Welcome to the American Ornithological Society 2018 Annual Conference. We are pleased to have you join us at the lovely Hilton El Conquistador Resort in Tucson, AZ.
Nest site selection is a critical choice that can influence reproductive fitness outcomes. Whereas the role of predation risk in influencing nest site selection has been well explored, the extent to which birds select nest sites on the basis of microclimatic variation remains unclear. Oviparous species must maintain a tight range of temperatures for the proper development of young, and exposure outside of this range can negatively affect fitness. Species living in open, arid systems such as the sagebrush steppe are particularly vulnerable to extreme weather variability during the breeding season. We focused on the three species of sagebrush-obligate songbird (Brewer's sparrow, sagebrush sparrow, sage thrasher) that differ in body size (10 - 50g) and breed within high-elevation, arid shrublands in Wyoming, USA to investigate whether temperature differs between used and unused nest sites at two spatial scales. We predicted that birds, especially the smaller species that may be more vulnerable to physiological stress, should select nest niches and shrubs that modulated temperature variation. Temperature variation was significantly lower at Brewer's sparrow nest niches compared to paired unused niches, and at nest shrubs compared to unused shrubs within a 5-m radius during daylight hours. There were no significant differences in temperature variation or mean temperature at either scale for the two larger species. An important next step is to examine how variation in nest temperatures affects reproductive fitness metrics, such as nestling growth and size at fledging.
