Social monogamy in a territorial salamander

Social monogamy? which does not necessarily imply mating or genetic monogam y, is important in the formation of male-female pair associations. We opera tionally define social monogamy as occurring when two heterosexual adults, exclusive of kin-directed behaviour, direct significantly less aggression a nd significantly more submission towards each other, and/or spend significa ntly more time associating with each other relative to other adult heterose xual conspecifics. Long-term pair associations (i.e. those lasting through a lengthy breeding season) that are characteristic of social monogamy are c ommon in some taxa but are virtually unknown in amphibians. Recent studies, however, have suggested that red-backed salamanders, Plethodon cinereus, h ave complex (for amphibians) social systems. Our laboratory experiments tes ted the hypothesis that red-backed salamanders found in pairs in the forest display behaviours consistent with social monogamy. During the summer nonc ourtship season, newly collected male-females pairs showed no preference to associate with their partners more than with a novel conspecific of the op posite sex. However, during the autumn courtship season, paired males and f emales significantly directed preferential behaviours towards their partner s rather than towards a surrogate or a novel paired salamander. Focal anima ls showed no significant preferences when presented with their partner and a novel single salamander, but they never directed preferential behaviours towards a novel salamander (whether paired or single) or a surrogate. These results are the first to suggest that a salamander species engages in soci al monogamy. Furthermore, our results suggest that social monogamy may not inhibit paired males and females from displaying alternative strategies: pr eferring partners when extrapair associations may be disadvantageous (i.e. the extrapair animal is already paired) but not preferring partners when ex trapair associations may be advantageous (i.e. the extrapair animal is sing le). (C) 2000 The Association for the Study of Animal Behaviour.