May 157.35 144.42

June 113.20 126.87

July 183.56 230.55

August 236.75 282.13

September 254.59 233.39

October 183.60 208.92

November 204.64 193.00

December 207.33 167.44

22

Fig.-1.8 Average total hardness in ppm recorded at T.S.

23

Table-1.9: Monthly average calcium hardness in ppm recorded at T.S.

Month Ca++ Hardness-2005 Ca++ Hardness-2006

January 124.80 133.70

February 143.70 125.85

March 102.40 107.80

April 87.80 90.10

May 85.90 84.25

June 63.10 72.75

July 108.33 150.35

August 162.52 210.00

September 184.47 190.00

October 142.42 170.75

November 165.50 167.40

December 169.75 152.35

24

Fig-1.9 Monthly average calcium hardness in ppm recorded at T.S.

25

Table-1.10: Monthly average magnesium hardness in ppm

recorded at T.S.

Month Mg++ Hardness-2005 Mg++ Hardness-2006

January 62.40 70.10

February 50.35 45.50

March 52.75 56.25

April 55.18 50.80

May 64.45 60.17

June 50.10 54.12

July 75.23 80.20

August 74.45 72.13

September 70.12 43.39

October 41.18 38.17

November 39.14 25.60

December 37.58 15.09

26

Fig-1.10 Monthly average magnesium hardness in ppm recorded at T.S.

27

Table-1.11: Monthly average chlorinity in ppm recorded at T.S

Month Chlorinity-2005 Chlorinity-2006

January 142 106

February 143 113

March 145 123

April 150 132

May 155 137

June 160 140

July 102 107

August 110 112

September 114 120

October 125 122

November 135 132

December 140 140

28

Fig.-1.11 Monthly average chlorinity in ppm recorded at T.S

WATER – DEPTH:

The highest average depth of water during the study period was in 2005 which occurred in July

and was 3.04 meter and lowest water depth was in June 2005 and 2006 and was 0.60 metre. (Table-

1.12).

29

Table-1.12: Monthly average water depth in metres at T.S.

Month 2005 2006

January 1.37 1.67

February 1.21 1.52

March 0.91 1.52

April 0.91 1.37

May 0.79 0.91

June 0.6 0.6

July 2.74 3.04

August 2.59 2.59

September 2.59 2.43

October 2.43 2.13

November 2.13 1.98

December 1.52 1.82

30

Fig.-1.12 Monthly average water depth in metres at T.S.

31

VEGETATION:

The vegetation of the TS can broadly be categorized into two groups:

Aquatic and Terrestrial.

AQUATIC:

A. Submerged rooted vegetation Ceratophyllam demersum and Hydrilla veorticillata.

B. Free floating vegetation Eichhornia crassipes and Algae.

C. Rooted floating vegetation Ipomoea aquatica, Neptunia oleracea.

Terrestrial vegetation of the TS is of scrub type. Acacia nilotica is a dominant tree species

which is also found within the pond. There are agricultural fields and the landscape has trees of Acacia

nilotica, Prosopis chilensis, P. cineraria, Balanties algytiaca, Salvadora persica and S. oleoides.

Bushes of Zizyphus sp. and those of Capparis deciduas are common.

FLORA:

A check list of the macrophytes (aquatic and terrestrial) recorded at TS is given in Appendix-1.

FAUNA:

The fauna other than birds includes several species of invertebrates and vertebrates. Among the

invertebrates, some of protozoa: Volvox sp., Amoeboid forms, coelenterata: Hydra, arthropoda:

Daphnia sp., Cyclops sp., Cypris sp. etc.

Among the vertebrates,

32

FISHES: Channa punctatus, Heleropneustes fossilis, Chela bacaila, Barlous stigma

AMPHIBIANS: Bull frog (Hoplobatrachus tigerinus), Marbled Toad (Bufo stomaticus).

REPTILES:

Rat snake (Ptyas mucosus), Cobra (Naja naja), Garden Lizard (Calotes versicolor), Bengal

Monitor (Varanus bengalensis), Indian Flapshell Turtle (Lissemys punctata).

MAMMALS:

Eight species of mammals have been listed by (Rajyagor 1975) such as Common Langur

(Presbytis entellus), Jungle Cat (Felis chaus), Common Mongoose (Herpestes edwardsi), Jackal

(Canis aureus), Pale Hedgehog (Parachinus micropus), Grey Mask Shrew (Suncus murinus), Indian

Flying fox (Pteropus giganteus) and Nilgai (Boselaphus tragocamelus).

ANTHROPOGENIC INFLUENCES:

Agriculture, industries, fishing, oil drilling, tourism and livestock grazing were found to be the

human activities noticed and documented at T.S. Each activity posed some kind of threat to waterfowl

and also to human denizens living around T.S. The following threats were identified: non-ecofriendly

irrigation practice, use of pesticides and fertilizers, intensification of agriculture, shift towards growing

cash crops, proliferation of industries in the catchment area of TS, pollution by hazardous industries,

and diversion of agricultural land for industry, oil spills from oil wells, intensive fishing, poaching of

birds, littering, noise pollution and disturbance due to livestock movement. Irrigation, pollution by

pesticides and industry and intensive fishing by far posed the biggest threats to waterfowl at T.S.

CHAPTER-2

POPULATION OF THE

PISCIVOROUS BIRDS

33

CHAPTER – 2

POPULATION OF PISCIVOROUS BIRDS

INTRODUCTION

Population censusing is a methodological problem in ecology, particularly for mobile animals

which are distributed over a large area. Most ecological studies of birds use abundance or number of

birds per unit area as the basic information on their population. A measure of the relative abundance of

most birds is generally easy to obtain because of their relatively large size, conspicuous behaviour, and

diurnal habits. An accurate figure on the population of birds, however, is more difficult because birds

are highly mobile and have the ability to interact with an observer.

The quality of the wetland can be assessed by monitoring the population of wetland birds.

However, no serious attempt has been made to study the population of wetland birds in our country

except the study of reports (Prakash 1988), resident ducks (Sridharan 1989) and migratory ducks

(Bhupathy 1991) of Keoladeo National Park.

METHODOLOGY:

I got an inspiration to prepare the checklist of avifauna from my three years experience of the

Sardar Sarvor Project of the Nal Sarover and my M.Phil. work at Gujarat University, Ahmedabad and

I also join the survey of avifauna conducted by the Forest Department, Gujarat in 2006 at Thol Bird

Sanctuary so , I found it interesting for the census of waterfoul population . Initialy I surveyed three

sites of T.S. Site – A : From ONGC well located in the north central part (Vegetative and Puddles).

Site - B: From Jethlaj village (Vegetative and Puddles). Site – C: From front side of watch tower

(Fully open and deep water). Which were different from each other such as loction, concerning area,

watertable, water quality, surrounding area, vegetation etc.

34

In the present study population of weatland birds was estimated by direct count method.

(Sivasubramanian 1992). Several other workers have also used this method for various birds. (Weller,

1975; Kand, 1981; Sjoberg, 1981; Shah et. al, 1983; Perinnou, 1987; Prakash, 1988; Sridharn, 1989;

Bhupathy, 1991.)

The survey of three sites of this area was done during January 2005 to December 2006. Counts

were carried out from 6:30 a.m to 11:00 a.m 20X50 binocular was used. Every site was being visited

monthly. So that the figures for the population census such as means, median and standard deviation,

percentage, average etc. can be acquired obtained.

Speices diversity index was calculated using the Shannon-Weiner index “H” formula

(Levins1968):

s1

i n ii 1

H P L P

Where Pi = n1

------ --

N

(ni = number of ith

species, N = sum of ni )

s = number of species

The species diversity index was the lowest during Augest (3.17) and highest in February (4.83)

during 2005. In 2006 it was the lowest in September (3.73) and highest in January (4.91) repectively

(table-2.5)

RESULTS AND DISCUSSION

Of 23 species of fish eating birds recorded from the sanctuary, 6 species were of swimming

birds while 13 species of wading birds and 4 species of diving birds. The highest number recorded was

35

of Rosy Pelican whereas the lowest was that of the Little Blue Kingfisher Population and status of fish

eating birds during the study period is summarized in (Table: 2.3 & 2.4.) The fish eating bird’s

population fluctulates with water level in T. S. They congregate in large numbers for breeding during

monsoon when water depth is higher. During winter (moderate water depth), only resident birds and

late breeders stay in the T. S. when water levels receeds during spring and early summer, large

expanse of shallow marsh and swamp dry up. This forces the fish to congregate in small pools there by

providing a highly concentrated and easily harvestable energy source for fish eating birds. Further, in

late summer, most of these pools also dry up forcing the dispersal of the few remaining birds from the

sanctuary.

36

TABLE-2.1: Number of species recorded in each month at the three sites with

mean, median and standard deviation

Month Site – A Site – B Site – C

January – 05 18 20 11

February – 05 15 20 11

March – 05 15 18 10

April – 05 12 18 10

May – 05 11 18 10

June – 05 09 17 09

July – 05 11 17 09

August – 05 11 16 09

September – 05 10 10 09

October – 05 11 11 10

November – 05 12 13 11

December – 05 13 15 11

January – 06 14 22 11

February – 06 14 23 11

Mean ` 12.57 17.00 10.14

Median 12.00 17.50 10.00

S. D. 02.41 03.80 00.86

Minimum 09 10 09

Maximum 18 23 11

Site – A : ONGC well located in the north central part (Vegetative and Puddles).

Site – B : From Jethlaj village (Vegetative and Puddles).

Site – C : From front side of watch tower (Fully open and deep water).

37

Fig.-2.1 Number of bird species recorded in each month at three sites

with mean, median and standard deviation

38

Table-2.2: Number of bird species recorded in each month at

three sites with mean, median and standard deviation

Site – A Site – B Site – C

January–06 14 22 11

February–06 14 23 11

March–06 16 17 11

April–06 11 17 10

May–06 10 18 11

June–06 10 15 9

July–06 10 17 10

August–06 12 16 9

September–06 11 15 10

October–06 12 12 10

November–06 12 12 13

December–06 13 14 17

January–07 17 23 11

February–07 15 22 11

Mean 12.64 17.35 11

Median 12 17 11

S. D. 2.27 3.81 2

Minimum 10 12 9

Maximum 17 23 11

Site – A : ONGC well located in the north central part (Vegetative and Puddles).

Site – B : From Jethlaj village (Vegetative and Puddles).

Site – C : From front side of watch tower (Fully open and deep water).

39

Fig.-2.2 Number of species recorded in each month at three sites

with mean, median and standard deviation

40

Table–2.3 : Month-wise census of individual Piscivourous birds at T.S. – 2005

No. Species Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

1 Large Cormorant 285 280 260 250 200 190 180 280 300 295 293 289

2 Indian Shag 317 315 290 272 247 200 250 320 340 330 323 318

3 Little Cormorant 232 228 200 190 175 165 190 225 250 247 239 235

4 Darter 8 7 5 4 0 2 2 3 6 10 9 8

5 Pelican 150 170 120 35 0 0 0 0 0 0 10 38

6 Grey Heron 50 49 38 35 32 30 30 35 50 58 50 50

7 Purple Heron 55 52 50 45 42 40 42 45 47 58 58 60

8 Pond Heron 37 35 32 31 28 25 20 28 30 34 39 35

9 Large Egret 55 52 50 48 40 32 28 20 38 68 55 58

10 Median Egret 90 85 80 75 40 32 20 34 102 90 88 89

11 Little Egret 92 90 85 80 70 67 40 32 58 120 100 95

12 Cattle Egret 128 120 87 75 68 55 40 70 120 170 150 135

13 Painted Stork 55 57 28 18 12 10 12 28 30 40 52 60

41

14 Openbill Stork 32 26 17 12 10 5 0 0 6 32 38 40

15 White Ibis 87 80 79 60 65 50 55 55 50 100 90 85

16 Black Ibis 28 21 20 15 13 12 17 23 25 28 30 29

17 Glossy Ibis 30 26 36 29 25 24 23 19 21 26 31 31

18 Eurasian Spoonbill 485 450 350 300 90 102 150 200 225 500 489 480

19 Ruddy Shelduck 200 120 0 0 0 0 0 0 0 15 120 250

20 River Tern 10 12 8 6 5 5 4 3 2 4 5 7

21 Little Tern 12 15 5 6 5 4 7 3 5 3 2 22

22 White Breasted Kingfisher 7 5 6 5 5 4 3 5 5 7 5 6

23 Little blue Kingfisher 6 7 7 5 5 4 5 6 6 7 6 5

TOTAL : 782 596 465 399 411 434 459 577 774 814 797 751

42

Table–2.4 : Month-wise census of individual piscivourous birds at T.S. – 2006

No. Species Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

1 Large Cormorant 300 302 200 190 185 150 180 190 320 321 305 304

2 Indian Shag 395 390 385 355 300 290 290 345 400 397 394 396

3 Little Cormorant 270 257 233 180 175 100 185 240 294 280 279 276

4 Darter 10 11 8 5 1 5 5 6 5 12 13 11

5 Pelican 250 321 300 65 39 0 0 0 0 0 38 120

6 Grey Heron 48 51 32 30 30 31 37 48 50 56 55 53

7 Purple Heron 59 55 52 50 35 37 40 44 58 58 57 58

8 Pond Heron 47 37 32 30 32 19 12 28 52 53 50 42

9 Large Egret 55 50 47 40 28 30 32 45 62 68 70 62

10 Median Egret 95 86 70 61 50 35 137 140 135 120 112 100

11 Little Egret 98 91 76 79 54 57 153 41 62 110 108 102

12 Cattle Egret 123 115 104 101 93 75 117 150 150 137 132 130

13 Painted Stork 110 120 100 90 88 82 62 56 78 60 72 122

43

14 Openbill Stork 100 116 91 83 77 60 65 125 119 118 120 122

15 White Ibis 88 82 76 80 82 65 32 28 57 70 92 90

16 Black Ibis 20 5 22 12 10 15 18 17 21 32 3 4

17 Glossy Ibis 26 24 20 18 15 11 24 22 31 37 29 23

18 Eurasian Spoonbill 134 105 137 137 95 80 87 144 148 160 144 140

19 Ruddy Shelduck 300 120 0 0 0 0 0 0 0 20 150 275

20 River Tern 8 2 7 6 5 4 0 0 3 5 4 5

21 Little Tern 12 15 8 3 2 1 4 5 4 6 8 10

22 White Breasted Kingfisher 3 8 4 5 6 5 5 4 6 7 9 8

23 Little blue kingfisher 6 7 5 5 4 3 2 1 2 4 6 7

TOTAL : 864 1040 661 493 449 373 381 414 380 524 854 960

44

POPULATION OF SWIMMING BIRDS

LARGE CORMORANT

Among three sp. of cormorants, the population of a large cormorant was average.

