State-dependent foraging among social fish in a risky environment

Area of Science:

• Behavioral Ecology
• Animal Behavior
• Predator-Prey Dynamics

Background:

• Foraging in the presence of predators is risky.
• Social animals form groups for anti-predator benefits, but this increases conspicuousness.
• Individual energetic state influences risk-taking during foraging.

Purpose of the Study:

• To investigate how energetic state affects risk-taking in social foraging.
• To examine the trade-off between food acquisition and safety in goldfish groups.
• To understand the impact of individual energetic condition on group dynamics and predator-prey interactions.

Main Methods:

• Mixed groups of underfed and well-fed goldfish were exposed to an avian predator (little egret).
• Individual refuge use and foraging decisions were recorded.
• Predation success and foraging outcomes were analyzed in relation to fish energetic state and group size.

Main Results:

• Underfed goldfish engaged in riskier foraging, making more outings and emerging first from refuge.
• Underfed fish consumed more food but did not experience higher mortality rates.
• Predator attacks favored groups of three or more, and the initial emergent fish were safer.

Conclusions:

• Energetic condition is a key driver of individual risk-taking in social foraging.
• Differences in energetic state influence foraging success and group fission-fusion dynamics.
• Foraging in larger groups presents significant risks, despite collective anti-predator advantages.