Evolution of Alarm Signals in Ungulates with Special Reference to White-Tailed Deer

Abstract

Two types of conspicuous alarm signals in white-tailed deer [Odocoileus virginianus] were examined with respect to groups of closely related (female, young) and nonrelated (male) animals on the Edwin S. George Reserve in SE Michigan [USA]. No difference was detected in the frequency of tail flagging used by the 2 types of groups. Tail flagging in white-tailed deer and the ungulate rump-patch phenomenon in general serves as socially cohesive signals that help to keep individuals in groups for antipredator benefits. In woodland species with "on-off" rump patches, this signal functions principally during flight situations after cryptic strategies have failed. In plains species with large permanently visible rump patches, the signal functions not only during flight but also as a constant source of reference for location of other members of the group. A highly significant difference in frequency of snorting was found between related and unrelated groups. Snorting is usually given in circumstances of little risk to the giver, where the individual might have slipped off undetected. Snorting in related groups follows a kin-selection model, while its low frequency in unrelated groups follows a selfish-behavior model. Hypotheses concerning alarm signals in ungulates are discussed in detail.