scholarly journals Maximizing foraging success: the roles of group size, predation risk, competition, and ontogeny

Ecosphere ◽  
2018 ◽  
Vol 9 (10) ◽  
pp. e02456 ◽  
Author(s):  
William D. Hintz ◽  
David G. Lonzarich
Keyword(s):  
Predation Risk ◽  
Group Size ◽  
Foraging Success

scholarly journals Disturbed flow in an aquatic environment may create a sensory refuge for aggregated prey

PeerJ ◽  
2017 ◽  
Vol 5 ◽  
pp. e3121 ◽  
Author(s):  
Asa Johannesen ◽  
Alison M. Dunn ◽  
Lesley J. Morrell
Keyword(s):  
Predation Risk ◽  
Group Size ◽  
Aquatic Environment ◽  
Olfactory Cues ◽  
Flowing Water ◽  
Foraging Success ◽  
Disturbed Flow ◽  
Fish Predators ◽  
Aggregation Size ◽  
Predator Foraging

Predators use olfactory cues moved within water and air to locate prey. Because prey aggregations may produce more cue and be easier to detect, predation could limit aggregation size. However, disturbance in the flow may diminish the reliability of odour as a prey cue, impeding predator foraging success and efficiency. We explore how different cue concentrations (as a proxy for prey group size) affect risk to prey by fish predators in disturbed (more turbulent or mixed) and non-disturbed (less mixed) flowing water. We find that increasing odour cue concentration increases predation risk and disturbing the flow reduces predation risk. At high cue concentration fish were able to locate the cue source in both disturbed and non-disturbed flow, but at medium concentrations, predators only located the cue source more often than expected by chance in non-disturbed flow. This suggests that objects disturbing flow provide a sensory refuge allowing prey to form larger groups, but that group sizes may be limited by level of disturbance to the flow.

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.

THE EFFECT OF HANDLING TIME ON INTERFERENCE AMONG HOUSE SPARROWS FORAGING AT DIFFERENT SEED DENSITIES

Behaviour ◽  
2001 ◽  
Vol 138 (5) ◽  
pp. 597-614 ◽  
Author(s):  
Cheryl Johnson ◽  
James W.A. Grant ◽  
Luc-Alain Giraldeau
Keyword(s):  
Group Size ◽  
Ideal Free Distribution ◽  
Passer Domesticus ◽  
Handling Time ◽  
Foraging Success ◽  
House Sparrows ◽  
Interference Models ◽  
Foraging Time ◽  
Ideal Free ◽  
The Ideal

AbstractInterference models of the ideal free distribution (IFD) assume competition among foraging animals causes intake rates to decline with increasing competitor density and that the strength of the decline influences forager distributions among food patches. However, the resulting distributions of animals may depend on which components of foraging success contribute to interference. We examined the effect of group size (1-13 birds) on the prey encounter rates, handling times, and foraging rates of house sparrows, Passer domesticus, feeding at three seed densities in a suburban backyard. House sparrows did not experience interference during search. Interference arose primarily from foraging time lost handling seeds. Foraging rates decreased with increasing seed density as a consequence of increased handling times. Also, birds experiencing significant increases in handling time with group size suffered most from interference. Our results suggest that animals adjust handling time to avoid costly aggressive interactions, indicating that handling time may be an important component of interference in some foraging systems. Future studies estimating interference should try to identify which components of foraging contribute to interference, paying particular attention to handling times for species that monitor and avoid competitors.

Vigilance in Przewalski's gazelle: effects of sex, predation risk and group size

2009 ◽  
Vol 277 (4) ◽  
pp. 302-308 ◽  
Author(s):  
Z. Li ◽  
Z. Jiang ◽  
G. Beauchamp
Keyword(s):  
Predation Risk ◽  
Group Size
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