NO. 241 March 1980

ATOLL RESEARCH BULLETIN

241. Geography and Ecology of Little Cayman Ediled by D.R. Sroddm and M.E.C. GiglioLi

Issued by THE SMITHSONIAN INSTlTUTION Washington, D.C., U.S.A.

Issued by THE SMIrI'NS0NIAN INS'I'ITUI'ION

ashington. L3.C.. U.S.A. March 1980

ACKNOWLEDGEMENT

The A t o l l Resea rch B u l l e t i n i s i s s u e d by t h e Smi thson ian I n s t i t u t i o n , a s a p a r t of i t s a c t i v i t y i n t r o p i c a l b i o l o g y , t o p l a c e on r e c o r d i n f o r m a t i o n on t h e b i o t a of t r o p i c a l i s l a n d s and r e e f s , and on t h e envi ronment t h a t s u p p o r t s t h e b i o t a . The B u l l e t i n i s s u p p o r t e d by t h e N a t i o n a l Museum of N a t u r a l H i s t o r y and is produced and d i s t r i b u t e d by t h e Smi thson ian P r e s s . The e d i t i n g i s done by members of t h e Museum s t a f f and by D r . D. R. S t o d d a r t ,

The B u l l e t i n was founded and t h e f i r s t 117 numbers i s s u e d by t h e P a c i f i c S c i e n c e Board, N a t i o n a l Academy o f S c i e n c e s , w i t h f i n a n c i a l s u p p o r t from t h e O f f i c e of Naval Research . Its p a g e s were l a r g e l y d e v o t e d t o r e p o r t s r e s u l t i n g from t h e P a c i f i c S c i e n c e Board ' s C o r a l A t o l l Program,

The s o l e r e s p o n s i b i l i t y f o r a l l s t a t e m e n t s made by a u t h o r s of p a p e r s i n t h e A t o l l Research B u l l e t i n r e s t s w i t h them, and s t a t e m e n t s made i n t h e B u l l e t i n do n o t n e c e s s a r i l y r e p r e s e n t t h e v i ews of t h e Smi thson ian n o r t h o s e of t h e e d i t o r s of t h e B u l l e t i n .

IT, R, h'osberg I a n G , MacIn ty re Me-Ti. S a c h e t

Smi thson ian ins tiru t i o n Vash ing ton , D. C. 2G560

D. R, S t o d d a r t

Department of Geography U n i v e r s i t y of Cambridge Downing P l a c e Cambridge, England

ATOLL RESEARCH BULLETIN

No. 241

OELOCY OF LIT

@:clltd 1n D.R. 3 t o t l r i a n t anti 11.E.(:. d;ielioli

P l a t e 1. The south c o a s t of L i t t l e Cayman, from t h e -

southeas t ; noon cumulus extending along t h e l eng th of t he i s l a n d

CONTRIBUTORS

R.R. ASKEW Department of Zoology, The Universi ty , Manchester, England

A.W. DIAMOND Department of Zoology, Univers i ty of Nairobi , Nairobi , Kenya

M. E. C. G I G L I O L I Mosquito Research and Control Uni t , Grand Cayman, Cayman I s l ands , West Ind ie s

M.V. HOUNSOME The Manchester Museum, Manchester, England

G.W, POTTS Marine Bio logica l Associat ion of t h e U . K . , The Marine Laboratory, Plymouth, England

G.R. PROCTOR Natural History Divis ion, I n s t i t u t e of Jamaica, Kingston, Jamaica

D.R. STODDART Department of Geography, Universi ty of Cambridge, Cambridge, England

C . WOODROFFE Department of Geography, Univers i ty of S h e f f i e l d , She f f i e ld , England

iii

CONTENTS

S c i e n t i f i c survey of L i t t l e C a y m a n

D.R. Stoddart

G e o l o g y and g e o m o r p h o l o g y of L i t t l e C a y m a n

D.R. Stoddart

M a n g r o v e s e d i m e n t s of L i t t l e C a y m a n

C . Woodroffe

T h e zonat ion of rocky l i t t o r a l areas around L i t - t l e C a y m a n

T h e l i t t o r a l f ishes of L i t t l e C a y m a n

G. W . P o t t s

V e g e t a t i o n of L i t t l e C a y m a n

D . R . Stoddar t

C h e c k l i s t of the p lan t s of L i t t l e C a y m a n

G.R. P r o c t o r

'l'errestrial f a u n a [ e x c l u d i ~ l q b i r d s and i n s e c t s ) or' L i t t l e C a ynan

