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.
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