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AERIAL CENSUS OFELEPHANTS AND OTHERLARGE HERBIVORES IN THESAVE VALLEYCONSERVANCY, ZIMBABWE:2001

K. M. Dunham

WWF - SARPO Occasional PaperNumber 5

June 2002

This census was carried out jointly by the Department of National Parks and Wild Life Management andWWF-SARPO (WWF Project No: ZW 0025). This report has also been published by the Department of National Parksand Wild Life Management.

The 2001 aerial survey and this publication were made possible through support made available by the Office of USAID Harareunder the terms of project 613-0241 and grant 690-0251-4-9001-00.The opinions expressed herein are those of the author and do not necessarily reflect the view of USAID.This material has been produced by the authority of, and for the use of CAMPFIRE in Zimbabwe, for information purposes only.

1

SUMMARY

Elephants and other large herbivores, wild and domestic, in the Save Valley Conservancy, insouth-eastern Zimbabwe, were surveyed from the air during the period 29 September – 6October 2001. This was the first time that the Conservancy has been included in a nation-wide survey of Zimbabwe’s elephant population. The area surveyed totalled 3484 km2. Theoverall sampling intensity was 22.5 %.

The survey was designed to estimate the number of elephants. Some large herbivores are noteasily seen from the air and their numbers were undoubtedly underestimated. Nonetheless,population estimates are given for these species, because the estimates provide useful indicesof abundance (with measures of precision) that can be used to determine spatial distribution,as well as temporal trends in population number. No corrections have been applied to any ofthe estimates to compensate for any undercounting or missed animals.

The estimated population numbers of the principal large herbivores were: elephant 535 (95%confidence interval (CI) 60.2 %); buffalo 733 (CI 92.2 %); wildebeest 2902 (CI 40.1 %),zebra 2710 (CI 24.3 %); kudu 1716 (CI 15.1 %); impala 12204 (CI 15.7 %); eland 1300 (CI33.5 %); waterbuck 212 (CI 60.9 %); giraffe 278 (CI 48.9 %); sable 79 (CI 114.3 %); cattle1274 (CI 39.9 %); sheep and goats 740 (CI 86.9 %); and donkeys 80 (CI 72.8 %). Theestimated total number of elephant carcasses represented 1.65 % of the estimated totalnumber of live and dead elephants.

Huts erected by squatters were observed in the southern half of the Conservancy: theestimated number of huts was 3014 (CI 17.4 %).

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TABLE OF CONTENTS

SUMMARY................................................................................................................................1LIST OF TABLES......................................................................................................................3LIST OF MAPS..........................................................................................................................4INTRODUCTION......................................................................................................................5METHODS.................................................................................................................................5

Survey Area .............................................................................................................................5Survey Design..........................................................................................................................6Flight Procedure .....................................................................................................................6Strip Width and Calibration....................................................................................................7Data Analysis ..........................................................................................................................8Animal Distribution.................................................................................................................8

RESULTS...................................................................................................................................9DISCUSSION...........................................................................................................................10

Influence of Squatters on Wildlife Populations.....................................................................10Number of elephants .............................................................................................................10

REFERENCES .........................................................................................................................11ACKNOWLEDGEMENTS......................................................................................................12Appendix 1. Calibration to determine strip width ....................................................................40Appendix 2. Aerial survey flight summary ..............................................................................41Appendix 3. Transect start and end points. ..............................................................................42Appendix 4. Transect Summaries.............................................................................................49

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LIST OF TABLES

Table 1. Sampling statistics for the 2001 aerial survey of elephants and other large herbivoresin the Save Valley Conservancy.......................................................................................14

Table 2 : Population estimates and statistics for Elephant in the Save Valley Conservancy...15Table 3 : Population estimates and statistics for Elephant Bulls in the Save Valley

Conservancy .....................................................................................................................15Table 4 : Population estimates and statistics for Elephant Cows in the Save Valley

Conservancy .....................................................................................................................15Table 5 : Population estimates and statistics for Buffalo in the Save Valley Conservancy.....15Table 6 : Population estimates and statistics for Black Rhino in the Save Valley Conservancy

..........................................................................................................................................18Table 7 : Population estimates and statistics for Rhinos (species unspecified) in the Save

Valley Conservancy..........................................................................................................18Table 8 : Population estimates and statistics for Eland in the Save Valley Conservancy........18Table 9 : Population estimates and statistics for Sable in the Save Valley Conservancy ........18Table 10 : Population estimates and statistics for Zebra in the Save Valley Conservancy......22Table 11 : Population estimates and statistics for Wildebeest in the Save Valley Conservancy

..........................................................................................................................................22Table 12 : Population estimates and statistics for Waterbuck in the Save Valley Conservancy

..........................................................................................................................................22Table 13 : Population estimates and statistics for Kudu in the Save Valley Conservancy ......22Table 14 : Population estimates and statistics for Giraffe in the Save Valley Conservancy ...27Table 15 : Population estimates and statistics for Impala in the Save Valley Conservancy....27Table 16 : Population estimates and statistics for Warthog in the Save Valley Conservancy .27Table 17 : Population estimates and statistics for Ostrich in the Save Valley Conservancy ...27Table 18 : Population estimates and statistics for Ground Hornbills in the Save Valley

Conservancy .....................................................................................................................31Table 19 : Population estimates and statistics for Cattle in the Save Valley Conservancy .....31Table 20 : Population estimates and statistics for Sheep and Goats in the Save Valley

