Analysis of habitat-selection rules using an individual-based model

Abstract

Abstract - Despite their promise for simulating natural complexity,individual-based models (IBMs) are rarely used for ecological research or resource management. Few IBMs have been shown to reproduce realistic patterns of behavior by individual organisms.To test our IBM of stream salmonids and draw conclusions about foraging theory,we analyzed the IBM ’s ability to reproduce six patterns of habitat selection by real trout in simulations contrasting three alternative habitat-selection objectives:maximizing current growth rate, current survival probability,or ‘‘expected maturity ’’(EM). EM is the product of (1) predicted survival of starvation and other mortality risks over a future time horizon,and (2) the fraction of reproductive size attained over the time horizon. Minimizing the ratio of mortality risk to growth rate was not tested as a habitat-selection rule because it produces nonsensical results when any habitat yields negative growth rates. The IBM simulates habitat selection in response to spatial and temporal variation in mortality risks and food availability as fish compete for food. The model fish move each daily time step to maximize their habitat-selection objective with no other restrictions (e.g.,territoriality) imposed.

Citation

Railsback, Steven F.; Harvey, Bret C. 2002. Analysis of habitat-selection rules using an individual-based model. Ecology 83(7): 1817-1830.