Factors Influencing Apparent Nest Success in Eastern Bluebirds

Abstract

Collection of basic breeding biology data and analysis of factors that can impact the apparent nest success of passerines is critical in tracking population dynamics and making decisions concerning conservation. The Eastern Bluebird (Sialis sialis) is one species of concern whose declines in abundances fueled the common practice of establishing artificial nest boxes. I carried out my study in 2019 on the SUNY Brockport campus using 20 Audubon and 20 Peterson nest boxes to investigate what variables may impact fledgling success, including egg and nestling traits as well as site characteristics. Egg mass and volume tended to be larger in Audubon boxes, which also appeared to have higher success rates, but only egg volume was significant. Peterson style boxes were chosen more often, however. Vegetation variables revealed no statistical significance between successful and unsuccessful nests, but literature supports their strong effect on nest success. Larger sample sizes would have helped reinforce my results. However, they do offer interesting opportunities for conservationists in terms of box type and habitat when considering Eastern Bluebird nesting success.