Back to the basics of anti-predatory vigilance: the group-size effect

@article{Lima1995BackTT,
  title={Back to the basics of anti-predatory vigilance: the group-size effect},
  author={Steven L. Lima},
  journal={Animal Behaviour},
  year={1995},
  volume={49},
  pages={11-20}
}
  • S. L. Lima
  • Published 31 January 1995
  • Psychology
  • Animal Behaviour
Abstract A negative relationship between group size and levels of individual vigilance is widespread in socially feeding vertebrates. The main explanation of this ‘group-size effect’, the many-eyes hypothesis, is based on the simple premise that as group size increases, there are progressively more eyes scanning the environment for predators. Thus an individual forager can devote less time to vigilance (and more time to feeding) as group size increases without any lessening of the group's… Expand
Anti-predatory vigilance and the limits to collective detection: visual and spatial separation between foragers
TLDR
It is argued that collective detection is not only an important determinant of the group size effect, but also that the phenomena of collective detection and risk dilution are interdependent. Expand
Interactions among social monitoring, anti-predator vigilance and group size in eastern grey kangaroos
TLDR
The results highlight the crucial roles of both social and anti-predator components of vigilance in the understanding of the relationship between group size and vigilance, as well as in the synchronization of vigilance among group members. Expand
The contingencies of group size and vigilance
TLDR
This work uses game theory and the fitness-generating function to determine the ESS level of vigilance of an individual within a group, and finds that vigilance decreases with group size as a consequence of the many-eyes and dilution effects, but increases with group sizes as a result of the attraction effect. Expand
Is the magnitude of the group-size effect on vigilance underestimated?
TLDR
A methodological issue that arises when fitting statistical models to vigilance data is drawn attention to, which is the percentage of time spent vigilant by focal individuals in a group as a function of group size. Expand
Should vigilance always decrease with group size?
TLDR
Results indicate that increased allocation of time to scrounging during search can add to the overall level of vigilance and even counteract the expected decrease in vigilance with group size, but the addition of scrouging was found to have little impact on vigilance while in the food patch. Expand
Group-enhanced predator detection and quality of vigilance in a social ground squirrel
TLDR
The results show that this invasive species displays specific antipredator behaviours to different aerial and terrestrial predators compared to predators in their endemic range despite the trade-off with foraging, and broadens the understanding of antipredators and risk-sensitive behaviour. Expand
Back to the basics of antipredatory vigilance: can nonvigilant animals detect attack?
TLDR
It is demonstrated that actively feeding, free-living, dark-eyed juncos, Junco hyemalis, have a considerable ability to detect approaching predators even when not overtly vigilant, although their detection ability is greater when they raise their heads. Expand
Why individual vigilance declines as group size increases
A reduction in individual vigilance with an increase in group size is one of the most frequently reported relationships in the study of animal behaviour. It has been argued that this phenomenon mayExpand
The effect of social facilitation on vigilance in the eastern gray kangaroo, Macropus giganteus
TLDR
The results show that the decision of an individual to exhibit a vigilant posture depended on what it and other group members had been doing at the preceding second and on group size, which increases the understanding of the much-studied relationship between vigilance and group size. Expand
Coordination, independence or synchronization of individual vigilance in the eastern grey kangaroo?
TLDR
The relation between vigilance and group size in the eastern grey kangaroo, Macropus giganteus, is studied, analysing vigilance at two structural levels, individual vigilance and collective vigilance of the group to support a hypothesis of allelomimetic vigilance. Expand
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References

SHOWING 1-10 OF 42 REFERENCES
Evolutionarily stable levels of vigilance as a function of group size
An animal's level of vigilance is usually interpreted as a trade-off between gaining food and reducing the danger of predation. In the context of a group of animals, vigilance has been analysed usingExpand
PREDATOR VIGILANCE AND GROUP SIZE IN MAMMALS AND BIRDS: A CRITICAL REVIEW OF THE EMPIRICAL EVIDENCE
  • M. Elgar
  • Psychology, Medicine
  • Biological reviews of the Cambridge Philosophical Society
  • 1989
TLDR
Most of the studies fail to adequately demonstrate an unambiguous relationship between vigilance behaviour and group size, but many studies reveal interesting features of the relationship between Vigilance and Group size that should provide fruitful avenues for future research. Expand
The effects of mixed-species flocking on the vigilance of shorebirds: Who do they trust?
TLDR
The effect of mixed species flocking on vigilance is investigated in two species of wading bird wintering on rocky shores, finding that both turnstones and purple sandpipers ‘share’ vigilance with conspecifics, but also with some other waders; the extent of sharing appears to depend on the relative size of, and habitat overlap with, the other species. Expand
Group Vigilance and Shoal Size in a Small Characin Fish
TLDR
The importance of the enhanced predator detection ability of fish shoals and the social transmission of alarms within them is discussed in relation to predator avoidance behaviour and other activities of fish in shoals. Expand
Should co-operative groups be more vigilant than selfish groups?
We develop four simple models of group vigilance that illustrate the conditions under which co-operative groups should be more or less vigilant than selfish groups. In the first model, preyExpand
The early warning function of flocking in birds: An experimental study with captive quelea
TLDR
Two tests are described, using the weaverbird quelea, of the proposed early warning function of flocking in birds, which shows that larger flocks detect a predator sooner than single birds. Expand
Vigilance and perception of flock size in foraging house sparrows (Passer domesticus L.)
TLDR
Evaluated the importance of flockmate perception in the scanning behaviour of free-living house sparrows Passer domesticus by observing them at an artificial feeder, finding that perception of flockmates is clearly important if individuals' vigilance behaviour depends as much on the behaviour of other individuals as on the flock size. Expand
FLOCKING AS A POSSIBLE PREDATOR DEFENSE IN DARK-EYED JUNCOS
TLDR
I predict flock size and location have 4 behavioral effects: birds in large flocks are less vigilant than birds in smaller flocks, and birds inLarge flocks devote more time to activities other than vigilance. Expand
Contrasting effects of protective and obstructive cover on avian vigilance
TLDR
An experiment on wild house sparrows, Passer domestieus, and starlings, Sturnus vulgaris, in which distance from protective and obstructive cover had contrasting effects on vigilance as predicted by compensatory logic. Expand
Time Budgeting and Group Size: A Test of Theory
TLDR
Foraging flocks of granivorous Yellow-eyed Juncos were studied for two winters to test hypothesized relationships between group size and time budgets, finding that Dominants apparently forage more efficiently than subordinates because of differences in habitat utilization and time allocation. Expand
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