Comparing tree swallow dispersal strategies in a continuous mainland environment

Area of Science:

• Ecology and evolutionary biology
• Animal behavior
• Population dynamics

Background:

• Dispersal is a key factor in animal behavior with significant ecological and evolutionary impacts.
• Understanding individual variation in dispersal remains a challenge in empirical research.
• Long-term studies are crucial for assessing the causes and consequences of dispersal.

Purpose of the Study:

• To investigate the long-term fitness consequences of dispersal in female tree swallows.
• To compare the life history of "immigrant" (dispersing) and "local" (non-dispersing) female tree swallows.
• To examine how environmental factors influence the fitness of dispersers versus non-dispersers.

Main Methods:

• Analysis of 16-year life history data for 867 known-age female tree swallows.
• Categorization of females into "immigrant" and "local" based on natal origin.
• Comparison of fitness outcomes and responses to environmental variables (weather, predation, social factors).

Main Results:

• Local females were more successful in recruiting their offspring into the study population.
• Dispersal status interacted with environmental conditions to affect relative fitness.
• Immigrant females exhibited resilience to environmental variability, while local females showed sensitivity.

Conclusions:

• Dispersal influences fitness through broad spatial scales rather than local distances.
• Local breeders are more susceptible to environmental stressors at their breeding sites.
• Further research should integrate behavior, physiology, and fitness across environmental contexts to understand dispersal impacts.