E D I T O R S ' N O T E
I n l i n e w i t h o u r p o l i c y o f n o t i s s u i n g s h o r t a r t i c l e s a s sepa- r a t e numbers w i t h t h e i r own t i t l e p a g e s , t h e f o l l o w i n g a r t i c l e s a r e o f f e r e d a s p a r t s o f a s i n g l e number. They have accumulated o v e r a c o n s i d e r a b l e p e r i o d s i n c e t h e l a s t I s l a n d News and Comments a p p e a r e d . They a r e grouped roughly a c c o r d i n g t o t h e i r g e o g r a p h i c and s u b j e c t i n t e r e s t .
Contents
An e a r l y r e p o r t o f t h e f l o r a and f a u n a o f t h e Aldabra Page
group, by E. P. Diamond 1
Geochemistry and mineralogy o f c a r b o n a t e r o c k samples
from Aldabra A t o l l , I n d i a n Ocean, by Stephen T. T r u d g i l l 11 H i s t o r y o f g o a t s i n t h e Aldabra Archipelago, by D. R .
S t o d d a r t
A b b o t t ' s booby on Assumption, by D. R . S t o d d a r t
P e n e t r a t i o n o f h o s t p l a n t t i s s u e s by t h e s t y l e t s o f t h e c o c c o i d
Icerya seycheZZamun
( ~ o c c o i d e a : ~ a r g a r o i d e a ) on Aldabra A t o l l , b y S. BlackmoreM e t e o r o l o g i c a l d a t a from U l u l I s l a n d , Namonuito A t o l l by John Byron Thomas and Mary Durand Thomas Marine b e n t h i c a l g a e of Kayangel A t o l l , P a l a u , by
Roy T. Tsuda
Q u a l i t a t i v e assessment o f a s t e r o i d s , e c h i n o i d s and
h o l o t h u r i a n s i n Yap Lagoon, by Deborah A. Grosenbaugh
Acanthaster
i n t h e c u l t u r e s o f h i g h i s l a n d s , by C h a r l e s B i r k e l a n dAcanthaster
a s , a r e c u r r i n g phenomenon i n Samoan h i s t o r y by John M. F l a n i g a n and A u s t i n E. LambertsD i s t r i b u t i o n and abundance o f t h e Crown-of-Thorns S t a r f i s h
(Acanthaster plan&)
around Tongatapu I s l a n d , Tonga, by M. P. F r a n c i sR a t s as a v i a n p r e d a t o r s : d i s c u s s i o n , by W. R . P. Bourne Layard's b i r d h u n t i n g v i s i t t o Tromelin o r Sandy I s l a n d i n
December
1856,
by R . K. BrookeA s u b m e r s i b l e , r e c h a r g e a b l e , e l e c t r i c d r i l l , by W. H.
Easton
A r t i f i c i a l r e e f s i n Discovery Bay, Jamaica, by Michael J . Risk
D i s t r i b u t i o n o f t h e decapods Brachyura and Anomura ( e x c l u d i n g ~ a g u r i d e a ) o f t h e Cryptofauna i n t h e r e e f s n e a r T u l e a r , by M i r e i l l e Peyrot-Clausade
AN EARLY FS3PORT OF THE FLORA AND FAUNA OF THE ALDABRA GROUP by E.P. ~ i a m o n d l
I n t r o d u c t i o n
Among t h e r e c o r d s i n t h e N a t i o n a l Archives of M a u r i t i u s a t P o r t Louis i s a copy of t h e e a r l i e s t known d e t a i l e d r e p o r t on t h e f l o r a and fauna of t h e Aldabra g r o u p , made by S e r g t . F. R i v e r s of t h e S e y c h e l l e s C o n s t a b u l a r y . I t was s e n t by t h e C i v i l Commissioner f o r t h e S e y c h e l l e s t o h i s s u p e r i o r , t h e Governor of M a u r i t i u s o n December 30, 1878. The o r i g i n a l was forwarded t o London and a copy k e p t i n t h e S e y c h e l l e s N a t i o n a l Archives and a n o t h e r i n t h e M a u r i t i u s Archives. A t h i r d copy i s t o be found i n t h e Giinther P a p e r s i n t h e B r i t i s h Museum ( N a t u r a l H i s t o r y ) a l t h o u g h I have n o t seen i t . A l a t e r l e t t e r i n t h e M a u r i t i u s Archives s u g g e s t s t h a t a n o t h e r , more d e t a i l e d r e p o r t by R i v e r s may have been made and s e n t t o t h e Royal S o c i e t y sometime i n February 1879, though I have been unable t o t r a c e it. The importance of t h i s r e p o r t t o t h e s t u d y o f t h e changes on t h e Aldabra group l i e s i n i t s e a r l y d a t e and t h e a p p a r e n t l y knowledgeable and c a r e f u l o b s e r v a t i o n o f t h e
r e p o r t e r
.
The r e p o r t i s d a t e d 11 December 1878 and i s s i g n e d by F. R i v e r s who i s s a i d , i n a c o v e r i n g l e t t e r , t o be o f Canadian e x t r a c t i o n and t o have been a seaman b e f o r e ' s e t t l i n g i n S e y c h e l l e s . The r e p o r t i s E n g l i s h w i t h c r e o l e names g i v e n f o r most of t h e p l a n t s and animals.
I have w r i t t e n t h e E n g l i s h common name, i f t h e r e i s one, i n p a r e n t h e s e s a f t e r t h e c r e o l e one a n d , w i t h t h e f i r s t r e f e r e n c e o f each s p e c i e s , have i n c l u d e d t h e s c i e n t i f i c name a s w e l l . There may be some c o n f u s i o n i n t h e u s e of c r e o l e names, which w i l l be d i s c u s s e d i n t h e c o n c l u s i o n . D e t a i l e d i n f o r m a t i o n a b o u t anchorages and g e o l o g i c a l f o r m a t i o n o f t h e i s l a n d s w i l l n o t be i n c l u d e d i n t h i s paper b u t can be found i n t h e r e p o r t i t s e l f .
AS t o v e
R i v e r s a r r i v e d on Astove on 1 0 October 1878. He r e p o r t e d t h a t he c o u l d f i n d no t r a c e s o f v i s i t s by fishermen and w h a l e r s , though t h e r e was a w e l l i n t h e s o u t h e a s t which had been dug by a shipwrecked crew
'some y e a r s a g o ' .
C/O
Department of Zoology, U n i v e r s i t y o f N a i r o b i , N a i r o b i , Kenya A t o l l Res. B u l l . No. 2 5 5 : 1-10,1981.
Coconuts and Other Vegetation
Rivers r e p o r t e d t h a t t h e i s l a n d had no t r e e s except a few s t u n t e d 'mangliers' (mangroves of any s p e c i e s ) and was covered with bush. He mentioned two i n d i v i d u a l coconut t r e e s , p l a n t e d i n r e c e n t y e a r s , and
implied t h a t few i f any o t h e r s had y e t been p l a n t e d . F i s h
Rivers r e p o r t e d thae f i s h ' a r e n o t found i n q u a n t i t y ' , b u t t h a t the most common were; ' v a r v a r a s ' (Lutjanus b o h a r ) , ' c a p i t a i n e s r o u g e s '
( L e t n r i n u s k a l l o p t e r u s o r L . n e b u l o s u s ) , 'carangues' ( A l e c t i s i n d i c u s o r Caranx s p . ) and ' v i e l l e s ' (Plectroponus maculatus o r a s e r r a n i d ) .
[ ~ h e s e and a l l o t h e r t r a n s l a t i o n s of c r e o l e f i s h names a r e taken from J . L . B . Smith and Mary Smith ~ i s h e s o f t h e S e y c h e l l e s , 1969.1
T u r t l e s
In S e y c h e l l e s c r e o l e , a green t u r t l e i s a ' t o r t i ' while a Hawksbill t u r t l e i s c a l l e d a ' c a r e t ' . When t r a n s l a t i n g ' t o r t i ' i n t o E n g l i s h , S e y c h e l l o i s o f t e n use only t h e word ' t u r t l e ' without t h e ' g r e e n ' . Thus when Rivers uses t h e word t u r t l e alone he means only green t u r t l e s , which i s made c l e a r by t h e c o n t e x t i n t h e f u l l r e p o r t .
' T u r t l e s 1 (green t u r t l e , Chelonia mydas) were s a i d t o be very abundant, although i t was not the breeding season and Rivers estimated t h a t h i s s h i p , probably a small schooner, could t a k e a complete cargo of t u r t l e s i n t h r e e days. He r e p o r t e d f i n d i n g 1 2 young t u r t l e s i n t h e b e l l y of a ' v a r v a r a '
.
F r i g a t e b i r d s (Freqata s p . ) and ' a i g r e t t e '( e g r e t s ) wexe a l s o s a i d t o prey on young t u r t l e s b u t no evidence was given.
Birds
Aquatic b i r d s were s a i d t o be few with f r i g a t e s and ' a i g r e t t e ' p r e s e n t i n small numbers. 'Corbijeaux' (whimbrel, Numenius phaeopus) and ' a l l o u e t t e s ' (small waders and shore b i r d s ) were s a i d t o be
p l e n t i f u l . Of t h e land b i r d s , a ' r a l l e ' ( r a i l , probably Dryolimnus c u v i e r i ) was mentioned, a l s o t h e 'crow of Madagascar' ( p i e d crow,
Corvus a l b u s ) a small s p e c i e s of ' c o l i b r i ' ( s u n b i r d , probably Necterina sovimanqa) and a ' c a r d i n a l ' (Foudia sp. with r e d plumage)
.
A 'merle '( b u l b u l , Hypsipetes s p . ) and a 'pigeon h o l l a n d a i s ' (Alectroenas s p . ) were s a i d t o be p r e s e n t and ' s m a l l e r and p a l e r than those found a t S e y c h e l l e s '
.
Other animals
Land c r a b s were s a i d t o be p l e n t i f u l and 'cypaye' (coconut c r a b , Birqus l a t r o ) was mentioned by name.
Discussion
Trees and o t h e r v e g e t a t i o n
Rivers d e s c r i b e s t h e i s l a n d a s covered i n bush with a few s t u n t e d mangroves, which c o i n c i d e s with t h e d e s c r i p t i o n of Bayne e t a l . (1970b) g e n e r a l l y , although a l a r g e number of p l a n t e d coconuts had changed t h e appearance of t h e i s l a n d by 1968. I t i s i n t e r e s t i n g t o n o t e , however, t h a t Rivers d i d n o t mention Casuarina woodland d e s c r i b e d by Bayne e t a l . on t h e western r i m of the i s l a n d . Fosberg and Renvoize (1970) r e c o r d a
r e p o r t of i t s presence i n 1919, s u g g e s t i n g t h a t t h e s e C a s u a r i n a were i n t r o d u c e d between 1878 and 1919.
Marine Fauna
Bayne
e t
a l . do n o t mention f i s h b u t a g r e e w i t h R i v e r s t h a t Astove i s a major b r e e d i n g ground f o r green t u r t l e s . The p r e s e n c e of young t u r t l e s i n a f i s h ' s stomach i m p l i e s t h a t t h e r e had been l a y i n g two t o 23 months b e f o r e ( l a t e J u l y o r e a r l y August). Hawksbill t u r t l e s( E r e t m o c h e l y s i m b r i c a t a ) a r e n o t mentioned by R i v e r s and a r e s a i d t o be r a r e by Bayne
e t
a l .Land fauna o t h e r t h a n b i r d s
Giant t o r t o i s e s ( G e o c h e l o n e g i g a n t e a ) r e p o r t e d by R o t h s c h i l d on Astove i n 1915 were n o t r e c o r d e d by R i v e r s i n 1878. T h i s i s p e r h a p s a r e f l e c t i o n of t h e low numbers of t h e p o p u l a t i o n a t t h a t d a t e , s e e n a l s o on Aldabra ( s e e Aldabra s e c t i o n ) . Both R i v e r s and Bayne
e t
d l . a g r e e on t h e abundance of coconut c r a b s .B i r d s
Bayne
e t
d l . a g r e e w i t h R i v e r s r e p o r t o f t h e small number o f s e a b i r d s on Astove. They do n o t mention t h e f r i g a t e s b u t t h e s e may have been wanderers from Cosmoledo o r Aldabra. I t i s w i t h h i s account of l a n d b i r d s t h a t R i v e r s d i f f e r s markedly from a l l l a t e r r e p o r t e r s(summarised by Benson 1 9 7 0 b ) . The r a i l , p i e d crow and s m a l l s u n b i r d a r e c o n s i s t e n t w i t h o t h e r r e p o r t s b u t t h e ' m e r l e ' , t h e ' p i g e o n
h o l l a n d a i s ' and t h e c a r d i n a l a r e n o t . The word ' m e r l e ' i s used i n S e y c h e l l e s t o mean a b u l b u l . I t might p o s s i b l y be a p p l i e d t o a medium s i z e d t h r u s h - l i k e b i r d o f a n o t h e r genus b u t t h e r e i s no b i r d known from Astove t o f i t t h i s d e s c r i p t i o n . Moreover R i v e r s was a p p a r e n t l y a c a r e f u l o b s e r v e r f a m i l i a r w i t h S e y c h e l l e s s p e c i e s . The
' p i g e o n h o l l a n d a i s ' i s s o c a l l e d a f t e r t h e Dutch f l a g w i t h d i s t i n c t bands o f r e d , white and b l u e . I t i s even l e s s l i k e l y t o be mistaken
f o r any o t h e r s p e c i e s . A s a n o t h e r A l e c t r o e n a s a p p e a r s t o have become e x t i n c t a t a n e a r l y d a t e on Farquahar ( S t o d d a r t and Benson 1 9 7 0 ) , i t i s p o s s i b l e t h a t t h e same t h i n g o c c u r r e d on Astove, between 1878 and
Dupont's v i s i t i n 1907. I t i s however t o n o t e t h a t Dupont r e p o r t e d s e e i n g a S t r e p t o p e l i a p i c t u r a t a i n 1907 which no o t h e r o b s e r v e r h a s e v e r recorded. The ' c a r d i n a l ' which, a s i t s name i m p l i e s , must have r e d plumage a t some s t a g e of i t s l i f e c y c l e i s t h e S e y c h e l l e s c r e o l e name
f o r F o u d i a m a d a g a s c a r i e n s i s . R i v e r s ' c a r d i n a l must t h e r e f o r e have been a F o u d i a s p . ( s e e under Aldabra d i s c u s s i o n ) .
Cosmoledo
On h i s a r r i v a l i n t h e Cosmoledo group R i v e r s r e p o r t e d t h a t it was f r e q u e n t l y v i s i t e d by fishermen and w h a l e r s a s i n d i c a t e d by t u r t l e remains on t h e beaches. A h u t and ' t u r t l e p a r k ' ( e n c l o s u r e i n t h e s e a f o r keeping t u r t l e s f r e s h b e f o r e shipment) on Menai I s l a n d had been r e c e n t l y b u r n t and d e s t r o y e d . A h u t on Wizard I s l a n d which had been b u i l t from t h e wreckage of t h e Merry Monarch had a l s o been b u r n t . There were a l s o , s i g n s o f t h e f e l l i n g o f mangroves.
Trees and o t h e r v e g e t a t i o n
~ i v e r s r e p o r t e d t h a t some p a r t s of t h e i s l a n d would be s u i t a b l e f o r growing v a r i o u s palms. What he d e s c r i b e s a s t h e 'remnants of a n o l d grove o f coconut t r e e s ' e x i s t e d on Menai and t h o s e s t i l l s t a n d i n g were b e a r i n g f r u i t abundantly. He b e l i e v e d palms took longer t o mature on Cosmoledo t h a n on o t h e r i s l a n d s because of t h e ' g r e a t s t e r i l i t y o f t h e i s l a n d s ' . Menai was d e s c r i b e d a s 'almost covered' with mangroves, some of about 40 o r 50 f e e t i n h e i g h t and 2 o r 3 f e e t i n diameter.
F i s h
F i s h were abundant and he e s t i m a t e d t h a t 8 men could s a l t o r d r y 8000 l b s of f i s h a month. I n R i v e r s ' o p i n i o n , t h e c a p t u r e o f t h i s q u a n t i t y would n o t e x h a u s t t h e supply a s no s m a l l f i s h were t a k e n .
The most common s p e c i e s were ' c a p t a i n e s r o u g e s ' , ' v a r v a r a s ' , ' c a r a n g u e s ' , ' v i e l l e s '
,
' m u l l e t s ' ( ~ v l l o i d i c h t h y u s f l a v i l i n e a t u s , a Mugilidae o r Polyremus kuru, ' c r o i s s a n t s ' ( s p e c i f i c name unknown), ' c h i r u g i e n s '(surgeon f i s h , ~ c a n t h u r i d a e )
, '
l i o n s'
(Holocentridae) and r a i e s'
of d i f f e r e n t k i n d s ( r a y s , Stoasodon m a r i n a r i , D a s y a t i s uarnak, Taenuira melanospila o r Torpedo fuscomaculata).
T u r t l e s and Crustacea
Both t u r t l e s (green t u r t l e s ) and ' c a r e t ' ( h a w k s b i l l t u r t l e s ) were abundant though t h e l a t e October, e a r l y November o f R i v e r s ' v i s i t was
' n o t y e t t h e s e a s o n ' . Crabs were s a i d t o abound i n t h e marshes.
B i r d s
B i r d s of a l l k i n d s were p l e n t i f u l . ' F r e g a t e s l ( f r i g a t e s )
,
booby ' o f t h r e e d i f f e r e n t s p e c i e s ' (Sula s p p . ) ' p a i l l e en queue' ( t r o p i c - b i r d s , (Phaethon l e p t u r u s o r P. r u b r i c a u d a ) , ' c o r d o n n i e r s ' ( l e s s e r noddies, Anous t e n u i r o s t r i s ), '
f o u q u e t s (wedgetailed shearwater s,
P u f f i n u s p a c i f i c u s )
,
' g o e l e t t e s ' ( s o o t y t e r n , S t e r n a f u s c a t a ),
and ' f a n c h i n s ' ( b r i d l e d t e r n s , S t e r n a a n a e t h e t u s ) were l i s t e d . R i v e r s s a y s t h a t t h e same l a n d b i r d s were found on Cosmoledo a s on Astove, b u t i n g r e a t e r numbers, and t h a t t h e r e was a l s o a ' t o u r t o r e l l e rouge'( t u r t l e dove, S t r e p t o p e l i a p i c t u r a t a )
.
Other animals
R i v e r s r e p o r t e d a few g o a t s on Menai b u t suggested t h a t t h e y d i d n o t do well t h e r e , a s many s k e l e t o n s were found i n t h e bushes. He suggested t h a t t h e reason may have been t h e s c a r c i t y o f r a i n on t h e i s l a n d on t h e y e a r o f h i s v i s i t .
Discussion
Coconuts and o t h e r v e g e t a t i o n
The p r e s e n t v e g e t a t i o n of t h e group a s d e s c r i b e d i n Bayne e t a l . - -
(1970a) i s more v a r i e d than R i v e r s b r i e f d e s c r i p t i o n s u g g e s t s , no doubt p a r t l y a s a r e s u l t of i n t r o d u c t i o n s s i n c e 1878. However, it i s t h e p l a n t s a l r e a d y p r e s e n t i n h i s time which a r e most i n t e r e s t i n g . The ' o l d grove of coconuts1 of 1878 was r e p o r t e d i n 1822 by Capt. Moresby ( c i t e d i n Bayne e t a l . 1 9 7 0 a ) . Moresby a l s o r e p o r t e d t r e e s resembling Casuarinas which R i v e r s d i d n o t mention, though he r e c o r d s them o n o t h e r i s l a n d s .
Land fauna
R i v e r s d i d n o t r e p o r t s e e i n g g i a n t t o r t o i s e s , b u t t h e r e a s o n s may have been t h e same a s on Astove ( s e e Astove d i s c u s s i o n ) . The g o a t s which R i v e r s thought were doing p o o r l y s t i l l remained, though i n s m a l l numbers, i n 1901 and had gone from Menai by 1968, though they were s t i l l on North-east I s l a n d i n 1961 (Bayne e t a l . 1 9 7 0 a ) .
Sea b i r d s
R i v e r s r e p o r t e d 3 d i f f e r e n t s p e c i e s o f s u l i d s a s d i d Bayne et a l . (1970a) i n 1968. One s p e c i e s was undoubtedly S u l a s u l a . I t i s however v e r y e a s y t o mistake immature white boobies (Sula d a c t y l a t r a ) f o r mature brown boobies (Sula l e u c o g a s t e r ) . The o n l y evidence f o r t h e presence of S u l a l e u c o g a s t e r i s a s k i n i n t h e N a t i o n a l museum o f Kenya i n N a i r o b i . T h i s s k i n has been m i s i d e n t i f i e d and i n f a c t i s S u l a d a c t y l a t r a (A.W. Diamond p e r s . comm. )
.
I t i s , o f c o u r s e , remote p o s s i b l e t h a t R i v e r s knew h i s boobies w e l l and d i d i n f a c t s e e a t h i r d s p e c i e s , perhaps S u l a a b b o t t i known from Assumption a t about t h a t d a t e c o l l e c t i o n by Abbott i n 1893 ( S t o d d a r t , Benson and Peake 1 9 7 0 ) .R i v e r s r e p o r t e d o n l y ' c o r d o n n i e r ' o r l e s s e r noddies (Anous t e n u i r o s t r i s ) w h i l e Bayne e t a l . saw o n l y common noddy ( A . s t o l i d u s ) which i n c r e o l e i s c a l l e d 'maqua'. I t i s p o s s i b l e t h a t R i v e r s missed s e e i n g common noddies which n e s t o n l y on small i s l e t s around t h e lagoon
(A.W. Diamond p e r s . comm.), b u t t h e f a c t t h a t Bayne e t a l . (1970a) saw no l e s s e r n o d d i e s , s u g g e s t s t h a t he may have mistaken t h e two v e r y s i m i l a r s p e c i e s . However, s i n c e n e i t h e r p a r t y was on t h e i s l a n d f o r more than a few d a y s , t h e two s p e c i e s might b o t h o c c u r , p o s s i b l y a t d i f f e r e n t s e a s o n s .
The f a c t t h a t wedgetailed s h e a r w a t e r s r e p o r t e d by R i v e r s were n o t s e e n by o r r e p o r t e d t o Bayne e t a l . (1970a) s u g g e s t s t h a t t h e y may have become e x t i n c t s i n c e 1878. The young b i r d s and eggs a r e commonly e a t e n by S e y c h e l l o i s fishermen who would t h e r e f o r e be aware i f t h e y were s t i l l e x t a n t ; t h e same h a b i t would account f o r t h e i r e x t i n c t i o n . The
e x t i n c t i o n may a l s o be t h e r e s u l t o f t h e r a t s , which were p r e s e n t by 1901 ( c i t e d by Bayne e t a 1 .) , i f n o t e a r l i e r .
Land b i r d s
R i v e r s r e c o r d s t h e l a n d b i r d s a s t h e same a s Astove i . e . a r a i l , p i e d crow, s u n b i r d , b u l b u l , c a r d i n a l and 'Pigeon h o l l a n d a i s ' , a s w e l l a s a t u r t l e dove. The f i r s t t h r e e and t h e t u r t l e dove were a l s o r e p o r t e d by Dupont i n 1907 (Benson 1 9 7 0 a ) . The p i e d crow and t h e s u n b i r d s t i l l e x i s t a n d ~ e n s o n s u g g e s t s t h a t f u t h e r i n v e s t i g a t i o n o f remoter p a r t s of t h e a t o l l may r e v e a l a r e l i c t p o p u l a t i o n s o f t h e r a i l and t u r t l e dove. For t h e p o s s i b i l i t i e s o f t h e e x t i n c t i o n o f t h e b u l b u l ' c a r d i n a l ' and 'pigeon h o l l a n d a i s ' , s e e t h e d i s c u s s i o n s on Aldabra and Astove.
Assumption I s l a n d
R i v e r s n e x t went t o Assumption where t h e e x t e n s i v e mining f o r guano had n o t begun. He s a i d , i n f a c t , t h a t t h e r e was n o t h i n g t o i n d i c a t e t h a t i t had even been v i s i t e d r e c e n t l y .
Coconuts and o t h e r v e g e t a t i o n
The i s l a n d was covered w i t h bushes of ' b o i s amanthe' (Pemphis a c i d u l a ) and o t h e r s h r u b s on which were found a s m a l l l i a n e used f o r d y i n g , c a l l e d ' o r s e i l l e ' which was common i n Madagascar. There were a l s o a few s t u n t e d ' a f f o u c h e ' ( F i c u s s p . ) and ' b o i s de n a t t e ' a s w e l l a s mangroves. R i v e r s mentioned one coconut t r e e a s marking t h e landing, b u t gave no i d e a how many o t h e r s t h e r e might have been. The ' a f f o u c h e ' was a p p a r e n t l y t h e p r e f e r r e d food of t h e g o a t s on t h e i s l a n d who would e a t even i t s b a r k .
F i s h and t u r t l e s
R i v e r s r e p o r t e d t h a t f i s h were found on t h e r e e f s b u t n o t i n q u a n t i t y , t h e most common being ' c a r a n g u e s ' and ' v a r a v a r a s ' . The green t u r t l e s were s a i d t o be numerous and a l s o ' b e t t e r and f a t t e r ' t h a n t h o s e of o t h e r i s l a n d s . Hawksbills, however, were n o t numerous.
B i r d s
Aquatic b i r d s were found, b u t n o t i n l a r g e numbers and no names were given. Of t h e l a n d b i r d s , R i v e r s s a i d 'pigeon h o l l a n d a i s ' i s n o t
found b u t t h e r e s t were ' l i k e t h e o t h e r i s l a n d s ' . Other animals
Goats had been l e f t on t h e i s l a n d by p a s s i n g s h i p s and R i v e r s thought t h a t t h e r e were 500 t o 600 of them. He d e s c r i b e d them a s being o f 2 o r 3 d i f f e r e n t s p e c i e s a l l i n ' f i n e c o n d i t i o n ' .
Discussion
I t seems l i k e l y t h a t R i v e r s s p e n t o n l y a s h o r t time a t Assumption, f o r he d e s c r i b e s i t i n l e s s d e t a i l t h a n t h e o t h e r i s l a n d s . By t h e time of l a t e r r e p o r t s , mining had s t a r t e d o r was about t o s t a r t and
subsequently d e s t r o y e d t h e n a t u r a l v e g e t a t i o n t o a g r e a t e x t e n t . F i s h and t u r t l e s
The green t u r t l e p o p u l a t i o n which R i v e r s d e s c r i b e d a s numerous h a s been reduced d r a s t i c a l l y on Assumption ( S t o d d a r t , Benson and Peake 1 9 7 0 ) . B i r d s
R i v e r s d e s c r i b e s t h e i s l a n d b i r d s a s being t h e same a s t h e o t h e r i s l a n d s i . e . Cosmoledo and Astove, excepz f o r t h e absence o f t h e
'pigeon h o l l a n d a i s ' . Since he had p r e v i o u s l y s a i d t h a t t h e r e were t u r t l e doves on Cosmoledo and n o t on Astove, h i s remark i s ambiguous.
The f a c t t h a t N i c o l l i n 1906 and F r y e r i n 1908 both recorded t h e p r e s e n c e o f t h e t u r t l e dove ( S t o d d a r t e t a l . 1970) s u g g e s t s t h a t he i n t e n d e d t o i n c l u d e i t on h i s l i s t . I t i s c l e a r t h a t he meant t o i n c l u d e t h e s u n b i r d , p i e d crow, ' c a r d i n a l ' , r a i l and b u l b u l . The s u n b i r d s t i l l e x i s t e d on Assumption i n 1968 and probably t h e p i e d crow a s w e l l
( S t o d d a r t e t a l . 1 9 7 0 ) . A r a i l (Dryolimnas a b b o t t i ) became e x t i n c t between 1908 and 1937 ( S t o d d a r t e t a 1
.
1970).
A s i n t h e c a s e of Astove and Cosmoledo, n e i t h e r t h e b u l b u l nor t h e ' c a r d i n a l ' were recorded by any o t h e r v i s i t o r s t o t h e i s l a n d . T h i s omission i s more s t r i k i n g on Assumption because Abbott c o l l e c t e d t h e r e , though n o t i n t h e o t h e ri s l a n d s , i n 1893, and y e t f a i l e d t o f i n d e i t h e r s p e c i e s . However, both
s p e c i e s a r e s u s c e p t i b l e t o r a t s which may have been t h e cause of t h e i r e x t i n c t i o n . I t i s u n f o r t u n a t e t h a t Rivers d i d n o t l i s t t h e s e a b i r d s i n d e t a i l , s o t h a t we cannot know whether he saw S u l a a b b o t t i which Ahbott c o l l e c t e d 15 y e a r s l a t e r .
Rivers appears t o have s p e n t more time on Aldabra than on t h e o t h e r i s l a n d s . He gave d e t a i l s of p l a c e names and geography o f t h e i s l a n d and r e p o r t e d t h a t i t was f r e q u e n t l y v i s i t e d . Although he speaks o f
'fishermen t h a t have been t h e r e f o r a long time f i s h i n g ' , he makes no suggestion t h a t t h e r e was a permanent s e t t l e m e n t .
Coconuts and o t h e r v e g e t a t i o n
Coconuts and maize were grown on t h e small i s l a n d s i n t h e lagoon.
Michel was s a i d t o have about 20 grown coconut t r e e s while La Poste on I l e P i c a r d was d i s t i n g u i s h e d by t h e presence of a coconut t r e e . Two o r t h r e e s t u n t e d takarnaka t r e e s (Calophyll um i n o p h y l l um) were t h e
landmark f o r t h e well a t Takamaka. Mangroves were growing on a l l t h e i s l a n d s with t h e l a r g e s t being 4 t o 5 f e e t i n diameter. The t r e e s were, according t o R i v e r s , commonly 2 t o 3 f e e t i n diameter and 40 t o 50 f e e t high. Mangrove timber was s a i d t o be good f o r b u i l d i n g because i t was s t r a i g h t and long l a s t i n g . Cedar I s l a n d had some ' f i l a o '
(Casuarina) while 'vacoa Maron' (Pandanus s p . ) occurred on a l l t h e i s l a n d s i n q u a n t i t y . The ' b o i s t a n g u i n ' of Madagascar (Euphorbia ?
a b b o t t i ? ) was p r e s e n t a s well a s some ' b o i s de n a t t e ' and ' a f f o u c h e ' , though R i v e r s d i d n o t s p e c i f y where t h e s e t r e e s occurred.
F i s h , t u r t l e s and o t h e r marine fauna
R i v e r s r e p o r t e d t h a t t h e f i s h were of t h e same s p e c i e s and i n t h e same numbers a s t h e y were on Cosmoledo. A s well a s t h e s e s p e c i e s t h e r e were ' L i c o r n e ' (unicorn f i s h , Axinurus thynnoides) s i m i l a r t o t h e one a t Mauritius. Green t u r t l e s were a s abundant a s on Cosmoledo, b u t
hawksbill was f a r more numerous and ' g e n e r a l l y o f b e t t e r q u a l i t y ' . The r e e f s were s a i d t o be f u l l of s h e l l s , with ' p e a r l o y s t e r s ' i n q u a n t i t y , b u t Rivers was prevented from looking f o r them by bad weather.
B i r d s
R i v e r s l i s t s ' s e r i n s ' ( s e e d i s c u s s i o n ) , ' c a r d i n a l ' (Foudia
eminentissima o r F. madagascariensis,see d i s c u s s i o n ) , pigeon h o l l a n d a i s , hawks (Falco s p . probably F. n e w t o n i ) , crows (Corvus a l b u s ) , s u n b i r d s , t u r t l e doves, r a i l s ,
'
toulouse'
( c o u c a l,
Centropus toulou),
b u l b u l s(Hypsipetes madagascariensis)
,
' c o r b i j e a w r of two s p e c i e s , 'one white and almost a s l a r g e a s a goose' [ s a c r e d i b i s , T h r e s k i o r n i s a e t h i o p i c a ] ' , t h e o t h e r t h e same a s i n S e y c h e l l e s , (whimbrel), flamingoes(Phoenicopterus r u b e r o r P. m i n o r ) , 'veuve' and ' p i e ' ( s e e d i s c u s s i o n ) . R i v e r s r e p o r t e d t h a t t h e r e were 'almost a l l k i n d s o f a q u a t i c b i r d s i n q u a n t i t y , b u t l i s t s o n l y ' a l l o u e t t e s ' (small s h o r e b i r d s and waders) and
' c a v a l i e r ' ( c r a b p l o v e r Dromas a r d e o l a ) . Land animals
R i v e r s r e p o r t e d t h a t 'by a l l appearances t h e r e i s [ s i c ] p l e n t y of t o r t o i s e s on t h e s e i s l a n d s ' . However, though he saw ' t r a c e s ' of them,
he never saw a t o r t o i s e , nor d i d he, o r any o f t h e fishermen he spoke t o , ever. s e e a dead c a r c a s e o r s h e l l , though t h e fishermen sometimes c a p t u r e d t h e animals f o r food. R i v e r s s a i d t h a t t h e l a r g e s t t o r t o i s e s were from I l e P i c a r d b u t t h a t t h e y were commonly caught on t h e p l a i n s a t Cinq Cases. He f e l t t h a t , a s it was t h e d r y season when he was t h e r e , t h e t o r t o i s e s were 'hidden i n h o l e s ' o r shady p l a c e s . When it r a i n e d , they were s a i d t o come o u t and be more e a s i l y caught. On Grand I l e 'some y e a r s ago' p i g s were r e l e a s e d which d e s t r o y e d many young t o r t o i s e s , b u t t h e p i g s were b e l i e v e d t o have d i e d o u t because they were a l l males. There were numbers of ' f l y i n g f o x e s ' ( F r u i t b a t s , Pteropus s e y c h e l l e n s i s ) , and land c r a b s 'of every d e s c r i p t i o n ' were abundant. A few g o a t s were found on I l e P i c a r d and had been l e t l o o s e on o t h e r i s l a n d s . There were a l s o ' l a r g e l o c u s t s o f t h e Madagascar s p e c i e s
' .
Discussion
Coconuts and o t h e r v e g e t a t i o n
I t i s apparent t h a t on Aldabra i n R i v e r s ' day, a s on o t h e r i s l a n d s , coconut t r e e s were n o t s o widespread a s they a r e today. I f , a s Fosberg
(1971) s u g g e s t s Casuarina i s an introduced p l a n t on t h e a t o l l , it was p r e s e n t by 1878. Takamaka t r e e s a r e s t i l l mainly r e s t r i c t e d t o t h e a r e a c a l l e d a f t e r them. The l a r g e s t mangroves d e s c r i b e d by Rivers a r e l a r g e r than any now p r e s e n t on t h e a t o l l , b u t Rivers may have been i n a c c u r a t e i n h i s e s t i m a t i o n o f p r o p o r t i o n s a s h i s diameter seems e x c e s s i v e (A.W. Diamond, p e r s . comm.).
B i r d s
Rivers r e p o r t e d ' c a r d i n a l ' and ' s e r i n ' f o r Aldabra, b u t ' c a r d i n a l ' o n l y f o r Astove, Cosmoledo and Assumption. ' c a r d i n a l ' i s p r e s e n t S e y c h e l l e s c r e o l e f o r t h e introduced ~ o u d i a madagascariensis. By i m p l i c a t i o n , i t must be used f o r a b i r d which has r e d plumage a t some s t a g e . I t i s never, f o r example, used f o r F. s e y c h e l l e n s i s , which i s never r e d . ' S e r i n ' on t h e o t h e r hand i s used today f o r females of both s p e c i e s of Foudia. However, when white-eyes were s t i l l common i n
S e y c h e l l e s , i t was used a t d i f f e r e n t times f o r .Zosterop& modesta and 2. mayottensis. R i v e r s probably knew one of t h e S e y c h e l l e s white-eyes.
I t seems s t r a n g e t h e r e f o r e , t h a t he d i d n o t r e p o r t white-eyes on Astove o r Cosmoledo where they were recorded a f t e r 1878 (Benson 1970a, 1970b), e s p e c i a l l y s i n c e he d i d record ' c a r d i n a l ' on t h e s e i s l a n d s a s well a s on Assumption. No o t h e r observer has recorded Foudia from t h e s e i s l a n d s and i t might be suggested t h a t R i v e r s mistook white-eyes f o r female Foudia. This mistake i s however, most u n l i k e l y , s i n c e , i f he d i d n o t know a white-eye he would have c a l l e d a female Foudia a ' s e r i n ' .
Therefore, t h e b i r d s on Astove, Cosmoledo, and Assumption must have been Foudia w i t h r e d plumage. Foudia eminentissima on Aldabra i s i n breeding d r e s s i n November and December when Rivers was t h e r e and i t i s l i k e l y t h a t Foudia on o t h e r i s l a n d s i n t h e n e i g h b u r h o o d would have s i m i l a r breeding seasons. (September -March, according t o Benson and Penny, 1 9 7 1 ) . The fody on Astove, Cosmoledo and Assumption may have been Foudia eminentissima a subspecies of which appears on t h e -Cornores and i n Madagascar.as well a s on Aldabra, (Benson 1 9 6 7 ) . The reason f o r i t s e x t i n c t i o n on Astove and Cosmoledo i s n o t known b u t i t i s r e p o r t e d on Aldabra t o be very s u s c e p t i b l e t o r a t s (Rattus r a t t u s , F r i t h 1 9 7 6 ) ,
a s i s Foudia s e y c h e l l e n s i s (Diamond and Feare, i n p r e s s )
.
Rivers mentioned a b i r d l i k e a 'veuve' which i s i n Seychelles c r e o l e , a p a r a d i s e f l y c a t c h e r (Tersiphone corvina)
.
However, he n o t e s t h a t i t i s n o t the same s p e c i e s , a s both male and female have long t a i l s and a r e black. This b i r d i s c l e a r l y the Aldabra drongo(Dicrurus a l d a b r a n u s ) . Rivers a l s o r e p o r t e d hearing a ' p i e ' which he d i d n o t s e e , though he implied t h a t fishermen had done s o . ' P i e ' o r ' p i e chanteuse' i s c r e o l e f o r t h e magpie robin (Copsychus seychellarum), t h e ' p i e ' implying a black and white colouring and t h e 'chanteuse' a
song. Although t h e fishermen probably both saw and heard t h i s b i r d , Rivers only heard i t . I t need n o t t h e r e f o r e have been a magpie r o b i n , which i s , a t p r e s e n t , r e s t r i c t e d t o Seychelles, b u t t h e r e seems no o t h e r l i k e l y candidate e i t h e r r e s i d e n t o r migrant. I t does n o t sound l i k e the Aldabra warbler a t a l l . (Diamond, p e r s . comm.). A s t h e magpie robin was introduced t o Alphonse a t a l a t e r d a t e , it i s p o s s i b l e t h a t Rivers heard a b i r d t h a t had been introduced t o Aldabra, but t h i s i s unlikely. A l l the o t h e r b i r d s l i s t e d by Rivers s t i l l occur on Aldabra.
Land animals
I t i s obvious from Rivers d e s c r i p t i o n t h a t t h e t o r t o i s e population of the i s l a n d s was much lower i n 1878 than a t p r e s e n t ( s e e summary i n S t o d d a r t 1971)
.
Rivers r e p o r t merely confirms t h e f i n d i n g s of o t h e r r e p o r t e r s t h a t population l e v e l s were very low a t the end of then i n e t e e n t h century. I t must be noted t h a t f o r e a r l y v i s i t o r s , t r a v e l was much more d i f f i c u l t than today, with no outboard motors and well c u t p a t h s . T o r t o i s e s i n remoter a r e a s would not have been found because these a r e a s were n o t explored. Rivers record o f g o a t s appears t o be t h e e a r l i e s t . I t i s however, p o s s i b l e t h a t goats a s well a s p i g s have introduced and e x t i r p a t e d more than once. (Stoddart 1971)
Fish and o t h e r marine fauna
Though Aldabra i s s t i l l a major breeding ground of green t u r t l e s , i t i s impossible t o compare p r e s e n t day population l e v e l s with Rivers unquantified remarks. I t i s c e r t a i n however t h a t t h e population has declined on Aldabra, although the hawksbill population may not have done so. ( J . F r a z i e r 1971.) The hawksbill s h e l l of ' b e t t e r q u a l i t y ' was the famous Aldabra 'blonde' s h e l l . The p e a r l o y s t e r and the
unicorn f i s h s t i l l occur.