Conservancy .....................................................................................................................31Table 21 : Population estimates and statistics for Donkeys in the Save Valley Conservancy.31Table 22 : Number estimates and statistics for Huts built by squatters in the Save Valley

Conservancy .....................................................................................................................33Table 23 : Population estimates and statistics for old Elephant Carcasses (age category 3), and

carcass ratios (all elephant carcasses) in the Save Valley Conservancy ..........................33Table 24 : Population estimates and statistics for Unidentified Carcasses in the Save Valley

Conservancy .....................................................................................................................33

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LIST OF MAPS

Map 1. The survey area - the Save Valley Conservancy in south-eastern Zimbabwe. ............13Map 2. The distribution of elephant during sample survey of SVC.........................................16Map 3. The distribution of buffalo during sample survey of SVC...........................................17Map 4. The distribution of rhinos during sample survey of SVC. ...........................................19Map 5. The distribution of eland during sample survey of SVC..............................................20Map 6. The distribution of sable during sample survey of SVC. .............................................21Map 7. The distribution of zebra during sample survey of SVC..............................................23Map 8. The distribution of wildebeest during sample survey of SVC. ....................................24Map 9. The distribution of waterbuck during sample survey of SVC......................................25Map 10. The distribution of kudu during sample survey of SVC. ...........................................26Map 11. The distribution of giraffe during sample survey of SVC..........................................28Map 12. The distribution of impala during sample survey of SVC. ........................................29Map 13. The distribution of warthog during sample survey of SVC. ......................................30Map 14. The distribution of domestic livestock during sample survey of SVC. .....................32Map 15. The distribution of squatters’ huts during sample survey of SVC. ............................34Map 16. The distribution of zebra in relation to the distribution of squatters’ huts.................35Map 17. The distribution of wildebeest in relation to the distribution of squatters’ huts. .......36Map 18. The distribution of kudu in relation to the distribution of squatters’ huts. ................37Map 19. The distribution of impala in relation to the distribution of squatters’ huts. .............38Map 20. The distribution of warthog in relation to the distribution of squatters’ huts. ...........39

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INTRODUCTION

Large wild and domestic herbivores were censused in the Save Valley Conservancy, south-eastern Zimbabwe, as part of a countrywide programme to survey all significant elephantpopulations in Zimbabwe. This was the first time that this area has been included in thesurvey programme. The southern tip of the conservancy touches the MalilangweConservancy, which contains resident elephants and is adjacent to Gonarezhou National Park.The National Park is part of the Greater Limpopo Transfrontier Park (formerly called theGaza-Kruger-Gonarezhou Transfrontier Park) and the elephant population in GonarezhouNational Park was surveyed during August 2001 (Dunham 2002).

Most of the elephants in the original population within the Save Valley Conservancy (SVC)were shot when the area was used for cattle ranching. The current population is derived froma very few animals that survived that extermination campaign, together with elephants thathave been translocated there since. Up to 59 elephants (captured as young animals duringculls in Zimbabwe’s Parks & Wild Life Estate) were freed during 1982-1992, and 141 and400 elephants from Gonarezhou NP were released in SVC during 1992 and 1993 respectively(Mockrin 2000). The groups of elephants released during 1992 and 1993 included animals ofall ages and both sexes, but there was a strong bias towards females amongst the adultanimals. Among the animals freed during 1993, there were relatively few immature animals,presumably because young animals had high mortality rates during the 1991/92 drought.Consequently, more than 50 % of the elephants released during 1993 were females aged about15 years or older (Mockrin 2000). At the end of 1993, the population of elephants in the SVCwas believed to number about 600 animals, but there has been no post-release monitoring ofthe elephants.

METHODS

Survey Area

The survey area covered 3484 km2 and was entirely within the Save Valley Conservancy(SVC), to the west of the Save River, and to the south of the Masvingo-Birchenough Bridgetar road. The conservancy is a conservation area comprised of twenty-two properties, twentyprivately-owned and two owned by government. The boundary of the conservancy was adouble, electrified fence, but major stretches of the fence have been stolen recently. When itwas complete, the fence hindered but did not prevent the movements of elephants.

The boundary of the SVC was digitised from the Surveyor General’s 1:250 000 maps of theregion. To simplify survey design, the SVC was divided into four strata, using the boundaryfence, the Turgwe River and the north-south gravel road as strata boundaries. A digital filecontaining the co-ordinates (in degrees latitude and longitude) of the boundaries of four stratawas converted into bna-format that could be used by the WWF software for designing aerialsurveys. The bna file was imported into the software CARTALINX (Hagan, Eastman &Auble 1998) and the area of each stratum determined.

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Survey Design

The procedures used followed those well established for aerial surveys of African largeherbivores (Norton Griffiths 1978) and utilised during earlier surveys of large herbivores inZimbabwe.

Systematic, parallel transects were positioned across each stratum. Transects were arranged atright angles to the principal environmental feature within a stratum (see Map 1 and Table 1for transect orientations). The distance between adjacent transects was 1.5 km. The highsampling intensity was chosen so that this survey, the first ever of the SVC elephantpopulation, would provide a good data set for the planning of future surveys.

