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Welty, Justin L. – Costs and benefits of variable nest density in Burrowing Owls: Effects on predation, ectoparasites, egg yolk hormones, and productivity

Justin Welty holding burrowing owlMy research focuses on the costs and benefits of group living in western burrowing owls (Athene cunicularia hypugaea). These owls live in underground burrows and can live within close proximity to other owls (semi-colonial). However, many owls also live without other burrowing owls in a kilometer or more from their nest. I am looking at whether the distance between nests influences the behavior and success of the owls. I am looking at predation, ectoparasite levels, yolk androgens, and nest productivity. Predation is determined through the monitoring of actual nests and experimentally through the placement of dummy nests in grouped and solitary configurations. Behavior towards predators is determined by dragging a fake badger past the nest and recording the results. Ectoparasite levels are counted on the adults and nestlings. In addition, some nestlings had their ectoparasite levels experimentally lowered to see if that would improve nestling body condition. Yolk samples were extracted from 2 eggs per nest to determine if yolk androgens were influenced by laying order and distance to nearest neighbor. Finally, nests were monitored to determine what the nestling productivity was and whether the distance to neighbors influenced this productivity.

Thesis Abstract

This thesis was awarded Boise State University’s Distinguished Master’s Thesis Award for 2011-2012