Does vigilance always covary negatively with group size? Effects of foraging strategy

Barbosa, Andrés

doi:10.1007/s10211-002-0059-0

Cited by 42 publications

(21 citation statements)

References 22 publications

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“…Because of decreased scramble competition, the flock size effect on congregating feeding and vigilance behavior should not be expected. Besides, contrary to other studies where flocks included up to hundreds of individuals (Barbosa 2002;Boukhriss et al 2007), flock size varied from 1 to 25 in the study area. Individuals in smaller group may not need to compete for resources.…”

Section: Discussionmentioning

confidence: 49%

“…Some bird species, such as Lapwing (Vanellus vanellus), can gather information about its predators when searching for prey. Thus, flock size effect cannot be observed in bird species with this strategy (Barbosa 2002). Although the detection of predators when head is down may not be as effective as when head is up , some species with large visual field can scan for predators while their heads are down.…”

Section: Discussionmentioning

confidence: 92%

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The effects of flock size and human presence on vigilance and feeding behavior in the Eurasian Coot (Fulica atra L.) during breeding season

Severcan

Yamaç

2010

acta ethol

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Group size influences individual vigilance in different bird species. Most studies have shown that animals spend more time for feeding and less time on vigilance when in groups. Apart from group size, additional factors, such as group density, age, sex, and season, are considered to influence vigilance behaviors. The aim of the present study was to investigate the effects of flock size and human presence on vigilance and feeding in the Eurasian Coot (Fulica atra) during the breeding season. This work was performed in Yorukkirka Lake (Eskisehir, Turkey) from March to August 2005. No correlation was found between flock size and vigilance rates during either human absence or presence. On the other hand, when comparing behavioral differences between human presence and absence, humans appeared to have an important negative effect on vigilance rates, vigilance duration, and feeding behavior, regardless of flock size.

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Section: Discussionmentioning

confidence: 49%

Section: Discussionmentioning

confidence: 92%

The effects of flock size and human presence on vigilance and feeding behavior in the Eurasian Coot (Fulica atra L.) during breeding season

Severcan

Yamaç

2010

acta ethol

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“…Vigilance is not straightforward to document in rapidly moving shorebirds with short handling times and few pauses while foraging (Barbosa 2002). How vigilance influences foraging speed is not known in sandpipers, and as such it is difficult to make unambiguous predictions for the safety hypothesis.…”

Section: Discussionmentioning

confidence: 96%

Foraging speed in staging flocks of semipalmated sandpipers: evidence for scramble competition

Beauchamp

2012

Oecologia

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Foraging speed is a key determinant of fitness affecting both foraging success and predator attack survival. In a scramble for food, for instance, evolutionary stable strategy models predict that speed should increase with competitor density and decrease when the risk of attack by predators increases. Foraging speed should also decrease in richer food patches where the level of competition is reduced. I tested these predictions in fall staging flocks of semipalmated sandpipers (Calidris pusilla) foraging for an evasive prey. Capture rate of these prey decreased with sandpiper density as the presence of competitors reduced the availability of resources for those behind. Foraging speed was evaluated indirectly by measuring the time needed to cross fixed boundaries on mudflats over 6 years. As predicted, foraging speed increased with sandpiper density and decreased with food density, but, unexpectedly, increased closer to obstructive cover where predation risk was deemed higher. When foraging closer to cover, from where predators launch surprise attacks, the increase in foraging speed may compensate for an increase in false alarms that interrupted foraging. While foraging in denser flocks decreases foraging success, joining such flocks may also increase safety against predators. In semipalmated sandpipers that occupy an intermediate position in the food chain, foraging behavior is influenced simultaneously by the evasive responses of their prey and by the risk of attack from their own predators.

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“…It has been found, however, that the group size effect is not typical for all mammals (Treves 2000;Laundre et al 2001;Barbosa 2002;Cameron and Du Toit 2005;Shorrocks and Cokayne 2005). For example, female impala (Aepyceros melampus) spend less time being vigilant and more time feeding as their group size increases, but territorial males showed no significant changes in vigilance with increasing group size because of the time spent watching their females and looking out for rival males (Shorrocks and Cokayne 2005).…”

Section: Introductionmentioning

confidence: 91%

Seasonal and sexual variation in vigilance behavior of goitered gazelle (Gazella subgutturosa) in western China

Xia

Yang

et al. 2011

J Ethol

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Animals receive benefits from social behavior. As part of a group, individuals spend less time having to be vigilant. This phenomenon, called the ''group size effect,'' is considered the most dominant factor in an animal's demonstrated level of vigilance. However, in addition to group size, many other social and environmental factors also influence the degree of vigilance, including the season of the year and the sex of the individual. In our study, we examined the vigilant behavior of goitered gazelles in the Xinjiang Province in western China to test whether and how seasons, the yearly breeding cycle, and group size affect vigilance. According to our results, we found that seasonal factors were not a substantial influence on a gazelle's level of vigilance, while group size had a tangible effect. In comparison, the yearly breeding cycle (a natural phenomenon) was the most powerful factor: it significantly changed the degree of vigilance in females during birthing and males during rut. Anthropogenic factors (unnatural phenomena) were also potential causes of increased vigilance in both sexes during winter.

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Does vigilance always covary negatively with group size? Effects of foraging strategy

Cited by 42 publications

References 22 publications

The effects of flock size and human presence on vigilance and feeding behavior in the Eurasian Coot (Fulica atra L.) during breeding season

The effects of flock size and human presence on vigilance and feeding behavior in the Eurasian Coot (Fulica atra L.) during breeding season

Foraging speed in staging flocks of semipalmated sandpipers: evidence for scramble competition

Seasonal and sexual variation in vigilance behavior of goitered gazelle (Gazella subgutturosa) in western China

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