Surveys were designed using WWF’s custom software (AIRDESW, version dated 29/05/97).Given a stratum boundary in the form of a bna file, and the transect orientation and spacing,this program generated flight lines (the transects), with the first flight line offset from the endof the stratum by the random number entered as the “offset”. The start and end points for eachtransect were transferred as waypoints to a GPS receiver in the plane prior to flying eachstratum.

Flight Procedure

The aircraft used was a Cessna 206. It was fitted with a radar altimeter and a Trimble TNL2000 GPS receiver. During surveys, the aircraft was flown at approximately 160 km per hourat about 300 feet above ground level. The actual height was recorded from the radar altimeterevery 30 seconds (of time) while flying along transects and later the mean height for eachtransect was calculated. Navigation along the transects was undertaken by the pilot, withreference to the GPS receiver and a course deviation indicator mounted in the aircraft’sinstrument panel.

The aircraft crew included a pilot (Charles Mackie), a recorder (Kevin Dunham) who sat nextto the pilot, and two observers (Fungai Muroki and Bruce Davison) who sat behind the pilotand recorder. Both observers had previous experience of observing during aerial surveys. Allfour crew could talk to one another through an intercom system.

All animals seen by the observers within the strips (see section Strip Width and Calibrationbelow) were called to the recorder, who wrote down the species, the number of individuals ofthe group that were within the strip, and the GPS location against the time (to the nearest 30seconds) after the start of the transect. To simplify recording, location was noted simply aslatitude. The recorder used a stopwatch to record the time (to the nearest second) taken to flyeach transect. A Garmin III GPS receiver was used to record automatically each flight path,with the plane’s location recorded every 500 m along the flight path. Each flight path wassaved as a ‘track log’ and, at the end of the survey, all track logs were transferred to acomputer.

Although the survey was designed especially to count elephants, all wild herbivores largerthan impala were counted, together with domestic cattle, sheep, goats and donkeys. Sheep andgoats could not be differentiated from the air and were lumped together as “sheep and goats”.

During the survey, groups of elephant bulls were differentiated from elephant cow herds,although the latter may have included some bulls. Elephant carcasses were recorded andclassified as:

Carcass Definition

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category

1 Fresh: intact; white droppings of vultures visible; vegetationtrampled; fluid stain on ground around carcass visible(animal likely to have died within the last 3 months).

2 Recent: pieces of hide still attached; skeleton still partlyarticulated; no vulture droppings; no trampled vegetation; nofluid stain evident (less than 1 year old, but generally sincethe last rainy season, i.e. 3 to 8 months old).

3 Old: bones scattered and bleached (probably died during orbefore the last rainy season, i.e. more than 8 months old butgenerally more than 1 year old and up to several years old).

The carcass “ratio”, sensu Douglas-Hamilton et al. (1992), (although it is not a ratio, but apercentage) was calculated as the estimated number of all elephant carcasses (i.e. agecategories 1, 2 and 3) as a percentage of the estimated number of all elephants (i.e. live +dead). Carcasses that could not be identified as elephant carcasses were recorded as“unidentified carcasses”.

Both black rhinoceros and white rhinoceros are present in the study area and observers couldnot always distinguish the two species from the air. Ostriches were recorded because they arelarge herbivores that are ecologically similar to large mammalian herbivores. Groundhornbills are large and conspicuous birds and any seen during the survey were recorded, at therequest of the DNPWLM ornithology section.

Huts built by squatters and poachers’ camps were also recorded. The latter were identified bythe presence of meat racks (horizontal branches mounted above the ground), with or withoutmeat, or meat hanging in trees.

Some large herbivores, e.g. kudu, are not easily seen from the air and their numbers wereundoubtedly underestimated. Nonetheless, population estimates are given for these species,because the estimates provide useful indices of abundance (with measures of precision) thatcan be used to determine spatial distribution, as well as temporal trends in population number.No corrections have been applied to any of the estimates to compensate for anyundercounting or missed animals.

All strata were flown during the period 29 September – 6 October 2001 (Table 1).

Strip Width and Calibration

Two fishing rods were attached with custom brackets to each wing strut, so that the rodspointed backwards and parallel to the ground during level flight. The distance between therods on each strut was arranged so that, when the aircraft was flying at 300 feet agl, thedistance represented a strip about 150 m wide on the ground. Each rod was marked with asmall piece of tape to provide the observers with a “decision point” (it was at this point thatthe observer decided whether an animal was inside the strip).

The strip widths were calibrated by flying the aircraft at right angles across an airstrip thathad two sets of large-sized numbers (from 1 to 30) arranged at 10 meter intervals along theside of the airstrip. The numbers were arranged as 30, 29, 28 ….1, 0, 1, …..28, 29, 30, with 0

8

near the centre of the airstrip. Each observer noted the largest and smallest number within hisstrip and the recorder noted the aircraft’s height, which varied between 240 and 300 feet.

The nominal combined strip width at 300 feet was determined by averaging the combinedstrip widths, after adjusting these to 300 feet agl (see Appendix 1 for data and calculations).

Data Analysis

Population estimates and confidence intervals for individual strata were calculated withWWF’s custom software (AIRSURVW, version dated 22/05/97), which uses Jolly’s (1969)method 2 for unequal-sized sample units. Given the combined strip width when the plane wasflying at 300 feet, and the mean height for each transect, the software determined the actualcombined strip width for each transect. The area of each transect was calculated as theproduct of the actual combined strip width and the transect length (provided by AIRDESW).Search intensity (in minutes km-2) for a stratum was defined as the total time spent flying alltransects within that stratum, divided by the total area of those same transects. The greater thesearch intensity, the less the probability that observers will not observe animals that arewithin the strips.

