Thermoregulation and Evaporative Water Loss in Chinese Bulbuls Pycnonotus sinensis
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① School of Life and Environmental Sciences,Wenzhou University,① School of Life and Environmental Sciences,Wenzhou University,① School of Life and Environmental Sciences,Wenzhou University,① School of Life and Environmental Sciences,Wenzhou University,① School of Life and Environmental Sciences,Wenzhou University,① School of Life and Environmental Sciences,Wenzhou University

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    Abstract:

    Basal metabolic rate (BMR, seen as the body’s physiological maintenance cost) is thought to be a major hub of physiological mechanisms connecting life history characteristics, and evaporative water loss (EWL) is a physiological indicator used to measure water relations in inter– or intraspecific studies of birds. In this study, we examined body temperature (Tb), metabolic rate (MR) and EWL at ambient temperatures (Ta) between 5 and 35 ?C in summer–acclimatized Chinese bulbul (Pycnonotus sinensis) that were captured in Wenzhou . Experiments were carried out in July 2011. Body mass was determined immediately upon capture with a balance, and the mean body mass was 29.6 ± 1.7 g. Animals were transported to the laboratory and caged for 1 week (50 cm × 30 cm × 20 cm) outdoors under natural photoperiod and temperature. Birds’ metabolic rates were measured with an open–circuit respirometry system. A ‘U’ tube (containing silica gel) was connected in series behind the respiratory chamber and weighed (±0.1mg). The amount of evaporative water lost by each bird was absorbed by the silica gel and could therefore be measured by reweighing the U tube at the end of the measurement. We found that mean Tb was 40.7±0.1?C and average minimum thermal conductance (C) was 0.15 ml O2 g-1 h-1 ?C-1. The thermal neutral zone (TNZ) was 25.0~32.0?C and BMR was 3.67±0.03 ml O2 g-1 h-1. Below the lower critical temperature of the TNZ, MR increased linearly with decreasing Ta according to the relationship: MR (ml O2 g-1 h-1) = 5.296–0.068 Ta. EWL increased with Ta according to the relationship: Log EWL (mg H2O h-1) =1.563 0.021 Ta which exceeded metabolic water production at Ta > 16.4?C. Chinese bulbuls had lower levels of BMR and high levels of thermal conductance, compared with the predicted values based on their body masses, and it also had wide TNZ. It suggests that EWL plays an important role in thermoregulation

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XIA Su–Su, YU Cheng–Cheng, SHEN Li–Yu, ZHANG Yi–Ying, ZHENG Wei–Hong, LIU Jin–Song. 2014. Thermoregulation and Evaporative Water Loss in Chinese Bulbuls Pycnonotus sinensis. Chinese Journal of Zoology, 49(6): 830-840.

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History
  • Received:January 11,2014
  • Revised:August 26,2014
  • Adopted:August 21,2014
  • Online: November 06,2014
  • Published: