Putting ourselves in a striped snake's shoes: thermal sensitivity of locomotor performance in a melanistic/striped colour‐dimorphic snake

Intermorph differences of thermoregulatory abilities in colour‐polymorphic (dimorphic) species have been demonstrated in many ectotherms. Usually, these studies reported slower body warming in pale‐coloured morphs than in dark‐coloured morphs. Under this circumstance, one way in which pale‐coloured individuals can manage their slower body warming is to perform better at lower temperatures than dark‐coloured individuals. If this is the case, the former need not necessarily raise their body temperature to the same level as the latter. Based on this scenario, intermorph differences in thermal sensitivity of performance were examined using the melanistic/striped colour‐dimorphic snake Elaphe quadrivirgata as a model species. As an indication of performance capability, the crawling speed was measured at several temperatures. Although striped individuals exhibited slower body warming than melanistic individuals under experimental conditions, the former did not exhibit faster crawling speed than the latter at lower temperatures. Shape and position of the performance curve were almost identical between melanistic and striped individuals, indicating a highly static nature in thermal sensitivity of crawling. Coupled with the results of field studies, it is suggested that striped individuals manage their slower body warming by efforts of behavioural thermoregulation. The possible significance of ecological performance in the wild was discussed.