Possibly, they are unable to catch the fish in low water depth and this might explain their

low numbers in the Sanctuary. Junor (1972) has noted that White breasted cormorant can

dive to a maximum depth of 5.5 m in comparison to only 2.1 m for the Darter.

The fluctuation in the population of the large cormorant showed a similar trend

during the study (Tables–2.3 & 2.4). The Large Cormorant extensively used the lake

mainly during the breeding season (July to September). They started arriving during July

end and the number gradually built and till November, the population remained almost

stable. The lowest population was during March to June in all the years. This was related

mainly to the water level. Large Cormorant prefers deeper open water for feeding and in

summer most of the open water area dried up leaving only puddles available.

INDIAN SHAG

Indian Shag, a breeding migrant was observed in high number during 2006. The

low population in 2005 might be due to comparatively low rainfall. Population of Indian

Shag reached a peak in July and remained stable till October. The decline of population

started during November and most of them left by February. Dispersal of juveniles and

adults occurs at the end of nesting. Dispersal usually occurs from areas where resources

are scarce or unavailable to more favorable areas (Byrd 1978). For example, after

completing nesting in Florida, birds tend to disperse northward into temperate marshes

45

(Kushlan and Robertsen 1977). The peak (fig.-2.3b) in September - October 2006 was due

to the successful hatching.

LITTLE CORMORANT

The Little Cormorant was observed in all the months except May. The highest

population was recorded in July - November 2006.

DARTER

Darter was observed in very low population in the sanctuary. The highest

population (13 birds) in two years was recorded in November 2006.

PELICANS

Pelicans are winter visitors to the T.S. Pelicans start arriving in the Sanctuary by

November in a year of normal rainfall. The highest population was observed in February

2006.

46

Fig.-2.3a Month-wise census of Large Cormorant at T.S. – 2005, 2006

47

Fig.-2.3b Month-wise census of Indian Shag at T.S. – 2005, 2006

48

Fig.-2.3c Month-wise census of Little Cormorant at T.S. – 2005, 2006

49

Fig.-2.3d Month-wise census of Darter at T.S. – 2005, 2006

50

Fig.-2.3e Month-wise census of Pelican at T.S. – 2005, 2006

51

POPULATION OF WADING BIRDS

Wading birds are conspicuous members of the aquatic avifauna of Thol Bird

Sanctuary. Herons, Egrets, Storks, Ibises and Spoonbill occupy high - levels in the aquatic

food chains and appear to be sensitive to disturbance in aquatic ecosystems.

HERONS

The population of four species of herons namely Grey Heron, Purple Heron, Night

Heron and Pond Herons was higher during autumn and winter.

Highest population of Grey heron was in October 2005 (Fig-2.3f). However, all

the months except those in summer had approximately 35 individuals in 2005 and 30 in

2006. Maximum of 60 Purple Herons were recorded in December 2006(Fig-2.3g)

The Pond Heron was recorded during all the months during the study. The highest

number was recorded in November 2006(Fig-2.3h).

EGRETS

All the egret species except Cattle Egret showed a similar trend in the population.

Large Egret, Median Egret and Little Egret were recorded mostly in breeding seasons.

They were present in almost all the months inside the sanctuary, although in varying

numbers (Fig-2.3i, j, k, l).

52

STORKS

The population trend of two species of Storks showed two different patterns as

discussed below:

OPENBILL AND PAINTED STORK:

The openbill and painted stork are mainly breeding migrants. Even though openbill

stork's number was average in all the months (Fig-2.3m), their peak population was in the

end of monsoon and early winter. Poor feeding conditions resulting from a shift in natural

hydrologic cycles might have affected stork nesting population in several ways besides

reducing nesting success such as causing lack of nest initiation and emigration to other

breeding regions. Quality of feeding condition is probably an important cue for population

fluctuation in many stork species (Kushlan et al. 1975, Kushlan 1976c, Frederic and

Collopy 1988, Rodgers 1987).

Among the colonial fish eating birds, the Painted Stork is the last to commence

breeding inside the sanctuary. The population of the Painted Stork was very high inside

the 5sanctuary. The highest population of 122 (Table-2.3) individuals was recorded in

December 2006.

IBIS AND SPOONBILL:

A large number of white Ibis was observed only during the winter. Population was

low during summer.

The Spoonbill was recorded thoughout winter and spring in both the years of

study (more than 450 birds in October and November 2005). As in the case of white Ibis

53

and Glossy Ibis, this was due to the normal rainfall of the year. Fig.-2.3p shows that the

Indian Black Ibis was very low during its breeding period i.e. from June to October.

Fig.-2.3f Month-wise census of Grey Heron at T.S. – 2005, 2006

54

Fig.-2.3g Month-wise census of Purple Heron at T.S. – 2005, 2006

55

Fig.-2.3h Month-wise census of Pond Heron at T.S. – 2005, 2006

56

Fig.-2.3i Month-wise census of large Egret at T.S. – 2005, 2006

57

Fig.-2.3j Month-wise census of Median Egret at T.S. – 2005, 2006

58

Fig.-2.3k Month-wise census of Little Egret at T.S. – 2005, 2006

59

Fig.-2.3l Month-wise census of Cattle Egret at T.S. – 2005, 2006

60

Fig.-2.3m Month-wise census of Painted Stork at T.S. – 2005, 2006

61

Fig.-2.3n Month-wise census of Openbill Stork at T.S. – 2005, 2006

62

Fig.-2.3o Month-wise census of White Ibis at T.S. – 2005, 2006

63

Fig.-2.3p Month-wise census of Black Ibis at T.S. – 2005, 2006

64

Fig.-2.3q Month-wise census of Glossy Ibis at T.S. – 2005, 2006

65

Fig.-2.3r Month-wise census of Eurasian Spoonbill at T.S. – 2005, 2006

66

Fig.-2.3s Month-wise census of Ruddy Shelduck at T.S. – 2005, 2006

67

DIVING BIRDS

Two species of Kingfisher are included in the diving birds. They constituted only

1.5 % of the total population of fish eating birds. River Tern and Little tern are also

included in the diving birds group. Terns contributed more than 60% of the total

population of diving birds. A maximum of Little Terns (22) was recorded in December

2005. In November 2006, the lake had higher number (9) of common Kingfisher.

The population of Piscivorous birds have long been a focus for conservation

action, particularly for efforts to preserve the wetlands on which they depend. They are

worthy of such attention not only for aesthetic value but also as useful indicators of the

ecological health of these ecosystems.

Fig.-2.3t Month-wise census of River Tern at T.S. – 2005, 2006

68

Fig.-2.3u Month-wise census of Little Tern at T.S. – 2005, 2006

69

Fig.-2.3v Month-wise census of White Breasted Kingfisher at

T.S. – 2005, 2006

70

Fig.-2.3w Month-wise census of Little Blue Kingfisher at

T.S. – 2005, 2006

71

Table-2.5 Shannon-weiner species diversity Index of the Piscivorous

Birds during various months 2005 - 2006

MONTHS YEAR 2005 YEAR 2006

JANUARY 4.60 4.91 HIGHEST

FEBRUARY 4.83 HIGHEST 4.15

MARCH 4.35 4.44

APRIL 4.13 4.59

MAY 3.95 4.43

JUNE 3.78 4.14

JULY 3.25 3.91

AUGUST 3.17 LOWEST 4.03

SEPTEMBER 3.53 3.73 LOWEST

OCTOBER 3.87 4.56

NOVEMBER 4.23 4.45

DECEMBER 4.57 4.43

72

0.0

1.0

2.0

3.0

4.0

5.0

6.0

JANU

ARY

MARC

HM

AY

JULY

SEPTEM

BER

NOVEM

BER

YEAR 2005

YEAR 2006

Fig.-2.5 Shannon-weiner species diversity Index of the Piscivorous birds

during various months – 2005-2006

CHAPTER-3

HABITAT UTILIZATION BY THE

PISCIVOROUS BIRDS

73

CHAPTER – 3

HABITAT UTILIZATION BY THE PISCIVOROUS BIRDS

INTRODUCTION

Study on the field characteristics, status, distribution and notes on the general

ecology of most of the Indian birds are available (Baker 1922-32, 1932-35; Whistler and

(1935), Ali and Ripley 1983, Bhupathy 1985, Jayaraman 1985). However, specific

information on the habitat requirement of most of the birds are lacking in the country.

Kahl (1972a, 1972b) descrided the feeding seasonality, food consumption and

feeding behavior in different habitats for some species of storks. Kent (1986, 1987)

reported the effects of varying behavior, foraging efficiency of egrets in different habitats.

Feeding habitats of nesting, spatial use, social influence, foraging divisions, patch use and

seasonality of wading birds in different habitats are described by Erwin (1981-1985).

Habitat generally refers to the place where each kind of organism is normally

found. In other words it refers to the place where the animal lives. And such an assessment

of specific habitat requirement of individual species is vital for the management of a

species. Learning the habitat is one of the foremost steps in studying an organism (Odum

1971). Lack (1967) summarized that the birds recognize their ancestral habitat by

conspicuous though not necessary features. Habitat association of land bird species have

been assessed mainly by using foliage measurements, such as volume of foliage height

diversity (MacArthur et al. 1967).

74

Custer and Osborn (1978) studied the feeding habitat use of colonially-breeding

herons, egrets and ibises in North Carolina. Kushlan (1976c) described the feeding and

habitat preference of the White Ibis in Southern Florida. Meyerriecks (1962) and Kushlan

(1976b) found that longer - legged herons feed in deeper water than shorter- legged ones.

Rodgers (1983) described the foraging methods of herons in different habitat in Florida.

Food of the Night Heron and Little Egret in different habitat has been studied by Fasola

(1981). Fasola (1986) reported the resource use of foraging herons in Agricultural and

non-agricultural habitats in Italy. Kushlan et al. (1985), studied the foraging niche

relations of wading birds in tropical wet Savannas. Habitat use of Herons and Egrets in

North America is documented by Recher and Recher (1980) Prey consumption of wood

storks in different habitats was reported in Everglades National Park (Ogden et al. 1978).

Cooper (1985a), Hafner and Brittons (1983), Hafner (1982), Kushlan and Kushlan (1977),

Kushlan (1981), Mock and Mock (1980).

Habitat use by bird species at TS was recorded on each visit. These categories were

- open water, puddles and peripheral region. The activities were categorized as foraging,

resting, roosting and breeding. Open water habitat over other categories was used highly

by waterfowl like all ducks, storks, herons, egrets, spoonbills, ibises and many waders.

Use of edge and puddles by nearly half the species was in accordance with a high diversity

of small waders at TS, which used this habitat extensively for foraging and roosting. Out

of 77 sp. listed (Thol Report – 2002), majority of species used TS for foraging and resting

(82 % and 75 %) In contrast, only 56 % species used it for roosting. There were some

species like egrets, spoonbills, cormorants with confirmed breeding record of T. S.

75

METHODOLOGY:

The study of habitat utilization of wetland birds was done; simultaneously

the study of population dynamics and breeding biology was also performed. Total 6

habitats were classified; among these most of the habitats used by wetland birds were

observed during the study period. Regular habitat surveys were conducted by walking and

recording the number of individuals and the habitat in which they were sited. This study

was done continuously for two years. At different sites, different species were also

recorded from time to time to study a general preference of a specific water body. Birds

were observed from 40-50 m distance by using 20 × 50 binoculars walking slowly 300 to

400 hrs.

The preference for a particular habitat by different species and utilization of each

habitat by them were studied. Habitats were classified into the following 6 types according

to the dominant plant community and water regime.

(1) OPEN WATER

This site is fully open and has deep water. Birds can be observed from the bank as

entry in the lake is not allowed. The observation was done early in the morning, at the

afternoon and in the evening through binocular and telescopy from the watchtower.

