H R Pulliam

Bio: H R Pulliam is an academic researcher. The author has contributed to research in topics: Flocking (behavior). The author has an hindex of 1, co-authored 1 publications receiving 1145 citations.

The Economics of Fleeing from Predators

Abstract: Publisher Summary The chapter describes a simple economic model that predicts in a qualitative way on how costs (lost feeding opportunity and risk) interact to produce an optimal flight distance from approaching predators. Animals often defer the decision to flee from an approaching predator and continue with their ongoing activities. The view is that, a profitable approach to the problem of why such decisions are deferred, and how they are eventually made, is to view the process as an economic, one in which the relative costs of fleeing and staying change as a predator approaches. It is suggested that the economic approach will prove useful in analyzing many aspects of predator-prey interactions.

A novel swarm intelligence optimization approach: sparrow search algorithm

Abstract: In this paper, a novel swarm optimization approach, namely sparrow search algorithm (SSA), is proposed inspired by the group wisdom, foraging and anti-predation behaviours of sparrows. Experiments ...

Predator vigilance and group size in mammals and birds: a critical review of the empirical evidence

Abstract: One commonly cited benefit to animals that forage in groups is an increase in the probability of detecting a predator, and a decrease in the time spent in predator detection. A mathematical model (Pulliam 1973) predicts a negative relationship between group size and vigilance rates. Over fifty studies of birds and mammals report that the relationship at least partly explains why individuals forage in groups. This review evaluates the strength of these conclusions based on their evidence. Those variables that may confound the relationship between vigilance and group size are outlined, and their control is assessed for each study. The variables I consider to be important include the density and type of food; competition between individuals; the proximity to both a safe place and the observer; the presence of predators; the visibility within the habitat; the composition of the group; the ambient temperature and the time of day. Based on these assessments, most of the studies fail to adequately demonstrate an unambiguous relationship between vigilance behavior and group size. Nevertheless, many studies reveal interesting features of the relationship between vigilance and group size that should provide fruitful avenues for future research.

Population Responses to Patchy Environments

Abstract: discon­ tinuities on many scales in time and space. The patterns of these discontinuities produce an environmental patchwork which exerts powerful influences on the distri­ butions of organisms, their interactions, and their adaptations. Consideration of this environmental patch structure is critical to both the theory and management of populations. Despite the obvious heterogeneity of natural sys­ te.ms, most of the models that form the theoretical fabric of population biology and ecology (and that are increasingly conditioning our perception of reality) tell mathe­ matical stories of populations

Grazing Lawns: Animals in Herds, Plant Form, and Coevolution

Abstract: Many grazing animals in both terrestrial and aquatic ecosystems form dense herds that maintain the vegetation in their concentration areas at very low statures. Studies of the effects of large ungu...