Meeting Abstract
Most research on migration has focused on obligate migrants. In contrast, facultative migrants, whose movements are less predictable in timing and direction, have received much less attention. We used captive pine siskins (Spinus pinus), nomadic and irruptive migrants, as a model to investigate facultative migration. Wild-caught birds were held on naturally changing photoperiods; their behavior was recorded and patterns of fat deposition were measured. Captive pine siskins exhibited periods of migratory restlessness (MR) similar to that described in obligate migrants. Night activity was characterized by jumping and rapid wing flapping. As in obligate migrants, pine siskins exhibited a period of quiescence prior to the onset of night activity. We also found that the expression of MR varied across the year, with night activity being highest during the spring and summer. Finally, the expression of MR was associated with increases in fat deposition. Overall, our results indicate strong similarities in the behavioral and physiological changes associated with migration in facultative and obligate migrants. Furthermore, our findings suggest that migratory behavior in this species is driven, at least in part, by seasonal mechanisms.
