Barn Swallow ( Hirundo rustica ) colony relocation in western Massachusetts

Abstract

Populations of Barn Swallows ( Hirundo rustica ) have declined throughout northeastern North America. Modern farming techniques, reduced insect prey populations caused by pesticide exposure, and mortality associated with climate changes have been postulated as causes of these declines. Evidence is equivocal that loss of nesting sites has adversely influenced regional population levels. Nonetheless, removal of a nesting site from a wildlife sanctuary created a contentious public debate between local animal protectionists, a statewide conservation organization, and a federal wildlife agency. We implemented and evaluated a two-year project aimed at mitigating the loss of this nesting site. In year one, when the abandoned horse stable that was planned for demolition was occupied by a breeding colony of approximately 40 pairs, we enhanced an existing nearby structure that was occupied by five pairs by placing seed nests that had been harvested from the horse stable, installing artificial nest platforms, and using vocalization playbacks. In year two, we deployed additional seed nests within the alternate nesting site that had been collected during demolition of the stable. Within three years, the alternate site supported a breeding colony that was approximately 93% in size of the colony that had previously been in the stable. There was no evidence that the nesting behavior of birds occupying the alternate site was affected by the forced relocation: the number of second broods, clutch sizes, body masses of both sexes, and within- and among-season survival did not differ significantly between the original and relocated nesting sites.

Keywords

• aerial insectivores
• colony relocation
• hirundo rustica
• nesting behavior
• survival