Comparative analysis of behavioural response of captive-reared and wild-trapped Northern Bobwhites to simulated predator attacks

Abstract

Isolated populations of Northern Bobwhites (Colinus virginianus) have declined causing many landowners to attempt population restoration by releasing captive-reared birds. These attempts have resulted in high mortality rates, which we hypothesised are caused by captive-reared birds exhibiting more naÏ ve predator avoidance behaviour than wild birds. Captive-reared and wild-trapped Northern Bobwhites were subjected to raptorial and terrestrial predator simulations and their responses were recorded on high definition video. We recorded the time to predator detection, time to anti-predator defence, and reaction type for comparative analysis. Captivereared birds detected simulated predators quicker than wild-trapped birds, but time to mount an anti-predator defence was not different between groups. The response type, however, was different between groups. Captivereared birds typically flushed when encountering a simulated predator; yet, wild-trapped birds did not flush at all, and typically ran or held when subjected to the simulated predators. We hypothesise that flushing is a naÏ ve anti-predator response that results in revealing of position in the presence of a threat, thereby increasing the individual risk of predation. These results potentially illuminate at least one reason why captive-reared Northern Bobwhite releases have been largely unsuccessful.