Nest Site Selection and Consequences for Reproductive Success of the Endangered Mariana Crow (Corvus kubaryi)

Abstract

Reasons for the decline of the Mariana Crow (Corvus kubaryi) on the Western Pacific island of Rota are currently unknown, but a need to protect nesting habitat has been suggested. We examined 55 actual nest sites and 60 random sites from 1997 to 1999 to investigate habitat characteristics specific to crow nest sites. Both nests and random plots were predominantly in limestone forest habitat. Discriminant function analyses indicate actual nest sites were differentiated from random sites based on a higher percentage of canopy cover and mean DBH of papaya (Carica papaya) and woody vines, as well as a higher stem count of species associated with limestone forests. This resulted in correct classification of a potential site as nesting versus random in 92% of the cases. Actual nests were .300 m from buildings, while random sites averaged (6 SE) 226.7 6 71.6 m from a building. Actual nest sites were about twice as far from a road as random nest sites. Twenty-eight of the 55 active nests fledged young. Nests in native forests were associated with higher reproductive success than nests in more disturbed areas. These findings suggest that damage to habitat from anthropogenic or natural causes may be limiting nesting success. Received 19 February 2010. Accepted 22 November 2010.