Foraging on spatially distributed resources with sub-optimal movement, imperfect information, and travelling costs: Departures from the ideal free distribution

Matsumura S, Arlinghaus R, & Dieckmann U (2010). Foraging on spatially distributed resources with sub-optimal movement, imperfect information, and travelling costs: Departures from the ideal free distribution. Oikos 119 (9): 1469-1483. DOI:10.1111/j.1600-0706.2010.18196.x.

[img]
Preview
Text
Foraging on spatially distributed resources with sub-optimal movement, imperfect information, and travelling costs departures from the ideal free distribution.pdf - Published Version
Available under License Creative Commons Attribution.

Download (1MB) | Preview

Abstract

Ideal free distribution (IFD) theory offers an important baseline for predicting the distribution of foragers across resource patches. Yet it is well known that IFD theory relies on several over-simplifying assumptions that are unlikely to be met in reality. Here we relax three of the most critical assumptions: (1) optimal foraging moves among patches, (2) omniscience about the utility of resource patches, and (3) cost-free travelling between patches. Based on these generalizations, we investigate the distributions of a constant number of forgers in models with explicit resource dynamics of logistic type. We find that, first, when foragers do not always move to the patch offering maximum intake rate (optimal foraging), but instead move probabilistically according to differences in resource intake rates between patches (sub-optimal foraging), the distribution of foragers becomes less skewed than the IFD, so that high-quality patches attract fewer foragers. Second, this homogenization is strengthened when foragers have less than perfect knowledge about the utility of resource patches. Third, and perhaps most surprisingly, the introduction of travelling costs causes departures in the opposite direction: the distribution of sub-optimal foragers approaches the IFD as travelling costs increase. We demonstrate that these three findings are robust when considering patches that differ in the resources carrying capacity or intrinsic growth rate, and when considering simple two-patch and more complex multiple-patch models. By overcoming three major over-simplifications of IFD theory, our analyses contribute to the systematic investigation of ecological factors influencing the spatial disribution of foragers, and thus help in deriving new hypotheses that are testable in empirical systems. A confluence of theoretical and empirical studies that go beyond classical IFD theory is essential for improving insights into how animal distributions across resource patches are determined in nature.

Item Type: Article
Research Programs: Evolution and Ecology (EEP)
Bibliographic Reference: Oikos; 119(9):1469-1483 (September 2010) (Published online 13 April 2010)
Depositing User: IIASA Import
Date Deposited: 15 Jan 2016 08:43
Last Modified: 22 Jul 2016 12:05
URI: http://pure.iiasa.ac.at/9206

Actions (login required)

View Item View Item

International Institute for Applied Systems Analysis (IIASA)
Schlossplatz 1, A-2361 Laxenburg, Austria
Phone: (+43 2236) 807 0 Fax:(+43 2236) 71 313