C e r i o n I r m a ( M a y n a r d ) (Molluscs: C e r i o ~ l i d a e 1 or? L i t t l e C a y m a n

M.V. H o u n s o m e and R . R . A s k e w

T h e insect fauna of L i t t l e C a y m a n

R . R . A s k e w

T h e O d o n a t a of t h e C a y m a n Is lands

R . R . A s k e w

T h e b u t t e r f l y ( L e p i d o p t e r a , R h o p a l o c e r a ) fauna of the C a y m a n I s lands

Page 1

11

1 7

2 3

4 3

5 3

7 1

8 1

91

9 7

115

R.R. A s k e w

13. Hawkmoths (Lepidoptera, Sphingidae) of L i t t l e Cayman 139

R. R . Askew

14. Ecology and species turnover of the b i r d s of L i t t l e Cayman 141

A.W. Diamond

15. The Red-footed Booby colony on L i t t l e Cayman: s i z e , s t r u c t u r e and s igni f icance 165

A.W. Diamond

16. L i t t l e Cayman: ecology and s igni f icance

D.R. Stoddart

LIST OF PLATES

1. The south c o a s t of L i t t l e Cayman, from the southeas t ; noon cumulus extending along the length of the i s l a n d F r o n t i s p i e c e

Fo l lowing page 16

2. Sparrowhawk H i l l from the no r th c o a s t beach r idge

3. Limestone r i d g e in land of t h e c o a s t a l s a l t pond a t Charles Bight

4. Limestone r idge and c o a s t a l sand f l a t and s a l t pond a t Mary's Bay

5. Dissected sur face on the Bluff Limestone (6032 1763) ; che s i d a s of t he frame a r e 50 cm long

6. De ta i l of sur face d i s sec t ion on Bluff Limestone

7. Large dol ine i n Bluff Limestone (6028 1778)

8. Cave speleothems revealed by roof co l l apse (6003 1781)

9. Bluff coas t a t East Poin t

10. Ironshore platform west of Calabash Spot

11. D i p l o r i a colcmiss i n coas t a l Ironshore a-t S a l t Rocks

I%, Strombus she i l s I n c o a s ~ a l Ironshore a t S a l t Rocks

13. Ironshore deposiLs on the landward margins of t h e Blossom Vi l lage lagoon

14. Potholes i n the Ironshore sur face a t S a l t Rocks

15. Bedded c a l c a r e n i t e s overlying r ee f f a c i e s i n t h e Ironshore a t S a l t Rocks

16. De ta i l of t h e bedded c a l c a r e n i t e s a t S a l t Rocks

17. Beach r idge e a s t of P i r a t e ' s Poin t

18. Beach r idge a t Calabash Poin t

19. Sand beach r idge with juveni le C a s u a r i n a i n Wearis Bay

2 0 . Storm wash-over cobbles nor th of East Rocky Poin t , Blossom

Bay

2 1 . Hurricane-deposited storm blocks on the Ironshore platform south of t h e a i r s t r i p (5957 1737)

F o l l o w i n g page 42

Preston Bay showing the exposed l i t t o r a l rocks and sandybeach above them

West End Rocks with a l a r g e l i t t o r a l rock pool i n t he f oreg.-ound

E c k i r l i n u s n o d i a l o s u s i n c r ev ices wi-th L i t t o r i n a z i c z a c on the upper m i d l i t t o r a l region of Pres-ton Bay

T e c t a r i i a s rnuz- icatus (arrowed) among the leaves of ,Sesuvium p o r t u l a c a s t r u m a.t West End Rocks

N e r i t a p e l o r o n t a and N. t e s s e l l a t a on rocks a t t he m i d l i t t o r a l zone, E c b i n i n u s n o d u l o s u s and L i t t o r i n a z i c z a c a r e p re sen t i n c r ev ices

T u r b i n a r i a t u r b i n a t a , P a d i n a s a n c t a e - c r u c i s and D i c t y o t a sp. i n t he lower m i d l i t t o r a l zone a t West End Rocks