References
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J . ,
Grubb, P . , Hutson, A . , Poore, M.E.D., S t o d d a r t , D.R., and Taylor, J . D . 1970b. Geography and ecology of Astove. A t o l l Res. B u l l . 136: 83-99.Benson, C.W. 1967. The b i r d s o f Aldabra and t h e i r s t a t u s . A t o l l R e s . B u l l . 118: 63-111.
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F r i t h , C.B. 1976. A twelve-month s t u d y of t h e Aldabra Fody F o u d i a e m i n e n t i s s i m a a l d a b r a n a . I b i s , 118: 155-178.
N i c o l l , M . J . 1906. The b i r d s c o l l e c t e d and observed d u r i n g t h e voyage o f t h e ' V a l h a l l a '
.
I b i s , ( 8 ) 6: 666-712.R o t h s c h i l d , W . 1915. On t h e g i g a n t i c l a n d - t o r t o i s e s o f t h e S e y c h e l l e s and Aldabra-Madagascar Group, w i t h some n o t e s on c e r t a i n forms o f t h e Mascarene Group. N o v i t a t e s Zool. 22: 418-442.
Smith, J.L.B. and Smith, M.M. 1963. T h e f i s h e s o f S e y c h e l l e s . Grahamstown: Department of Ichthyology, Rhodes U n i v e r s i t y . S t o d d a r t , D.R. 1971. S e t t l e m e n t , development and c o n s e r v a t i o n of
Aldabra. P h i l . T r a n s . R . S o c . L o n d . B . 260: 611-628.
S t o d d a r t , D.R. and Benson, C.W. 1970. An o l d r e c o r d o f a Blue Pigeon
~ l e c t r o e n a s s p e c i e s and s e a - b i r d s on Farquhar and Providence.
A t o l l R e S . B u l l . 136: 35-36.
S t o d d a r t , D . R . , Benson, C.W. and Peake, J . F . 1970. E c o l o g i c a l change and e f f e c t s o f phosphate mining on Assumption I s l a n d . toll R e s . B u l l . 136: 121-145.
Passe Gionnet
ILE MALABAR
X ,
x Sample Locations0
. . .
.w"
T T H E S P E S I A C C O R D I A
V C A S U A R I N A S SCAEVOLA O S U R I A N A
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COCONUT WOODLAND H E R B M A Ta
S A N DFENWFh ERODING SHORE
-
BEACH RIDGE CREST PHOSPHORITE0 200
I
Fig. 2. Bird Island in 1976
B E R M
-
2 -1 0 1 2 3 4-
2 -1 0 1 2 3 4Fig.
3.
Beach sediment at Bird IslandP1. 1. B i r d I s l a n d :
Suriana
zone on t h e n o r t h e a s t s h o r eP1. 2 . B i r d I s l a n d :
Pisonia
andCordia
woodland w i t hSuriana
on t h e n o r t h e a s t s h o r eP1. 3. B i r d I s l a n d :
T o u r n e f o r t i a
p a r k l a n d i n t h e n o r t h e a s tP1.
4.
B i r d I s l a n d : t r e e - l i k eT o u r n e f o r t i a
i n t h e n o r t h e a s tP1.
5 .
B i r d I s l a n d : p i o n e e r sedges and ScaevoZa on t h e e a s t s h o r eP1.
7.
B i r d I s l a n d : p i o n e e r s e d g e s ,ScaevoZa
andTournefortia
on t h e n o r t h e a s t s h o r e
P1.
8.
B i r d I s l a n d : a i r s t r i p from t h e s o u t h e a s t2. P l a n t s r e c o r d e d from B i r d I s l a n d
POLYPODIACEAE A c r o s t i c h u m aureum L .
F r y e r , i n C h r i s t e n s e n (1912) [ i n e r r o r f o r Denis I s l a n d ? ]
~ e p h r o l e p i s b i s e r r a t a (Sw. ) S c h o t t
P - r o c t e r 4040 ( ~ a h e ) ; F r y e r , i n C h r i s t e n s e n (1912) ; G a r d i n e r , i n C h r i s t e n s e n (1912) ; F e a r e , s i g h t .
N e p h r o l e p i s mu1
ti
f l o r a (Roxb. ) J a r r e t t S t o d d a r t 7110 (US).P o l ypodi urn scol o p e n d r i a Bum. f
.
F r y e r , s. n. (K) ; F r y e r , i n C h r i s t e n s e n (1912 ) ( a s P. p h y m a t o d e s )
[ ~ y p h a j a v a n i c a S c h n i z l e x Rohrb.
F r y e r , i n Summerhayes (1931) ( i n e r r o r f o r Denis I s l a n d ? ) ]
POTAMOGETONACEAE T h a l a s s o d e n d r o n c i l i a t u r n (Forsk. ) d . H a r t .
Cymodocea c i l i a t a ( F o r s k . ) Ehrenb. ex Aschers.
S t o d d a r t 7123 (US) ; F r y e r , s i g h t (1910) ( a s Cymodocea)
.
*Cynodon d a c t y l o n (L. P e r s .
S t o d d a r t 7112 (US); P r o c t e r , s i g h t .
* D a c t y l o c t e n i u m a e g y p t i u m (L. ) Willd.
S t o d d a r t 7072 (US); P r o c t e r , s i g h t ; F e a r e , s i g h t .
* D i g i t a r i a h o r i z o n t a l i s Willd.
P r o c t e r 4049 (MAHE).
ho leu sine i n d i c a (L. Gaertn.
P r o c t e r 4049 (MAHE); Coppinger, i n Hemsley 1 ) ; Feare, s i g rht.
Enteropogon monostachyum K. Schum. ex Engl.
P r o c t e r , s i g h t .
Enteropogon s e c h e l l e n i s (Barker) Dur. and Schinz S t o d d a r t 7064 (US)
,
7091 (US); P r o c t e r , s i g h t . E r a g r o s t i s subaequiglumis Renv.P r o c t e r 4044 (MAHE) ; S t o d d a r t 7074 (US).
* ~ r a g r o s t i s t e n e l l a (L.) Beauv. ex R. and S. v a r . t e n e l l a P i g g o t t , s. n. (K) ; S t o d d a r t 7081 (US) ; P r o c t e r
,
s i g h t . E r a g r o s t i s t e n e l l a v a r . i n s u l a r i s Hubb.Vesey-FitzGerald 5656 (K)
.
Lepturus repens ( F o r s t . R. B r .
F r y e r , s i g h t , i n Summerhayes (1931).
F r y e r , s i g h t , i n Summerhayes (1931) [ l o c a l i t y a s " I l e aux ~ a c h e s " ]
.
Pennisetum p o l y s t a c h i o n ( L . ) Schult.
F r y e r , no number, i n Summerhayes (1931).
*Saccharurn officinarum L.
Coppinger, s i g h t (1885)
.
Sporobolus v i r g i n i c u s ( L
.
KunthF r y e r , no number, i n Summerhayes (1931); P r o c t e r , s i g h t . Stenotaphrum micranthum (Desv. Hubb.
Stenotaphrum subulatum Trin.
P r o c t e r 4041 (MAHE); S t o d d a r t 7073 (US), 7129 (US); Feare, s i g h t .
*Zea mays L.
F r y e r , s i g h t (1910)
.
CYPERACEAE Cyperus sp.
S t o d d a r t 7120 (US)
.
Cyperus conglomeratus Rottb.
P r o c t e r 4037 (MAHE) ( a s C. p a c h y r h i z a ) ; S t o d d a r t 7071 (US); Feare, s i g h t ( a s C. pachyrhiza)
.
Cyperus dubius Rottb.
Mariscus d u b i u s (Rottb. )
Fryer 26 (K) (as Mariscus dregeanus) ; P r o c t e r 4038 (MAHE) ; F e a r e , s i g h t .
Cyperus l i g u l a r i s L .
M a r i s c u s l i g u l a r i s (L. ) Hutchinson
F r y e r 25 (K) (as Mariscus r u f u s ) ; J e f f r e y 1201 (MAHE) ( m i s - l a b e l l e d : t h i s specimen i s from Denis I s l a n d ) ; S t o d d a r t 7087 (US).
PALMAE
*Cocos n u c i f e r a L.
Coppinger, s i g h t (1885); F r y e r , s i g h t ( 1 9 1 0 ) ; P i g g o t t , s i g h t ( 1 9 6 9 ) ; P r o c t e r , s i g h t ; F e a r e , s i g h t ; S t o d d a r t , s i g h t .
ARACEAE
*Alocasia m a c r o r r h i z a ( L . ) S c h o t t . S t o d d a r t 7109 (US)
.
Colocasia e s c u l e n t a (L. ) S c h o t t . S t o d d a r t 7118 (US).
LILIACEAE sensu l a t i s s i m o
*Agave r i g i d a Northrop v a r . s i s a l a n a P e r r . e x Engelm.
Agave s i s a l a n a P e r r .
F e a r e , s i g h t ; S t o d d a r t , s i g h t .
*Crinum s p . ?
S t o d d a r t 7116 (US)
.
MUSACEAE
*Mum sapientum L .
F e a r e , s i g h t ; S t o d d a r t , s i g h t .
MARANTACE AE
*Maranta arundinacea L
.
F r y e r , s i g h t , i n Summerhayes ( 1 9 3 1 ) ; P r o c t e r , s i g h t .
CASUARINACEAE
C a s u a r i n a e q u i s e t i f o l i a
L .S t o d d a r t 7107 (US), 7133 (US) ; Coppinger, s i g h t (1885) ; F r y e r s i g h t (1910); P i g g o t t , s i g h t (1969); P r o c t e r , s i g h t ; F e a r e , s i g h t .
MORACEAE
* A r t o c a r p u s a l t i l i s
( p a r k . ) Fosb.S t o d d a r t , s i g h t ( j u v e n i l e ) .
F i c u s
sp.S t o d d a r t 7098 (US); F e a r e , s i g h t .
