Paving the way: Multifunctional nest architecture of the Rock Wren

Abstract

ABSTRACT Some avian species augment nest cups by building associated architectural structures that may mitigate predation, parasitism, and/or hatching failure. Because effective nest construction is integral to reproductive success, architectural structures associated with nests are predicted to provide functional benefits. Rock Wrens (Salpinctes obsoletus) stereotypically augment their soft cup nests with a pavement of stones, apparently incurring considerable energy costs. We quantified Rock Wren stone use and measured how stones occlude nest cavities. We examined whether Rock Wrens adjust individual stone-carrying effort in response to nest cavity opening size and tested 3 hypotheses about the benefits of cavity occlusion: (1) stones ameliorate temperature fluctuations and improve nest thermoregulation; (2) stones improve nest microclimates by keeping them dry; and (3) stones have the potential to reduce nest predation by alerting incubating females when predators approach. We found that individual nes...