Why White-Tailed Deer Flag Their Tails

Abstract

Four previously published hypotheses that have been used to explain the function of tail flagging in white-tailed deer were tested by comparing the behavior of deer during the approach of a person on foot to that expected under each of the hypotheses. Deer tend to tail flag toward an approaching person and, when they have the opportunity to do so, do not flag toward conspecifics only. Both single deer and deer in groups flag their tails. Deer are more likely to tail flag when they flee at safe distances and they are less likely to tail flag on their 2nd flight. The observations do not support the flash behavior and risk-prone alarm signal hypotheses but, based on a single predictive test, do support the risk-free alarm signal and cohesive signal hypotheses. The detection signal hypothesis, which states that tail flagging functions do inform the approaching predator that it has been detected, is supported by all 3 predictive tests.