* F i c u s b e n g h a l e n s i s
L.S t o d d a r t 7097 (US).
F i c u s nautarum
BakerF r y e r , no number, i n Summerhayes (1931); P r o c t e r , s i g h t .
AMARANTHACEAE
A c h y r a n t h e s a s p e r a
L.
P r o c t e r , s i g h t .
A c h y r a n t h e s a s p e r a
cf.
v a r .f r u t i c o s a
Boerl.E. S. Brown i n 1952-1953 (BM)
.
A c h y r a n t h e s a s p e r a
c f . v a r .v e l u t i n a
(H. and S.) Townsend S t o d d a r t 7079 (US); F e a r e , s i g h t .*Amaranthus d u b i u s
Mart. e x T h e l l . S t o d d a r t 7103 (US), 7127 ( U S ) .*Amaranthus c a u d a t u s
L.F r y e r , no number, i n Summerhayes (1931).
*Amaranthus c l e r a c e u s
L . Feare,
s i g h t .NYCTAGINACEAE
B o e r h a v i a d i f f u s a
L .( s e n s u l a t o )
(prob. = B .r e p e n s
L . ) F r y e r 32 (K).B o e r h a v i a r e p e n s
L. v a r .P r o c t e r 4043 (MAHE) ( v a r
. m a r i s - i n d i c a
Fosb. ) ; S t o d d a r t 7083 (US) ; F e a r e,
s i g h t .* B o u g a i n v i l l e a g l a b r a
Choisy S t o d d a r t 7102 (US).
P i s o n i a g r a n d i s
R. B r .S t o d d a r t 7080 ( U S ) ; F e a r e , s i g h t .
PORTULACACEAE
P o r t u l a c a o l e r a c e a
L. v a r .g r a n u l a t o - s t e l l u l a t a
v. P o e l l n .S t o d d a r t 7088 (US); Coppinger, i n Hemsley (1885); P r o c t e r , s i g h t ; F e a r e , s i g h t .
LAURACEAE
C a s s y t h a f i l i f o r m i s
L.S t o d d a r t 7077 ( U S ) ; F r y e r , s i g h t (1910); P r o c t e r , s i g h t ; F e a r e , s i g h t .
HERNANDIACEAE
Hernandia s o n o r a
L.Hernandia p e l t a t a
Meissn.Hernandia n y m p h a e a e f o l i a
( P r e s l ) K u b i t z k i F r y e r , s i g h t (1910) (as H .p e l t a t a ) .
CAPPARIDACEAE
*Cleome v i s c o s a
L . F e a r e , s i g h t .* c l e o m e gynandra
L .G
y n a n d r o p s i s gynandra
(L. ) B r i q . P r o c t e r 4046 (MAHE) ; F e a r e , s i g h t .MORINGACEAE
*Moringa o l e i f e r a Lam.
S t o d d a r t 7122 (US) ; Feare
,
s i g h t .CRASSULACEAE
*Kalanchoe p i n n a t a
(Lam.) P e r s .S t o d d a r t 7084 (US); P r o c t e r , s i g h t ; F e a r e , s i g h t .
LEGUMINOSAE
C a e s a l p i n i a b o n d u c
(L. ) Roxb.c a e s a l p i n i a b o n d u c e l l a
(L. ) Flem.F r y e r 7 (K)
.
C a s s i a o c c i d e n t a l i s
L.P r o c t e r , s i g h t ; F e a r e , s i g h t .
S e s b a n i a s e r i c e a
(Willd. LinkS t o d d a r t 7105 (US); Coppinger, i n Hemsley (1885) ( a s
S . a c u l e a t a
P e r s . ).
ZYGOPHYLLACEAE
T r i b u l u s c i s t o i d e s
L.S t o d d a r t 7130 (US) ; F r y e r , s i g h t (1910) ; P r o c t e r , s i g h t ( a s
T r i b u l u s
s p . ) ; F e a r e , s i g h t .SURIANACEAE
S u r i a n a m a r i t i m a
L.S t o d d a r t 7069 (US); Coppinger, i n Hemsley ( 1 8 8 5 ) ; F e a r e , s i g h t . EUPHORBIACEAE
A c a l y p h a i n d i c a
L .F r y e r 27 (K) ; P r o c t e r 4045 (MAHE) ; S t o d d a r t 7082 (US) ; F e a r e
,
s i g h t .
*Euphorbia c y a t h o p h o r a
Murr.F r y e r , no number, i n Summerhayes (1931) ( a s E .
h e t e r o p h y l l a
L..
* E u p h o r b i a h i r t a
L.S t o d d a r t 7114 (US); P r o c t e r , s i g h t ; F e a r e , s i g h t .
Euphorbia p r o s t r a t a
A i t .P r o c t e r , s i g h t ; F e a r e , s i g h t .
* P e d i l a n t h u s ti th y m a l o i d e s
(L. P o i t . S t o d d a r t 7117 (US).* P h y l l a n t h u s a m a r u s Schum.
S t o d d a r t 7 1 2 5 ( U S ) .
P h y l l a n t h u s m a d e r a s p a t a n u s L.
S t o d d a r t 7 0 6 2 ( U S ) .
* ~ i c i n u s c o m m u n i s L .
S t o d d a r t 7 0 6 3 ( U S ) ; P r o c t e r , s i g h t ; F e a r e , s i g h t .
SAPINDACEAE
* C a r d i o s p e r m u m h a l i c a c a b u m L . F r y e r 2 4 ( K ) .
MALVACEAE
* A b u t i l o n i n d i c u m ( L . ) S w e e t
S t o d d a r t 7106 ( U S ) , 7 1 2 1 ( U S )
--
; C o p p i n g e r , i n H e m s l e y ( 1 8 8 5 ) ; P r o c t e r , s i g h t ( a s A b u t i l o n m a u r i t i a n u m ) ; F e a r e , s i g h t .* G O S S ~ P ~ U ~ h i r s u t u m L.
S t o d d a r t 7 1 0 4 ( U S ) ; C o p p i n g e r , s i g h t ( 1 8 8 5 ) ; P r o c t e r , s i g h t Cas G o s s y p i u m p u r p u r a s c e n s ) ; F e a r e , s i g h t .
* M a l v a s t r m c o r o m a n d e l i a n m ( L
.
) G a r c k e P r o c t e r , s i g h t ; F e a r e , s i g h t .* S i d a a c u t a B u m . f.
F e a r e
,
s i g h t . S i d a p a r v i f o l i a DC.S t o d d a r t 7 1 2 4 ( U S ) .
T h e s p e s i a p o p u l n e a (L.) S o l .
ex
C o r r e a S t o d d a r t 7 0 7 6 ( U S ) ; F e a r e , s i g h t .GUTTIFERAE C a l o p h y l l u m i n o p h y l l u m L.
F r y e r 17 ( K ) ; S t o d d a r t 7 0 9 9 ( U S ) ( v a r . t a k a m a k a ~ o s b . ) ; F e a r e , s i g h t .
* T u r n e r a u l m i f o l i a
L.S t o d d a r t 7067 (US); P r o c t e r , s i g h t ; F e a r e , s i g h t .
PASS IFLORACEAE
* P a s s i f l o r a s u b e r o s a
L.S t o d d a r t 7090 (US); F r y e r , no number, i n Summerhayes ( 1 9 3 1 ) ; P r o c t e r , s i g h t ; F e a r e , s i g h t .
CARICACEAE
* C a r i c a papaya
L.S t o d d a r t 7085 (US); Coppinger, s i g h t ( 1 8 8 5 ) ; F r y e r , s i g h t ( 1 9 1 0 ) ; P i g g o t t , s i g h t ( 1 9 6 9 ) ; P r o c t e r , s i g h t ; F e a r e , s i g h t .
CUCURBITACEAE
* C u c u r b i t a
s p.
S t o d d a r t 7108 (US)
.
* C u c u r b i t a
c f. maxima
Duchesne S t o d d a r t 7134 (US).
* C u c u r b i t a m o s c h a t a
DuchesneP r o c t e r , s i g h t ; F e a r e , s i g h t .
[ ~ e m p h i s a c i d u l a
F o r s t .F r y e r , s i g h t , i n Summerhayes ( 1 9 3 1 ) ; P r o c t e r , sic f o r
S u r i a n a m a r i t i m a
L. ) ]COMBRETACEAE
T e r m i n a l i a c a t a p p a
L.F r y e r 16 (K)
.
APOCYNACEAE
rht ( b o t h i n e r r o r
* C a t h a r a n t h u s r o s e u s
(L. G . DonV i n c a r o s e a
L.L o c h n e r a r o s e a
(L. SpachF r y e r 29 (K) ( a s
L o c h n e r a r o s e a )
; S t o d d a r t 7086 (US),
7101 (US) ;P i g g o t t , s i g h t (1969) ; F e a r e , s i g h t .
* Plumeria
sp.S t o d d a r t , s i g h t ( j u v e n i l e ) .
CONVOLWLACEAE
*Ipomoea b a t a t a s
(L. Lam.F r y e r , no number, i n Summerhayes (1931).
Ipomoea macrantha
R. and S.Ipomoea t u b a
( S c h l e c h t . ) G. DonS t o d d a r t 7093 (US) ; F r y e r , s i g h t (1910) ; F e a r e , s i g h t .
Ipomoea pes-caprae
(L.
) R. B r .S t o d d a r t 7075 (US) ( v a r .
b r a s i l i e n s i s
(L. ) v. O o s t s t r . ) ; F r y e r , s i g h t ( 1 9 1 0 ) ; P r o c t e r , s i g h t ; F e a r e , s i g h t .BORAGINACEAE
C o r d i a s u b c o r d a t a
Lam.S t o d d a r t 7078 (US); F e a r e , s i g h t .
~ o u r n e f o r t i a a r g e n t e a
L. f.
Messerschmidia a r g e n t e a
(L. f.
) J o h n s t .S t o d d a r t 7068 (US) ; Coppinger, i n Hemsley (1885) ; F r y e r , s i g h t ( 1 9 1 0 ) ; P r o c t e r , s i g h t ; F e a r e , s i g h t .
VERBENACEAE
L i p p i a ~ o d i f l o r a
(L.
