First description of the nest and eggs of the Socorro Mockingbird

摘要

The Socorro Mockingbird (Mimodes graysoni) represents a monotypic genus endemic to Isla Socorro, Mexico (Brattstrom and Howell 1956). Formerly abundant on Socorro, this species has declined since the middle of this century (Jehl and Parkes 1982) and now numbers between approximately 100 (Castellanos and Rodriguez-Estrella 1993) and 300 individuals. As a consequence of its restricted range and small population size, Mimodes is considered critically endangered (Collar et al. 1992). Possible causes of the species' decline include predation from feral cats, habitat destruction caused by feral sheep, and competition with recently arrived Northern Mockingbirds (Mimus polyglottos) (Jehl and Parkes 1982). Determining what action is needed to prevent the extinction of Mimodes will require understanding of the species' breeding biology. However, almost nothing of this bird's natural history is known. Here we present the first description of the nests and eggs of the Socorro Mockingbird, along with preliminary observations about breeding seasonality and behavior derived from our ongoing field study of the conservation status of Mimodes graysoni.