Harbour Porpoises Are Flexible Predators Displaying Context-Dependent Foraging Behaviours.

Area of Science:

• Marine Mammal Behavior
• Behavioral Ecology
• Predator-Prey Dynamics

Background:

• Opportunistic predators exhibit adaptable foraging strategies for diverse prey.
• Harbour porpoises (Phocoena phocoena) are marine mammals with high energy demands and varied diets.
• Limited knowledge exists on harbour porpoise foraging behavior due to observation difficulties.

Purpose of the Study:

• To investigate the foraging behavior of harbour porpoises in Danish coastal waters.
• To identify behavioral adaptations and context-dependent strategies used by porpoises during prey capture.
• To understand the role of information transfer and social learning in porpoise foraging.

Main Methods:

• Utilized Unmanned Aerial Vehicle (UAV) recordings in Danish coastal waters.
• Analyzed video data to identify and quantify foraging events during daylight hours.
• Observed individual and group foraging behaviors, including prey type and capture strategies.

Main Results:

• Foraging behavior was observed in nearly 60% of UAV recordings.
• Harbour porpoises demonstrated flexibility, foraging on single fish, schools of fish, individually, and in groups.
• Behavioral adaptations suggest information transfer and social learning influence prey capture strategies.

Conclusions:

• Harbour porpoises are flexible and opportunistic predators with sophisticated foraging tactics.
• Coastal areas are crucial for harbour porpoise energy acquisition.
• Porpoise foraging in coastal zones creates potential conflicts with anthropogenic activities like fisheries, increasing bycatch risk.