East End showing t h e s t eep and deeply d i s s e c t e d l i t t o r a l region

T e c t a r i u s r n u r i c a t u s i n l a r g e numbers i n -the s u p r a l i t t o r a l f r i n g e a t Eas t End

~ c a r ~ t h o p l e u r a i j r a n u l a t a i n shallow rock pools i n t he lower m i d l i t t o r a l zone

Rock pool a t West End Rocks showing P u p e r i t a pupa and L i t t o r i n a m e s p i l l u r n sca t t e r ed over the bottom of the pool

v i i

35. P u p e r i t a pupa gathered on a rocky pinnacle within a rock pool

36. Diadema a n t i l l a r u m i n a low t i d e l e v e l rock pool a t Preston

Bay

F o l l o w i n g page 7 0

37. Dry evergreen f o r e s t south of Sparrowhawk H i l l ; note t h e human f i g u r e i n the c e n t r e of t h e p i c t u r e (6003 1775)

38. Dry evergreen woodland in land from Jackson's Bay (5977 1768)

39. Dry evergreen t h i c k e t on Sparrowhawk H i l l (6004 1780)

40. Open dry evergreen t h i c k e t on the northern s lopes of Sparrowhawk H i l l (6003 1781)

41. A c r o s t i c h u m aureum i n l imestone so lu t ion holes nor th of Blossom Vi l lage (5953 1750)

42. Wind-sheared c o a s t a l hedge of Cocco loba w i f e r a , Owen Is land

4 Pioneer H y m e n o c a l l i s l i t o r e a and o ther herbaceocs p ioneers a t Sandy Point

44. Decapitated coconuts on t h e c o a s t a l beach r idge near West Point

45. Coconut p l a n t a t i o n with many dead t r e e s on Owen Is land

46. Low R h i z o p h o r a i n the c o a s t a l lagoon e a s t of Diggary 's Poin t (6030 1773)

47, T a l l A v i c e n n i a woodland i n Tarpon Lake

4 8 , ' i 'a i l l i i l i zophora ;.ioociland i n Tarpon Lake

49- I n t e r i o r of t a l l Ri i i zophora woodland a t Tarpon Lake

50, Dwarf in land Rhi zophora i n an i n t e r i o r depression (5975 17613

51. Inland S e s u v i u ~ n marsh with open pools a t t h e e a s t end of the i s l a n d (6074 1795)

F o l l o w i n g page 96

52. The s i t e on the t rans- i s land t r ack no r th of Blosson Vi l lage where l i v i n g Cerion n a n u s was found. The s n a i l s were l i v i n g on shrubs of E v o l v u l u s a r b u s c u l a here seen growing on t h e pa th

v i i i

53 . C e r i o n nanus and young C.pannosum on a s ing le p lan t of E v o l v u l u s a r b u s c u l a . Inse t : a l i v i n g specimen of C . nanus

54. Six s h e l l s of C . nanus with an example of C . pannosum f o r comparison ( t o the same s c a l e ) . Four typ ica l s h e l l s a r e shown together with two examples of extremes i n length/height r a t i o

LIST OF FIGURES

F o l l o w i n g page 10

1. Location of t he Cayman I s l ands

2 . Iilonth1.y r a in fa l l . a t L i t t l e Cayman

F o l l o w i n g page 1 6

3. Topography of L i t t l e Cayman, based on the Direc tora te of Overseas Surveys l:25,000 map (1965)

4 . Topographic t r a v e r s e s A-F: f o r l oca t ions see Figure 3

5. Geology and h a b i t a t s of L i t t l e Cayman

6. Topographic p r o f i l e s a t S a l t Rocks

7. Beach r idge and c l i f f e d coas t p r o f i l e s : f o r l o c a t i o n s see Figure 3

8. Size composition of beach sediments

F o l l o w i n g page 22

9 , Topographic p r o f i l e of in land dwarf Rhi zophora scrub

LO, Topographic p r o f 1 I . e ~ of A, Fhi zophora woodland a t Tarpon Lake, I3, North coas t salt-pond Rhizopi loza woodland near Sparrowhawk Hil. l

