Competition and Facilitation Influence Central Place Foraging Ecology in a Colonial Marine Predator

Area of Science:

• Behavioral Ecology
• Animal Behavior
• Coloniality Studies

Background:

• Coloniality is influenced by social foraging, with trade-offs between information sources and food competition.
• Understanding these trade-offs is crucial for comprehending colonial living dynamics.

Purpose of the Study:

• To investigate social foraging behavior in breeding adult northern gannets (Morus bassanus).
• To examine the relationship between foraging effort, sociality, and colony proximity.

Main Methods:

• Utilized animal-borne GPS, cameras, and dive recorders to track northern gannets.
• Analyzed dive patterns for prey depletion evidence and quantified sociality during various behaviors and distances from the colony.

Main Results:

• Dive probability and depth increased with distance, indicating prey depletion zones around the colony.
• Gannets displayed high sociality during foraging and commuting, especially when returning to the colony in flocks.
• Social foraging was more prevalent farther from the colony, suggesting a response to resource distribution.

Conclusions:

• Northern gannets engage in context-dependent social foraging despite intraspecific competition.
• Aggregation far from the colony may be driven by prey depletion but offers benefits like local enhancement and flocking.
• Competition can paradoxically facilitate group foraging in colonial species.