Journal ArticleDOI
Time Budgeting and Group Size: A Test of Theory
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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.Abstract:
Foraging flocks of granivorous Yellow-eyed Juncos (Junco phaeonotus) were studied for two winters to test hypothesized relationships between group size and time budgets Required feeding time is so large that it constrains aggression At low temperatures (high foraging requirements) a large flock forms in the area of maximal food availability Group size decreases at warmer temper- atures, since the constraints on aggression are reduced Group size variance responds similarly As group size increases, individuals scan less often for approaching predators The time saved is employed to increase feeding rates, unless aggression levels are extremely high Rates of aggressive interaction increase with group size, and with both ambient temperature and food density Dominants apparently forage more efficiently than subordinates because of differences in habitat utilization and time allocation These differences are consistent with the hypothesized correlation between increasing dominance and greater overwinter survivorshipread more
Citations
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Behavioral decisions made under the risk of predation: a review and prospectus
Steven L. Lima,Lawrence M. Dill +1 more
TL;DR: This work has shown that predation is a major selective force in the evolution of several morphological and behavioral characteristics of animals and the importance of predation during evolutionary time has been underestimated.
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Predator vigilance and group size in mammals and birds: a critical review of the empirical evidence
TL;DR: 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.
Journal ArticleDOI
Grazing Lawns: Animals in Herds, Plant Form, and Coevolution
TL;DR: Natural selection at the individual level, acting on both animals and plants to produce coevolution among members of the same trophic web, can regulate such ecosystem processes as energy flow and nutrient cycling, and contribute to species coexistence and the resultant species diversity of communities.
Journal ArticleDOI
Why individual vigilance declines as group size increases
TL;DR: In this paper, the authors pointed out that the functional explanation of the group size eVect remains unclear, and suggested that the individual risk hypothesis, with group vigilance as one element, provides a more general framework for understanding variation in vigilance behaviour with group size and with other factors.
Journal ArticleDOI
Physiological consequences of habitat selection
TL;DR: Analyses of the physiological consequences of habitat selection are exemplified in several case studies, the importance of considering food and other factors in the analyses is stressed, and an extension to endotherms is briefly discussed.
References
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