000028654 001__ 28654
000028654 005__ 20131002113958.0
000028654 0248_ $$aoai:doc.rero.ch:20120307114823-YM$$punifr$$ppostprint$$prero_explore$$zcdu34$$zthesis_urn$$zreport$$zthesis$$zbook$$zjournal$$zcdu574$$zcdu16$$zpreprint$$zcdu1$$zdissertation
000028654 041__ $$aeng
000028654 080__ $$a574
000028654 100__ $$aBrechbühl, Rolf$$uDepartment of Biology, Ecology and Evolution Unit, University of Fribourg, Switzerland
000028654 245__ $$9eng$$aDiet choice of a predator in the wild: overabundance of prey and missed opportunities along the prey capture sequence
000028654 269__ $$c2011-12-14
000028654 520__ $$9eng$$aOptimal diet theory (ODT) postulates that predators adjust their foraging decisions by calculating a prey value from the potential biomass gain, handling time, prey vulnerability and encounter rate. Tests of ODT have however so far mainly been restricted to laboratory settings. By video surveillance, we gathered a large data set of more than 2000 field observations of crab spider (Misumena vatia) encounters with potential prey. We then tested whether the complex ODT or two simpler models (prey identity and prey traits) best explain foraging decisions. Insect prey were killed with an average chance of 3.5% when alighting on an inflorescence harboring a spider. Spiders refused to attack suitable prey in 46–79% of encounters when prey was in attack range, indicating an over-abundance of prey relative to the needs of the spiders. Reduction of opportunities to capture prey along the prey capture sequence differed among pollinator groups, with syrphids and solitary bees showing strong avoidance of spiders early in the sequence and bumblebees resisting the final strike. Simple prey traits explained foraging decisions better than ODT, which was not supported. In the absence of food limitation, optimality decisions may be less stringent. The over-abundance of prey indicates that, in contrast to current theory, prey encounter rates are not the most important factor driving predator foraging decisions. Our results are highly coherent with those obtained in earlier field studies on patch leaving strategies and predator-prey encounters. Prey over-abundance and non-optimal predator behavior are apparently not uncommon in nature, and we highlight some of the implications for predator-prey theory.
000028654 695__ $$9eng$$aattack rate ; capture success ; crab spider ; encounter rate ; handling time ; Misumena vatia ; optimal diet theory ; predator avoidance ; preference ; prey size ; prey value ; vulnerability
000028654 700__ $$aCasas, Jérôme$$uInstitut de Recherche sur la Biologie de l'Insecte, Université de Tours, France
000028654 700__ $$aBacher, Sven$$uDepartment of Biology, Ecology and Evolution Unit, University of Fribourg, Switzerland
000028654 773__ $$g2011/2/12/art133$$tEcosphere
000028654 775__ $$gPublished version$$ohttp://dx.doi.org/10.1890/ES11-00323.1
000028654 8564_ $$fbac_dcp.pdf$$qapplication/pdf$$s1368940$$uhttp://doc.rero.ch/record/28654/files/bac_dcp.pdf$$yorder:1$$zpdf
000028654 918__ $$aFaculté des sciences$$bDécanat, Ch. du Musée 6A, 1700 Fribourg$$cBiologie
000028654 919__ $$aUniversité de Fribourg$$bFribourg$$ddoc.support@rero.ch
000028654 980__ $$aPOSTPRINT$$bUNIFR$$fART_JOURNAL
000028654 990__ $$a20120307114823-YM