In my recent blog about our discovery of Wedge-tailed Shearwaters occupying burrows on Mahe, I mentioned that White-tailed Tropicbirds were the only seabird that had survived in numbers as a breeding species on the larger granitic islands of Seychelles. They had survived despite a large and still increasing human population and the commensal predators that they had brought with them – rats, cats, tenrecs and dogs. The human population had an appetite for catching and eating birds whose behaviour was adapted to life on islands without these threats, rendering the tropicbirds defenceless against this exploitation.
When I first arrived in Seychelles in December 1971, White-tailed Tropicbirds were the first seabirds that I saw, soaring high around the steep and inaccessible granite cliffs of the highest mountains. Living at the Tea Company at Sans Souci I was able to watch them every day on the Morne Blanc cliff face. This was the habitat that I had seen described for White-tailed Tropicbirds on the main islands. In an unpublished report in 1936 Desmond Vesey-Fitzgerald said that they laid their eggs “on lofty mountain ledges”, while much later (1974) Malcolm Penny (Birds of Seychelles and the outlying islands) said that on the larger islands they nested in high mountain forest. More recently, Adrian Skerrett and Ian Bullock (2001, Birds of Seychelles) said that a few birds “nest high on the larger islands such as Mahe …..”. On smaller rocky islands that are free of rats and cats (e.g. Aride, Cousin, Cousine), White-tailed Tropicbirds nested abundantly, as they still do, both on the ground and in cavities in trees, sometimes 10 m or more above the ground. Small numbers nest in similar habitats on the two low-lying coralline islands of Bird and Denis.
But times are changing, and for the better. The contrast of its pure white plumage and its spectacularly long central tail feathers against a background of pure blue sky can now be enjoyed over much of Mahe, even from its beaches. White-tailed Tropicbirds have enjoyed a major comeback over recent decades and are no longer restricted to high altitude cliffs on Seychelles’ main islands. They have spread right down to the coast, and we have seen the progress of one nest in a cavity in a Takamaka tree at the top of a beach in south Mahe. The cavity is less than 2 metres above the sand and several chicks have been successfully reared in this nest site over the past few years. This is despite abundant rats, cats and dogs in the vicinity. In addition, a much larger and active human population, including residents and tourists, generates more disturbance than was prevalent in the 1970s.
What has undoubtedly changed is the human appetite for hunting and eating seabirds such as White-tailed Tropicbirds. The year-round ready availability of foods, both locally grown and imported, and improved living standards of most Seychellois, have almost certainly contributed to the decline in the eating of wildlife. It might even be that the current desire for fast foods, and the explosion in their availability, have contributed to wildlife conservation, albeit at the expense of human health!
The downhill march of White-tailed Tropicbirds matches the expansion of Seychelles Blue Pigeons and Seychelles Bulbuls. These birds were also hunted, for sport as well as food, up to at least the 1970s and were at that time restricted to high altitude forests, but both are now common at sea level.
While introduced predators, which are still common on the main islands, were undoubtedly detrimental to native birds of Seychelles, the hunting of birds by people appears to have been the major driver of decline and restricted distribution of some species on the most populated islands.