11, Map of L i t t l e Cayman showing the main coas t a l sampling a reas

1 2 . Graphs of the d a i l y t i d a l range during t h e per iod of t h e expedit ion together with hourly t i d a l he ights on a neap t i d e and a spr ing t i d e . The da ta were provided by D r . K. George and based on f i g u r e s obtained from A d m i r a l t y T i d e T a b l e s , Vol. 11, 1975

P r o f i l e of t h e shore a t Preston Bay with an i n d i c a t i o n of t h e v e r t i c a l zonat ion of t h e l i t t o r a l spec ies . The i n s e t shows how on t h e upper shore some spec i e s remain i n pools ( N e r i t a v e r s i c o l o r ) , i n mois t c r ev ices ( L i t t o r i n a z i c z a c ) , and on the open rock ( E c h i n i n u s n o d u l o s u s and N o d i l i t t o r i n a t u b e r c u l a t a ) . L i t t o r i n a z i c z a c r e f e r s t o t he appropr ia te spec i e s of t he L. z i c z a c "complex" (Borkowski and Borkowski, 1969) found i n an a rea , and does so i n subsequent f i g u r e s

Histograms i n d i c a t i n g t h e d i s t r i b u t i o n of four spec i e s of gastropod along t h e j e t t y a t Preston Bay. Black columns r ep resen t t h e e a s t s i d e of t h e j e t t y and s t i p p l e d columns t h e west s i d e

P r o f i l e of t h e shore a t West End Rocks wi th an i n d i c a t i o n of t h e v e r t i c a l zonat ion of t h e common l i t t o r a l spec i e s

P r o f i l e of t h e shore a t J ackson ' s Bay Poin t i n d i c a t i n g t h e v e r t i c a l zonation of t h e common l i t t o r a l spec i e s . The d o d i e occurrence of some l i t t o r i n i d s and n e r i t e s i s a r e s u l t of t h e i r presence on a l a r g e boulder found j u s t below MLWM

The d i s t r i b u t i o n of rno l lu sca~~ zones around. a bou.ld.er a t Jackson ' s Bay Poin t ( see Figure 1 6 ) . It should be not iced t h a t t h e r e i s a d i f f e r e n c e i n t he e x t e n t of t h e zones on the seaward and landward s i d e s of the boulder

P r o f i l e of t h e shore a t t h e Eas t End i n d i c a t i n g t h e d i s t r i b u t i o n of t he common l i t t o r a l spec ies

Out l ines and o r i e n t a t i o n s of l i t t o r a l rock pools a t West End Rocks and Jackson ' s Bay. Pools A , B and C occurred a t approximately mid-tide l e v e l s and D, E and F a t low t i d e l e v e l s . A diagrazmacic secclon X-Y of pool A i s given with the d i s t r i b u ~ i o n of some of t h e common rock pool i n v e r t e b r a t e s

t70110winy page 52

20. Dlagran! of ( a ) Splash Zone and. (b) S u y e Zone ; > O O ~ S wi th t h e i r t y p l c a i inhabitants: 1, Eucinostoiilus a r q e n c e u s ; 2 . B a t h y g o b i u s s o p o r a t o r ; 3. Hbudefduf s a x a t i l i s ; 4. L u t j a n u s apodus; 5. Gerres c i n e r e u s ; 6. Tomicodon f a s c i a t u s ; 7 . A d i o r y x v e x i l l a r i u s ; 8 . Eupomacentrus l e u c o s t i c t u s ; 9. P u p e r i t a pupa; 10. A c e t a b u l a r i a s a n c t a e - c r u c i s ; 11. Thalassoma b i f a s c i a t u m ; 1 2 . Diadema a n t i l l a r u m ; 13. C a n t h i q a s t e r r o s t r a t a ; 14. L i t t o r i n a mespil lurn; 15. Echidna c a t e n a t a

Fo l lowing page 70

2 1 . Habi ta t s and geology of L i t t l e Cayman

2 2 . Vegetation and topography of Owen I s l and

Fol lowing page 90

23. Number of spec ie s (o ther than i n s e c t s and b i r d s ) and sampling s i t e s , L i t t l e Cayman, 1975

Fol lowing page 11 4

24. The progression of i n s e c t spec ies recorded on L i t t l e Cayman by da tes . F u l l c i r c l e s s i g n i f y d a t e s on which ha l f t he f i n a l t o t a l of spec ie s i n each group were found. The l i g h t t r a p was f i r s t operated on 14 J u l y , t he Malaise t r a p on 16 J u l y , and the main c e n t r a l f o r e s t c o l l e c t i o n s were made on 28 July

