PYGMY NUTHATCH FEEDS MOUNTAIN BLUEBIRD NESTLINGS

Abstract

Instances of adults of one avian species unilaterally feeding the young of another species have been reported for a variety of passerines (Powell 1946, Logan 1951, Eddinger 1970, Moore 1973). This unusual behavior sometimes occurs following a recent nesting failure by the feeding adults (Lack 1946:87, Norris 1958, Skutch 1976:370), but there are also reported nest failures caused by errors in feeding (Williams 1942). Documentation of whether a nest failure precedes or follows a feeding error requires knowledge of the nesting histories of all birds involved in an interspecific feeding, and these histories are often unknown.