This covers comparatively deeper area of the lake spread over on either side of the

dykes and towards the middle of the aquatic blocks with submerged vegetation. This area

is the front-side of the lake in the open water area beyond 2 meters from the edge of the

pond. Dominant submerged vegetations are Ceratophyllum demersum and Hydrilla

veorticillata, free floating vegetation Eichhornia crassipes and rooted floating vegetations

76

are Ipomoea aquatica, Neptunia oleracea. This serves as the chief attraction for all

swimming birds. This habitat was used highly by all ducks storks, herons, egrets,

spoonbills, ibises and many waders probably due to the presence of a roosting tree in the

water area.

(2) SHALLOW WATER WITH SPARSE VEGETATION

This site is located on both the sides of the pathway while entering the sanctuary.

While walking along the path wader birds could be observed here. Apart from this such

site is also located near Jethlaj villege.

At the edge, the water level is much less and irregularly distributed amongst the

patches of grass and open water is areas with sparse vegetation which usually are covered

by a film of water. In this habitat, the vegetation is neither very low, nor is the water

volume very open. Ipomoea aquatica forms the major vegetation in these areas. Shallow

water with sparse vegetation attracts Ciconidae family sp.and several wading birds could

be seen.

(3) GRASS PATCH

This site is located on north central side where cultivation of Acacia is there

below which grass patches can be seen. Here wading birds could be observed mostly while

walking along the path.

In this type of habitat, the grass grows very thick and forms a kind of mat. This

comes up during the monsoon and spring when the grasses are at their peak of vegetative

77

growth. In winter, however, decomposition of grass makes these areas less prominent and

attracts several waterfowl species.

(4) IPOMOEA + GRASS

This site is also seen both the sides of the sanctuary, mostly camp side. The

observation was done mostly in the morning and in the evening while walking and here

Ardeidae family sp. could be seen.

It is a mixture of Ipomoea sp. and grass. At certain places Eleocharis sp. patches are

also included. Mostly to be seen in the area of transition between grass and Ipomoea

patches.

(5) TREES AND BRANCHES HANGING OVER WATER

(CULTIVATION AREA)

This site is situated near Jethlaj village. Where entire area is covered with Acacia

nilotica trees which could be observed while walking and used binocular.

Tress mainly on the edge of the dyke forms the resting habitat for many birds. The

entire aquatic area of the sanctuary is intersected with a number of Acacia nilotica planted

on dykes. On either side of these dykes, apart from the clumps of Acacia sp., Salvadora

sp., Butea sp., Cassia sp., Prosopis sp., Madhuca sp. and Manilkara sp., other bushes are

also noticed. This serves as the chief attraction for many diving birds and these trees serve

as nesting sites for various aquatic birds.

78

(6) PUDDLES

This site is located on the front side of the watchtower and the other site is scattered

from North side of the sanctuary which could be observed while walking and used

binocular.

The water level drops during the dry season (May - June), leaving only a few pools in

the deeper areas. Aquatic organisms are concentrated in these increasingly smaller areas

and become readily utilizable food for highly mobile predators, particularly wading birds.

79

Plate: 3.1

Roosting of the swimming birds

1) A large group of Pelicans and 2) A large group of Cormorants

80

Plate: 3.2

1) Eurasian Spoonbill – as a wader, with sparse vegetation

2) Black-Crowned Night- Heron roosting on the tree

81

Plate: 3.3

1) Roosting time: Black-Crowned Night Heron on the Accasia nilotica

tree.

2) Purple Heron foage using Stand and Wait method in shallow water

with sparse vegetation

82

Plate: 3.4

1) Immature black-Crowned Night Heron forages by walking

through shallow water with sparse vegetation.

2) Indian Pond Heron forages by a type of Stand and Wait method.

83

Plate: 3.5

Diving Birds

1) At the edge of a mound - Little Blue Kingfisher

2) River Tern at its roosting site.

84

Table-3.1 Percentage frequency of Wading birds (Ardeidae) recorded

in various habitats

No. Habitat Grey

Heron

Purple

Heron

Pond

Heron

Cattle

Egret

Median

Egret

Little

Egret

Large

Egret

Night

Heron

Total

1. Open Water 4 5 2 0 5 6 7 6 35

2. Shallow

water +

Sparce

vegetation

15 12 10 7 25 12 15 5 101

3. Grassy patch 7 18 3 5 10 6 3 0 45

4. Grass +

Ipomoea

10 11 12 2 9 4 8 0 56

5. Trees and

branch over

water

7 7 6 21 6 7 7 28 89

6. Puddles 3 1 2 6 2 1 2 0 17

7. Total

observations

2388 3211 4217 2120 4258 3310 3720 1017 -

85

Fig.-3.1

Percentage frequency of wading birds recorded in various habitats

0

5

10

15

20

25

30

Grey Heron Purple Heron Pond Heron Cattle Egret Median Egret Little Egret Large Egret Night Heron

Pe

rce

nta

ge

(%)

Open Water Shallow w ater + Sparse vegetation Grassy patch Grass + Ipomoea Trees and branch over w ater Puddles

86

Table-3.2 Percentage frequency of Wading birds (Ciconiidae)

recorded in various habitats

No. Habitat Painted

Stork

Openbill

Stork

White

Ibis

Glossy

Ibis

Spoonbill Total

1. Open Water 4 0 3 0 12 19

2. Shallow water +

Sparce vegetation

12 2 15 10 35 74

3. Grassy patch 5 1 10 07 0 23

4. Grass + Ipomoea 4 1 8 5 10 28

5. Trees and branch

over water

20 4 18 7 12 61

6. Puddles 2 3 2 2 1 10

7. Total observations 2530 760 3578 2722 4329 -

87

Fig.-3.2

Percentage frequency of wading birds recorded in various habitats

0

5

10

15

20

25

30

35

40

Painted Stork Openbill Stork White Ibis Glossy Ibis Spoonbill

Pe

rce

nta

ge

(%)


88

Table-3.3 Percentage frequency of Swimming birds recorded in

various habitats

No. HabitatLarge

Cormorant

Indian

Shag

Little

CormorantDarter Pelicans

1. Open Water 35 38 40 7 70

2.

Shallow water +

Sparse vegetation 20 22 25 2 0

3. Grassy patch 2 3 2 1 0

4. Grass + Ipomoea 3 4 4 1 0

5.

Trees and branch

over water 5 4 2 1 3

6. Puddles 8 6 7 1 2

7. Total observation 2720 2350 2620 1240 600

89

Fig.-3.3

Percentage frequency of Swimming Birds recorded in various habitats

0

10

20

30

40

50

60

70

80

Large Cormorant Indian Shag Little Cormorant Darter Pelicans

Pe

rce

nta

ge

(%)


90

Table-3.4 Percentage frequency of Diving birds recorded in

various habitats

No. HabitatWhite breasted

Kingfisher

Little Blue

Kingfisher

River

Tern

Little

Tern

1. Open Water 5 4 7 3

2.

Shallow water + Sparse

vegetation 7 6 0 0

3. Grassy patch 0 0 0 0

4. Grass + Ipomoea 2 3 1 0

5. Trees and branch over water 3 4 1 0

6. Puddles 6 4 1 0

7. Total observation 2503 2304 1891 1087

91

Fig.-3.4

Percentage frequency of Diving Birds recorded in various habitats

0

1

2

3

4

5

6

7

8

White breasted Kingfisher Little Blue Kingfisher River Tern Little Tern

Pe

rce

nta

ge

(%)



A total of 06 habitat types were considered of which two, namely tree and branch

over water and grass mound were purely nesting habitats. Hence, only the remaining 04

habitats were utilized for feeding by the Piscivorous birds.

SWIMMING BIRDS

Among 06 habitat types, Cormorants used the open water habitat and puddles for

both feeding and non-feeding activities. Six habitats were used for feeding while only two

habitats namely edge of the dykes trees and branch over water and cultivation area and

grassy patch with sparse vegetation were used for nesting. All species of cormorants

preferred open water + sparse vegetation for feeding. Darter used 3 habitats for feeding

92

and only one habitat namely trees and branch over water for roosting. Among feeding

habitats, the highest number of birds like Pelicans were observed in open water. The

preference of open water for feeding is mainly due to the feeding behavior of diving birds.

WADING BIRDS

Herons & Egrets

Except the Night-Heron, all the other herons used all habitats for feeding and non

feeding activities (Table – 3.1). The Night Heron used mostly used three habitats. The

highest used habitat was Trees and branch over water. The highest used habitat was

shallow water with sparse vegetation for the Grey Heron, Purple Heron, Pond Heron and

all types of Egrets. Second preferred habitat was Grassy patch and Grass + Ipomoea. The

highest preference of this habitat reflects the feeding behavior of these species. The Grey,

Purple Herons and Large Egret are long-legged birds and hence capable of wading through

the shallow water and feed. Whereas, the Pond Heron and Night Heron, as they are short

legged birds, prefer to wait at the edge of the water and strike when the prey appears.

Thus, the Grey and Purple Heron preferred shallow water + sparse vegetation and Night

Heron and Pond Heron did so mainly on the edge of the dykes for feeding.

STORKS

The open water habitat mostly was never used by openbill stork whereas both the

storks used all the habitats for feeding. Trees and branch over water were used in nesting.

During monsoon, they fed in the puddles available in land area and during summer, they

93

utilized the puddles available in the drying aquatic area. In winter, they used shallow water

+ sparse vegetation and grassy patch habitat for feeding.

IBIS AND SPOONBILL

Large number of white Ibis feed in various microhabitats such as shallow water +

sparse vegetation, grass patch and grass + Ipomoea. The highest numbers of spoonbill

were in shallow water + sparse vegetation. Large numbers of birds were observed in reed,

open water and edge of the habitat (Table-3.2). The selection of habitat for feeding reflects

the feeding behavior of each species. The spoonbill was seen to feed in shallow water with

sparse vegetation and edge of the dyke, their nesting site was upon trees and branches

hanging over water and in cultivation area.

DIVING BIRDS

Diving birds include two species of kingfishers, namely the common kingfisher

and white breasted kingfisher and two species of terns. River Tern and Little Tern. The

common kingfisher preferred shallow water + sparse vegetation and white breasted

kingfisher, the reed. The terns are large birds as compared to the kingfisher and hence their

highly preferred habitat was open deep water for feeding. The white breasted kingfisher

utilized mostly reed as feeding perch.

SEASONALITY OF FORAGING HABITAT

As the summer advances, water in the wetland area recedes fast into comparatively

deeper area and along with the water the aquatic organisms including fish also move into

these pools and puddles. As a result, these pools and puddles become teemed with fish

attracting a large number of herons, ibises and storks. When the rainy season begins in the

94

Thol Lake, remnant fish stocks move out of pools and puddles by surface water that rises

throughout the marsh system. As the fry enter the park along with the water, the waders

have a feast, picking up the tiny fry from the shallow areas. Later when the water level

rises and before the vegetation gets established (to provide perch for the birds), many of

the herons catch the fish by hawking (Sivasubramaniam 1988). Such seasonality of

foraging habitat in wading birds was reported earlier by Kushlan (1976b) and Willard

(1977). Seasonal variation in the habitat use of the Piscivorous birds have been given in

the Fig.-3.5.

95

Table-3.5 SEASONAL VARIATION IN THE HABITAT UTILIZATION OF PISCIVOROUS BIRDS

NoName

O.

WA

SW.

SVG

G.

PAT

GR.

IP

TR.

BOW PUD

O.

WA

SW.

SVG

G.

PAT

GR.

IP

TR.

BOW PUD

O.

WA

SW.

SVG

G.

PAT

GR.

IP

TR.

BOW PUD

1.

Large

Cormorant 35 25 5 9 11 15 25 30 6 10 10 19 45 20 5 10 15

2.

Indian

Shag 50 22 3 3 15 7 40 10 5 3 35 7 50 10 3 3 30 4

3.

Little

Cormorant 30 20 7 10 30 3 45 25 5 5 20 0 30 20 3 4 40 3

4. Darter 38 25 3 2 27 5 40 35 0 0 25 0 45 25 0 0 30 0

5. Pelican 90 0 5 5 0 0 0 0 0 0 0 0 0 0 0 0 0 0

6.

Grey

Heron 5 30 20 20 7 18 8 20 22 25 10 15 5 25 21 23 10 15

96

7.

Purple

Heron 2 28 20 20 10 20 8 25 23 22 12 10 0 35 21 24 5 15

8.

Pond

Heron 2 25 20 20 10 23 4 27 23 25 6 15 1 22 23 21 13 20

9.

Large

Egret 20 15 17 13 18 17 25 15 12 10 10 28 15 22 23 27 9 4

10.

Median

Egret 5 25 18 22 8 12 5 22 15 15 28 15 5 18 28 22 9 18

11.

Little

Egret 18 22 15 15 10 20 15 10 3 2 15 35 8 22 18 12 17 23

97

No. NameO.

WA

SW.

SVG

G.

PAT

GR.

IP

TR.

BOWPUD

O.

WA

SW.

SVG

G.

PAT

GR.

IP

TR.

BOWPUD

O.

WA

SW.

SVG

G.

PAT

GR.

IP

TR.

BOWPUD

12. Cattle Egret 0 20 28 22 18 12 0 25 28 13 22 12 0 24 2 22 28 3

13.

Painted

Stork 10 25 12 13 25 15 18 14 5 5 28 30 8 20 8 4 45 15

14. White Ibis 20 25 15 15 10 15 22 25 12 17 12 22 8 12 16 14 35 15

15. Glossy Ibis 5 35 20 22 25 13 10 30 10 10 25 15 3 35 10 12 15 10

16.

