Tail-flagging and other antipredator signals in white-tailed deer: new data and synthesis

We present a series of predictions concerning the costs and benefits of antipredator behavior in ungulates and then test them with data on white-tailed deer reacting to a human on foot. Costs of tail-flagging were apparently low and no data supported the idea that flagging serves as a warning signal to conspecifics, in either this or in other studies. Flagging deer fled at greater speeds than nonflaggers, indicating that flagging could possibly signal prey's ability to escape. Dropping the tail at the end of the flight may additionally have made deer inconspicuous. Snorting did not appear directed at conspecifics, and comparative data suggest that it signals that the predator has been detected. In contrast, foot-stamping was effective in alerting other deer to the observer's presence. Deer may have bounded to clear obstacles along their flight path. These preliminary data indicate that several aspects of antipredator behavior in white-tailed deer may be pursuit-deterrent signals, and they therefore highlight the necessity of observing natural predators' reactions to signals given by deer in future studies.