Metabolism and thermoregulation between Mrs Hume’s Pheasant (Syrmaticus humiae) and Elliot’s Pheasant (S. ellioti)

To understand metabolic adaptations, the basal metabolic rate (BMR) of Mrs Hume’s Pheasant (Syrmaticus humiae) and Elliot’s Pheasant (Syrmaticus ellioti) were investigated. Metabolic rate (MR), body temperature (Tb ) and thermal conductance (C) were determined in both species at a temperatrue range of 5 − 35 ℃, respectively. Oxygen consumption was measured with a closed circuit respirometer. The thermal neutral zones (TNZ) were 24.5 − 31.6 ℃, and 23.0 −29.2 ℃, respectively. With a temperature range of 5 − 35 ℃, Mrs Hume’s Pheasant and Elliot’s Pheasant could maintained stable Tb at a mean of (40.47±0.64) and (40.36±0.10) ℃, respectively. Mean BMRs within TNZs were (1.36±0.84) mLO2/(g·h) for Mrs Hume’s Pheasant and (2.03±0.12) mLO2/(g·h) for Elliot’s Pheasant, which were 77% and 86% of the expected value based on their body mass, respectively. Thermal conductance of Mrs Hume’s Pheasant and Elliot’s Pheasant were (0.12±0.01) and (0.17±0.01) mLO2/(g·h·℃), below the lower critical temperature, respectively, which were 119% and 124% of the expected value based on their body mass, respectively. The ecophysiological characteristics of these species were low metabolic rate, high body temperature, and high thermal conductance, which allow both species to better adapt to the warmer climate environment in south China.