Eurasian

Spoonbill 10 30 10 10 20 20 15 35 10 10 15 15 5 30 10 15 25 15

17.

Ruddy

Shelduck 85 10 0 0 0 5 0 0 0 0 0 0 0 0 0 0 0 0

18. River Tern 95 0 0 0 0 5 95 0 0 0 0 5 95 0 0 0 0 5

19. Little Tern 90 0 0 0 0 10 0 0 0 0 0 0 0 0 0 0 0 0

98

20.

White

breasted

Kingfisher 25 20 0 0 45 10 30 15 0 0 30 25 35 25 0 0 25 15

21.

Common

Kingfisher 15 35 0 0 30 20 10 40 0 0 40 10 10 35 0 0 35 20

1. O. WA = OPEN WATER

2. SW. SVG = SHALLOW WATER + SPARSE VEGETATION

3. G. PAT = GRASSY PATCH

4. GR. IP = GRASS + IPOMOEA

5. TR. BOW = TREES AND BRANCH OVER WATER

6. P.U.D. = PUDDLES

99

Fig-3.5a SEASONAL VARIATION IN THE HABITAT UTILIZATION OF PISCIVOROUS BIRDS

LARGE CORMORANT

WINTER

O.WA

35%

SW.SVG

G.PAT

5%

GR.IP

9%

TR.BOW

11%

PUD

15%

SUMMER

O.WA

25%

SW.SVG

30%G.PAT

GR.IP

10%

TR.BOW

10%

PUD

19%

MONSOON

O.WA

45%

G.PAT

5%

GR.IP

10%

TR.BOW

15%

PUD

5%

SW.SVG

20%

100

O.WA

50%

TR.BOW

30%

SW.SVG

10%

PUD

4%

GR.IP

3%G.PAT

3%

O.WA

50%

SW.SVG

22%

G.PAT

3%

GR.IP

3%

TR.BOW

15%

PUD

7%

O.WA

40%

SW.SVG

10%

TR.BOW

35%

G.PAT

5%

GR.IP

3%

PUD

7%

Fig-3.5b SEASONAL VARIATION IN THE HABITAT UTILIZATION OF PISCIVOROUS BIRDS

INDIAN SHAG

WINTER SUMMER MONSOON

101

O.WA

30%

TR.BOW

40%

G.PAT

3%

GR.IP

4%

PUD

3%

SW.SVG

20%

O.WA

30%

SW.SVG

20%G.PAT

7%

GR.IP

10%

TR.BOW

30%

PUD

3%

c

O.WA

45%

SW.SVG

25%

TR.BOW

20%

GR.IP

5%

G.PAT

5%

Fig-3.5c SEASONAL VARIATION IN THE HABITAT UTILIZATION OF PISCIVOROUS BIRDS

LITTLE CORMORANT


102

O.WA

45%

TR.BOW

30%

SW.SVG

25%

O.WA

40%

TR.BOW

25%

SW.SVG

35%

O.WA

38%

SW.SVG

25%

G.PAT

3%

GR.IP

2%

TR.BOW

27%

PUD

5%

c

Fig-3.5d SEASONAL VARIATION IN THE HABITAT UTILIZATION OF PISCIVOROUS BIRDS

DARTER


103

O.WA

90%

GR.IP

5%G.PAT

5%

Fig-3.5e SEASONAL VARIATION IN THE HABITAT UTILIZATION OF PISCIVOROUS BIRDS

PELICAN

WINTER

104

O.WA

5%

G.PAT

21%

GR.IP

23%

TR.BOW

10%

PUD

15%

SW.SVG

26%

O.WA

8%

TR.BOW

10%

PUD

15%

GR.IP

25%G.PAT

22%

SW.SVG

20%

O.WA

5%

SW.SVG

30%

G.PAT

20%

GR.IP

20%

TR.BOW

7%

PUD

18%

c

Fig-3.5f SEASONAL VARIATION IN THE HABITAT UTILIZATION OF PISCIVOROUS BIRDS

GREY HERON

WINER SUMMER MONSOON

105

O.WA

0%

G.PAT

21%

GR.IP

24%

TR.BOW

5%

PUD

15%

SW.SVG

35%

O.WA

8%

TR.BOW

12%

SW.SVG

25%

G.PAT

23%

GR.IP

22%

PUD

10%

O.WA

2%

SW.SVG

28%

G.PAT

20%

GR.IP

20%

TR.BOW

10%

PUD

20%

c

Fig-3.5g SEASONAL VARIATION IN THE HABITAT UTILIZATION OF PISCIVOROUS BIRDS

PURPLE HERON


106

O.WA

1%

G.PAT

23%

TR.BOW

13%

PUD

20%

GR.IP

21%

SW.SVG

22%

O.WA

4%

TR.BOW

6%

PUD

15%

GR.IP

25%

G.PAT

23%

SW.SVG

27%

O.WA

2%

SW.SVG

25%

G.PAT

20%GR.IP

20%

TR.BOW

10%

PUD

23%

c

Fig-3.5h SEASONAL VARIATION IN THE HABITAT UTILIZATION OF PISCIVOROUS BIRDS

POND HERON


107

O.WA

15%TR.BOW

9%

PUD

4%

G.PAT

23%

SW.SVG

22%

GR.IP

27%

O.WA

25%

TR.BOW

10%

SW.SVG

15%

G.PAT

12%

GR.IP

10%

PUD

28%O.WA

20%

SW.SVG

15%

G.PAT

17%

GR.IP

13%

TR.BOW

18%

PUD

17%

c

Fig-3.5i SEASONAL VARIATION IN THE HABITAT UTILIZATION OF PISCIVOROUS BIRDS

LARGE EGRET


108

O.WA

5%

TR.BOW

9%

PUD

18%

GR.IP

22%

SW.SVG

18%

G.PAT

28%

O.WA

5%

TR.BOW

28%

PUD

15%

GR.IP

15%

G.PAT

15%

SW.SVG

22%

O.WA

6%

SW.SVG

28%

G.PAT

20%

GR.IP

24%

TR.BOW

9%

PUD

13%

c

Fig-3.5j SEASONAL VARIATION IN THE HABITAT UTILIZATION OF PISCIVOROUS BIRDS

INTERMEDIATE MEDIAN EGRET


109

O.WA

8%

TR.BOW

17%

PUD

23%

G.PAT

18%

SW.SVG

22%

GR.IP

12%

O.WA

18%

TR.BOW

19%

SW.SVG

13%

G.PAT

4%

GR.IP

3%

PUD

43%

O.WA

18%

SW.SVG

22%

G.PAT

15%

GR.IP

15%

TR.BOW

10%

PUD

20%

c

Fig-3.5k SEASONAL VARIATION IN THE HABITAT UTILIZATION OF PISCIVOROUS BIRDS

LITTLE EGRET


110

SW.SVG

20%

G.PAT

28%

GR.IP

22%

TR.BOW

18%

PUD

12%

c

TR.BOW

35%

PUD

4%

GR.IP

28%

SW.SVG

30%

G.PAT

3%

TR.BOW

22%

PUD

12%

GR.IP

13%

G.PAT

28%

SW.SVG

25%

Fig-3.5l SEASONAL VARIATION IN THE HABITAT UTILIZATION OF PISCIVOROUS BIRDS

CATTLE EGRET


111

O.WA

8%

TR.BOW

45%

PUD

15%

GR.IP

4%

SW.SVG

20%

G.PAT

8%

O.WA

18%

TR.BOW

28%

SW.SVG

14%

G.PAT

5%

GR.IP

5%

PUD

30%

O.WA

10%

SW.SVG

25%

G.PAT

12%GR.IP

13%

TR.BOW

25%

PUD

15%

c

Fig-3.5m SEASONAL VARIATION IN THE HABITAT UTILIZATION OF PISCIVOROUS BIRDS

PAINTED STORK


112

O.WA

8%

TR.BOW

35%

PUD

15%

G.PAT

16%

SW.SVG

12%

GR.IP

14%

O.WA

20%

TR.BOW

11%

PUD

20%

GR.IP

15%G.PAT

11%

SW.SVG

23%

O.WA

20%

SW.SVG

25%

G.PAT

15%

GR.IP

15%

TR.BOW

10%

PUD

15%

c

Fig-3.5n SEASONAL VARIATION IN THE HABITAT UTILIZATION OF PISCIVOROUS BIRDS

WHITE IBIS


113

TR.BOW

18%

PUD

12%

O.WA

4%

GR.IP

14%

SW.SVG

40%

G.PAT

12%

O.WA

10%

TR.BOW

25%

SW.SVG

30%

G.PAT

10%

GR.IP

10%

PUD

15%

O.WA

4%

SW.SVG

29%

G.PAT

17%

GR.IP

18%

TR.BOW

21%

PUD

11%

c

Fig-3.5o SEASONAL VARIATION IN THE HABITAT UTILIZATION OF PISCIVOROUS BIRDS

GLOSSY IBIS


114

O.WA

5%

TR.BOW

25%

PUD

15%

G.PAT

10%

SW.SVG

30%

GR.IP

15%

O.WA

15%

TR.BOW

15%

PUD

15%

GR.IP

10%

G.PAT

10%

SW.SVG

35%

O.WA

10%

SW.SVG

30%

G.PAT

10%

GR.IP

10%

TR.BOW

20%

PUD

20%

c

Fig-3.5p SEASONAL VARIATION IN THE HABITAT UTILIZATION OF PISCIVOROUS BIRDS

EURASIAN SPOONBILL


115

O.WA

85%

SW.SVG

10%

PUD

5%

Fig-3.5q SEASONAL VARIATION IN THE HABITAT UTILIZATION OF PISCIVOROUS BIRDS

RUDDY SHELDUCK

WINTER

116

O.WA

95%

PUD

5%

PUD

5%

O.WA

95%

PUD

5%

O.WA

95%

Fig-3.5r SEASONAL VARIATION IN THE HABITAT UTILIZATION OF PISCIVOROUS BIRDS

RIVER TERN

SUMMER MONSOON WINTER

117

O.WA

90%

PUD

10%

Fig-3.5s SEASONAL VARIATION IN THE HABITAT UTILIZATION OF PISCIVOROUS BIRDS

LITTLE TERN

WINTER

118

O.WA

35%

TR.BOW

25%

PUD

15%

SW.SVG

25%

O.WA

25%

SW.SVG

20%

TR.BOW

45%

PUD

10% O.WA

30%

TR.BOW

30%

PUD

25%

SW.SVG

15%

Fig-3.5t SEASONAL VARIATION IN THE HABITAT UTILIZATION OF PISCIVOROUS BIRDS

WHITE BREASTED KINGFISHER


119

TR.BOW

35%

PUD

20%

O.WA

10%

SW.SVG

35%

O.WA

10%

TR.BOW

40% SW.SVG

40%

PUD

10%

O.WA

15%

SW.SVG

35%TR.BOW

30%

PUD

20%

Fig-3.5u SEASONAL VARIATION IN THE HABITAT UTILIZATION OF PISCIVOROUS BIRDS

COMMON KINGFISHER


120

CHAPTER – 4

FOOD AND FEEDING HABITS OF

THE PISCIVOROUS BIRDS

INTRODUCTION:

The ways in which animals partition the available resources have aroused

considerable interest, particularly in efforts aimed at demonstrating the competitive

exclusion principle or at determining the limiting similarity of coexistence (Cole 1960,

Hardin 1960, MacArthur and Levins 1967, Miller 1967, Lack 1971, May and MacArthur

1972, Cody 1974, Pianka 1974, 1975). These studies examined food as the limiting

resource by measuring prey size, bill size, foraging behaviour and prey availability. The

emphasis on food as the limiting resource seems partly historical in that Elton (1927)

developed his conceptual frame work of niche in terms of the feeding behaviour and food

requirement of species.

Several studies on piscivorous birds have touched upon some of these

considerations and have generally shown that congeneric piscivorous birds differ by their

size, behaviour, feeding sites or food (Carrick 1959, Meyerriecks 1962, Jenni 1969, Kahl

1971a, Kushlan 1976b, Willard 1977, Custer and Osborn 1978, Thompson 1978, Hoffman

1978, Recher and Recher 1980 and Kent 1986).

The conservation and management of piscivorous birds throughout their range

have evoked considerable interest and concern (Cambray 1985). Their relatively high

121

energy demand and locally large population make them important components of aquatic

ecosystems. Inter-specific differences in size, habitat use, sociality, distribution, responses

to seasonal environmental pressure and food habits. Resource partitioning studies analyse

how inter-specific competition limits the number of coexisting species. Competition, here

defined as the simultaneous demand by two or more organisms of different species

for such limited resources as food or space (Koplin and Hoffman 1968) has been studied

by both, observing and describing systems and by perturbing and then observing the

systems.

Predation by piscivorous birds is one of the forces determining the functional

characteristic of this system by existing control pathways of energy flow. The tactical

aspects of predation, such as relationship between prey availability and prey consumption

and between defensibility and territory size function in determining the nature of the fish

to piscivorous birds energy flow. Similar relationship should exist in other feeding habitats

that taken together determine the regional pattern of habitat use, prey consumption and the

way piscivorous birds meet daily and seasonal food requirements.

