Implications of Foraging Behavior

by

Ronald C. Ydenberg

• LAST REVIEWED: 30 September 2013
• LAST MODIFIED: 30 September 2013
• DOI: 10.1093/obo/9780199830060-0005

Introduction

The scientific study of ecology began in the 20th century with ideas about population dynamics and trophic interactions in food webs. The study of animal behavior developed around mid-century. Borrowing ideas from the rapidly expanding field of economics, the notion that one could think of foragers as clever strategists with flexible behavior came along in the 1960s. In subsequent decades “optimal foraging” grew rapidly. Analogous lines of thinking for other behaviors such as mate selection, parental care, life histories, and social interactions merged to form behavioral ecology in the 1970s and 1980s. Foraging theorists originally aimed to apply their thinking to population and community ecology. Facing criticism from ecologists, many instead developed strong links with ethology, experimental psychology, and neurobiology. But in the last two decades a series of discoveries have helped move the study of foraging toward fulfilling its ambitions of explaining “higher order” ecological phenomena such as predator-prey relationships and community structure. These discoveries are the subject of this bibliography. The most basic insight came from another notion borrowed from economics: that of a trade-off. Given a trade-off, a behavior can do one of two things well, or both moderately well, but cannot maximize both things at once. For example, an animal can forage quickly, but it cannot watch for predators, mates, or competitors at the same time. The trade-off between foraging and predation risk became fundamental. As the 21st century arrived, ecologists began to realize that anti-predator behavior has effects on populations and communities at least as big and as important as those attributable to the prey killed by predators. These discoveries are currently spurring ecologists to develop new theoretical and empirical techniques to investigate the role of foraging behavior in population ecology and community structure.

General Overviews

Introductions to foraging can be found in Stephens and Krebs 1986 and in Stephens, et al. 2007. The OBO article Optimal Foraging pertains especially to the former; the latter volume devotes much more space to the themes covered here. Sibly and Smith 1985 introduced the idea that fitness-maximizing behavior should have profound effects on population dynamics, but it hardly considered the idea that anti-predator behavior might be so important. However, that thought was nascent in the 1980s, and Lima and Dill 1990, a review of foraging under the risk of predation, was perfectly timed to influence the field. Kotler and Holt 1989 was the first to recognize density-mediated and behaviorally (here called “trait”) mediated effects of predators (see Effects on Population Dynamics) and noted that the latter can be as large or larger than the former. Werner and Peacor 2003 brings this to the wider attention of ecologists by drawing together the relevant literature and emphasizing their unexpectedly large magnitude. Railsback and Harvey 2012 points out that new theoretical structures are needed to understand all the empirical results flooding in. As their title suggests, foraging theory is for the first time in its history accused of falling behind rather than racing recklessly ahead of the data.

• Kotler, B. P., and R. D. Holt. 1989. Predation and competition: The interaction of two types of species interactions. Oikos 54:256–260.

  DOI: 10.2307/3565279

  Introduced the distinction between density- and trait-mediated effects to the ecological literature. The paper anticipates many discoveries of the subsequent twenty years and is well worth reading again.

• Lima, S. L., and L. M. Dill. 1990. Behavioral decisions made under the risk of predation: A review and prospectus. Canadian Journal of Zoology 68:619–640.

  DOI: 10.1139/z90-092

  The literature available has increased many-fold since this paper was published, but this contribution remains valuable for its insights, in addition to its historical significance.

• Railsback, S. F., and B. C. Harvey. 2012. Trait-mediated trophic interactions: Is foraging theory keeping up? Trends in Ecology and Evolution.

  DOI: 10.1016/j.tree.2012.08.023

  An updated review, with an overview of methods to measure the size of trait-mediated effects.

• Sibly, R. M., and R. H. Smith. 1985. Behavioural ecology: Ecological consequences of adaptive behaviour. Oxford: Blackwell Scientific.

  An expansive volume treating many topics and anticipating themes that this review identifies as important. The two contributions by Geoff Parker are especially pertinent.

• Stephens, D. W., J. Brown, and R. C. Ydenberg, eds. 2007. Foraging: Behavior and ecology. Chicago: Univ. of Chicago Press.

  DOI: 10.7208/chicago/9780226772653.001.0001

  Reviews all aspects of the modern study of foraging. The first chapter gives an overview and chapter-by-chapter comparison with Stephens and Krebs 1986, showing where progress has and has not been made.

• Stephens, D. W., and J. R. Krebs. 1986. Foraging theory. Princeton, NJ: Princeton Univ. Press.

  Best and authoritative introduction to the subject, giving a rigorous derivation of the basic models and a historically valuable overview of where the field stood at the time. See also the OBO article Optimal Foraging.

• Werner, E. E., and S. D. Peacor. 2003. A review of trait-mediated indirect interactions in ecological communities. Ecology 84:1083–1100.

  DOI: 10.1890/0012-9658(2003)084[1083:AROTII]2.0.CO;2

  Develops the notion of “trait-mediated” (i.e., resulting from changes in prey behavior) versus “density-mediated” (i.e., resulting from prey death) effects on prey populations and communities, and emphasizes their ubiquity and magnitude.