Transects near the boundary of a stratum were often broken into two or more sections, withland outside the stratum between the sections. For the purposes of analysis, data for allsections of the same transect were combined and entered into the program as one transect.The value of Student’s t entered in the program to calculate the confidence interval was tn-1

for P = 0.05 (Rohlf & Sokal 1981).

Population estimates for the entire study area were calculated as the sum of the estimates forindividual strata. The confidence interval for the population estimate for the entire study areawas calculated as:

tv . �(Sum of Variances)

where:

v = the degrees of freedom estimated by Satterthwaite’s rule (Gasaway et al. 1986).

Animal DistributionFor each sighting of animals or huts in the survey strips, the location, stratum, transectnumber, observer, species and number of animals were entered in a GIS (IDRISI) database.This was used to prepare maps showing the distribution of different species in the SaveValley Conservancy.

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RESULTS

The estimated numbers of elephant, elephant bulls in bull groups, elephants in cow herds,buffalo, black rhino, rhino of undetermined species, eland, sable, zebra, wildebeest,waterbuck, kudu, giraffe, impala, warthog, ostrich and ground hornbill are given in Tables 2to 18. Estimates of the population number are given for each stratum and for the entireconservancy. Confidence intervals (CI) and confidence limits (CL) are 95 % confidenceintervals and limits. “No. seen” is the number seen in the strips during the survey. There maybe small errors in the sums given at the foot of some tables. These are rounding errors:estimates, variances and sums were calculated with great precision in a spreadsheet, beforebeing rounded to zero decimal places.

There was only a minor difference between the number of elephants seen by the left observerand the number seen by the right observer. The left observer saw nine elephant groupstotalling 68 animals (1, 1, 1 and 2 bulls, and 6, 7, 15, 17 and 18 elephants in cow herds), whilethe right observer saw 6 groups totalling 52 animals (1 and 1 bull, and 8, 12, 15 and 15 cows).If the difference between the numbers seen by the two observers was not due simply tosampling variation, but instead was due to the right observer missing some animals, theestimated number of elephants in the SVC would be increased by only 13 %. In other words,the estimated number of elephants in the SVC would be 605, which is well within theconfidence limits of the present estimate of 535.

The estimated numbers of domestic livestock, namely cattle, sheep and goats, and donkeys,are given in Tables 19 to 21. The estimated number of huts erected by squatters is given inTable 22.

No elephant carcasses of age categories 1 or 2 were seen. Just two elephant carcasses ofcategory 3 were seen, one in the north-east stratum and one (only a skull) in the south-weststratum. The carcass “ratio” was 1.65 % (Table 23). “Ratios” less than 9 % are regarded asindicative of populations that are stable or increasing in number (Douglas-Hamilton et al.1992).

The estimated numbers of unidentified carcasses are given in Table 24. Other carcassesobserved were: one zebra (age category 1); one impala and one kudu (both category 2); andthree kudu (category 3).

No nyala or tsessebe were seen during the survey. Small numbers of duiker (2 sightings ofsolitary animals), klipspringer (1 sighting of 2 animals), bushbuck (3 sightings of solitaryanimals), bushpig (4 sightings, each of 4 or 5 animals, all north of the Turgwe River),crocodile (1 sighting of 3 animals), hippopotamus (1 sighting of 3 animals) and domestichorses (2 sightings of 2 or 3 animals) were seen during the survey, but no attempt has beenmade to estimate the numbers of these species. There were four sightings (total of 7 animals)of domestic dogs and one sighting of two people equipped with bows and arrows. Nopoachers’ camps were seen.

The spatial distribution of the principal wildlife species within the survey area is shown inMaps 2 to 13. The distribution of domestic livestock is shown in Map 14 and the distributionof squatters’ huts is shown in Map 15. Maps 16 to 20 show the distribution of the fivecommonest wildlife species in relation to the distribution of squatters’ huts.

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DISCUSSION

Influence of Squatters on Wildlife Populations

The density of wild animals was low in areas where squatters’ huts were abundant. This couldhave resulted from: a reduction in animal numbers as a result of the squatters’ activities; orthe movement of animals out of these areas; or a combination of these factors. Theinformation collected during this study does not allow one to determine whether the lowdensity was a result of a change in animal numbers, or a change in animal distribution.

Number of elephants

This survey has estimated that there were 535 elephants in the SVC during 2001. Theconfidence interval of this mean estimate was large (60 %), despite the high samplingintensity, and the lower and upper confidence limits were 213 and 857. The large confidenceinterval resulted from the high variability in elephant group size and the fact that herds werewidely scattered throughout the SVC. Even with the results of this survey, it is not obvioushow stratification could be improved to reduce the confidence interval in a future survey.

