420 PERCY SLADEN TRUST EXPEDITION 



Gannets are everywhere extremely abundant : the usual species is the red-footed Sula 

 leucoqaster, but Sula piscator (cyanops ?) and Sula capucina also occur. 



Of migratory birds a fair variety of waders were noticed. Curlews and whimbrels 

 (Numenius arquatus, N~. phceopus) were very abundant in the swamps until January, 

 when they commenced to leave. Turnstones (Strejosilas interpret) were abundant along 

 the beach and had not diminished at all in number when I left the atoll in January. It is 

 presumed that all these birds go north to breed and therefore their winter wanderings 

 must be extremely wide. 



(c) Reptilia. Undoubtedly the most interesting animal on the atoll is the giant 

 land tortoise (Testudo elephantina). It still occurs in fair numbers on the extreme east of 

 Main Island and is scattered in small numbers in the rest of the island. It is also found 

 on Malabar and Picard Islands, but it is stated to have been reintroduced. This is 

 certainly the case in regard to Picard, but there is no evidence as regards Malabar. 



The species obtained on Main Island is Testudo elephantina, and a further species, 

 T. daudinii*, is supposed by Voeltzkow and others to have inhabited Malabar Island and 

 to have given rise to those at present existing on the Seychelles. Only two tortoises were 

 found on Malabar, both young specimens, and these were indistinguishable from the Main 

 Island tortoises. 



The question as to the number of species is further complicated by the fact that 

 T. elephantina has been divided into several species. It seems probable, however, that 

 these animals, free from enemies, would be able to vary somewhat without harm to them- 

 selves, and that the species into which T. elephantina was divided were based on such 

 minor variations. No evidence was obtained indicative of more than one species. 



The most interesting point in connection with the land tortoises is undoubtedly their 

 distribution. It is generally supposed either (l) that Aldabra had a previous land con- 

 nection, or (2) that the tortoises were placed there by man. It has already been shown 

 that the first alternative is not possible, and it remains to deal with the second. If it 

 were possible to consider Aldabra alone human transportation might give a natural 

 explanation. It is necessary, however, to consider the other islands on which giant land 

 tortoises have occurred")". These are (1) the Seychelles Group, (2) the Mascarenes, 

 (3) Madagascar, (4) the Galapagos, (5) Oosmoledo, (6) Assumption, and probably 

 (7) St Pierre, the last three being added in the course of the expedition here described. 

 A previous land connection may explain the existence of tortoises in the localities Nos. 2, 

 3, 4, and with the exception of Bird and Dennis Islands of No. 1 also. It is totally 

 inapplicable however to Cosmoledo, Assumption, St Pierre and Bird and Dennis Islands, 

 all of which are of purely oceanic origin. As regards Dennis Island a certain amount of 

 history exists: it was discovered in 1773 \ and was described as being covered with land 

 tortoises and sea turtles, a clear distinction being made between land and marine tortoises. 

 Bird Island was also described in much the same terms. Both Bird and Dennis were 

 visited by the author§ and they are merely sand cays built up by the waves. On Cosmoledo 



* It may be stated, as a personal opinion, that the modern Seychelles tortoises are very probably true 

 descendants of the original tortoises which occurred in the Archipelago when it was discovered, 

 t In recent times. \ Geographical Journal, 1907, p. 154. 



§ Trans. Linn. Soc. Ser. 2, Vol. xiv. p. 15 (Percy Sladen Trust Expedition, Vol. iii., p. 15). 