) Michx.Phyla n o d i f l o r a
(L. GreeneF r y e r 31 ( K ) ; P r o c t e r 4042 ( M A H E ) ; S t o d d a r t 7066 s i g h t .
S t a c h y t a r p h e t a j a m a i c e n s i s
(L.) Vahl S t o d d a r t 7065 (US); P r o c t e r , s i g h t ;LABIATAE
* P l e c t a n t h r u s
sp.S t o d d a r t 7115 (US).
SOLANACEAE
F e a r e , s i g h t .
*Capsicum minimum
Roxb. (= C .f r u t e s c e n s
L.?) F e a r e , s i g h t .* D a t u r a m e t e l L .
S t o d d a r t 7 0 9 5 ( U S ) ; P r o c t e r , s i g h t ; F e a r e , s i g h t .
* N i c o t i a n a t a b a c u m L . F r y e r , s i g h t ( 1 9 1 0 )
.
*Solanurn m e l o n g e n a L
.
F e a r e , s i g h t . S o l a n u m n i g r u m L. ( s . I . )
S t o d d a r t 7 1 2 6 ( U S ) ; F e a r e , s i g h t
SCROPHULARIACEAE S t r i g a a s i a t i c a ( L . ) 0 . K t z e .
F r y e r 3 3 ( K )
.
BIGNONIACEAE
* ~ a b e b u i a h e t e r o p h y l l a ( L . ) H e m s l .
S t o d d a r t 7 0 9 6 ( U S ) , 7 1 0 0 ( U S ) ; F e a r e , s i g h t ( a s T a b e b u i a r o s e a ) .
ACANTHACEAE A s y s t a s i a m u l t i f l o r a Kl.?
S t o d d a r t 7 1 1 9 ( U S ) .
* A s y s t a s i a g a n g e t i c a ( L . ) T . A n d e r s . (= A s y s t a s i a m u l t i f l o r a K l . ? ) P r o c t e r , s i g h t ; F e a r e , s i g h t .
RUBIACEAE G u e t t a r d a s p e c i o s a L .
S t o d d a r t 7 0 9 2 ( U S ) , 7 1 3 2 ( U S ) ; F e a r e , s i g h t . M o r i n d a c i t r i f o l i a L .
F r y e r 4 ( K ) .
GOODENIACEAE S c a e v o l a t a c c a d a ( G a e r t n . R o x b .
S t o d d a r t 7 0 7 0 ( U S ) ; F r y e r , s i g h t ( 1 9 1 0 ) ( a s S c a e v o l a k o e n i g i i ) ; P i g g o t t , s i g h t ( 1 9 6 9 ) ; P r o c t e r , s i g h t ( a s S c a e v o l a f r u t e s c e n s ) ;
Feare,
s i g h t .COMPOS ITrn
Vernonia cinerea
(L. ) Less.S t o d d a r t 7061 ( U S ) ; F r y e r , no number, i n Summerhayes ( 1 9 3 1 ) ; P r o c t e r , s i g h t ; F e a r e , s i g h t .
SOURCES
Coppinger c o l l e c t i o n : l i s t e d by Hemsley ( 1 8 8 5 ) , pp. 16-17; a d d i t i o n a l s i g h t r e c o r d s i n Coppinger (1885).
F r y e r c o l l e c t i o n : F r y e r ' s p a p e r on B i r d I s l a n d (1910) and h i s
manuscript d i a r y ; enumerations of f l o w e r i n g p l a n t s i n Summerhayes (1931) and o f f e r n s i n C h r i s t e n s e n (1912).
P r o c t e r c o l l e c t i o n s : Department of A g r i c u l t u r e , Mahe, and enumeration of c o l l e c t i o n s and s i g h t r e c o r d s i n ' L i s t of p l a n t s r e c o r d e d on B i r d I s l a n d on 14 J u l y 1 9 7 0 1 , t y p e s c r i p t .
J e f f r e y c o l l e c t i o n : Department o f A g r i c u l t u r e , Mahe.
F e a r e r e c o r d s : s i g h t r e c o r d s c i t e d i n F e a r e (1979).
S t o d d a r t c o l l e c t i o n : d e t e r m i n a t i o n s by F.R. Fosberg.
A few m i s c e l l a n e o u s c o l l e c t i o n s i n h e r b a r i a i n d i c a t e d .
S p e c i e s marked
*
a r e judged t o b e i n t r o d u c e d .Some of t h e s i g h t r e c o r d s may w e l l b e m i s i d e n t i f i c a t i o n s .
3. Geography and ecology of Denis I s l a n d , Seychelles
INTRODUCTION
Denis I s l a n d i s l o c a t e d on t h e n o r t h e r n margin of t h e Seychelles Bank i n l a t i t u d e 3O48'S. and l o n g i t u d e 55°40'E., 89 km n o r t h n o r t h e a s t of Mahe and 52 km e a s t of Bird I s l a n d . I t i s 2000 m long, has a maximum width i n t h e n o r t h of 1380 m , and has a t o t a l a r e a of 1 2 0 ha
(48 p e r c e n t l a r g e r t h a n Bird I s l a n d ) (Figure 4 ) .
The i s l a n d was discovered by and named a f t e r Denis de Trobriand, i n command of t h e E t o i l e , i n August 1773, b u t t h e f i r s t f u l l account r e s u l t e d from t h e v i s i t of J . C . F . Fryer i n August 1908 (Fryer 1910).
Subsequently t h e i s l a n d was v i s i t e d by B.H. Baker, C . J e f f r e y and C.J.
P i g g o t t i n t h e e a r l y 1960s (Table 51, b u t t h e only connected account of t h e n a t u r a l h i s t o r y of Denis remains t h a t of Fryer. The p r e s e n t paper i s based on a v i s i t on 10-11 December 1977; it b r i n g s t o g e t h e r t h e e x i s t i n g l i t e r a t u r e , i n c l u d i n g unpublished m a t e r i a l i n t h e
Seychelles Archives, and a l s o provides an account of t h e v e g e t a t i o n and f l o r a .
MORPHOLOGY AND STRUCTURE
Denis i s an i s l a n d formed e n t i r e l y of carbonate sands which have been e x t e n s i v e l y phosphatised. The beaches a r e narrow and a p p a r e n t l y s t a b l e ; t h e r e a r e no pronounced s p i t s o r beach r i d g e s , a s a t Bird I s l a n d , and no storm d e p o s i t s . The average s u r f a c e e l e v a t i o n i s probably only about 2.5 m, r i s i n g t o 3.5 m i n t h e n o r t h and n o r t h e a s t , though no i n s t r u m e n t a l determinations have been made. About 80 p e r c e n t of t h e s u r f a c e a r e a i s occupied by phosphate rock, t o t a l l i n g about 95 ha, and t h i s r e a c h e s t h e c o a s t t o form i r r e g u l a r c l i f f s about 2 m h i g h a t t h e southwest corner (Muraille Bon Dieu) ( P l a t e s 9 and 10) and a t t h e pronounced i n d e n t a t i o n on t h e e a s t c o a s t (Sans Tache). A s on Bird I s l a n d , t h e upper s u r f a c e of t h e phosphate rock i s blocky and i r r e g u l a r , w i t h many loose fragments. The lower s u r f a c e of
cementation i s i r r e g u l a r and l o b a t e , forming p i l l a r s and i n l e t s i n t h e c l i f f s ( P l a t e 11; a l s o i l l u s t r a t e d by F r y e r 1910, P l a t e 2 ) . T h i s morphology i s i d e n t i c a l t o t h a t of s i m i l a r rocks a t Raine I s l a n d , Great B a r r i e r Reef, where t h e lower s u r f a c e i s a l s o exposed i n c l i f f s .
2 6
Table 5. S c i e n t i f i c s t u d i e s a t Denis I s l a n d
Date
1775 12 Aug.
1906 29-31 March
1908 2-8 August
1927
1960 Sept
1962 March
1977 10-11 December
V i s i t o r
D. de Trobriand E t i o l e
W. F. Stephens
J.C.F. F r y e r
J . Hornell E . S. Brown
C . J . P i g g o t t B.H. Baker C. J e f f r e y F.L. Lambrecht D.R. S t o d d a r t
S u b j e c t Discovery
Phosphate
General survey and c o l l e c t i n g C o l l e c t i n g I n s e c t s
Coconuts Geology Botany I n s e c t s Botany
General ecology
P u b l i c a t i o n De Trobriand, i n Fauvel 1909 Stephens 1906aI 1906b
Fryer 1910
Burleigh 1979
Mattingly and Brown 1955
P i g g o t t 1968, 1969 Baker 1963
J e f f r e y 1962 Lambrecht 1971 T h i s p a p e r
According t o P i g g o t t (1968, 551, t h e phosphate rock i s more t h a n 1 . 2 m t h i c k i n t h e n o r t h e a s t b u t t h i n n e r elsewhere. Baker (1963, 41-46) d e s c r i b e s a double horizon of cementation i n t h e n o r t h e a s t , i n t h e f o l l o w i n g s e c t i o n : 5-46 cm: phosphate rock, 30-90 cm: unconsolidated sand, 18-30 an: phosphate rock. According t o Baker t h e phosphate rock i s t h i c k e r i n t h e c e n t r e of t h e i s l a n d , where it forms a s i n g l e horizon.
The cemented m a t e r i a l i s o v e r l a i n by guano, much of which h a s been removed f o r e x p o r t . P i g g o t t (1969, 63) terms t h e s u p e r f i c i a l m a t e r i a l a Jemo S e r i e s s o i l , i n c o n t r a s t t o t h e Shioya S e r i e s of t h e r e s t o f t h e i s l a n d , and Baker (1963) g i v e s t o t a l P2O5 c o n t e n t of guano samples of 31.5, 28.2 and 7.8 p e r c e n t .
Towards t h e e a s t e r n s i d e of t h e i s l a n d t h e r e a r e e l o n g a t e water- f i l l e d d e p r e s s i o n s about 1 m below t h e g e n e r a l s u r f a c e l e v e l . I t i s n o t known whether t h e s e a r e n a t u r a l o r whether t h e y r e s u l t from guano- digging o p e r a t i o n s e a r l i e r t h i s c e n t u r y . They c o n t a i n f r e s h w a t e r and hydromorphic s o i l s , which a r e unusual on western Indian Ocean c o r a l i s l a n d s . P i g g o t t (1969, 63) g i v e s t h e f o l l o w i n g p r o f i l e :
C-13 cm Black c l a y loam with c o a r s e s o f t crumb s t r u c t u r e , c o n t a i n i n g about 10 p e r c e n t P2O5 and 20 p e r c e n t o r g a n i c m a t t e r .
