Optimal foraging on the roof of the world: Himalayan langurs and the classical prey model

Abstract

Optimal foraging theory has only been sporadically applied to nonhuman primates. The classical prey model, modified for patch choice, predicts a sliding “profitability threshold” for dropping patch types from the diet, preference for profitable foods, dietary niche breadth reduction as encounter rates increase, and that exploitation of a patch type is unrelated to its own abundance. We present results from a one-year study testing these predictions with Himalayan langurs (Semnopithecus entellus) at Langtang National Park, Nepal. Behavioral data included continuous recording of feeding bouts and between-patch travel times. Encounter rates were estimated for 55 food types, which were analyzed for crude protein, lipid, free simple sugar, and fibers. Patch types were entered into the prey model algorithm for eight seasonal time periods and differing age-sex classes and nutritional currencies. Although the model consistently underestimated diet breadth, the majority of non-predicted patch types represented rare foods. Profitability was positively related to annual/seasonal dietary contribution by organic matter estimates, while time estimates provided weaker relationships. Patch types utilized did not decrease with increasing encounter rates involving profitable foods, although low-ranking foods available year-round were taken predominantly when high-ranking foods were scarce. High-ranking foods were taken in close relation to encounter rates, while low-ranking foods were not. The utilization of an energetic currency generally resulted in closest conformation to model predictions, and it performed best when assumptions were most closely approximated. These results suggest that even simple models from foraging theory can provide a useful framework for the study of primate feeding behavior.

Particularism and the retreat from theory in the archaeology of agricultural origins

“…A review of the past few years of biological literature finds persistent employment of OFT models, with empirical data often showing good fits with their predictions in a variety of organisms (e.g., refs. [71][72][73][74]. OFT applications in human research also continue apace with valuable insights on varied topics (e.g., refs.…”

Optimal Foraging Theory’s Application to Internet Sex Offender Search Behavior: A Theoretical Model for Computer Forensic Investigations

“…This optimal foraging pattern of food allocation has been identified in various types of biological research on birds [20,22,27]; mammals [23][24][25]; and insects [28]. In the late 1970s and early 1980s, foraging techniques were identified by Winterhalder [29] in human hunter-gather societies on the boreal forest Cree, by O'Connell and Hawkes [30] on the Alyawara of Australia, and by Hill and Hawkes [31] in four Amazonian Indian populations.…”

“…The prey choice and diet breadth category refers to an animal's choice of one type of food over another. It has been found in several studies [23][24][25] that animals will pass by certain items in search of others that will yield greater energy intake when such items are clumped or available in a patchy manner. When resources are evenly distributed throughout an environment, it is said to be homogeneous, which leads foragers to consume items randomly and exploit resources in proportion to their availability [19].…”

“…As foraging animals will pass by some patches of food in favor of others that yield a greater source of energy intake [23][24][25], we expect Internet sex offenders to bypass certain websites and entities in favor of others. In determining what websites warrant further allocation of time, Internet sex offenders must have a plan that guides their search.…”

“…As research has shown, sexually themed websites are popular patches for offenders. We know from the biological foraging literature [23][24][25] that animals will bypass certain food for others that yield a higher energy return. We expect Internet sex offenders to do the same; meaning offenders would bypass certain websites they considered inadequate for optimization in search of those websites where offenders could gain more of the content their desire, thus optimizing their search.…”