Meeting Abstract
In dynamic environments, it is essential for organisms to possess plastic behavioral traits that allow them to react to changes. One such trait that is essential to reproductive success is nest site selection. For the dark-eyed junco (Junco hyemalis), a songbird that primarily nests on the ground, nest site may be influenced by varying levels of predation pressure. Previous work suggests that the abundance of the primary nest predator, the eastern chipmunk (Tamias striatus), along with other rodents fluctuates in response to varying levels of acorn mast production and influences nest success. Varying small rodent abundance and the resulting predation pressure may favor an ability of female juncos to assess and adjust their nest site to the optimal location from year to year to maximize fitness. To determine if predation pressure influences nest site selection and nest success, we compiled data from previous studies on small rodent predator abundance and nest sites at Mountain Lake Biological Station. As predation pressure is not the only dynamic factor that may influence nest site location, we also investigated the role of weather. Here, we demonstrate that rodent abundance significantly predicts when the first off-ground nest is found as well as the proportion of off-ground nests found within a given year. Weather, in terms of temperature and precipitation, did not predict the prevalence of off-ground nests. Surprisingly, off-ground nests were not more likely than on-ground nests to be successful, even in years of high rodent abundance. We discuss possible explanations for this finding.