Given the large confidence interval, it is not possible to say whether, since 1993, the numberof elephants in the SVC has stayed approximately constant at about 600, or has increased byup to 250 animals. Even if the population had increased by 250 animals, the implied rate ofincrease of the population is relatively low, given the strong bias towards adult femalesamongst the released animals. However, the 1992 reintroduction was prompted by the severedrought of 1991/92 that affected much of southern Africa. During droughts in East Africa, theconception rate amongst elephant cows dropped to zero, as both the age of first conceptionincreased among young cows, and the intercalving interval increased for older cows (Moss1988). Evidence that the 1991/92 drought in southern Africa had a similar effect is suggestedby the observation that at Madikwe Game Reserve in South Africa - where 194 elephantsfrom Gonarezhou NP were freed during 1993 (Garai 1994) - few calves were born during1994 (M. Hofmeyr, pers. comm.). Thus, it is likely that the calving rate at SVC was low atthis time.

The SVC elephant population has suffered some human-induced mortality since the releases:one elephant was rumoured to have been killed in the Devuli Resettlement Area soon after itsrelease; during 2000, four elephants that left the SVC after squatters damaged the electrifiedboundary fence were shot by the DNPWLM; and another two animals were killed after theywere injured by snares set by poachers in the SVC (Mochrin 2000). During 2001, anotherthree or four elephants died after being injured by snares.

The possibility that some elephants left the SVC, either soon after their release (beforeconstruction of the boundary fence was complete) or more recently (after long stretches of theboundary fence were destroyed) cannot be ruled out. Analysis of the 2000 and 2001 recordsof elephant movements into and out of Malilangwe Conservancy (S. Clegg, unpubl. data)revealed that there was no net movement of elephants into or out of Malilangwe during 2000.But during 2001, two cow herds, including a group of 30 animals, moved into Malilangweduring June, without any corresponding records to indicate that they had left that conservancybeforehand.

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REFERENCES

Douglas-Hamilton, I., Michelmore, F. & Inamdar, A. (1992). African Elephant Database. UNEP,Nairobi.

Dunham, K.M. (2002). Aerial census of elephants and other large herbivores in GonarezhouNational Park and some bordering lands, Zimbabwe: 2001. Project Paper no. 80, WWF-SARPO, Harare.

Gasaway, W.C., DuBois, S.D. Reed, D.J. & Harbo, S.J. (1986). Estimating moose populationparameters from aerial surveys. Biological Papers of the University of Alaska 22. 108 pp.

Gibson, D. (1999). Aerial census of elephants and other large animals in north westernMatabeleland and the Zambezi Valley and escarpment, 1998. Project Paper no. 70, WWF-SARPO, Harare.

Garai, M. (1994). The effects of boma design on stress-related behaviour in juvenile translocated African elephants. Pachyderm 18: 55-60.

Hagan, J.E., Eastman J.R. & Auble, J. (1998). Cartalinx: the spatial data builder. User’s guide.Clark Labs, Clark University, Worcester, MA.

Jolly, G.M. (1969). Sampling methods for aerial censuses of wildlife populations. E. Afr. Agric.For. J. 34: 46-49.

Mockrin, M.H. (2000). The restocking of the Save Valley Conservancy with African elephants:an assessment of the translocation exercises and a model to predict population growth.Unpublished report to the SVC.

Moss, C.J. (1988). Elephant Memories: thirteen years in the life of an elephant family. WilliamMorrow & Co., New York.

Norton Griffiths, M. (1978). Counting Animals. Second edition. African Wildlife LeadershipFoundation, Nairobi.

Rohlf, F.J. & Sokal, R.R. (1981). Statistical Tables. Second edition. W.H. Freeman & Co., SanFrancisco.

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ACKNOWLEDGEMENTS

The author is grateful to the following:

• Mr Charles Mackie who was the pilot for the survey;

• Mr Bruce Davison (Ecologist, DNPWLM ) and Mr Fungai Muroki (Senior Ranger,DNPWLM) who were the observers for the survey;

• the staff of Chishakwe Ranch, Senuko Ranch and the Malilangwe Conservation Trust fortheir hospitality and assistance to the survey team during the fieldwork;

• the SVC Technical Advisory Committee and its chairman, Dr Alistair Pole, for theirsupport for this survey;

• the International Finance Corporation (SME Programme), which provided the additionalfunding that allowed the high sampling intensity;

• Dr Ivan Bond of WWF SARPO who managed the aerial survey programme, but stillretained his sense of humour; and

• Dr Markus Hofmeyr (formerly veterinarian at Madikwe Game Reserve), Mrs Sarah Cleggand Ms Miranda Mockrin who provided unpublished data and/or reports on elephants inMadikwe Game Reserve, Malilangwe Conservancy and the SVC respectively.

13

NW NE

SW

SE

32.0

-20.5

-20.0

NorthGrid

Map 1. The survey area - the Save Valley Conservancy in south-eastern Zimbabwe.Bold lines indicate strata boundaries, labels indicate strata names, and thin, parallel lines

indicate transects. The Turgwe River was the boundary between the north and south, and thegravel road was the boundary between the east and west.

