Alonso, J.C., J.A. Alonso, L.M. Bautista and R. Muñoz-Pulido. 1995. Patch use and decision making in common cranes. Anim. Behav. 49: 1367-1379.          

Abstract. The marginal value theorem states that foragers should leave patches when the instantaneous capture rate has fallen to the average capture rate for the habitat. This predicts that patch residence time should increase with increasing patch quality and decrease with increasing habitat quality. These and other predictions from prescient, Bayesian and fixed-time models were tested using observations on 14 radio-tagged free-living common cranes, Grus grus, foraging in cereal farmland. Cranes behaved as Bayesian foragers. Their intake rates on leaving patches changed with patch and habitat quality. The behaviour of cranes was consistent with marginal value theorem predictions only in patches where energy return was lower than required to meet daily food requirements. In contrast, birds left richer patches earlier than expected and at higher intake rates than poor patches. In addition, cranes stayed longer in larger flocks. These results suggest that cranes changed their foraging rules according to their expected energy balance.      


This material has been published in Animal Behaviour (1995) 49: 1367-1379, the only definitive repository of the content that has been certified and accepted after peer review. Copyright and all rights therein are retained by The Association for the Study of Animal Behaviour. This material may not be copied or reposted without explicit permission. This article is available at the International Digital Electronic Access Library (IDEAL).