Response of breeding European Storm Petrels Hydrobates pelagicus to habitat change

Abstract

Mainly through trampling and manuring, ground-nesting seabirds induced significant habitat changes both on vegetation cover and soil in one of the largest French colonies of European Storm Petrel Hydrobates pelagicus, Habitat deterioration led to a high level of erosion and the collapse of many former Rabbit Oryctolagus cuniculus burrows previously occupied by breeding Storm Petrels. The loss of burrows accelerated in recent years since Great Cormorants Phalacrocorax carbo bred on the islet with growing numbers. The main consequence of this disturbance was at first shifting of breeding Storm Petrels from burrows to rocky sites, reflecting some behavioral plasticity to buffer environmental variability. But over 18 years, a significant decrease in breeding numbers of Storm Petrels was recorded and attributed to continuous nest site destruction. Thus, other behavioral responses were also suspected, such as temporary non-breeding or emigration of birds that have to find a new nest site. Such a problem of heavy erosion and loss of nesting habitat could induce serious detrimental effects on burrowing seabirds breeding in a limited number of colonies.