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Table 1. Sampling statistics for the 2001 aerial survey of elephants and other large herbivores in the Save Valley Conservancy

Hours flownStratum name Area (km2) Transectspacing

(km)

Transectorientation

(°)

Number oftransects

(= n)

Percentof

stratumsampled

Time andDate sampled

Transects Stratum Total

Searchintensity(minutes

km-2)

SVC North-west 513 1.5 90 35 22.93 am & pm 3/10 1.92 2.75 4.33 0.98SVC North-east 1125 1.5 90 37 22.20 am & pm 5/10,

am 6/104.32 5.43 6.18 1.04

SVC South-west 857 1.5 135 32 22.64 am & pm 2/10 3.29 4.02 5.38 1.02SVC South-east 989 1.5 135 41 22.54 pm 29/9

am 30/9pm 1/10

3.74 4.73 7.05 1.01

Total 3484 km2 Overall 22.51 % Mean 1.01

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Table 2 : Population estimates and statistics for Elephant in the Save ValleyConservancy

Stratum Estimate No. Seen Variance % CI LowerCL

UpperCL

Density(km-2)

SVC North-west 74 17 3347 158.6 0 192 0.15SVC North-east 270 60 13038 85.7 39 502 0.24SVC South-west 102 23 4222 130.4 0 234 0.12SVC South-east 89 20 5797 173.4 0 243 0.09

Totals 535 120 26403 60.2 213 857 0.15

Table 3 : Population estimates and statistics for Elephant Bulls in the Save ValleyConservancy


UpperCL

Density(km-2)


Totals 31 7 134 74.0 8 54 0.01

Table 4 : Population estimates and statistics for Elephant Cows in the Save ValleyConservancy


UpperCL

Density(km-2)


Totals 504 113 26269 63.8 182 825 0.15

Table 5 : Population estimates and statistics for Buffalo in the Save Valley Conservancy


UpperCL

Density(km-2)


Totals 733 165 115611 92.2 57 1409 0.21

16

1 bull2 bulls6 - 10 cows11 - 15 cows

16 - 20 cows

Save River

River

Property Boundary

Elephant group size and composition

Map 2. The distribution of elephant during sample survey of SVC.Only groups seen within the survey strips are included on the distribution maps.

17

20

35

50

60

Buffalo group size

Map 3. The distribution of buffalo during sample survey of SVC.

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Table 6 : Population estimates and statistics for Black Rhino in the Save ValleyConservancy


UpperCL

Density(km-2)


Totals 18 4 88 107.0 0 36 0.01

Table 7 : Population estimates and statistics for Rhinos (species unspecified) in the SaveValley Conservancy


UpperCL

Density(km-2)


Totals 18 4 121 124.7 0 40 0.01

Table 8 : Population estimates and statistics for Eland in the Save Valley Conservancy


UpperCL

Density(km-2)


Totals 1300 291 47945 33.5 865 1735 0.37

Table 9 : Population estimates and statistics for Sable in the Save Valley Conservancy


UpperCL

Density(km-2)


Totals 79 18 2007 114.3 0 169 0.02

19

1 Black2 Blacks2 Species?

Rhino group size

Map 4. The distribution of rhinos during sample survey of SVC.Some rhinos could not be identified to species.

20

12 - 56 - 1011 - 15

16 - 20

21 - 25

26 - 30

Eland group size

Map 5. The distribution of eland during sample survey of SVC.

21

12 - 56 - 1011 - 15

Sable group size

Map 6. The distribution of sable during sample survey of SVC.

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Table 10 : Population estimates and statistics for Zebra in the Save Valley Conservancy


UpperCL

Density(km-2)


Totals 2710 608 109219 24.3 2053 3367 0.78

Table 11 : Population estimates and statistics for Wildebeest in the Save ValleyConservancy


UpperCL

Density(km-2)


Totals 2902 653 344056 40.1 1739 4066 0.83

Table 12 : Population estimates and statistics for Waterbuck in the Save ValleyConservancy


UpperCL

Density(km-2)


Totals 212 48 4262 60.9 83 342 0.06

Table 13 : Population estimates and statistics for Kudu in the Save Valley Conservancy


UpperCL

Density(km-2)


Totals 1716 386 17122 15.1 1457 1975 0.49

23

12 - 56 - 1011 - 15

16 - 20

21 - 25

Zebra group size

Map 7. The distribution of zebra during sample survey of SVC.

24

12 - 56 - 1011 - 20

21 - 30

31 - 50

Wildebeest group size

Map 8. The distribution of wildebeest during sample survey of SVC.

25

12 - 56 - 10

Waterbuck group size

Map 9. The distribution of waterbuck during sample survey of SVC.

26

1234

5

6 - 10

Kudu group size

Map 10. The distribution of kudu during sample survey of SVC.

27

Table 14 : Population estimates and statistics for Giraffe in the Save Valley Conservancy


UpperCL

Density(km-2)


Totals 278 63 4689 48.9 142 414 0.08

Table 15 : Population estimates and statistics for Impala in the Save Valley Conservancy


UpperCL

Density(km-2)


Totals 12204 2753 941169 15.7 10285 14123 3.50

Table 16 : Population estimates and statistics for Warthog in the Save ValleyConservancy


UpperCL

Density(km-2)


Totals 1279 288 17860 20.7 1014 1544 0.37

Table 17 : Population estimates and statistics for Ostrich in the Save ValleyConservancy


UpperCL

Density(km-2)


Totals 5 1 16 177.4 0 12 0.00

28

1234

6

12

Giraffe group size

Map 11. The distribution of giraffe during sample survey of SVC.

29

12 - 56 -1011 - 15

16 - 20

21 - 30

31 - 60

Impala group size

Map 12. The distribution of impala during sample survey of SVC.

30

1234

5

6

8

Warthog group size

Map 13. The distribution of warthog during sample survey of SVC.