More literature on feeding ecology of piscivorous birds in various countries is

known qualitatively and in some cases quantitatively. The motor patterns associated with

capturing, handling and swallowing prey have been summarized by various authors

(Meyerriecks 1962, Pringle 1964, Cunnigham 1965, Kahl 1964, Blaker 1969a, Carpenter

1971, Dennis 1971, Vestjens 1973, Snow 1975, Kushlan 1978b, Whitefield and Blaber

1978a, 1978b, Mock and Mock 1980, Moser 1986, and Forber 1989).

122

Piscivorous birds have been described in exhaustive literature describing their

foraging ecology and food habits. In India, very little information is available at present on

the food and feeding habits of the piscivorous birds (Abdulali 1967, Kahl 1971a, 1973,

Mukherjee 1971, 1975, Pandey 1975, Newton 1986, Johnson 1988, Ginwood and

Brockleshut 1984, Pal and Bala 1989, Johnson et al. 1990, Navroj 1990, Sivakumar et al.

1990).

Morphological adaptations for feeding have been reported (Hartman 1961, Huxly

1962, Humphrey and Parkes 1963, Kahl 1965, Duble and Mansuri 1969, Vanden Berge

1970, Payne and Ridey 1976, Recher and Recher 1980). Territorial foraging of piscivorous

birds have been reported by Meyerriecks (1962), Hedeen (1967), Recher and Recher

(1972), Snow (1975), Woolfenden et al. (1976), Mock and Mock (1980).

Foraging sociality of piscivorous birds has been described (Woolfenden et al.

1976, Kushlan 1978a, 1978b, Ruseell 1978, Blaker 1969a, 1971, Willard 1977, Whitefield

and Blaber 1978, Forber and Simpson 1982, Praulans and Versam 1985, Hafner 1982,

Erwin 1983, Scoh 1984). Food consumption of the adult and juvenile piscivorous birds

was well documented by various authors (Siegfried 1972, Kushlan and Kushlan 1977,

Ogdan et al. 1978, Whitefield and Blaber 1978a, 1978b, Kushlan 1979a, Junor 1972,

Draulans 1988).

Food requirements of the piscivorous birds have been extensively studied (Owen

1960, Kahl 1964, Kral and Figala 1966, Vaspemeanu 1968, Dusi and Dusi 1970, Kushlan

1977). More literature on seasonality of prey consumption of piscivorous birds is available

elsewhere (Carrick 1962, Kahl 1964, 1966, 1971b, Carroll 1967, Lowemc Connell 1967,

123

Klug and Boswell 1970, Siegfied 1972a, 1972b, Vermon 1971, Urban 1974, Ogden et al.

1978, and Kushlan 1978b, 1986).

The environmental determination of food dispersion is complex, but is critical for

understanding the feeding ecology of wading birds. Very few people have studied this

aspect (Owen 1957, Kahl 1964, Vespermeanu 1968, Kushlan et al. 1975, Kushlan 1976b,

Ogden et al. 1978). Prey selection of the piscivorous birds was worked out by various

authors (Siegfried 1972b, Kushlan and Kushlan 1977, Owen 1955, Kahl 1964, Willard

1977, Jackson 1984, Whitefield and Blaber 1978a, b; Kushlan 1979a, Mock and Mock

1980, Fasola 1981, Rodger Jr. 1976). Information on the feeding depth of the piscivorous

birds are incidental and general (Jenni 1969, Willard 1977, Recher and Recher 1980,

Whitefield and Blaker 1978a, b,; Forber and Simpson 1982).

METHODOLOGY:

As the present study was conducted at lake, puddles, sewage, canal and some of

human interference was very common. Only direct observation method was applied.

Generally observation was confined to birds within a distance of 40 to 50 m and

individuals selected as they were encountered. Where I had a choice of two or more

individuals of a species, I chose the nearest one. Observations continued until the bird

moved out of the scope for easy identification of prey.

Monthly observations were taken from 13to14 hrs. For accuracy 20 x 50 binocular

was used. Timing for different feeding techniques adopted by different birds was recorded

by stopwatch.

124

Table– 4.1 Average length of bill and tarsus of Piscivorous birds

No. Species Length of Bill

(mm)

Length of Tarsus

(mm)

1. Large cormorant 57-72 62-71

2. Indian shag 50-61 47-52

3. Little cormorant 29-34 35-40

4. Darter 74-90 42-47

5. Grey Heron 109-135 140-162

6. Purple Heron 115-144 121-145

7. Pond Heron 60-67 60-64

8. Cattle Egret 50-66 82-92

9. Large Egret 110-135 170-215

10. Median Egret 73-97 122-148

11. Little Egret 79-91 99-110

12. Night Heron 65-80 65-75

13. Painted Stork 252-278 240-250

14. Openbill stork 153-162 140-150

15. White Ibis 139-170 99-115

16. Spoon bill 180-228 130-165

17. WhiteBreasted Kingfisher 56-63 15-16

18. Common Kingfisher 42-46 8-10

125


FORAGING BEHAVIOUR:

Understanding the ecological aspects of foraging requires use of a standardized

nomenclature and knowledge on the distribution of various behaviors among piscivorous

birds. The use of various mechanisms for catching prey depends in part on a species’

morphological and physiological adaptations and on the availability of various types of

prey spacing system ranging from wide dispersion to aggregation, correlated with the

nature and defensibility of the food resources. Aggregative foraging leads to behavioral

associations such as commensalisms and prey robbing (Kushlan 1978a).

SWIMMING BIRDS

Among the swimming birds, the Large Cormorant, shag and Little Cormorant

forage solitarily but those from large populations forage in groups and exhibit

synchronous diving. While diving in pursuit of fishes, just the head was submerged

followed by rest of body, wings kept closed. Fishes were caught under water and the head

raised above water surface holding them between mandibles with the hook on the upper

mandibles often penetrating the lateral surface of the prey and swallowed the head first.

The Darter, found singly or in scattered twos and threes foraged by pursuit diving from the

surface, propelling themselves with their feet and keeping their wings half open. Fishes

were captured between mandibles and head was swallowed first.

The Great White Pelican does not dive for its food. Instead it catches its prey while

swimming. The Great White Pelicans like to come together in groups of a handful of birds

or so to feed, as they can thus cooperate and chase fish to one another. When this is not

126

easily possible for cocample in deep water where fish can escape by diving out of reach

they prefer to forage alone. But the birds also steal food on occasion sometimes from other

Pelicans sometimes from gulls.

DIVING BIRDS

Kingfishers fish by diving from a perch or from hovering flight. When hovering,

kingfishers usually fly parallel to the shoreline in a series of arcs with the hovering phase

representing the peak of each arc before diving the beak first into the water in the manner

described by most other observers. Alternatively, the bird dives straight into the water. In

successful dives if the fish was less than 20 mm long it was swallowed on the wing

otherwise it was carried to a firm perch where the fish was beaten and swallowed head

first (Table - 4.2). When fishing from a perch, the bird perches motionless on an elevated

branch, until the prey is sighted, and dives down to capture it and returns to the tree to

immobilize it by hammering it on the branch (Douthwatie 1976, Whitefield and Blaber

1978a). Fishes were normally captured at right angles to the longitudinal axis of the bill

and could be stunned easily because the head of the fish is projected from the side of the

beak.

127

Table - 4.2 Hunting distances and methods of feeding by Kingfisher

Common Kingfisher White breasted Kingfisher

Hovering height between 1-5(m) 2-25(m)

Distance between the perch

and the water surface

1-7 (m) 2-30(m)

Distance between the

shoreline and the hovering

site

<25 (m) Unlimited

Swallowed on the wing 127 (47 %) 82 (21 %)

Swallowed on the Perch 140 (55 %) 327 (82 %)

Total observations (n) 300 425

WADING BIRD

About 38 feeding methods are used by various species of wading birds (Kushlan

1978). It is generally known that some wading birds posses a varied foraging repertoire

and engage in the more active feeding behavior (Meyerriecks 1960, 1962, Kushlan 1978b,

Recher and Recher 1968, 1972, 1980). However, only a few studies have quantitatively

determined the frequency with which each species uses these feeding techniques

(Willard 1977) or whether their use varies with environmental parameters (Hafner 1982)

Rodgers Jr. (1983) described the efficiency and frequency of feeding methods among

species, age classes, colour phases and different environmental conditions.

128

Plate: 4.1

Feeding of large cormorant

1) Large cormorant catches the fish

2) A cormorant foraging by diving method

129

Plate: 4.2

1) Glossy Ibis catching the fish in the shallow water

2) Median Egret (in non breeding season) catching the fish with

sparse vegetation

130

Plate: 4.3

1) Wading birds like Painted Stork’s foraging by walking slowly

through shallow water

131

TYPES OF FEEDING BEHAVIOR

The methods adopted (as per Kushlan 1976a) for feeding by herons, egrets, storks,

ibis and spoonbill are grounded into 13 categories. And the frequency of the use of each

method is given in (Table 4.3):

1) Stand and wait (sw): A bird stands motionless in water waiting for prey to

approach.

2) Walk slowly (ws): moves slowly, stalking prey.

3) Walk quickly (wq): walks at relatively fast speed.

4) Running (Ru): moves quickly after a specific prey item.

5) Foot stirring (fs): Vibrates the tarsus in the water in soft mud.

6) Foot peddling (fp): Moves foot up and down.

7) Probing (Pr): quickly and repeatedly moves bill tip into and out of water.

8) Bill vibrating (BV): Rapidly opens and closes bill in water.

9) Diving (DI): Dives head first from perch.

10) Leap frog feeding (LF): Flies from back of feeding flock to front.

11) Aerial feeding (AF): while flying puts head first and catches prey.

12) Head swaying (HS): Moves head from side to side out of water, in either slow or

rapid sweeps.

13) Groping (GR): Places and holds bills opened in water.

132

Table-4.3 Occurrence of types of feeding behaviors among species

of Wading birds at Thol sanctuary

No. Sp./Behavior SW WS WQ RU FS FP PR BV DI LF AF GR HS

1. Grey Heron * * * - - - - - - * * - -

2. Purple Heron * * * - - - - - - - - - -

3. Pond Heron * * - - - - - - * * * - -

4. Night Heron - - * - - - - - * - - - -

5. Cattle Egret - * - * - * * - - - * - -

6. Large Egret * * * - * * - - - - - - -

7. Little Egret - * * * * - * - - - - - -

8. Median Egret - * * * - - - - - * * - -

9. Painted stork - * * * * * * - - - - * -

10. Openbill

Stork

- * * - - - * - - - - * -

11. White Ibis - * * - - - * - - - - * -

12. Glossy Ibis - * * - - - * - - - - * -

13. Spoon bill - * * * - - * - - - - - *

Fig-4.3 LEGENDS

* = occurs SW = Stand and Wait BV = Bill Vibrating

- = does not occur WS = Walk Slowly DI = Diving

WQ = Walk quickly LF = Leap frog feeding

RU = Running AF = Aerial feeding

FS = foot stirring GR = Groping

FP = foot peddling HS = Head swaying

PR = Probing

133

The Grey Heron, Purple Heron, Pond Heron and Large Egret fed mainly by the

method “stand and wait” and “walk slowly”. The Little Egret and Median Egret fed

mainly by walk slowly, “walk quickly” and “running”. The major feeding techniques of

the cattle Egret were walk slowly and running (35% and 29% resp.).The Night Heron

exhibited the highest frequencies of “walk quickly” (33%) and “diving” (30%) methods.

The painted stork, Open bill Stork and White Ibis fed mainly by probing the most

sedentary forager was Spoonbill, which spent over 60% of its time engaged in the head

swaying method.

Major feeding techniques adopted by wading birds in the present study were

similar to other reports (Table-4.5) which indicate that there is not much variation in

feeding techniques in different habitats and seasons.

All species used only a few foraging methods. The Painted Stork used seven

methods. The least number of feeding techniques (three) was used by the Purple Heron

(Table-4.4).

Most of the wading birds showed some tendency to change the frequency of

foraging methods with different habitats (Table-4.4) each species used one or more

feeding techniques and this apparently helped the bird to utilize the resources from

different zones. The aquatic area could be divided broadly into four habitats namely

(1) Open water (OW), (2) Shallow water + sparse vegetation, (SWSV) (3) Thick

vegetation (TV), and (4) Edge of the dyke and mound. (EDDM).

