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| title | chunk | source | category | tags | date_saved | instance |
|---|---|---|---|---|---|---|
| Central place foraging | 1/4 | https://en.wikipedia.org/wiki/Central_place_foraging | reference | science, encyclopedia | 2026-05-05T14:59:49.572605+00:00 | kb-cron |
Central place foraging (CPF) theory is an evolutionary ecology model for analyzing how an organism can maximize foraging rates while traveling through a patch (a discrete resource concentration), but maintains the key distinction of a forager traveling from a home base to a distant foraging location rather than simply passing through an area or travelling at random. CPF was initially developed to explain how red-winged blackbirds might maximize energy returns when traveling to and from a nest. The model has been further refined and used by anthropologists studying human behavioral ecology and archaeology.
== Case studies ==
=== Central place foraging in non-human animals === Orians and Pearson (1979) found that red-winged blackbirds in eastern Washington State tend to capture a larger number of single species prey items per trip compared to the same species in Costa Rica, which brought back large, single insects. Foraging specialization by Costa Rican blackbirds was attributed to increased search and handling costs of nocturnal foraging, whereas birds in Eastern Washington forage diurnally for prey with lower search and handling costs. Studies with sea birds and seals have also found that load size tends to increase with foraging distance from the nest, as predicted by CPF. Other central place foragers, such as social insects, also show support for CPF theory. European honeybees increase their nectar load as travel time to nectar sites from a hive increases. Beavers have been found to preferentially collect larger diameter trees as distance from their lodge increases.
=== Archaeological case study: acorns and mussels in California === To apply the central place foraging model to ethnographic and experimental archaeological data driven by middle range theory, Bettinger et al. (1997) simplify the Barlow and Metcalf (1996) central place model to explore the archaeological implications of acorn (Quercus kelloggii) and mussel (Mytilus californianus) procurement and processing. This model assumes foragers are gathering resources at a distance from their central place with the goal of efficiently returning the resource home. Travel time is expected to determine the degree to which foragers will process a resource in order to increase its utility prior to returning from a foraging location to their central place. Transport capabilities in aboriginal California were established by measuring the volume of burden baskets and extrapolating the load weight based on ethnographic data on basket use. Ethnographic and experimental data was used to estimate utility at each possible stage of processing. Examining ecology and procurement methods, the central place foraging model was used to predict the conditions in which field processing of the two species will occur.
Acorn: Most stages of acorn processing are extremely time consuming but only marginally increase utility, therefore the central place foraging model predicts that acorns should only be dried prior to transporting to central place. Further processing of acorns (cracking, shucking, and winnowing) increases efficiency only when foragers’ one way travel time reaches 25 hours. This corresponds to approximately 124.75 km, which exceeds the territory size of native groups in California dependent on acorns. Mussels: When foragers employ the plucking harvesting method, field processing is expected even with short travel distances, as the shell to meat ratio allows forager to increase efficiency by removing shell. Stripping will almost always result in central place processing, rather than field processing, as this harvesting method results in the procurement of a high percentage of small mussels with high shell to meat ratios. An understanding of central place foraging has implications for studying archaeological site formation. Variability of remains at sites can tell us about mobility – whether or not groups are central place foragers, what resource they’re mapping on to, and their degree of mobility. Based on central place foraging application for the processing of mussels and acorns, Bettinger et al. (1997) make several predictions for archaeological expectations. The study shows that procurement with field processing is more costly compared to foraging and processing resources residentially. These results imply that highly mobile foragers will establish a home base in close proximity to staple resources, and all processing of those resources will be done residentially. Less residentially mobile populations would in turn be mapped only onto a few resources, and would be expected to field process non-local resources on logistical procurement forays at greater distances from their central place. Processing debris from archaeological sites should reflect changes in mobility.
Acorns: Sites where the archaeobotanical remains are dominated by acorn can be assumed to be seasonal sites of highly mobile foragers that have mapped on to acorns for seasonal processing. Sites that have a mix of archaeobotanical remains with a decreased abundance in acorn remains and plant material that would be lost in early stages of field processing are interpreted as less residentially mobile settlements characterized by logistical procurement. Mussels: Interpretation of archaeological mussel shell is complicated because it is reliant on the condition of the mussel beds, distance to the mussel beds and the type of harvest method being employed. In general, however, sites closer to mussel beds should have larger mussel shell due to plucking and residential consumption. Sites far from mussel procurement beds would be expected to have a mix of mussel shell sizes due to stripping. The presence of higher amounts of small mussel shell could also indicate an increase in resource intensification.