Patch exploitation as choice: Symmetric choice in an asymmetric situation?

In the present paper, we explore a novel preparation for the study of animal choice behaviour designed to capture some aspects of naturally occurring patch exploitation. Although one can cast the problem of patch exploitation as a binary choice, naturally occurring patch-leaving decisions are inevitably asymmetric. We asked whether captive blue jays, Cyanocitta cristata, treat leaving and staying in the same way. To do this we factorially varied the delays associated with leaving and staying in a food patch. In addition, we manipulated our subject's level of motivation (e.g. hunger) using prefeeding treatments. We found that hungry subjects came closest to our prediction of treating leaving and staying in the same way, but that less motivated subjects showed a pronounced and surprising bias in favour of leaving. We discuss the implications of results for experimental and theoretical studies and choice behaviour. We suggest that students of choice behaviour need to understand the sources of such biases because naturally occurring choice situations are seldom perfectly symmetrical.