When Bird Island was first discovered by Europeans in the 1770s, it was described as being covered by “innumerable” birds and later visitors reaffirmed this, also mentioning scant vegetation. The discoverers did not name the birds they found but Sooty Terns were likely to have been the most numerous species. Other species, mainly ground nesting ones as the island did not support forest at that time, would have included Brown Noddies. In addition, records from visitors in the late 19th and early 20th centuries described two species of “gannets”: most were Masked Boobies and others appear from the description of their nests to have been Brown Boobies. Soon after people colonised the Seychelles islands, however, humans regarded Bird Island as a good source of food – birds and fish; both were harvested and salted for subsequent transport to the main inhabited islands 100 km to the south.
In the late 18th century coconuts were planted widely in Seychelles, including Bird Island, to produce copra, a valuable export product in addition to coconut’s many uses by local consumers. Planting of coconuts on Bird Island represented a huge habitat change, one that severely limited the amount of open ground required by Sooty Terns and the other ground-nesting species, but provided new nesting opportunities for tree-nesting species, including adaptable species such as Brown Noddies. The ground-nesting species were additionally extremely vulnerable to human harvesting of their eggs, chicks and adults, and they received a further setback in the early 20th century when the surfaces of many islands that had formerly supported huge seabird populations were mined for guano, the accumulated droppings of thousands of years’ of defaecation by these birds. Bird Island did not escape this trauma but the limited supplies were soon exhausted.
The world lost its appetite for copra in the mid-20th century and the value of coconut plantations in Seychelles (and elsewhere) plummeted. But advances in public transport in the first part of that century raised the prospect of tourism as a replacement source of income. International travellers included a proportion of enthusiastic birdwatchers and Bird Island’s owners began the process of de-coconutisation (a word you probably won’t find in any dictionary!), in order to provide more space for the by then relict population of only about 18,000 pairs of Sooty Terns. The outcome of that initiative is readily apparent today, with approximately half a million pairs providing the wonderful spectacle covering about 10 hectares of cleared land and managed for them in the north of the island each June to August.
The demise of the coconut plantation, and the associated control of “weeds” at ground level, allowed other vegetation to proliferate. This included some trees, especially Pisonia grandis, locally called Mapou but often given the English names Bird-catcher Tree or Lettuce Tree. The “birdcatcher” name refers to its sticky seeds, which adhere to feathers and the tree uses birds to disperse seeds widely, sometimes killing the birds in the process. It seems likely that Lesser Noddies, which roosted on Bird Island in large numbers in the 1970s and began breeding on the island in 1984, brought seeds to Bird Island, probably from breeding colonies on Aride, Cousin and Cousine Islands. This tree now dominates Bird Island’s broad-leaved woodland.
Bird Island’s seabirds received a further boost in the 1990s, when the owners imported expertise from New Zealand to eradicate Black Rats, which had colonised the island following accidental introduction by early seafarers. Some of the Brown Noddies, that had nested abundantly in the crowns of coconut trees during their heyday, began nesting additionally on the ground.
Other beneficiaries of the woodland and the rat eradication were White Terns (often erroneously called Fairy Terns in Seychelles) and White-tailed Tropicbirds. White Terns breed on branches of large bushes, small trees and up to 20 metres high in taller trees, especially Casuarina; they will also nest on ledges of buildings if not disturbed, including the hotel’s chalets and restaurant. They do not build a nest, simply laying their egg in a slight depression in the wood. White-tailed Tropicbirds prefer Casuarina trees on Bird Island, nesting in holes and crevices in the tree trunks or, where they are most visible to tourists, in the bases of the trees where the roots radiate outwards.
Another breeding seabird, far less likely to be seen by tourists, is the Wedge-tailed Shearwater. When they are not breeding they spend their lives at sea but during the breeding season they nest in burrows, either natural cavities in the ground or in tunnels that they make in sand. Within their burrows they are not visible to tourists but can be heard giving their wailing calls during the night. Tens of thousands of them can sometimes be seen in afternoons off the south-west coast of Bird Island, distinguishable by being dark birds with a characteristic swooping flight with few wing beats. At dusk a few can be seen approaching the island, especially on the west coast, as they return to their burrows. We do not know how many nest on Bird Island but calling birds can be heard widely during night time among the bushes near Hirondelle and along both sides of the airstrip.
Finally, a small cousin of the Sooty Tern, similarly dark above and white below, but more delicately built, is the Bridled Tern. They have the unusual habit in Seychelles of breeding at roughly 8-momth intervals. When not breeding, roosting Bridled Terns can be seen commonly in the evenings in Casuarina trees along the island’s south-west coast. As far as we know, there has been only one breeding attempt on Bird Island, when a bird laid an egg on a fallen tree trunk at Hirondelle in the 1990s. The egg was soon deserted and disappeared.