31

Table 18 : Population estimates and statistics for Ground Hornbills in the Save ValleyConservancy


UpperCL

Density(km-2)


Totals 102 23 930 59.1 42 162 0.03

Table 19 : Population estimates and statistics for Cattle in the Save Valley Conservancy


UpperCL

Density(km-2)


Totals 1274 288 64578 39.9 766 1782 0.37

Table 20 : Population estimates and statistics for Sheep and Goats in the Save ValleyConservancy


UpperCL

Density(km-2)


Totals 740 167 101789 86.9 97 1383 0.21

Table 21 : Population estimates and statistics for Donkeys in the Save ValleyConservancy


UpperCL

Density(km-2)


Totals 80 18 838 72.8 22 138 0.02

32

12 - 56 - 1011 - 15

16 - 20

21 - 25

26 - 30

2 - 56 - 1011 - 20

21 - 30

31 - 50

> 50

12 - 5

Cattle herd size

Sheep/goat herd size

Donkey group size

Map 14. The distribution of domestic livestock during sample survey of SVC.

33

Table 22 : Number estimates and statistics for Huts built by squatters in the Save ValleyConservancy


UpperCL

Density(km-2)


Totals 3014 682 66432 17.4 2490 3538 0.87

Table 23 : Population estimates and statistics for old Elephant Carcasses (age category3), and carcass ratios (all elephant carcasses) in the Save Valley Conservancy


UpperCL

Density(km-2)

CarcassRatio

SVC North-west 0 0 0 0.0 0 0 0.00 0SVC North-east 5 1 16 177.4 0 12 0.004 1.8SVC South-west 4 1 16 185.0 0 13 0.01 3.8SVC South-east 0 0 0 0.0 0 0 0.00 0

Totals 9 2 32 125.5 0 20 0.003 1.65

Table 24 : Population estimates and statistics for Unidentified Carcasses in the SaveValley Conservancy


UpperCL

Density(km-2)


Totals 157 35 732 34.6 103 211 0.05

34

1234

5

6 - 10

11 - 17

Number of Huts

Map 15. The distribution of squatters’ huts during sample survey of SVC.

35

12 - 56 - 1011 - 15

16 - 20

21 - 25

1234

5

6 - 10

11 - 17

Zebra group size

Number of Huts

Map 16. The distribution of zebra in relation to the distribution of squatters’ huts.

36

12 - 56 - 1011 - 20

21 - 30

31 - 50

1234

5

6 - 10

11 - 17

Wildebeest group size

Number of Huts

Map 17. The distribution of wildebeest in relation to the distribution of squatters’ huts.

37

1234

5

6 - 10

1234

5

6 - 10

11 - 17

Kudu group size

Number of Huts

Map 18. The distribution of kudu in relation to the distribution of squatters’ huts.

38

12 - 56 -1011 - 15

16 - 20

21 - 30

31 - 60

1234

5

6 - 10

11 - 17

Impala group size

Number of Huts

Map 19. The distribution of impala in relation to the distribution of squatters’ huts.

39

1234

5

6

8

1234

5

6 - 10

11 - 17

Warthog group size

Number of Huts

Map 20. The distribution of warthog in relation to the distribution of squatters’ huts.

40

Appendix 1. Calibration to determine strip width

Strip width (in meters) for one observer = 10 * (Difference + 1).

Combined strip width (in meters) = 10 * (Differenceleft + Differenceright + 2).

Left observer:Fungi Muroki

Right observer:Bruce Davison

Runno.

Outer Inner Strip Width Outer Inner Strip Width

Combinedstrip width

(m)

Heightagl (ft)

Widthat 300ft (m)

1 27 12 160 22 5 180 340 300 3402 21 3 190 23 11 130 320 300 3203 25 10 160 24 7 180 340 300 3404 23 6 180 24 10 150 330 300 3305 26 11 160 20 5 160 320 300 3206 21 5 170 22 10 130 300 300 3007 23 10 140 26 7 200 340 300 3408 20 5 160 26 12 150 310 300 3109 20 8 130 24 7 180 310 290 321

10 20 5 160 24 11 140 300 300 30011 26 11 160 20 6 150 310 300 31012 21 7 150 21 8 140 290 300 29013 28 13 160 - - 30014 21 6 160 22 8 150 310 300 31015 25 10 160 22 7 160 320 310 31016 22 6 170 22 9 140 310 300 31017 26 10 170 20 7 140 310 300 31018 20 4 170 24 11 140 310 300 31019 23 9 150 23 8 160 310 300 31020 22 5 180 23 5 190 370 300 37021 24 10 150 24 8 170 320 310 31022 19 6 140 20 8 130 270 250 32423 20 7 140 19 7 130 270 250 32424 20 5 160 27 13 150 310 300 31025 - 10 20 7 140 30026 26 9 180 27 9 190 370 300 37027 23 7 170 29 11 190 360 300 36028 28 11 180 26 7 200 380 300 38029 24 10 150 28 9 200 350 300 35030 25 10 160 26 9 180 340 310 32931 24 9 160 26 8 190 350 300 35032 26 9 180 27 9 190 370 300 37033 26 10 170 26 8 190 360 300 36034 26 8 190 29 10 200 390 300 39035 26 8 190 28 9 200 390 300 390

Mean combined strip width (in meters) at 300 feet agl = 332

41

Appendix 2. Aerial survey flight summary

Date Time Flight time(hours:minutes)

