The site lies at the southern end of the Amirantes chain, c.300 km south-west of Mahé. It is a more-or-less circular island with a high rim surrounding a central depression. Most of the land is exposed sandstone, guano having been removed during the last century. The island is a base for the commercial exploitation of seabirds, especially the eggs of Sterna fuscata. There is no permanent human population, but buildings have been constructed and are used during the nesting season (June–August). Visits are made at other times by residents of nearby Marie-Louise island and by fishermen. The island is almost treeless, being covered in grasses and other low-growing plants. Landing can be extremely difficult, with heavy swells sweeping round the island even during the calmest sea conditions.
See Box for key species. The island may once have had the largest colony of Sterna fuscata in Seychelles. There are old estimates that this colony used to number more than one million pairs, possibly indicating a substantial decline. The island also supports large but unknown numbers of Puffinus pacificus and Anous stolidus, which may prove to exceed threshold levels. There used to be large colonies of Sula leucogaster (extinct by 1995) and Sula dactylatra (now only a few pairs) and, at least until the 1970s, a small population of Puffinus lherminieri. Other species include Bubulcus ibis (53–62 pairs) and a few pairs of Gygis alba.
Non-bird biodiversity: The turtles Chelonia mydas (EN) and Eretmochelys imbricata (CR) nest and may be taken by poachers.
BirdLife International (2019) Important Bird Areas factsheet: Desnoeufs island. Downloaded from http://www.birdlife.org on 26/04/2019.