A Novel Antipredator Mechanism in Salamanders: Rolling Escape in Hydromantes platycephalus

Abstract

Antipredator mechanisms in salamanders involve behavioral responses that are usually combined with aposematic coloration and skin toxicity (Brodie, 1970, 1977, 1983; Dodd and Brodie, 1976). Behavioral responses range from immobility to active escape, including the adoption of stereotyped postures (Brodie, 1983). Escape mechanisms involve active responses like rapid coiling and uncoiling movements which flip or propel the animal, tail lashing, lateral writhing, and locomotion (Duellman and Trueb, 1986). Although escape responses are usually followed by immobility, no escape mechanism involving passive transport has been reported. Based on field observations, we document a novel antipredator mechanism in the salamander Hydromantes platycephalus that consists of body and tail coiling and limb tucking followed by passive rolling escape. Although coiling is widespread among salamanders, H. platycephalus performs it in the novel context of the steep slopes of the northern Sierra Nevada of California. This results in the peculiar antipredator mechanism of rolling escape. We observed Hydromantes platycephalus at two localities in California, in the vicinity of Sonora Pass: (1) the slopes of Blue Canyon in Stanislaus National Forest, Tuolumne County, and (2) near the Pacific Crest Trail in Toyabee National Forest, Mono County. We found 19 individuals at the first locality on 21 August and 11 September, 1993 and two at the second locality on 11 September, 1993. We observed defensive behavior of 10 individuals from the first locality and two from the second.