Tufted Titmice (Baeolophus bicolor) rear a mixed brood to apparent fledging in northeastern Arkansas

Abstract

Interspecific nest usurpation, a relatively common nesting strategy, is the act of one bird species taking over the nesting site of another species. Although used by secondary cavity-nesters, nest usurpation has never been reported for the Tufted Titmouse (Baeolophus bicolor). In this paper, we document a mixed brood successfully reared by Tufted Titmice after usurpation of an Eastern Bluebird (Sialia sialis) nest in northeastern Arkansas during the 2019 breeding season. We monitored the focal nest box every 3–4 d from the first sign of nest building on 23 March 2019 until chick fledging by 12 May 2019. The Tufted Titmice took over the nest at the time the Eastern Bluebird had laid its fourth egg in the nest. By the end of the nesting period, the Tufted Titmice fledged 2 of their own chicks and 3 Eastern Bluebird chicks. Such successful rearing of non-conspecific nestlings is rare and we discuss factors that may have allowed it.