No abstract

Baboons choose sleeping sites in the following descending order of preference: 1) steep cliff faces and caves, 2) taller emerging trees in continuous forests, 3) the canopy of contiguous forest without emerging trees, and 4) open woodland trees. Choice of sleeping sites in an order appearing to agree with degree of inaccessibility to most predators suggests the hypothesis that predation avoidance is the major basis for use and choice of particular sleeping sites. If this preference order for kinds of sleeping sites is applicable to other large primates, it suggests that spacing of adequate sleeping sites relative to the distribution and density of food resources is one factor contributing to group size and possibly other features of primate social structure. The relatively even distribution of numerous adequate sleeping sites in tropical forests may be one factor permitting evolution of small social units. By contrast, sparse distribution of sleeping sites relative to resource fields may permit the development of large social groups.

The analysis of animal socioeconomic systems, including those of man presented here, is based upon the interpretation of refuging (Hamilton et al 1), the rhythmical dispersal of groups of animals from and their return to a fixed point in space. A central thesis of this review is that analysis of the economics of refuging systems can lead to profitable analysis of central place systems (Losch 2) containing smaller numbers of individuals. The fixed point, the core (C) or central place (Losch 2) from which radial dispersal takes place, may be occupied by one individual or a group of them. In refuging systems many individuals disperse radially from C to some welldefined limit. Between C and this dispersal limit lies the arena (A) where resource acquisition takes place (Figure 1). This review considers the effect of parameters such as time, resource exploitation and renewal, locomotion capacity, group processes, and density upon energy transfer within these central place systems. Conclusions derived from these analyses have special significance to man because most modern and many early and undeveloped human populations are or were organized into refuging systems.Earlier analyses of refuging starlings, which forage in open country and use a winter roost as a core (Hamilton et al 1, Hamilton & Gilbert 5), led to the conclusion that the spatial distribution of individuals within A during the resource acquisition phase of the dispersion and contraction rhythm can be explained by assuming that intraspecific competition for resources declines with distance from C. However, the additional energy and the energy equivalent of time required to reach these more distant and less heavily exploited ranges act to limit dispersal distances. Accordingly, one individual might obtain as much energy by foraging longer near C as another individual that travels to less-exploited foraging grounds and expends more energy and time to get there. This balance of energy expended versus energy gained may explain the observation that some individuals in a population of starlings using the same roost travel as far as 80 km from C in their daily foraging activities while other individuals move less than 10 km from it. All morphologically similar individuals using the same C will be employing basically the same criteria in determining the optimum strategy for securing resources.It thus follows that if the strategies of all participating individuals come to equilibrium, they will be equivalent to one another in terms of net energy 263

No abstract

No abstract