THE INFLUENCE OF TAIL AUTOTOMY ON AGONISTIC BEHAVIOR IN A TERRITORIALSALAMANDER

Assessment of potentially asymmetrical characters (:such as fighting a bility and resident advantage) is often important in determining the o utcome of agonistic interactions. Loss of body parts, a predator defen ce mechanism used by many animals, may lead to a reduction in fighting ability and may be easily assessed by competitors. We investigated th e influence of tail loss on the expression of agonistic behaviour in t he territorial red-backed salamander, Plethodon cinereus. Residents an d intruders were matched for body size, and pairs were tested in all c ombinations of tailed or tailless residents with tailed or tailless in truders. Neither residents nor intruders altered their behaviour based on their own tail condition, but they did alter their behaviour based on the tail condition of their opponents. Intruders showed more aggre ssion or less submission towards tailless residents than towards taile d residents. When contests were between residents;Ind intruders of the same tail condition (both tailed or tailless), intruders were more ag gressive towards residents when both were tailless than when both were tailed, indicating that tail loss does not directly hamper aggressive displays. In contests where the asymmetry between residents and intru ders was small (based on tail condition and residency status), intrude rs showed more aggression and less submission than in contests where t he asymmetry was large. Residents did not differ in their behaviour fo r most comparisons. Thus, for intruders, the tail condition of residen ts is an important determinant of agonistic behaviour displayed in ter ritorial contests. For residents, factors other than tail condition (s uch as resource value) may be more likely to influence their behaviour . (C) 1998 The Association for the Study of Animal Behaviour.