State-dependent foraging among social fish in a risky environment

Jesse Balaban-feld, William A. Mitchell, Burt P. Kotler, Sundararaj Vijayan, Lotan T. Tov Elem, Zvika Abramsky

Research output: Contribution to journalArticlepeer-review

13 Scopus citations

Abstract

In the presence of a predator, foraging is a dangerous task. Social individuals can respond to risk by forming groups, benefiting from enhanced collective anti-predator behavior but suffering from increased conspicuousness to predators. Within groups, individuals exhibit variable foraging behavior. One important factor influencing risky foraging behaviour is current energetic state, and individuals must trade off food and safety by deciding when to leave a protected refuge in order to find food. We generated mixed groups of goldfish (Carassius auratus) containing equal numbers of underfed and well-fed individuals and examined individual refuge use and willingness to take risks venturing into risky foraging areas in the presence of an avian predator (little egret—Egretta garzetta). Underfed fish exhibited higher levels of risky behaviour by participating in more foraging outings and emerging from the refuge in frontal group positions, compared with well-fed individuals. As expected, underfed fish benefitted by consuming more food, but surprisingly did not experience higher rates of mortality. This may be due to the fact that the egret predator rarely captured the first fish to emerge from the refuge, preferentially attacked groups of three or more fish, and often captured fish in the chaotic period following a failed initial strike. We demonstrate how differences in energetic condition can influence risk-taking behaviours among social individuals that subsequently influence relative levels of foraging success and group fission–fusion dynamics. Moreover, our results illustrate the risk associated with foraging in larger groups.

Original languageEnglish
Pages (from-to)37-45
Number of pages9
JournalOecologia
Volume190
Issue number1
DOIs
StatePublished - 1 May 2019

Keywords

  • Costs and benefits
  • Group size
  • Hunger
  • Predator–prey
  • Trade-off

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics

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