Patch-use behaviour of small bluegill sunfish, Lepomis macrochirus, foraging for chironomid larvae, Chironomus riparius, was investigated in artificial macrophyte patches to examine search pattern within a patch and to determine the decision rule used by fish when leaving a patch. Fish were exposed to a sequence of habitats which differed in quality (i.e. total prey density); however, within a habitat all patches were of equal quality. When foraging in a single patch, fish encountered prey randomly, as evidenced by agreement between the distribution of intercapture intervals and the exponential distribution. Agreement between fish behaviour and predictions of a rate decision rule indicated that the decision to leave a patch was based on some estimate of capture rate in the patch. Predictions of how long fish should stay in a patch and how many prey they should capture during a patch visit were generated, using a giving-up time model based on an exponential distribution of intercapture intervals. Fish generally stayed longer and captured more prey than predicted by the model, using giving-up times that were longer than optimal. The relationship between rate of prey capture for the habitat and giving-up times was shaped such that fish minimized the cost, in terms of a decrease in capture rate, by overestimating rather than underestimating the optimal giving-up time.
ASJC Scopus subject areas
- Ecology, Evolution, Behavior and Systematics
- Animal Science and Zoology