Meeting Abstract
Movement patterns have wide-ranging effects on survival and population trends, and can greatly differ between individuals of the same species. However, we still do not understand the full suite of factors and mechanisms that generate differences in movement behavior. Hormones likely influence movement behavior, but their complete role is unclear. Glucocorticoid hormones (GCs) may contribute to vertebrate movement decisions; previous studies have demonstrated connections between GCs and movement during vertebrates’ breeding seasons. Here, we examine the relationship between GC expression, movement behavior (geographic space use, distance travelled) and parental provisioning of offspring in breeding tree swallows (Tachycineta bicolor). We ask whether baseline corticosterone (CORT, the avian GC) predicts female swallows’ fine-scale movement patterns and nestling provisioning rates, and if variation in these behaviors affects fitness (i.e. fledging success). To monitor movement behavior, we used two methods: solar-powered radio tags (“life tags”), which transmit unique identifying codes to an array of receivers across the breeding site; and a network of RFID boards, which record nest box visitation patterns. Because higher CORT tends to be associated with greater activity, we predicted that birds with higher baseline CORT would use larger geographic spaces for foraging, would travel farther, and would provision their nestlings more frequently. If our results show that CORT levels relate to movement and provisioning patterns, our findings would shed light on the role of GCs in coordinating movement, and how these movements relate to fitness outcomes.
