Dear Enemy Recognition and the Costs of Aggression between Salamanders

Abstract

Adult male and female red-backed salamanders, P. cinereus, employ dear enemy recognition, such that individuals are less aggressive (threat displays and biting) and more submissive toward familiar territorial neighbors than toward strangers. Pheromones are used to distinguish familiar from unfamiliar conspecifics. This behavior reduced the likelihood of escalated contests between neighbors. When combat does occur, bites are usually directed at the 2 most vulnerable parts of an opponent''s body. An attack to the tail might lead to autotomy of that organ, with resultant loss of fat reserves. Injury to the nasolabial grooves on the snout leads to impairment of their chemosensory function, resulting in reduced capture rate during foraging and perhaps in reduced ability to locate mates and competitors. Dear enemy recognition probably is an evolutionary response to the host cost and low payoff of escalated aggression among territorial neighbors.