Factors Influencing Cage Escape Behavior in a Migrating Passerine at a Stop-Over Site

Area of Science:

• Behavioral Ecology
• Avian Cognition
• Animal Migration

Background:

• Cognitive abilities are crucial for migratory birds navigating novel environments.
• Stop-over sites present challenges requiring effective problem-solving skills.
• The sedge warbler (Acrocephalus schoenobaenus) is a long-distance migratory passerine.

Purpose of the Study:

• To investigate factors influencing cognitive performance in migratory birds.
• To examine how age, sex, fuel reserves, activity, and mercury levels affect problem-solving behavior.
• To understand escape responses from an experimental cage in sedge warblers.

Main Methods:

• A problem-solving task involving escaping from an experimental cage was designed.
• The probability of escape was recorded after remote door opening.
• A mixed-effects Cox model was used to analyze escape probability.
• Factors analyzed included age, sex, horizontal/vertical activity, fuel reserves, and mercury levels.

Main Results:

• Higher horizontal movement variance during acclimatization increased escape probability.
• Sex significantly influenced escape probability in immature birds.
• Immature males were 2.3 times more likely to escape than immature females.
• Repeatability of escape response in recaptured individuals was low (7.3%).

Conclusions:

• Cognitive strategies, particularly risk-taking, differ between sexes in migratory birds.
• Male sedge warblers may adopt a high-risk, high-reward strategy, while females adopt a low-risk, low-reward strategy.
• These sex-specific strategies might relate to breeding roles and risk-partitioning.
• Individual escape responses showed low consistency, suggesting situational influences on behavior.