13-38 cm Brown phosphatic sandstone; very dark i n t h e upper p a r t b u t g e t t i n g p a l e below; t h e sand being f a i r l y coarse.
38-46 cm Coarse white sand, with t h e w a t e r t a b l e a t 46 an.
In a d d i t i o n t o t h e phosphate rock, beachrock outcrops e x t e n s i v e l y along t h e s o u t h e a s t shore, where it was noted by Fryer i n 1908.
Remnants of beachrock i n d i c a t e t h i s t h i s beach was formerly longer, b u t t h e c o a s t i t s e l f seems t o be a s t a b l e one. Beachrock a l s o outcrops i n t e r m i t t e n t l y along t h e shore of t h e west bay. T i d a l movement of sand suggests t h a t t h e beachrock i s much more e x t e n s i v e than t h e outcrops a t any time suggest.
A s a t Bird I s l a n d , s u r f a c e r e e f i s only e x t e n s i v e along t h e e a s t e r n s i d e of t h e i s l a n d . The shoal on which Denis s t a n d s i s very much s m a l l e r t h a n t h a t of Bird, and t h e surrounding s u r f a c e of t h e Seychelles Bank i s 55-75 m deep.
CLIMATE
R a i n f a l l r e c o r d s were maintained a t Denis I s l a n d from 1951 t o 1962 (Table 6 , Figure 5 ) . The mean annual r a i n f a l l over 1 2 y e a r s was 1730 mrn, with extremes ranging from 1176 t o 2643 rnm. I n t h e two y e a r s
(1961-62) f o r which r e c o r d s were a l s o k e p t a t Bird I s l a n d , t h e Denis I s l a n d r a i n f a l l was s u b s t a n t i a l l y g r e a t e r (12 p e r c e n t g r e a t e r i n 1961, a wet y e a r , and 19 per c e n t g r e a t e r i n 1962, an average y e a r ) . I t i s i n t e r e s t i n g t h a t t h e p a t t e r n of wet and dry y e a r s a t Denis during 1951-1962 c l o s e l y resembles t h a t a t D'Arros i n t h e northern Amirantes
(Stoddart, Coe and Fosberg 19791, suggesting a g e n e r a l r e g i o n a l c o n t r o l of r a i n f a l l v a r i a b i l i t y . December and January a r e t h e w e t t e s t months and J u l y much t h e d r i e s t . A l l months show considerable v a r i a t i o n i n r a i n f a l l t o t a l s from y e a r t o y e a r , b u t Denis does n o t experience t h e prolonged dry seasons and s e v e r e droughts which occur on c o r a l i s l a n d s i n t h e southern Seychelles.
VEGETATION
De Trobriand i n 1773 described t h e v e g e t a t i o n of Denis I s l a n d a s follows: "quelquespartiesdel'isle s o n t c o u p d e s p a r d e s e s p & c e s d e p r a i r i e s dont l ' h e r b e p a r a i t
tr8s
bonne q u e l q u ' a u t r e s p e t i t e s p o r t i o n s s o n t d'une t e r r e a s s e z s8che melge de s a b l e : environ l a moiti6 de l a s u r f a c e de l ' i s l e e s t couverte d ' a s s e z g r o s a r b r e s mais dont l e b o i s m'a sembl6 e t r e t r o p g r o s e t t r o p spongieux pour e t r e propre3
l a c o n s t r u c t i o n des vaisseaux" ( i n Fauvel 1909, 4 7 ) . These t r e e s may well have beenPisonia grandis. Fryer (1910, 19) u n f o r t u n a t e l y concluded t h a t " t h e v e g e t a t i o n i s of no i n t e r e s t , being a l l secondary i n c h a r a c t e r and dependent on t h e coconut c u l t i v a t i o n t o which i t s whole s u r f a c e i s devoted". He d i d , however, d i s t i n g u i s h a l i t t o r a l hedge of Scaevola, Tournefortia and Suriana (wrongly i d e n t i f i e d by both him and Summerhayes
(1931, 278) a s Pemphis a c i d u l a )
,
with Hibiscus t i l i a c e u s . TreesTable 6. Monthlv and annual r a i n f a l l records a t Denis I s l a n d
Year 1951 1952 1953 1954 1955 1956 1957 1958 1959 1960 1961 1962
Mean
-
Jan 253.7 281.2 221.0 300.0 541.3 210.0 350.3 104.6 322.6 134.6 419.9 429.5-
Feb 70.6 139.9 190.50 243.6 190.2
75.7 120.9 71.4 227.8 430.8 344.7
-
Mar 162.8 121.9 299.5 57.2 120.1 158.2 287.8 89.2 184.9 15.2 205.5 5.6Apr
54.9 105.4 75.4 12.2 129.8 97.8 67.8 158.7 129.3 200.2
78.2 118.1
May
161.5 40.6 66.8 120.6 11.9 147.3 124.2 277.9 61.2 93.7
0 202.9
-
Jun 0 140.972.6 106.7
0 0 60.2 638.0 23.9 95.7 27.7 84.1
J u l
-
0 52.8 76.2 86.9
0 0 36.1 24.1 22.9 38.1 64.3 20.8
Aug
142.2 133.1 82.6 150.4 79.2 85.6 13.5 35.8 99.8 45.7 259.8 112.5
-
Nov 0 128.5 230.1 100.6 53.6 99.3 248.9 167.9 181.9 9.9 292.3 97.0-
Dec 307.3 207.0 333.0 199.6 274.8 169.2 496.1 112.3 325.6 274.1 196.8 91.4Year 1491.5 1426.2 1867.9 1176.3 1737.9 1312.2 2181.3 1841.7 1630.0 1557 :O 2643.9 1893.1
Source: Stoddart (1971).
mentioned by him i n c l u d e d Casuarina, Calophyllum, Hernandia, F i c u s and P i s o n i a . He a l s o n o t e d t h e e x i s t e n c e of Typha; a l a r g e f e r n
(probably Acrostichum r a t h e r t h a n t h e Aspleniam he m e n t i o n s ) ; and Catharanthus, a s w e l l a s bananas and v a n i l l a . P i g g o t t (1969, 59-65) a l s o remarks on t h e number of l a r g e t r e e s i n t h e e a s t and c e n t r e of t h e i s l a n d (Calophyllum, Hernandia, P i s o n i a , Ficus, T e r m i n a l i a ) , and found b o t h Catharanthus and Cassytha t o b e widespread.
Based on t h e v i s i t i n 1977 and t h e map and c o l l e c t i o n s t h e n made, t h e f o l l o w i n g v e g e t a t i o n u n i t s may be d i s t i n g u i s h e d ;
1. L i t t o r a l hedge, dominated by Scaevola taccada b u t a l s o w i t h T o u r n e f o r t i a a r g e n t e a a n d s u r i a n a maritima, o f t e n much covered with Cassytha f i l i f o r m i s . On i t s landward s i d e both Guettarda s p e c i o s a and H i b i s c u s t i l i a c e u s a r e common, and i n p l a c e s , e s p e c i a l l y on t h e west and s o u t h e a s t s i d e s , Scaevola i s r e p l a c e d by Guettarda. The
l i t t o r a l hedge on t h e west s i d e i s narrower, l e s s continuous and more d i v e r s e , and i n p l a c e s (on t h e s l i g h t l y e r o d i n g n o r t h e a s t s h o r e and where t h e phosphate rock o u t c r o p s ) it i s e n t i r e l y l a c k i n g .
2. Casuarina woodland. Casuarina e q u i s e t i f o l i a i s e x t e n s i v e l y p l a n t e d a s a windbreak along t h e g r e a t e r p a r t of t h e c o a s t l i n e ( P l a t e
l o ) ,
forming a zone 20-100 m wide, o f t e n w i t h t h e t r e e s s e t o u t i n r e g u l a r rows. Many a r e t a l l and o l d and some a r e b e i n g removed f o r timber.3. Coconut woodland. T h i s covers t h e e n t i r e c e n t r e of t h e i s l a n d , and many of t h e t r e e s a r e about 80 y e a r s o l d . When t h e p l a n t a t i o n was begun on a commercial s c a l e i s n o t known, b u t it was probably about 1890. By 1903 t h e r e were 20,000 t r e e s y i e l d i n g 50,000 n u t s p e r month ( S e y c h e l l e s Archives C/SS/74(1), 1391, and by 1906 t h e y i e l d was 60,000 n u t s p e r month (Stephens 1906a). P i g g o t t (1969) found t h e p l a n t a t i o n w e l l managed, i n s p i t e of t h e age of t h e t r e e s and t h e e f f e c t s of Rhinoceros B e e t l e and c o c c i d s , and he commented on t h e high q u a l i t y of t h e copra i n s p i t e of t h e poor q u a l i t y of t h e n u t s . The p l a n t a t i o n s a r e s t i l l s c a t t e r e d with b r o a d l e a f t r e e s
-
massive B a r r i n g t o n i a and Calophyllum and s m a l l e r Tabebuia, Morinda, Terminalia and P i s o n i a . The f e r n Polypodium and Kalanchoe form e x t e n s i v e and dense ground cover on t h e phosphate a r e a s ; Catharanthus and o t h e r weedy p l a n t s a r e widespread. P i l e s of coconut husks a r e covered with t h e f e r n Nephrolepis.4. Marsh v e g e t a t i o n . The i n l a n d f r e s h w a t e r marshes s u p p o r t t a l l and i m p e n e t r a b l e s t a n d s of t h e f e r n Acrostichum speciosum and t h e b u l r u s h Typha j a v a n i c a ( P l a t e 1 2 ) . The l a t t e r i s r a r e on c o r a l i s l a n d s ; it i s common on high i s l a n d s i n t h e S e y c h e l l e s , n o t a b l y on P r a s l i n and Curieuse, which a r e t h e c l o s e s t h i g h i s l a n d s t o Denis. A l o c a s i a macrorrhiza i s c u l t i v a t e d i n t h e s e marshes.