Metabolism, body temperature and thermal conductance of fruit-doves (Aves: Columbidae, Treroninae)

Basal metabolic rate (MR), body temperature (T-b) and wet thermal conductance (C-wet) of three tropical species of fruit-doves were investigated at ambient temperatures (T-a) of 11-33degreesC in activity (alpha) and rest (rho) phases to investigate the possible effect of obligate frugivory on the physiology of columbids. The basal metabolic rates of Ptilinopus melanospila (black-naped fruit-dove, 94 g), Drepanoptila holosericea (cloven-feathered dove, 198 g) and Ducula pinon (Pinon's imperial pigeon, 748 g) are 20-38% lower than predicted for all birds, including granivorous columbid species from temperate and tropical regions. The MR was minimal at a T-a value of approximately 30degreesC (=lower critical temperature, T-1c) for all three species, indicating that these rainforest birds are not able to withstand high ambient temperatures as well as arid-adapted members of the pigeon family. Minimal wet-thermal conductance was, on average, higher than expected, indicating poor insulation in these tropical birds. Body temperatures were as expected; however, below T-1c the body temperatures decreased to levels of 35-36degreesC (T-a = 12degreesC). (C) 2002 Elsevier Science Inc. All rights reserved.