Limited Time Budget Research Articles

The scent‐marking behaviour of the spotted hyaena Crocuta crocuta in the southern Kalahari

All hyaenas scent mark their territories by smearing grass stems with paste from their subcaudal scent glands and by depositing faeces at latrines, but they adopt different strategies in terms of how they disperse these scent marks in their territories. For example, brown hyaenas living in the southern Kalahari deposit pastes and latrines throughout the whole of their territory, while spotted hyaenas living in the Ngorongoro Crater of East Africa place their scent marks strictly along the territorial borders. We have argued elsewhere (Gorman & Mills, 1984) that these different strategies are not species‐specific but are instead adaptive responses to local conditions. Here, we use data from a population of spotted hyaenas, living in small clans and large territories in the Kalahari, to test the hypothesis that hinterland marking is a response to the problem of marking a very large territory with a limited amount of scent and within a limited time budget.

A Combinatiorial Optimization Model for Transmission of Job Information Through Contact Networks

A combinatorial network model is constructed to describe the information structure of job finding in a homogeneous job market. A fundamental distinction is drawn between strong and weak contacts: strong contacts are assumed to have strict priority as recipients of information about the existence of job vacancies, while maintenance of a given strong contact requires more time than does maintenance of a weak contact. Facing a limited time-budget, each individual confronts a tradeoff between these two possible ways of investing time. In the model presently investigated, each individual is assumed to develop his contacts so as to maximize probability of getting some new job in the event that he loses his present job. Concepts of both stability and optimality are defined. It is found that if the probability of becoming jobless is low (u <<1), then a situation where all individuals choose only weak ties (all-weak network) will be stable and will be a Pareto optimum under the maximizing behavior assumed. Also, all-weak networks are the only Pareto optima in this case. For u near 1, a different situation obtains: now networks containing only strong ties will be stable and all-weak networks will be unstable. In this second limiting case, however, stability and optimality do not coincide: all-strong networks are not Pareto optimal.