Risk-sensitive foraging in bitterlings, Rhodeus sericus: effects of food requirement and breeding site quality

Abstract

Risk-sensitive foraging preferences in bitterlings were examined in relation to changing food deprivation and intake relative to estimated requirement. When running above estimated requirement and presented with a choice of constant and variable feeding stations, a group of seven fish were all risk-averse (avoiding high variance in reward rate). When running below, six out of the seven fish showed increased risk-aversion and one became risk-prone (choosing high variance). Increasing the degree of food deprivation while running below requirement for one of the risk-averse fish, however, resulted in a switch to risk-proneness, a response that was repeated in a second group of six fish running below requirement. Variance in reward rate also appeared to influence the choice of a potential breeding site by a male bitterling. When breeding sites of apparent equal quality were provided at the constant and variable feeding stations, the fish preferred the constant station; the variable station was preferred only when breeding site quality at the constant station was relatively low.