The sexual strategy of the central long‐toed salamander, Ambystoma macrodactylum columbianum, in south‐eastern Washington

The sexual strategies of salamanders are largely‘unobservable’owing to the low visibility typical of their preferred breeding habitats. We conducted both field and laboratory studies to investigate the sexual strategy of the North American central long‐toed salamander, Ambystoma macrodactylum columbianum. Capture‐recapture and cohort‐marking of salamanders at an aquatic breeding site indicated that males arrive before females and remain in the water for longer periods of time (measured in weeks, rather than days as for females). We estimate that the overall duration of the breeding season is short, three weeks or less. Courtship between single males and females is characterized by repeated bouts of axillary amplexus, separated by multiple episodes of spermatophore deposition. Amplectant males provide females with considerable tactile stimulation in the form of head‐rubbing. Unpaired males attempt to displace amplectant males from their partners by wrestling with them. In addition, unpaired males appear to interfere in ongoing courtship encounters during the spermatophore deposition stage, perhaps attempting to 'steal’inseminations. We suggest that explosive scramble‐competition polygyny best describes the mating system of A. m. columbianum. Operational sex ratios are probably male‐biased throughout the short breeding season, leading to intense competition among males for mates. Mate choice (by either sex) probably is of little importance as a determinant of mating success.