Light-induced mortality of petrels: a 4-year study from Réunion Island (Indian Ocean)

Abstract We report the results of a study of light-induced mortality of petrels at Reunion Island which holds two endemic endangered species, Barau’s petrel ( Pterodroma baraui ) and Mascarene petrel ( Pseudobulweria aterrima ), together with an endemic non threatened subspecies of Audubon’s shearwater ( Puffinus lherminieri bailloni ). We collected 2348 birds attracted to lights between January 1996 and December 1999, among which 70% were Barau’s petrels and 29% were Audubon’s shearwaters. We found also three specimens of the very rare Mascarene petrel. Most grounded birds were fledglings (94%). Light-induced mortality was seasonal and linked with the breeding schedule of each species. At least 20–40% of the fledglings of Barau’s petrels produced annually are attracted by lights. Light-induced mortality is a recent perturbation at Reunion Island. Thus, the effects of this disturbance on the population dynamics of these long lived seabirds may be hard to detect at the present time, but they are likely to occur in the near future. Conservation actions are proposed to limit the light-induced mortality together with other actions and long-term studies focused on the most endangered species.