Vigilance in human groups: a test of alternative hypotheses

Behaviour ◽  
2002 ◽  
Vol 139 (5) ◽  
pp. 695-711 ◽  
Author(s):  
◽  
◽  
◽  
Keyword(s):  
Predation Risk ◽  
Group Size ◽  
Inverse Relationship ◽  
Mate Guarding ◽  
Mate Searching ◽  
Clear Cut ◽  
Vigilance Behaviour ◽  
Alternative Hypotheses

AbstractHumans exhibit the same inverse relationship between group size and vigilance rates that has been classically described in animals. We collected data on natural human vigilance behaviour in two different contemporary environments (a large refectory-style cafeteria and open parks) to test between four alternative hypotheses for this relationship: predation risk, searching for friends, mate searching and mate guarding. The results demonstrate that, at least in contemporary city environments, humans monitor their surroundings largely for reasons motivated by mate searching. Data on whom subjects look at in a busy environment indicate that males are significantly more likely to attend differentially to female passers-by, but that females show a less clear-cut discrimination. We conclude that vigilance patterns are determined by locally salient functions.

scholarly journals Sleeping gulls monitor the vigilance behaviour of their neighbours

2008 ◽  
Vol 5 (1) ◽  
pp. 9-11 ◽  
Author(s):  
Guy Beauchamp
Keyword(s):  
Predation Risk ◽  
Group Size ◽  
Complex Flow ◽  
Vigilance Behaviour ◽  
Flow Of Information

Individuals in groups are often thought to scan their surroundings for threats independently of one another. Models, however, suggest that foragers should monitor the vigilance level of their neighbours to prevent cheating, and to gather information about incipient predation risk. Evidence for monitoring of vigilance is scant. Here, I examined changes in vigilance levels in sleeping gulls ( Larus sp.) surrounded by neighbours in various states of alertness. Controlling for group size and neighbour density, gulls interrupted sleep more often to scan their surroundings, and were therefore more vigilant, when their neighbours were alert rather than sleeping or preening. The results provide evidence for copying of vigilance within groups of birds, suggesting a complex flow of information about predation risk in groups.

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 prédation which are relaxed when this risk is reduced.

Hunted hunters? Effect of group size on predation risk and growth in the Australian subsocial crab spider Diaea ergandros

2013 ◽  
Vol 67 (5) ◽  
pp. 785-794 ◽  
Author(s):  
Bianca Unglaub ◽  
Jasmin Ruch ◽  
Marie E. Herberstein ◽  
Jutta M. Schneider
Keyword(s):  
Predation Risk ◽  
Group Size ◽  
Crab Spider

scholarly journals Group-size-mediated habitat selection and group fusion–fission dynamics of bison under predation risk

Ecology ◽  
2009 ◽  
Vol 90 (9) ◽  
pp. 2480-2490 ◽  
Author(s):  
Daniel Fortin ◽  
Marie-Eve Fortin ◽  
Hawthorne L. Beyer ◽  
Thierry Duchesne ◽  
Sabrina Courant ◽  
...  
Keyword(s):  
Habitat Selection ◽  
Predation Risk ◽  
Group Size ◽  
Group Fusion

Ecological drivers of group size in female Alpine chamois, Rupicapra rupicapra

Mammalia ◽  
2015 ◽  
Vol 79 (4) ◽  
Author(s):  
Roberta Chirichella ◽  
Andrea Mustoni ◽  
Marco Apollonio
Keyword(s):  
Predation Risk ◽  
Energy Intake ◽  
Group Size ◽  
Food Availability ◽  
Herd Size ◽  
Rupicapra Rupicapra ◽  
Trade Off ◽  
Mammalian Herbivores ◽  
Alpine Chamois

AbstractIn large mammalian herbivores, an increase in herd size not only reduces predation risk but also energy intake. As a consequence, the size of the groups made up by herbivores is often assumed to be the outcome of a trade-off depending on local predation risk and food availability. We studied Alpine chamois (

scholarly journals Prey synchronize their vigilant behaviour with other group members

