Mammalian predator distribution and abundance on the Virginia Barrier Islands in relation to breeding habitats of colonial birds (Procyon lotor, Mustela vison, Vulpes vulpes, Lutra canadensis).

摘要

The predator distribution, abundance, and impact on colonial nesting birds on the Virginia barrier islands (Virginia, USA) were studied by track surveys and live-trapping of raccoons (Procyon lotor). Six surveys on 23 islands were carried out between October 1998 and June 2000, and 57 raccoons were captured during 1062 trapnights on 8 islands and 2 mainland sites. Raccoons were found on 18 islands, American mink (Mustela vison ) on 8, red fox (Vulpes vulpes) on 6, and northern river otter (Lutra canadensis) on 6. Birds avoided islands with raccoons and red foxes (Spearman rank correlation 1999: n = 13; r _s = −0.56; p = 0.05; 2000: n = 14; r_s = −0.79; p 0.002). Raccoon relative abundance was best correlated (r = 0.99, p 0.001) with the area of the salt marsh. Islands with raccoons had more shrubs and were higher in elevation than islands without. One possible management solution to protect birds on some smaller islands is the removal of predators.