Fol lowing page 138

25. The r e l a t i o n s h i p between t h e numbers of b u t t e r f l y spec ies and t h e a r e a s (sq km on a logari thmic s c a l e ) of Cuba, Hispa.niola, Puerto Rico, Jamaica, and the Cayman I s l ands (r = 0.98)

26 . Map of L i t t l e Cayman showing l o c a l i t i e s mentioned i n t h e t e x t and the s i t u a t i o n of t h e t r a n s e c t s

2 7 . Associat ions between t h e b u t t e r f l y faunas of t h e Greater A n t i l l e s based upon mean va lues of Co le ' s Coef f i c i en t of Associat ion. The s c a l e r ep resen t s p o s i t i v e va lues of Co le ' s Coef f i c i en t

28. Numbers of b u t t e r f l i e s s igh ted a t hourly i n t e r v a . 1 ~ ( l o c a l t ime) during t r a n s e c t s on t h r e e days a t P i r a t e ' s P o i n t , L i t t l e Cayman. Shade temperatures a r e shown above. For each hour t h e columns r ep resen t (from l e f t t o r i g h t ) 16, 1 7 and 20 J u l y

30, Map showing locatl.on af th.e ma-is! h a b i t a t s on 1~it.t.l.e C'ai~mari,

place names, and c u t pa ths used a s t r a i l s ec t s

31. Feeding he igh t s of four insec t ivorous passe r ines on L i t t l e Cay~nan: ( a ) Caribbean Elaenia; (b) Bananaquit; ( c ) V i t e l l i n e Warbler; (d) Yellow Warbler. Ordinate: he ight i n i n t e r v a l s of 2 m ( G r = ground). Abscissa: percentage of feeding observa t ions i n each he ight c l a s s . White a reas ( r i g h t of 0 % ) : feeds on f r u i t (Elaenia, V i t e l l i n e Warbler) o r nec ta r (Bananaquit, Yellow Warbler) . Black a r e a s ( l e f t of 0%) : feeds on i n s e c t s . For sample s i z e s , s ee Table 29

x i i

Fol lowing page 170

32. Out l ine map of L i t t l e Cayman, showing t h e l o c a t i o n o f t h e booby colony and d e t a i l of t h e colony a r e a . Numerals r e f e r t o prev ious s i t e s of t h e colony (see t e x t ) . L e t t e r s r e p r e s e n t s e c t i o n s of t h e p r e s e n t c o l o n y used i n t h e census (see Table 30) . Arrows r ep re sen t main f l i g h t l i n e s

33. Diurnal v a r i a t i o n i n number of boobies p r e s e n t i n t h e sample a r e a of t h e colony

Fol lowing page 180

34. Recommended marine and t e r r e s t r i a l conservat ion a r e a s , L i t t l e Cayman

x i i i

LIST OF TABLES

R a i n f a l l records a t L i t t l e Cayman. Data by cour t e s ty of the Mosquito Research and Control Unit, Grand Cayman

Publ ica t ions on i n s e c t s of L i t t l e Cayman a r i s i n g from t h e Oxford Universi ty Expedition t o the Cayman I s l ands i n 1938

Size d i s t r i b u t i o n of t he common l i t t o r a l Mollusca around L i t t l e Cayman

Dis t r ibu t ion of l i t t o r a l Mollusca

C l a s s i f i c a t i o n of l i t t o r a l f i s h e s

Mean s i z e , sample s i z e and h a b i t a t preference of t h e f i s h e s found occupying s i x l i t t o r a l rock pools

T e r r e s t r i a l fauna of L i t t l e Cayman (excluding b i r d s and i n s e c t s ) , J u l y and August 1975

Species d i v e r s i t y i n each of the h a b i t a t types

Numbers of l i v i n g a d u l t Cerion nanus and Cerion pannosum found on Evolvulus p l a n t s , and the numbers of empty