2007 ◽  
Vol 274 (1615) ◽  
pp. 1287-1291 ◽  
Author(s):  
Olivier Pays ◽  
Pierre-Cyril Renaud ◽  
Patrice Loisel ◽  
Maud Petit ◽  
Jean-François Gerard ◽  
...  
Keyword(s):  
Predation Risk ◽  
Group Size ◽  
Prey Species ◽  
Group Members ◽  
The Individual ◽  
The Cost ◽  
Group Member

It is generally assumed that an individual of a prey species can benefit from an increase in the number of its group's members by reducing its own investment in vigilance. But what behaviour should group members adopt in relation to both the risk of being preyed upon and the individual investment in vigilance? Most models assume that individuals scan independently of one another. It is generally argued that it is more profitable for each group member owing to the cost that coordination of individual scans in non-overlapping bouts of vigilance would require. We studied the relationships between both individual and collective vigilance and group size in Defassa waterbuck, Kobus ellipsiprymnus defassa , in a population living under a predation risk. Our results confirmed that the proportion of time an individual spent in vigilance decreased with group size. However, the time during which at least one individual in the group scanned the environment (collective vigilance) increased. Analyses showed that individuals neither coordinated their scanning in an asynchronous way nor scanned independently of one another. On the contrary, scanning and non-scanning bouts were synchronized between group members, producing waves of collective vigilance. We claim that these waves are triggered by allelomimetic effects i.e. they are a phenomenon produced by an individual copying its neighbour's behaviour.

Does habitat type modify group size in roe deer and red deer under predation risk by Iberian wolves?

2008 ◽  
Vol 86 (3) ◽  
pp. 170-176 ◽  
Author(s):  
I. Barja ◽  
S. Rosellini
Keyword(s):  
Predation Risk ◽  
Group Size ◽  
Cervus Elaphus ◽  
Red Deer ◽  
Roe Deer ◽  
Habitat Type ◽  
Capreolus Capreolus ◽  
Antipredator Response ◽  
The Mean ◽  
Grouping Behavior

We examined whether group size in red deer ( Cervus elaphus L., 1758) and roe deer ( Capreolus capreolus (L., 1758)) under predation risk by Iberian wolves ( Canis lupus L., 1758) is affected by the type of habitat in which the deer reside. We hypothesized that group size (i) would be larger in open than in closed habitats, since it is an antipredator response, and (ii) would vary more with habitat type in the species that had higher wolf predation rates. In the study area, wolves were the only predator of wild ungulates, with roe deer being the main target prey. We performed monthly transects along paths to observe the group size of red and roe deer. In roe deer, the mean group size was significantly higher in open than in closed habitats, serving as an antipredator response. However, in red deer, habitat type did not affect group size. The results indicate that under predation risk by wolves the habitat type influences the grouping behavior of roe deer but not red deer. Furthermore, compared with forests, heaths offer less protection from predators and species in this habitat would benefit from larger group sizes.

Anti-predator behaviour of kudu and impala in response to mimicked African wild dog presence: do age and sex matter?

Behaviour ◽  
2015 ◽  
Vol 152 (9) ◽  
pp. 1209-1228 ◽  
Author(s):  
Esther van der Meer ◽  
Hervé Fritz ◽  
Olivier Pays
Keyword(s):  
Predation Risk ◽  
Lycaon Pictus ◽  
High Quality ◽  
Vigilance Behaviour ◽  
African Wild Dog ◽  
African Wild Dogs ◽  
Tragelaphus Strepsiceros ◽  
Wild Dog ◽  
Wild Dogs ◽  
Aepyceros Melampus

Predators not only prey upon certain prey species, but also on certain age–sex classes within species. Predation risk and an individual’s response to this risk might therefore vary with an individual’s characteristics. We examined the proportion of time different age–sex classes of kudu (Tragelaphus strepsiceros) and impala (Aepyceros melampus) spent high quality vigilant (costly vigilance that detracts from all other activities) in response to mimicked predation risk by African wild dogs (Lycaon pictus). For both species predation risk was the main factor determining the investment in high quality vigilance behaviour. Age–sex class-specific responses were not related to age–sex class specific lethality risk presented by African wild dogs. For impala, regardless of predation risk, age seemed to have some effect on the investment in high quality vigilance with sub-adult impala spending more time high quality vigilant than adult impala, which is possibly why African wild dogs predominantly preyed upon adult impala.

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