134

Table -4.4 Inter-specific comparison of the percentage frequency

of feeding behaviours

No.Piscivorous

BirdsSW WS WQ RU FS FP PR BV DI LF AF HS « GR

1. Grey Heron 55 30 10 0 0 0 0 0 0 5 0 0 1 0

2.Purple

Heron65 30 5 0 0 0 0 0 0 0 0 0 0 0

3. Pond Heron 45 15 10 0 0 0 0 0 15 10 5 0 0 0

4. Cattle Egret 0 20 40 30 0 0 0 0 0 10 0 0 1 0

5. Large Egret 40 30 10 0 5 0 0 0 0 0 10 0 5 0

6. Little Egret 0 30 20 10 13 0 0 12 0 8 7 0 0 0

7.Median

Egret0 50 15 0 0 0 0 0 0 17 13 0 5 0

8.Painted

Stork1 15 17 0 10 5 35 0 0 0 0 0 3 15

9. White Ibis 0 5 20 0 0 0 70 0 0 0 0 0 0 5

10. Spoon Bill 0 10 5 15 0 0 0 0 0 0 0 70 1 0

LEGENDS

SW = Stand and Wait

WS = Walk Slowly

WQ = Walk Quickly

RU = Running

FS = Foot Stirring

FP = Foot Peddling

PR = Probing

BV = Bill Vibrating

DI = Diving

LF = Leap Frog Feeding

AF = Areal Feeding

HS = Head Swaying

« = Other techniques exhibited < 5%

135

Fig.-4.4 Inter-specific comparison of the frequency of

feeding behaviours

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

Grey Heron

Purple Heron

Pond Heron

Cattle Egret

Large Egret

Little Egret

Median Egret

Painted Stork

White Ibis

Spoon Bill

SW WS WQ RU FS FP PR BV DI LF AF HS «

136

Table-4.5 Similarity of feeding behaviour of various birds between Thol bird sanctuary and elsewhere

Grey Purple Pond Night Cattle Large Medium Little Painted Openbill White Spoonbill

Heron Heron Heron Heron Egret Egret Egret Egret Stork Stork Ibis

SW 1,3,8,28 8,7,19 7,8 7,28 3,7,8,16,15,17,12,

WS 7,3,28 8,7,19 7,8 7,28 7,8,16,25 7,8,16,15,17,12, 7,8 1,2,16,7,8,28 24

WQ 3 7,12 8 3,7

RU 7 7,14,25 3 3,7 8 8

FS 7 21,3,7,28

RP 7 8

PR 7 8 8 8,20 8,24,26,21

BV 7 7

PI

IP 8,18 9,13 16 8

AP 29 6,7 7 7,10,11,30 7,6 4,6,5

137

GR 8

HS 8

1. Refner et al. (1982) 9. Wise and Grawfor (1973) 17. Willard (1977) 25. Blaber (1969)

2. Erwin et al. (1935) 10. Rodgers (1984) 18. Keyerriecks (1960) 26. Kushlan (1979)

3. Whitefield ana Blaber (1978) 11. Meyerricks (1952) 19. Tomilinson (1975) 27. Kushlan (1986)

4. Abdulali (1967) 12. Rodgers Jr. (1983) 20. Kahl (1971) 28. Fasola (1986)

5. Mathew (1983) 13. Gladstone (1977) 21. Kahl (1973) 29. Marshall (1961)

6. Sivasubramaniam (1988) 14. Jenni (1960) 22. Kahl (1972)

7. Kushlan and Hancock (1980) 15. Recher and Recher (1980) 23. Sivasubramaniam et al. (1989)

8. Ali and Ripley (1983) 16. Recher et al. (1983) 24. Kushlan (1977)

CHAPTER-5

BREEDING BIOLOGY OF THE

PISCIVOROUS BIRDS

138

CHAPTER – 5

BREEDING BIOLOGY OF THE PISCIVOROUS BIRDS

Introduction

The Thol Bird Sanctuary provides an ideal habitat for the colonial nesting birds.

There are dynamic locations inside the TS where they nest every year. In the present

study, details on breeding biology of the colonical breeders of Thol Bird Sanctuary were

gathered to examine the number of birds breeding inside the sanctuary and their major

breeding requirements.

Most piscivorous birds are colonial nesters except kingfisher (hole nester).

Colonial nesting is widespread among water birds, but relatively rare among terrestrial

birds (Lack 1966).

Considerable work has been done on the breeding biology and nesting

requirements of many colonial birds at several places. Breeding biology of White breasted

Cormorant Phalacrocorax carbo was studied by Olver and Kuyper (1978) and Reed

Cormorant Phalacrocorax africanus by Olver (1984), Bank Cormorant by Cooper (1985b,

1987) and Shag Phalacrocorx aristotalis by Snow (1960). Grey Heron Ardeo cineria has

been studied by Verwey (1930), Lowe (1954), Owen (1960), Milstein et al. (1970) and of

Purple Heron Ardea purpurea by Steinfatt (1939) and Tomlinson (1974a, 1974b, 1975).

The breeding biology of the Sacred Ibis has been studied by Urban (1974) and Spoonbill

by Kahl (1983) and Donald et al. (1982).

139

There is very little quantitative information available on breeding biology of the

colonial birds in India. Ali and Ripley (1968) gave general information on the nidification.

Singh et al. (1988) described the breeding biology of Painted stork and Openbill stork in

Bharatpur. Desai et al. (1978) studied the reproductive pattern of Painted stork in Delhi

zoo. Mukhopadhyay (1980) described the breeding biology of Openbill stork in Southern

Bengal. Parasharya (1984) did a detailed study on the breeding biology of some

Ciconiformes in selected coastal areas of Gujarat. Sivasubramaniam (1992) reported the

basic data on the breeding biology of the colonial nesting birds of Keoladeo National Park.

Dave (2002) reported the breeding biology of the colonial nesting birds at Rajkot in

Saurashtra.

METHODOLOGY:

During the present study nests were observed every 15 days at the nesting sites. All

nests were on the trees. All these nests were at different heights and in different canopies

of the trees. When the birds started to build the nest, the nest was given a number at all

selective sites. This number was maintained till the end of the nesting cycle and it was

considered as a nest number. The observations were recorded nest-wise on data sheets.

During egg laying period the observations of the nest was difficult sometimes. A boy was

employed to climb up the trees or in certain cases a set of mirrors on the pole was used to

observe the nest activities.

140

NEST LOCATION

There are three major nesting sites in the study area.

(1) Site A: This site is situated in northeast direction. Near this site, there are oil wells

belonging to ONGC. Trees include Neem - Azadirachta indica, Desi Baval -

Acacia nilotica, Gando Baval- Prosopis chilensis, Mithi Pilu - Salvadora oleoides,

Akdo - Calotropis gigantea etc. Wading birds' nesting was also seen here.

This is second largest colony of heronry in the sanctuary. The mounds are

situated 23 meters apart. Each mound has about 4-8 Acacia nilotica probably

because of crowding of trees on the mounds, they slant towards the water,

obviously for more light. 29 mounds were usually used by the nesting birds in the

area. 10 species of birds nested here; the most common among them were the

Openbill Stork (40) followed by the Indian Shag (20) Darter (2) Egrets (70) and

Herons (150), Pelicans (5) (2005)

(2) Site B: This site is situated near Jethlaj village, where whole area is covered with

Acacia nilotica trees having big nesting colonies of waders like Egrets, Herons, Spoonbill,

Ibis and swimmer’s like Cormorants on this site. Trees include Rayan - Manilkara

hexandra, Baval - Acacia nilotica, Mithi pilu - Salvadora oleoides, Khari pilu - Salvadora

persica, etc. are seen here.

This is first largest colony of heronry in the sanctuary. The nests were

located on a total of approximetly more than 550 trees mainly Acacia nilotica. The largest

number of nests in this area was the Indian Shag (300),Little Cormorant (400) Large

141

Cormorant (100) Spoonbill (200) Painted Stork (30) Darter (3) Egrets (250) Herons (70)

Ibis(50) were seen.

(3) Site C: This site is located on the front side of watchtower. The site is fully open

and having deep water. In certain areas of upper region, dense trees and other

vegetation cover was observed which is a favorable site for birds for resting and

roosting. There is a nesting site for some waders too. It is also Pelicans' favorite

resting place. In monsoon, water depth is about 6 to 8 feet and during winter, level

of water comes to 4 to 5 feet and in summer, it dries up to form small puddles.

Dense vegetation and big trees like Limdo - Azadirachta indica, Desi Baval -

Acacia nilotica, Mithi pilu - Salvadora oleoides, Piplo - Ficus religiosa, Herb -

Dholo, Dhanturo - Datura metal, Bhoy Ringani - Solanum surattense, Mindhi aval

- Cassia ilalica, Shurb - Nano akado - Calotropis procera, Akdo - Calotropis

gigantea etc. are found here.

About more than 150 trees closed formed the third major colony. The

largest number of nests in this area was of Spoonbill (200) Painted Stork (50) and Ibis

(100). The white Ibis had its largest number of nests here.

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Plate: 5.1

1) A Darter during the nesting phase

2) A Darter keeping guard on it’s nest with three juvenile

143

Plate: 5.2

1) Pelicans nest with four chicks

2) Chicks on a large platform on a Banyan tree

144

Plate: 5.3

The great white pelican looks after its nest

145

Plate: 5.4

1) A large nesting colony (site- b) on the Acacia trees

1) Egret`s juvenile is seen in the nest

146

Plate: 5.5

The Openbill stork collecting the nesting material in the heronaries.

147

Plate: 5.6

A Spoonbill’s nest

148

Plate: 5.7

1) The juvenile of Little Heron leaves the nest and is learning to fly

2) A juvenile of a White Ibis

149

Plate: 5.8

1) During the nesting phase White Ibis’s Chicks waiting for it`s food

from their parents

150

Plate: 5.9

1) A large nesting colony of Painted Storks

2) Openbill Stork`s juveline waiting for food.

151

Plate: 5.10

Marending Crows are the biggest predators of the chicks

152


Table-5.1 Breeding schedule of the Heronries during 2005-06

No. Species Initiation

of Nesting

week

A

Peak of

Nesting

week

B

End of

Nesting

week

C

No. of weeks

of nesting

(n)

Average

No. of

Nests

D

1. Large cormorant Aug. 1st Sept. 1st Nov. 3rd 15 150

2. Indian shag July 1st Sept. 2nd Oct. 3rd 15 320

3. Little Cormorant June 4th Sept. 1st Sept. 3rd 12 450

4.. Darter July 1st Sept. 2nd Nov. 4th 13 07

5. Grey heron July 1st Sept. 2nd Nov. 1st 17 20

6. Purple heron July 3rd Sept. 3rd Nov. 4th 18 35

7. Cattle Egret June 2nd Aug. 3rd Aug. 4th 10 220

8. Large Egret June 4th Aug. 4th Oct. 4th 17 175

9. Median Egret June 3rd Aug. 3rd Oct. 3rd 17 150

10. Little Egret June 3rd Aug. 3rd Oct. 3rd 17 275

11. Night heron July 1st Sept. 1st Sept. 4th 12 25

12. Painted stork Aug. 3rd Sept. 4th Feb. 2nd 24 125

13. Openbill stork May 4th Aug. 3rd Oct. 1st 18 50

14. Spoonbill June 3rd Aug. 4th Oct. 2nd 16 325

15. White Ibis June 4th Aug. 3rd Oct. 2nd 15 275

153

NOTE :

A. Week when the earliest nests were started.

B. Week when the maximum number of active nests were recorded.

C. Week when the last chicks left the nests.

D. Maximum number of active nests seen at the peak season.

Table-5.2 Clutch size and nesting cycle of the Heronry species

No. Species Clutch

Size

Nest

Building

period

(days)

Egg

laying

period

(days)

Incubation

period

(days)

Nestling

period

(days)

Complete

Nestling

cycle

(days)

1. Large

cormorant

3-5 6-8 3-7 22-24 40-45 60

2. Indian shag 3-5 5-8 6-7 26-28 42-47 58

3. Little

Cormorant

2-4 5-8 6-7 22-26 40-43 62

4.. Darter 4-5 6-9 6-7 23-26 43-48 72

5. Grey heron 3-4 5-7 5-7 23-25 41-47 62-70

6. Purple heron 3-5 5-7 5-7 23-26 40-42 70-85

7. Cattle Egret 3-5 5-10 5-7 22-24 42-49 75-85

8. Large Egret 3-4 4-10 5-7 25-26 42-49 76-95

9. Median Egret 2-4 4-11 5-7 22-23 38-42 70-80

154

10. Little Egret 2-4 4-7 5-8 21-23 42-43 75-85

11. Night heron 3-4 3-7 5-6 21-23 41-48 71-87

12. Painted stork 3-4 5-7 5-7 29-32 115-125 153-162

13. Openbill stork 4-5 5-11 5-8 28-30 100-122 80-95

14. Spoonbill 3-4 7-8 5-7 22-26 48-52 75-84

15. White Ibis 3-5 7-8 5-7 23-27 43-50 75-85

BREEDING SEASON OF THE COLONIAL WATER BIRDS

A generalized account of the breeding season and timings is given for individual

heronry species in the Indian subcontinent by Ali and Ripley (1968). The breeding seasons

of some individual species at inland sites are given by Lamba (1963), Bhatia and Desai

(1971), Desai et al. (1978), Breeden and Breeden (1982a, b) Salim Kumar (1982) and

Parasharya (1984).

All the species, except the Grey Heron and Purple Heron had only one breeding

season which was in the monsoon. The Grey and Purple Herons breed in summer also

depending upon the availability of water and fish inside the lake during this season.

However, in the summer of 2006, the Little Egret, Median Egret, Little Cormorant, Indian

Shag and Darter also bred, although in small numbers. A substantial quantity of water was

available during the summer of 2006. Sometimes, the breeding of Grey Heron and Purple

Heron in summer was due to the failure of nesting in the breeding season or whether it was

a second brood is uncertain. Hancock and Kushlan (1980) and Tomilnson (1974a, b)

reported that double breeding is rare in Grey Heron and Purple Heron.

155

Breeding of all heronry species, except the painted stork, begins in July and

extends up to October depending on the onset of rain and time of release of water from the

Eastern canal. The painted stork is a late breeder, starting towards the end of August or the

beginning of September and extending up to November or early December. Breeding

season, breeding schedule and breeding cycle are summarized in Table-5.1, 5.2.

The proximate factors which trigger off breeding in all the species, except the

Openbill stork were the inundation of the area and the appearance of a large number of fry

and fingerlings in the vicinity of the nesting site. Apparently openbills begin breeding only

after flooding, as it increases the availability of their food supply by bringing the Pila

Snails out of aestivation (Saxena 1956).

