Audience effects on alarm calling

Alarm calling may depend not only on the detection of predators but also on other factors, including the social factor which is reviewed here. Several species show that the presence of particular conspecifics, e.g. an audience, is necessary for alarm calling to occur. Thus, the social environment of the prey at the time of predator detection might be crucial in the process of alarm calling. Under what circumstances should audience effects appear? Social modulation of alarm calling should be present when the signal is addressed to other prey and absent when it is addressed to the predator. Whereas this may be correct in some cases, e.g. the snorting of the white-tailed deer (Odocoileus virginianus), it might be incorrect in other cases, e.g. the terrestrial alarm calling of Belding's ground squirrel (Spermophilus beldingi). Therefore, the intended receiver of alarm calls is one out of a number of factors which might predict the presence of an audience effect. Other factors have to considered such as for example the kind of strategy used to escape the predator and the time constraint associated with selective alarm signaling.