Effects of group size, habitat and hunting risk on vigilance and foraging behaviour in the Lesser Rhea (Rhea pennata pennata)

2012 ◽  
Vol 112 (1) ◽  
pp. 67-70 ◽  
Author(s):  
Fernando R. Barri ◽  
Nicolás Roldán ◽  
Joaquín L. Navarro ◽  
Monica B. Martella
Keyword(s):  
Group Size ◽  
Foraging Behaviour ◽  
Lesser Rhea

Effects of predation risk on foraging behaviour and group size: adaptations in a social cooperative species

2012 ◽  
Vol 84 (4) ◽  
pp. 823-834 ◽  
Author(s):  
Enrico Sorato ◽  
Philippa R. Gullett ◽  
Simon C. Griffith ◽  
Andrew F. Russell
Keyword(s):  
Predation Risk ◽  
Group Size ◽  
Foraging Behaviour

The Influence of Group Size On Predator Scanning and Foraging Behaviour of Wedgecapped Capuchin Monkeys (Cebus Olivaceus)

Behaviour ◽  
1986 ◽  
Vol 98 (1-4) ◽  
pp. 240-258 ◽  
Author(s):  
Jan R. De Ruiter
Keyword(s):  
Group Size ◽  
Foraging Behaviour ◽  
Group Formation ◽  
Food Competition ◽  
Food Sources ◽  
Capuchin Monkeys ◽  
Time Budgets ◽  
Large Group ◽  
Cebus Olivaceus ◽  
Travel Distances

AbstractThe behaviour of two groups of wedgecapped capuchin monkeys, Cebus olivaceus, a small one (n = 8) and a large one (n = 25) was recorded. Time budgets and other aspects of behaviour depended on group size. The differences can be explained as: adjustment to predation risk and intra-group food competition. In order to evade predation, members of the small groups scan more and stay at greater heights than those of the large group. Higher food competition within the large group was reflected in the composition of its diet, in longer travel distances, and higher levels of social behaviour. In particular during the dry season, the large group exploited unattractive and risky food sources. These results support ALEXANDER'S hypothesis on the causes of group formation.

scholarly journals Personality composition is more important than group size in determining collective foraging behaviour in the wild

2014 ◽  
Vol 281 (1796) ◽  
pp. 20141424 ◽  
Author(s):  
Carl N. Keiser ◽  
Jonathan N. Pruitt
Keyword(s):  
Group Size ◽  
Foraging Behaviour ◽  
Collective Behaviour ◽  
Nest Architecture ◽  
Social Spider ◽  
The Social ◽  
In The Wild ◽  
Behavioural Phenotypes ◽  
Collective Foraging ◽  
Animal Societies

Describing the factors that shape collective behaviour is central to our understanding of animal societies. Countless studies have demonstrated an effect of group size in the emergence of collective behaviours, but comparatively few have accounted for the composition/diversity of behavioural phenotypes, which is often conflated with group size. Here, we simultaneously examine the effect of personality composition and group size on nest architecture and collective foraging aggressiveness in the social spider Stegodyphus dumicola . We created colonies of two different sizes (10 or 30 individuals) and four compositions of boldness (all bold, all shy, mixed bold and shy, or average individuals) in the field and then measured their collective behaviour. Larger colonies produced bigger capture webs, while colonies containing a higher proportion of bold individuals responded to and attacked prey more rapidly. The number of attackers during collective foraging was determined jointly by composition and size, although composition had an effect size more than twice that of colony size: our results suggest that colonies of just 10 bold spiders would attack prey with as many attackers as colonies of 110 ‘average’ spiders. Thus, personality composition is a more potent (albeit more cryptic) determinant of collective foraging in these societies.

VIGILANCE IN BRONZE MANNIKIN GROUPS: THE CONTRIBUTIONS OF PREDATION RISK AND INTRA-GROUP COMPETITION

Behaviour ◽  
2000 ◽  
Vol 137 (5) ◽  
pp. 565-578 ◽  
Author(s):  
Nicola Coumi ◽  
Rob Slotow
Keyword(s):  
Predation Risk ◽  
Group Size ◽  
Foraging Behaviour ◽  
Random Numbers ◽  
Time Budgets ◽  
Group Competition ◽  
Measured Time ◽  
The Mean

AbstractWe describe foraging behaviour and time budgets of the gregarious bronze mannikin, Lonchura cucullata. In addition to being the first such study of a southern African granivore, this was the first study of a group-forager to differentiate between vigilance for other flock members (conspecifics) and vigilance for predators. We verified a perception of predation risk by placing five feeders at increasing distances from cover. The mean number of birds at a feeder decreased significantly with increasing distance from cover. We manipulated levels of aggression by restricting access to random numbers of feeding holes at various distances. The treatments succeeded in forcing birds to feed further from cover, and by inference, increased levels of aggression. We measured time budgets with focal samples on marked individuals. There was no influence of group size on time budgets. There was a non-significant (p < 0.06) trend for vigilance to increase with increasing distance from cover (predation risk). There was no pattern in the relative vigilance for predators as opposed to vigilance for other flock members (conspecifics), either with group size, distance from cover, or manipulated levels of aggression. Despite our inability to detect patterns of vigilance for other flock members, we emphasize the importance of studies to elucidate such a process.

scholarly journals Vigilance and foraging behaviour of female caribou in relation to predation risk

Rangifer ◽  
1997 ◽  
Vol 17 (2) ◽  
pp. 55 ◽  
Author(s):  
Pernille S. Bøving ◽  
Eric Post
Keyword(s):  
Predation Risk ◽  
Group Size ◽  
Rangifer Tarandus ◽  
Foraging Behaviour ◽  
West Greenland ◽  
Vigilance Behaviour ◽  
Calving Season ◽  
Lying Down ◽  
Behavioural Adaptations

Behaviour of female caribou (Rangifer tarandus) was investigated during the calving season on ranges in Alaska and West Greenland with the purpose of determining whether investment in vigilance behaviour differed between areas with and without natural predators of caribou. Female caribou in Alaska foraged in larger groups, displayed a higher rate of vigilance during feeding, spent less time feeding and, when lying, more often adopted a vigilant posture (with head up) than did female caribou in West Greenland. Moreover, a predation-vulnerable posture of lying down flat was observed in West Greenland but not in Alaska. Within Alaska, females with calves spent more time searching the environment than did those without calves. Finally, the amount of time individuals spent searching declined more gradually with group size in Alaska than in West Greenland, suggesting that what caribou perceive as a predator-safe threshold differs in the two areas. These results indicate that caribou, like several other species of ungulates, show behavioural adaptations to the risk of pr&eacute;dation which are relaxed when this risk is reduced.

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