Information acquisition and sociality among migratory birds
Information use is a key feature of adaptive behavior: the better informed an individual, the better it is able to adjust its behavior to meet the demands of a variable world. Therefore, most animals attempt to reduce environmental uncertainty by gathering information when it is available. However, tracking unpredictable ecological factors may carry costs as individuals invest valuable time and energy in the process of information acquisition. Social learning (i.e., use of social information inadvertently produced by other individuals) enables the individual to gain rapid and more complete assessment of its novel environment. This process may be particularly important for animals under time and energetic constraints, such as migrating birds that land at unfamiliar stopover sites to replenish depleted energy stores. Migration is an ideal context in which to examine how animals respond to multiple, simultaneous constraints (informational, time and energetic) because a successful migration depends on making appropriate decisions quickly under novel circumstances. In this dissertation, I investigate the mechanisms of information acquisition in the context of migration with particular attention to social learning. My research was organized around the following questions: (a) When are long-term spatial memories encoded during the life of a first-year migratory songbird? (b) Is the seasonally high degree of sociality observed during migration an indication of the increased value and use of social information in a stopover setting? (c) Can social learning speed up the familiarization process with a novel foraging environment? (d) Does the degree of social information use vary between seasons? I found evidence of relatively low investment in long-term spatial memory formation during migration in free living migratory thrushes. However, social affiliation reduced the novelty response in captive migrants and sped up the acquisition of a novel foraging technique. Interestingly, birds in migratory disposition were slower on a social learning task than birds in non-migratory condition. Finally, as indicated by the change in flocking propensity and space use, the value and use of social information seemed to decline over the course of the stopover period. These findings suggest that social learning plays an important role in the decision-making process during migration.