Transition to a Migratory State
Pine siskins (Spinus pinus) are facultative migrants, meaning their movements are unpredictable both in time and space. While the migratory cues that obligate migrants utilize to time their movements are fairly well known, the environmental cues that are used by facultative migrants are still unclear. Using controlled laboratory experiments I tested both predictable (photoperiod) and more variable (food availability) cues, as well as the role of social information in the timing of migratory movements.
Predictable vs. Unpredictable Cues
We found that increasing day length during the spring initiates a transition to a migratory life history stage, but that food abundance can fine-tune the timing of departure. We also examined the endocrine mechanisms involved and found that different hormones may be involved in regulating facultative migration in response to predictable and unpredictable cues.
We found that increasing day length during the spring initiates a transition to a migratory life history stage, but that food abundance can fine-tune the timing of departure. We also examined the endocrine mechanisms involved and found that different hormones may be involved in regulating facultative migration in response to predictable and unpredictable cues.
Experimental set-up for pine siskin experiments. The box on top of the cage is a passive infrared sensor and able to record each time a bird moves.
Social Cues
We've examined the role of social influences on migratory behavior. We're examining the role of vocal cues and the presence of a social partner, including potential mate, on the timing of migratory transitions. For these experiments we videotaped birds to analyze behavior at a more detailed scale.
We've examined the role of social influences on migratory behavior. We're examining the role of vocal cues and the presence of a social partner, including potential mate, on the timing of migratory transitions. For these experiments we videotaped birds to analyze behavior at a more detailed scale.