Page 2

5

32

3 6

4 5

4 6

8 4

87

s h e l l s of t he two spec ie s per 0.25 sq m , a t s i t e s A and B 94

Numbers of Evolvulus p l a n t s with and without Cerion of e i t h e r spec ie s a t s i t e s A and B 94

Numisers sf Evolvulus p l a t s car ry ing I.ive Cerion of one or both spec ies a t s i t e 8. The expected f i g u r e s assume a randoul d i s t r i b u t i o n of each spec ie s 9 0

Ordina~l d i s t r i b u t i o n of spec ies of i n s e c t s f o - a d on L i t t l e Cayman. N u h e r s of spec ies f o r North Mmerica nor th of Mexico a r e from Borror and DeLong (1966)

Within-family s i z e ranges of L i t t l e Cayman and B r i t i s h i n s e c t s . Dimensions a r e body length (excluding antennae and abdominal appendages) except f o r Odonata, Neuroptera and Lepidoptera where wing expanse i s given, and Scarabaeidae f o r which e l y t r a l length i s shown

Percentage composition of sweep-net saniples from L i t t l e Cayman compared with those repor ted by Janzen and Pond (1975) from Michigan, U.S.A.

xiv

Percentage composition of Malaise t r a p samples from L i t t l e Cayman, and from Surinam and Kansas (Matthews and Matthews 1971) 110

Comparison of l i g h t t r a p ca t ches of Macrolepidoptera on L i t t l e Cayman and a t Woodchester Park, Glouces te rsh i re , England. 111

Numbers of spec i e s caught by d i f f e r e n t methods on L i t t l e Cayman. F igu re s i n paren theses show t h e numbers of spec i e s caught only by the method i n d i c a t e d , and the percentages a r e of t h e numbers of spec i e s caught by each method o u t of t h e t o t a l number of spec i e s found on the i s l a n d belonging t o t h e group

Species of Odonata recorded from t h e Cayman I s l a n d s by t h e 1938 Oxford Univers i ty Expedi t ion and t h e 1975 Royal Society and Cayman I s l a n d s Government Expedi t ion

B u t t e r f l y spec i e s recorded by the 1938 and 1975 Expedi t ions t o t h e Cayman I s l a n d s

Matrix showing the numbers of spec i e s shared bstween Cuba, Hispaniola , Puer to Rico, Jamaica and t h e Cayman I s l ands (upper r i g h t ) , va lues f o r C o l e ' s c o e f f i c i e n t of a s s o c i a t i o n (lower l e f t ) , and t h e t o t a l number of b u t t e r f l y spec i e s recorded f o r each i s l a n d 132

Numbers of b u t t e r f l i e s counted p e r f i v e minutes i n each h a b i t a t zone on t h r e e t r a n s e c t s of L i t t l e Cayman 135

The spec i e s of land-birds breeding i n t h e Cayman I s l ands , and t h e i r d i s t r i b u t i o n elsewhere 14 3

D i s t r i b u t i o n a l a f f i x i t i e s of the breeding land--birds of the Cayman 1sianc"is and L i t t l e Cayman, F igures i n b racke t s show t h e nl-1;nber of Cen t r a l A ~ ~ r i c a n s p c c i e s t h a t a r e r e s t r i c t e d t o offs i lore i s l a n d s - 144

The endemic forms of Cay~iian i s l a n d s land-b i rds , and t h e i s l a n d s on which they breed. Popula-tions probably ex t inc - t a r e bracketed 145

D i s t r i b u t i o n of Cayman I s l a n d s endemic land-b i rds . F igures i n b racke t s show t o t a l s before r e c e n t e x t i n c t i o n s

Ex t inc t ions and c o l o n i s a t i o n s i n t h e Cayman I s l a n d s a v i f auna 149

Breeding records of L i t t l e Cayman b i r d s , 9 July-11 August 19 75 150

28 . Average number of b i r d s p e r hour recorded i n four h a b i t a t s on L i t t l e Cayman

29. Habi ta t s of breeding b i r d s of L i t t l e Cayman 15 2

30. Feeding methods of four insec t ivorous passe r ines on L i t t l e Cayman 154

31. Census of boobies along t h e southern edge of t h e colony, 0800-1000, 1 August 1975 167