During 2005, the nesting of Openbill stork was observed. The Openbill stork was

the first to arrive at the nesting site. They do so just before the onset of monsoon and begin

to build the nest but many waited for laying till the area was inundated. If monsoon fails

they don’t breed that year.

Pelicans are also colonial breeders. These birds arrive in late winter and their

breeding season continues from February to April. End of February or early of March,

they start construction of nest. In the present study only four pairs that built the nests on

the banyan tree. They made a large platform in top part of trees. The nest is a shallow

depression scraped on the tree in which some twigs, sticks, reeds or similar debris are

gathered. After about one week of courtship and nest building, the female lays a clutch of

usually 3 or 4 eggs.

156

Both the parents incubate for about 4 weeks. The young leave the nest 3-4 weeks

after hatching. At this point, usually only one young per nest has survived. They spend the

following month in a crèche or “Pod”, moulting into immature plumage and eventually

learning to fly. After fledging, the parents care for their chicks (Plate-5.3) some three more

weeks until the close family bond separates in late summer or early fall and the birds

gather in larger groups on rich feeding grounds in preparation for the migration.

REGULATION OF NESTING SEASON

A large number of studies made on the breeding patterns of birds have indicated

that every species of bird tends to bread at the time of the year when it can raise its young

most efficiently (Lack 1954, 1966). Those environmental factors that control efficiency of

breeding are called "Ultimate Factors" (Thomson 1950). The most important ultimate

factors for nearly all species of birds are the availability of adequate food supply. In the

present case the ultimate factor which determines the breeding season of all the wading

birds appeared to be the drying up of areas and the subsequent concentration of fish and

other organisms in shallow pools in comparatively deeper areas. Such mechanical

concentration of prey appears to be essential for any successful breeding in wading birds

(Kahl 1964, Kushalan et al. 1975). Both, the timing of breeding and the degree of breeding

success may be strongly affected by the rate of drying which concentrate the prey

(Kushaln et al. 1975, Clark and Clark 1979).

The food supply or its availability apart from being the most effective ultimate

factor apparently has an immediate influence on egg laying. For most species, the

production of eggs may depend upon the ability of females to collect the store nutrients

prior to the nesting attempt. (Ankney and Mac James 1978, Winkler and Waltes 1983,

157

Eldridge and Krapu 1988).Circumstantial and experimental evidence for the importance of

nutritional factors in spermatogenesis and egg laying are discussed by Marshall (1949),

Siivonen (1957), Assenmachar et al. (1965), Loft and Murton (1966), Lack (1967) and

Braithwaite and Frith (1970).

NEST BUILDING

The availability of nest building material was plenty in Thol Lake. Dry branches

and twigs of plants scattered on the ground were used for nest building. The nesting

material was re-used very commonly. Any nest abandoned during the nesting season was

occupied as such by a nesting pair, or it became a convenient source of material for the

nest- building in progress elsewhere.

Often if any nest in the vicinity was left unattended, a bird at a nest would steal the

material and add it to its own. Inter-specific stick steeling from the unguarded nest was

observed in many cases. Similar observation was made on Ardeola ibis (Valentine 1958,

Blaker 1969a), for Great Blue Heron by Pratt (1972) and Mock (1976), Great Egret by

Mock (1978), Reed Cormorant by Olver (1984) and for Whitebreasted Cormorant by

Olver and Kuyper (1978).

Little cormorant, Cattle Egret, Median Egret, Little Egret and Night Heron usually

steal the materials from nests of co-specific neighbors only. On the other hand, the other

birds were prone to steal the material not only from the co-specific neighbor, but also from

nests of the other relatively smaller species. The stick stealing birds could dismantle an

unguarded nest within a day or two, and they even ejected the eggs or chicks during the

process. In such a raiding and robbing operation, social dominance based more or less on

158

size of the inter-acting birds became operative. Dominance in this context refers to the

priority of success to resources that results from successful attacks, fights or supplants and

social dominance refers to inter-specific interactions (Morse 1974).

Mock (1976) observed that the Great Blue Heron (Ardea herodias) stole most of

the nest material from the nearby nests so the mates never lost visual contacts with each

other. Mock (1978) also recorded stick stealing in Casmerodius albus. Keeping the mate

in visual contact might help to strengthen the pair pond especially in the situation when

otherwise the male has to go long distances for collecting the nest material. The other two

subsidiary functions of the stick stealing could be the saving of energy by avoiding long

distant collecting trips and reducing the chances of predation.

NESTING PATTERN

It is usually the Openbill stork which first arrives at the nesting sites and occupies

the nesting trees. Although most species can be seen in both the large & small heronries,

some show a striking preference to a particular colony. The painted stork often keeps away

from other species. The white Ibis prefers a particular B site within a colony.

PARENTAL CARE

FEEDING THE CHICKS

In Cormorants and Darter, the chicks were fed on fish by both parents. Food was

regurgitated in small amounts into the open mouths of the chicks during the early stages of

development. At about two weeks of age, the chicks started to help themselves by

159

inserting their bills deep into the gullet of the parents. The parents were also seen

regurgitating water into the chick’s mouth.

In wading birds, freshly hatched chicks responded to the tactile and auditory

stimuli. They tried to stand erect on their weak legs with the support of the big abdomen,

raised the beak and gave short "Chick Chick" call. The adults regurgitated the food on the

nest floor, and the chicks in early stages, pecked the regurgitated matter and the chick even

begged at the parent's beak when it regurgitated. If the regurgitated food items were too

large for the chicks to swallow, the parents re-consumed them. As the chicks grew older,

the "chick chick" call became louder and was accompanied by the sidewise rocking

movement of the body. Older chicks grabbed the beak of the parent and pulled it down

violently to make them regurgitate. The chick grabbed the parents beak across the base so

that the regurgitated food directly passed on to it beak.

In white ibis, the young bird usually responds by increasing the volume and

increasing the frequency of its begging call, and by stretching and wobbling its neck and

head towards the adults. Then, sometimes with the aid of the parent, the young bird places

its bill into the parents partly-opened bill and moves its bill among the edge of the adults

bill until the head end anterior part of its neck are hidden inside the adults mouth cavity.

Feeding then takes place.

In cormorants and storks, the parents were also seen regurgitating water into the

chicks mouth, especially on hot days and this was observed in the Reed Cormorant

Phalacrocorax africanus (Olver 1984), White- breasted cormorant , Phalacrocorax carbo

160

(Olver and Kuyper 1978), Openbill Stork by (Kahl 1971c) and Blacknecked Stork

(Kahl 1971c, 1973).

GUARDING THE NEST

At least one parent actively guarded the chicks till they attained the age of 15 to 20

days. After that, the parent took up a perch some distance away from the nest and guarded

the chicks for a further period of 5 to 10 days and than finally left the chicks unguarded.

Thereafter, the parents returned to the nest only to feed the chicks or roost at night.

THERMOREGULATION

In most species, the adults shade small young much as they shade eggs. For

example, as the ambient temperature rises the parent stands over the nest, facing away

from sun, often angles the bill slightly skyward, flutters the gular area and lowers the

wings, which shade the young. During the hot hours of the day, almost all the guarding

birds in the colony were found keeping their face in the same direction. Direction of the

guarding bird changed with the position of the sun. The parents shading the chicks stood at

the edge of the nest, often keeping the legs flexed. Both the wings were partially or fully

kept loose so as to create a canopy under which the chicks were shaded. As the birds were

also susceptible to the sun heat, it seemed that the wing drooping posture had not only the

function of shading the chicks, but it also gave passage to the wind to pass through and

helped the bird in self thermoregulation. Kahl (1971) suggested that it is probable that the

function of shading the contents of the nest is often combined with self-thermoregulation

of birds by the spread-wing posture over egg or young in hot weather. The adult and

chicks started gular fluttering during the hot hours and such behavior was reported in Reed

161

Cormorant by Olver (1984), White breasted cormorant by Olverer and Kuyper (1978)

sacred ibis (Threskierns aethiopica) by urban (1974).

On several occasions, particularly during the warmest part of the day, the adult

cormorants and storks were seen regurgitating water in the nesting or drool it over the egg.

This behavior was noted in Openbill stork (Kahl 1971c), Blacknacked stork (Khal 1971c,

1973), Adjutant stork (Leptoptilos javanicus) Kahl (1971c), Marabou stork, whitebreasted

cormorant (Olver and kuyper 1978) and Reed Cormorant (Olver 1984), whether this was

mainly to cool the eggs or to maintain a proper humidity is not known.

PREDATION

Predation has frequently been implicated in the failure of heronry species (Dusi

and Dusi, 1967; Jenni, 1969; Pratt, 1972; Rodgers, 1987). The major predators in the area

during the egg laying period were crows (Plate-5.10) and during nesting period main

predators were Eagles and Marsh Harrier. During the incubation period the parent bird

deserts the nest at the approach of man. Eggs from these nests became vulnerable to the

crows. However, the parents do not desert the nest once the eggs are hatched as reported

elsewhere (Dusi and Dusi, 1967). During this period causality of chicks could occur if

man goes very close to the nest, the chicks become panicky and may fall into the water.

Chicks also fall from the nests due to the heavy wind or stormy weather and rain.

Some chicks were found hanging dead on the nest rim after heavy wind. Some chicks died

just because their one leg got trapped in a narrow branch.

162

ASYNCHRONOUS HATCHING

In a brood of three, the two older chicks were larger than a third chick. The

younger chick remained very small for a longer time and remained in the nest, while the

elder two roamed around the nesting tree. This difference in the growth of chicks was due

to the asynchronous hatching. The chicks hatched in the sequence in which the eggs were

laid. Therefore, the age difference between two chicks was quite often more than 5 days.

The parents feed the elder chicks which begged vigorously. So the younger chicks which

got less food remained smaller in size for a long time and even died due to starvation.

SUMMARY

163

SUMMARY

Piscivorous Birds are important components of wetland ecosystem as these birds

are at a relatively higher level in the food chain and represent a variety of predatory

niches. According to the feeding habits, the Piscivorous birds are grouped into three

categories, swimming birds (Pelecanidae and Phalacrocoracidae), wading birds (Ardeidae,

ciconidae and Threskiornithidae) and diving birds (Alcedinidae).

The present study was conducted in Thol Bird Sanctuary, Kadi Taluka, Mehsana

District, Gujarat, one of the famous sites for its wintering congregation of waterfowl and

massive colonies of nesting heronry species. The field study was conducted from January

2005 to January 2007.

Major objectives of the present study are: 1) to know the status of various bird

species by population assessment 2) to assess the habitat availability to various group of

birds 3) to assess the feeding methods adopted by birds to adjust to the environment. 4) to

assess breeding requirement and availability of resources in the area 5) to know the

ecological factors like water level, pH and salt contents, aquatic plants, fishes etc.

The population was assessed by direct counting of birds in all the aquatic sites out

of 23 species of fish eating birds, six species are swimming birds which contributed 35 %

of the overall population. Thirteen species of wading birds contributed about 63 % of the

population, and 2 % was contributed by the diving birds. Among all the fish eating birds

the highest number was of Pelicans followed by Indian shag. The Little blue Kingfisher

was the lowest in number. The highest average population of fish eating birds was in 2006

164

reaching the maximum number, in 2005 it was lowest. There is significant positive

relation between total population of Piscivorous birds and water depth, the fluctuation in

the water regime and related alternations in the habitat.

Habitats were classified into 6 types according to the dominant plant community

and water regime. The preference for a particular habitat by different species and

utilization of each habitat by them were studied by visiting various habitats regularly and

recording the occurrence of each species of swimming birds that preferred open water the

most, followed by shallow water + sparse vegetation for feeding. The Grey Heron and

Purple Heron preferred shallow water + sparse vegetation and the Night Heron and Pond

Heron did so mainly the edge of the dykes and mounds for feeding. All egrets except the

Cattle Egret preferred mainly shallow water + sparse vegetation for feeding. In the case of

the Cattle Egret the most preferred habitats were newly flooded area and grassy patch.

Painted Stork used mainly the sparse vegetation for feeding. The Openbill Stork preferred

mainly puddles for feeding. Large number of white Ibis, few of in shallow water + sparse

vegetation, grassy patch and Grass + Ipomea. The highest numbers of Spoonbill were in

shallow water. Common Kingfisher preferred shallow water + sparse vegetation and the

white breasted Kingfisher the reed beds. Among 12 species of wading birds, the Open bill

Stork had more specific habitat requirement while Large Egret, Little Egret and Pond

Heron had more flexibility in their habitat.

Food and feeding habits of the Piscivorous birds were studied by observing the

birds directly during different hours of the days. The swimming birds forage solitarily, but

those from large population forage in groups and exhibit synchronous diving. The diving

bird’s fish by diving from a perch or from hovering flight "Stand and wait", "walk

165

slowly", "walk quickly" and "running" were the major feeding techniques of the herons

and egrets. The two species of storks and white Ibis fed mainly by "probing". The

Spoonbill exhibited the highest frequencies of "Head Swaying Method". The Large Egret,

the Little Egret and the Painted Stork used eight methods. The last number of feeding

techniques (3) "Walk Quickly" was used by Purple Heron. Feeding behavior of the wading

birds related to the depth at which they foraged and the presence or absence of aquatic

macrophytes.

