Sex-related differences in metabolic rate and locomotor performance in breeding spotted salamanders (Ambystoma maculatum)

We investigated differences in metabolism and locomotor performance of male and female spotted salamanders (Ambystoma maculatum) collected during the breeding season. Male salamanders had faster voluntary crawling speeds than did both gravid and postgravid females. Burst swimming velocity was higher in males than in gravid females but not postgravid females, and there was no difference in burst crawling speeds between the sexes. Oxygen consumption during rest was greater in both gravid and nongravid females than in males, but there was no difference among the three groups in oxygen consumption during locomotion. Both male and postgravid females were able to sustain terrestrial locomotion on the treadmill longer than were gravid females. These findings suggest differences in locomotor performance and energetics between the sexes that may underlie differences in arrival times at breeding sites, frequency of participation in reproductive events, and survival.