page_title: Vigilance (behavioural ecology)
section_title: Advantages
hierarchical_section_title: Vigilance (behavioural ecology) / Vigilance in groups / Group foraging / Advantages
caption_attribution_description: English: Red-billed Quelea Quelea quelea flock at waterhole.
context_page_description: Vigilance, in the field of behavioural ecology, refers to an animal's examination of its surroundings in order to heighten awareness of predator presence. Vigilance is an important behaviour during foraging as animals must often venture away from the safety of shelter to find food. However being vigilant comes at the expense of time spent feeding so there is a trade-off between the two. The length of time animals devote to vigilance is dependent on many factors including predation risk and hunger.
  Vigilance is often observed in animals that forage in groups, such as yellow-eyed juncos and meerkats. Foraging in groups dilutes an individual's risk of predation, and allows them to reduce their own vigilance while the vigilance of the group is maintained. Alarm signals may be used to alert the group to the presence of predators. Groups of some species have at least one individual on sentry duty who looks out for predators on a perch while the rest of the group forages.
context_section_description: A group of animals may be better at both finding and capturing food than solitary animals. For species that feed on food that is patchy, the likelihood of locating food is greater if individuals search for food independently and inform the rest of the group when a food patch is found. Information sharing in this way has little cost to the individual who locates the food if it occurs in high abundance in the patch.
  Group hunting allows predators to take down larger prey, as well as prey that can outrun the predator but can be caught by an ambush. For example, lionesses (Panthera leo) hunt cooperatively for large prey such as zebra (Equus burchelli) and wildebeest (Connochaetes taurinus), with each lioness adopting particular positions in a formation. The presence of many predators also causes panic in groups of prey, often causing them to flee in different directions making it easier for the predators to single out a target.
  Foraging in a group also has some anti-predator benefits. Being part of a group dilutes an individual's risk of being attacked, as the more group members there are, the lower the probability that that individual will be the victim. Grouping may swamp the predator's capacity to capture prey - for example, hawks are unable to capture more than one yellow-eyed junco per attack. Large groups also cause predator confusion as it makes it difficult for prey to focus on one target. Groups of animals may engage in communal defences, such as mobbing, for further protection.
caption: Red-billed queleas form huge flocks of thousands of birds
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