Photoperiod Responses in Behavior and Corticosterone of a Facultative Migrant, the Anna’s Hummingbird Calypte anna
Sam Sandoval, Chelsea B. Johnson, Jesus Ovalle, Maya Razniak, Graciela Bejarano
Department of Biology
Faculty Supervisor: Derrick JE Groom
Abstract: There are two main types of migration, obligate migration, where birds move in a predictable manner and is primarily signaled by changing day length, and facultative migration, where movements are less predictable. The major drivers of obligate migration is a well studied phenomenon, but facultative migration is less understood. Because day length is one of the strongest environmental drivers of migratory behavior and physiology in obligate migrants, it may also do so for facultative migrants. We predict that the facultative migrant, Anna’s Hummingbird, Calypte anna, will show stereotypical migratory behaviors and corticosterone patterns under a migratory photoperiod, as seen in an obligant migrant. Thirteen individuals were placed under three different photoperiods that simulated long days, fall migration, and short days. We predict birds will show increased foraging activity, food intake, and higher corticosterone levels. By studying avian facultative migrants, we will deepen our understanding of migration diversity and evolution. This knowledge can help us identify common environmental drivers of migration across the avian clade.