Duty

28 Sept 2001 pm 2:05 Positioning, Harare to Malilangwe

29 am 1:00 Calibration

29 pm 2:10 Stratum South-east, transects 1-15

30 am 2:42 Stratum South-east, transects 16-31

30 pm 1:03 Flight aborted – radar altimetermalfunctioned

1 October am 1.5 hours Malilangwe to Harare. Repairs to radaraltimeter

1 pm 1.8 Harare to Malilangwe

1 pm 2:11 Stratum South-east, transects 32-41

2 am 3:31 Stratum South-west, transects 1-20

2 pm 1:52 Stratum South-west, transects 21-32

3 am 2:49 Stratum North-west, transects 1-21

3 pm 1:31 Stratum North-west, transects 22-35

5 am 2:47 Stratum North-east, transects 22-37

5 pm 1:28 Stratum North-east, transects 14-21

6 am 1:56 Stratum North-east, transects 1-13

6 am 0:30 Return observer to Malilangwe

6 pm 0:18 Positioning, Senuko to Chishakwe

6 October pm 1:30 Positioning, Chishakwe to Harare

42

Appendix 3. Transect start and end points.

SVC north-westNumber of transects : 35Transect Bearing : 90.00 DegreesTransect Spacing : 1.50 km

Transect # : 1AStart Lat : S 20 : 24.565 Start Lon : E 31 : 57.933Finish Lat : S 20 : 24.565 Finish Lon : E 31 : 59.507Length : 2.74 km

Transect # : 1BStart Lat : S 20 : 24.565 Start Lon : E 31 : 59.943Finish Lat : S 20 : 24.565 Finish Lon : E 32 : 5.931Length : 10.43 km

Transect # : 1CStart Lat : S 20 : 24.565 Start Lon : E 32 : 8.737Finish Lat : S 20 : 24.565 Finish Lon : E 32 : 10.579Length : 3.21 km

Transect # : 2Start Lat : S 20 : 23.755 Start Lon : E 32 : 9.985Finish Lat : S 20 : 23.755 Finish Lon : E 31 : 58.430Length : 20.12 km






Transect # : 8Start Lat : S 20 : 18.895 Start Lon : E 32 : 6.092Finish Lat : S 20 : 18.895 Finish Lon : E 31 : 59.541Length : 11.41 kmTransect # : 9

Start Lat : S 20 : 18.085 Start Lon : E 31 : 59.733Finish Lat : S 20 : 18.085 Finish Lon : E 32 : 5.897Length : 10.73 km









Transect # : 18Start Lat : S 20 : 10.795 Start Lon : E 32 : 6.519Finish Lat : S 20 : 10.795 Finish Lon : E 32 : 1.464Length : 8.80 kmTransect # : 19Start Lat : S 20 : 9.985 Start Lon : E 32 : 1.657

43

Finish Lat : S 20 : 9.985 Finish Lon : E 32 : 6.549Length : 8.52 km








Transect # : 27Start Lat : S 20 : 3.505 Start Lon : E 32 : 1.978Finish Lat : S 20 : 3.505 Finish Lon : E 32 : 6.318

Length : 7.56 km









SVC north-eastNumber of transects : 37Transect Bearing : 90.00 DegreesTransect Spacing : 1.50 km



Transect # : 3Start Lat : S 20 : 25.375 Start Lon : E 32 : 11.434Finish Lat : S 20 : 25.375 Finish Lon : E 32 : 16.747Length : 9.25 kmTransect # : 4Start Lat : S 20 : 24.565 Start Lon : E 32 : 16.789Finish Lat : S 20 : 24.565 Finish Lon : E 32 : 10.579Length : 10.81 km

44












Transect # : 16Start Lat : S 20 : 14.845 Start Lon : E 32 : 19.661













45






Transect # : 33Start Lat : S 20 : 1.075 Start Lon : E 32 : 6.533







SVC south-westNumber of transects : 32Transect Bearing : -45.00 DegreesTransect Spacing : 1.50 km






Length : 19.09 km





Transect # : 10

46













Length : 21.66 km












47

SVC south-eastNumber of transects : 41Transect Bearing : -45.00 DegreesTransect Spacing : 1.50 km











Transect # : 10









Transect # : 18Start Lat : S 20 : 39.208 Start Lon : E 32 : 0.967Finish Lat : S 20 : 45.850 Finish Lon : E 32 : 8.052Length : 17.39 kmTransect # : 19Start Lat : S 20 : 45.069 Start Lon : E 32 : 8.441Finish Lat : S 20 : 38.734 Finish Lon : E 32 : 1.683Length : 16.59 km


48

Length : 16.17 km











Transect # : 31












49

Appendix 4. Transect Summaries

Species codes:

Code SpeciesBkRh Black RhinocerosBuff BuffaloCatt CattleDog Domestic dogDonk DonkeyElC3 Elephant carcass, age category 3Eld ElandEleF Elephant cowEleM Elephant bullGhb Ground hornbillGrf GiraffeHipo HippoHuts Hut built by squatterImp ImpalaKudu KuduOst OstrichRhin Rhinoceros (species not determined)Sab SableShoa Sheep and/or goatsUnCa Carcass of unknown speciesWbck WaterbuckWbst WildebeestWhog WarthogZeb Zebra

Other abbreviations

Abbreviation Meaningn number of transects sampledN possible number of transects in

stratumt Student’s t value, P = 0.05T # transect number- no animals seen in strips

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