When first discovered Bird Island probably had few land birds and R W Coppinger, who visited in 1882, stated categorically that there were none. By 1907 John Fryer, as part of the Percy Sladen Trust expedition to the Indian Ocean, found that Madagascar Fodies and Barred Ground Doves had arrived on Bird Island, and Desmond Vesey-Fitzgerald found that by 1936 Common Mynas were breeding here. These species had been introduced to Seychelles by man, who was presumably responsible for introducing them to Bird Island from the granitic islands. While Madagascar Fodies and Barred Ground Doves are considered fairly innocuous on Bird Island in relation to other wildlife, they can be troublesome in the hotel restaurant, where they attempt to steal food from the serving area and from guests’ tables. Mynas also take advantage of these handouts but are additionally accomplished predators of the eggs of seabirds when their eggs are left unguarded, which can be frequent when the seabirds are disturbed by humans, both residents and tourists.
Although the record is poor, Domestic Chickens have probably been on the island almost as long as humans, in various states of captivity or freedom. Currently, chickens range freely over much of the island, following release from pens at the small farm at Hirondelle a few years ago. On environmental grounds their presence is undesirable. By scratching into the soil surface they deplete fauna that are essential for maintaining soil health and fertility, at the same time preventing the successful germination of new plant life. As a result, soils regularly scraped by chickens are effectively deserts, with the frequently disturbed upper levels prone to drying out in the hot climate. This is readily apparent on Bird Island under Veloutye (Scaevola) and other bushes and trees, where soils are powdery and bare. Around the hotel chickens make a lot of noise in the early mornings and take the eggs of ground-nesting Brown Noddies. Chickens also take Sooty Tern eggs, but rather than venturing into the heart of the colony where they would be subjected to attack by the stabbing bills of incubating birds, the chickens confine themselves to the area where eggs are harvested, where adult Sooty Terns are less aggressive. Chickens may have provided one benefit on Bird Island, however; they are known to eat Giant Centipedes! Having trodden on two of these animals during my time in Seychelles, I can confirm that the scarcity of these centipedes, which can be up to 20 centimetres long, relieves sandaled walkers from the risk of excruciating pain!
The status of two of Seychelles’ endemic birds on Bird Island is well established. The Seychelles Sunbird is one of the commonest and widespread of Seychelles’ birds. Bird Island appears to have been too isolated for the species to have arrived without human assistance. Rachel Bristol, a Seychelloise conservation scientist, recognised that Bird Island had an abundance of nectar-producing flowers and insects and so should be capable of supporting a Sunbird population. In 2006 she caught 40 birds on Mahe and sent them to Bird Island by aeroplane for release on arrival. The introduction was highly successful and they are now widespread and even enter the hotel’s chalets to admire themselves in the mirrors!
Seychelles Blue Pigeons, on the other hand, colonised Bird Island naturally. In the 1970s they were largely confined to the high-altitude forests of Mahe, Praslin and La Digue. This restricted range probably resulted from excessive hunting; Blue Pigeons were considered tasty additions to diet by the Seychellois and good sporting targets, especially by youngsters with catapults. Relaxation of hunting led the birds on the main islands to increase in numbers and to descend from the mountains and to inhabit, or probably re-inhabit, lowlands by the coast where their main food, fruit, was abundant. Population increase was accompanied by range expansion to some of the smaller islands, including Cousin, Cousine and Aride Islands north of Praslin. From there they colonised Denis Island, about 60 kilometres to the north, and by the early 21st century they began nesting on Bird, over 50 kilometres west, where they are now well established and seen commonly in trees around the chalets.
Bird Island’s remaining three land birds have different and less well-known histories. Coppinger reported in 1882 that white egrets were common but whether they occurred naturally or had been introduced is unknown. In the 1970s they nested in a tall Casuarina tree at Passe Cocos, on the west coast, and fed mainly in grasslands in the Sooty Tern nesting area and where grass had replaced coconut plantation on what is now the airstrip; their diet comprised mainly insects. During the Sooty Tern breeding season, however, they chased recently-fed chicks, forcing them to regurgitate the fish and squid that constituted the chicks’ last meals and provided the egrets with superabundant highly nutritious food. Cattle Egrets last bred on the island in 1995, after which they appear to have succumbed to the poison that eradicated the rats.
Moorhens – the same species that occurs in Europe – were recorded on Bird Island by John Fryer in 1907 but during my 9-months residence in 1972 and 1873 I did not see any. On my return in 1993 they were present and have remained common, following increases on many other small islands in Seychelles. Now they are seen all over the island, in both woodland and open areas, where they eat seeds, fruit, invrtebrates and occasionally eggs of ground-nesting birds.
Seychelles formerly had its own subspecies of Turtle Dove but after human settlement the somewhat larger, grey-headed, subspecies from Madagascar was introduced, allegedly to provide more hunting opportunities. As a result, the slightly smaller and redder Seychelles form was largely replaced by the introduced form, but some birds with characteristics of the Seychelles subspecies survived on Cousin, Cousine and Aride islands. In the 1970s I saw only one Turtle Dove on Bird Island, a juvenile, but found a specimen of another from Bird Island in the Natural History Museum, UK, that has been shot here in 1940. In 1993 Turtle Doves were present in small numbers and intriguingly they showed characteristics of the Seychelles form. Following the provision of abundant food on the island (this will be explained in a following blog), the number of Turtle Doves increased and most then resembled the larger, grey-headed Madagascar Turtle Dove. Now, in 2019, food is again more limited and numbers have declined and have a predominance of red-headed birds. We seem to have here a hybrid population that can swing between expressions of head and body colour!