Of the 23 species of Piscivorous birds, 14 were colonial breeding. Site A & Site B

were the colonial water birds' nesting sites frequently. There are two breeding seasons for

colonial breeders, one in monsoon and the other in summer. All the species, except the

Grey Heron and Purple Heron, had only one breeding season which was in the monsoon.

The Grey Heron and Purple Heron bred in summer also. Breeding of all heronry species,

except the Painted stork begin in July and extends up to October. The Painted stork starts

towards the end of August. The date of release of water is also equally important. The time

of release of water does have a role in the nesting success of a various species. The major

predators during the egg laying period are eagles. The population and breeding success of

these colonial breeders in this sanctuary mainly depend on the quantum of annual input of

water, time of release and recruitment of fry into the sanctuary. The proximate factors

which trigger off breeding in all the species were the inundation of the area and the

appearance of a large number of fry in the nesting site. The food supply or its availability

apart from being the most effective ultimate factor apparently has an immediate influence

on egg laying. Ecological parameters such as date of water release, quantum of water input

and fish fry were correlated with the nesting success.

166

The time of release of water determines the annual cycle of many of the heronry species.

The extent of water spread area affects the breeding seasonality of most of the heronry

species. Maintenance of a particular water level or definite quantum of water supply every

year would help in breeding of many bird species. The staple food for the adult as well as

chicks of almost all the heronry species is fish. Therefore the influx of fish fry with water

from the canals determines the breeding success. The appropriate time for water release is

July, so that birds get adequate time to lay and raise the chicks before winter. From the

study it is understood that the water management and control of aquatic vegetation are

very essential for the survival of all the heronry species.

167

APPENDIX - I

FLORA:

A Check list of the macrophytes (aquatic and terrestrial) recorded at TS:

Scientific name Local Name Form

1 2 3

MENISPERMACEAE

Cocculus hirsutus Vevdi H

CAPPARACEAE

Capparis deciduas Kerdo S

Capparis sepiaria Kanther S

Cleome viscose Pili Talavani H

ELATINACEAE

Bergia ammannioides H

Bergia suffruticosa Ropatri H

MALVACEAE

Suaeda sp. - H

TILIACEAE

Corchorus aestuans Chunch H

Corchorus fascicularis - H

Corchorus olitorius - S

Corchorus sp. - H

168

ZYGOPHYLLACEAE

Tribulus terrestris Bethu Gokhru H

BALANITACEAE

Balanites aegyptiaca Ingorio, Hingoriyo T

MELIACEAE

Azadirachta indica Limdo T

CELASTRACEAE

Maytenus emarginata Viklo S

RHAMNACEAE

Zizyphus nummularia Chani Bor S

SAPINDACEAE

Cardiospermum halicacabum Kagdoliyo CI

ANACARDIACEAE

Mangifera indica Ambo, Keri T

PAPILIONACEAE

Alhagi pseudalhagi - S

169


1 2 3

Alysicarpus sp. - H

Butea monosperma Khakharo T

Crotalaria burhia Kharshan S

Derris indica Karanj T

Indigofera linnaei Fatakiya H

Indigofera oblongifolia Zil. Ziladi S

Melilotus alba Jungli Methi H

Melilotus indica - H

Rhynchosia minima Nani Kamalvel Tw

Tephrosia purpurea Sarpankho H

Trigonella occulta - H

CEASALPINIACEAE

Bauhinia racemosa Asotri T

Cassia auriculata Aval S

Cassia fistula Garmalo T

Cassia italica Mindhi Aval H

Cassia occidentalis Kasundri H

Cassia roxburghii - T

Cassia siamea - T

Cassia tora Kuvandio H

Tamarindus indica Amli T

MIMOSACEAE

170

Acacia nilotica Desi Baval T

Acacia sp. - T

Albizia odoratissima Dholo Sirisi T

Neptunia oleracea Lajalu H

Prosopis cineraria Khijado T

Prosopis chilensis Gando Baval S/T

CUCURBITACEAE

Coccinia grandis Ghiloda CI

Mukia maderaspatana Chanak Chibhdi CI

Trichosanthes cucumerina Jangli Parval CI

MOLLUGINACEAE

Glinus lotoides Mitho Okharad H

RUBIACEAE

Oldenlandia sp. - H

ASTERACEAE

Amberboa ramose Bada Vard H

171


1 2 3

Eclipta prostrate Bhangro H

Grangea maderaspatana Zinki Mundi H

Launaea procumbens Moti Bhonpatri H

Sphaeranthus indicus Gorakh Mundi H

Tridex procumbens Pardesi Bhangro H

Vernonia cineraria Sahadevi H

Xanthium strumarium Gadariyu H

SAPOTACEAE

Madhuca indica Mahudo T

Manilkara hexandra Rayan T

SALVADORACEAE

Salvadora oleoides Mithi Pilu T

Salvodora persica Khari Pilu T

ASCLEPIADACEAE

Calotropis procera Nano akado S

Calotropis gigantean Akdo S

GENTIANACEAE

Enicostema hyssopifolium Mamejevo H

EHRETIACEAE

Cordia gharaf Nani Gundi T

172

BORAGINACEAE

Coldenia procumbens Basario Okharad H

Heliotropium indicum Hathisundho H

CONVOLVULACEAE

Convolvulus microphyllus Shankhavali H

Cressa cretica Khariyu H

Evolvulus alsinoides Kali Shankhavali H

Ipomoea aquatica Nada ni Vel H

Ipomoea fistulosa Naffat Val S

Rivea hypocrateriformis Fang CI

SOLANACEAE

Datura metal Dholo Dhanturo H

Solanum indicum Ubhi Ringani H

Solanum surattense Bhoy Ringani H

MARTYNIACEAE

Martynia annua Vinchhudo H

ACANTHACEAE

Justicia simplex - H

173


1 2 3

Lapidogathis trisnerivis Haran Charo H

Peristrophe bicalyculata Kali Anghedi H

VERBENACEAE

Clerodendrum multiflorum Arani S

LAMIACEAE

Ocimum basilicum Damro H

Ocimum canum Ran Tulsi H

NYCTAGINACEAE

Achyranthes aspera Andhedo H

Pupalia lappacea Lampadi H

CHENOPODIACEAE

Chenopodium album Chil Bhaji H

POLYGONACEAE

Polygonum plebeium - H

EUPHORBIACEAE

Euphorbia hirta Dudheli H

Euphorbia nivulia Thor S

Euphorbia orbiculata - H

ULMACEAE

Holoptelea integrifolia Kanjo T

MORACEAE

174

Ficus religiosa Piplo T

Ficus virens Pipal T

CYPERACEAE

Cyperus sp. - H

POACEAE

Cynodon dactylon Darba H

Eragrostis sp. - H

URTICACEAE

Ficus benghalensis Banyan Tree T

NOTES :

1: In addition to the plants, like Sesbania sp., Echinochloa colonum, Nymphaea

sp., (Common Lilly) and Astereacantha longifolia / Hygrophila auriculata) are

also recorded in the environs.

2: Abbreviations :

H: Herb S: Shrub T: Tree Tw: Twiner CI: Climber

175

APPENDIX - II

A. Waterfowl recorded during Phase-I (September 1999-March 2000) :

I. FAMILY : DENDROCYGNIDAE

1. Whistling – Duck Dendrocygna javanica

II. FAMILY : ANATIDAE

2. Greylag Goose Anser anser

3. Bar-Headed Goose Anser indicus

4. Ruddy Shelduck Tadorna ferruginea

5. Comb Duck Cairina scutulata

6. Eurasian Wigeon Anas Penelope

7. Mallard Anas platyrhynchos

8. Spot-Billed Duck Anas poecilorhynca

9. Northern Shoveler Anas clypeata

10. Northern Pintail Anas acuta

11. Common Teal Anas crecca

12. Common Pochard Aythya ferina

13. Ferruginous Pochard Aythya nyroca

14. Tufted Duck Aythya fuligula

III. FAMILY : ALCEDINIDAE

15. Common Kingfisher Alcedo atthis

IV. FAMILY : HALCYONIDAE

16. White - Throated Kingfisher Halcyon smyrnensis

V. FAMILY : CERYLIDAE

176

17. Pied Kingfisher Ceryle rudis

VI. FAMILY : STRIGIDAE

18. Brown Fish Owl Ketupa zeylonensis

VII. FAMILY : GRUIDAE

19. Sarus Crane Grus antigone

20. Demoiselle Crane Grus virgo

21. Common Crane Grus grus

VIII. FAMILY : RALLIDAE

22. White - Breasted Waterhen Amaurornis phoenicurus

23. Common Moorhen Gallinula chloropus

24. Common Coot Fulica atra

IX. FAMILY : SCOLOPACIDAE

25. Black - tailed Godwit Limosa limosa

26. Eurasian Curlew Numenius arquata

27. Spotted Redshank Tringa erythropus

28. Common Redshank Tringa tetanus

29. Marsh Sandpiper Tringa stagnatilis

30. Common Greenshank Tringa nebularia

31. Green Sandpiper Tringa ochropus

177


32. Wood Sandpiper Tringa glareola

33. Common Sandpiper Actitis hypoleucos

34. Little Stint Calidris minuta

35. Temminck's Stint Calidris temmickii

36. Ruff Philomachus pugnax

X. FAMILY : JACANIDAE

37. Pheasant - Tailed Jacana Hydrophasianus chirugus

38. Bronze - Winged Jacana Metopidius indicus

XI. FAMILY : BURHINIDAE

39. Great Thick – Knee Esacus recurvirostris

XII. FAMILY : CHARADRIIDAE

40. Black - Winged Stilt Himantopus himantopus

41. Pied Avocet Recurvirostra avosetta

42. Pacific Golden Plover Pluvialis fulva

43. Little Ringed Plover Charadrius dubius

44. Kentish Plover Charadrius alexandrinus

45. Lesser Sand Plover Charadrius mongolus

46. Red - wattled Lapwing Vanellus indicus

47. Sociable Lapwing Vanellus gregarious

48. White - tailed Lapwing Vanellus leucurus

XIII. FAMILY : GLAREOLIDAE

49. Small Pratincole Glareola lacteal

178

XIV. FAMILY : LARIDAE

50. Brown - Headed Gull Larus brunnicephalus

51. Gull - Billed Tern Gelochelidon nilotica

52. River Tern Steran aurantia

53. Black - Bellied Tern Steran acuticauda

54. Whiskered Tern Chelidonius hybridus

XV. FAMILY : ACCIPITRIDAE

55. Eurasian Marsh Harrier Circus aeruginosus

XVI. FAMILY : PODICIPEDAE

56. Little Grebe Tachybaptus ruficollis

XVII. FAMILY : PHALACROCORACIDAE

57. Little Cormorant Phalacrocorax niger

XVIII. FAMILY : ANHINGIDAE

58. Darter Anhinga melanogaster

XIX. FAMILY : ARDEIDAE

59. Little Egret Egretta garzetta

60. Western Reef Heron Egretta gularis

61. Grey Heron Ardea cinerea

62. Purple Heron Ardea purpurea

63. Great Egret Casmerodius albus

179


64. Intermediate Egret Mesophoyx intermedia

65. Cattle Egret Bubulcus grayii

66. Indian Pond Heron Ardeola grayii

67. Little Heron Butorides striatus

68. Black -crowned Night Heron Nycticorax nycticorax

XX. FAMILY : PHOENICOPTERIDAE

69. Greater Flamingo Phoenicopterus rubber

XXI. FAMILY : THRESKIORNITHIDAE

70. Glossy Ibis Plegadis falcinellus

71. Black - Headed Ibis Threskiornis melanocephalus

72. Black – Ibis Pseudibis papillosa

73. Eurasian Spoonbill Platalea leucorodia

XXII. FAMILY : PELECANDIAE

74. Great White Pelican Pelecanus onocrotalus

XXIII. FAMILY : CICONIIDAE

75. Painted Storck Mycteria leucocephala

76. Asian Openbill Anastomus oscitans

77. Woolly - Necked Stork Ciconia episcopus

78. White Stork Ciconia ciconia

XXIV. FAMILY : PASSERIDAE

79. White Wagtail Motacilla alba

80. Yellow Wagtail Motacilla flava

180

Additional waterfowl species recorded at TS during Phase - II (August 2000-March 2001)

81. Cotton Pygmy – Goose Nettapus coromandelianus

82. Garganey Anas quequedula

83. Gadwall Anas strepera

84. Purple Swamphen Porphyrio porphyrio

85. Red - necked Phalarope Phalaropus lobutus

86. Oriental Pratincole Glariola maldivarum

87. Little Tern Sterna albifrons

88. Yellow - legged / Huglin's Gull Larus cachinnans / huglinii

89. Great Cormorant Phalacrocorax carbo

90. Dalmatian Pelican Pelecanus crispus

91. Greater Spotted Eagle Aquila clanga

92. Osprey Pandion haliatus

Identification Requiring Further confirmation

1. Black - header Gull Larus ridibundus

2. Indian Cormorant Phalacrocorax fiscicollis

3. Common Snipe Gallinago gallinago

Species recorded at TS in past (not seen during present study)

1. Lesser Flamingo Phoenicopterus minor

2. Great Reed Warbler Acrocephalus arundinaceous

3. White - browed Wagtail Motacilla maderaspatensis

4. Indian Skimmer Rynchops albicollis

5. Black Tern Chlidonias niger

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