title: Life in extreme environments: Investigations on the ecophysiology of a desert bird, the Australian Diamond Dove (Geopelia cuneata Latham).
abstract: The Diamond Dove, Geopelia cuneata, is the world's second smallest (ca. 35 g) species of the columbid order. The Diamond Dove is endemic in the arid and semiarid Mulga and Spinifex regions of Central and Western Australia. It regularly encounters ambient temperatures (Ta) in its habitat above +40° C, especially when foraging for seeds on bare ground cover, and may be found at up to 40 km from water. This entails extreme thermal stress, with evaporative cooling constrained by limited water supply. Energy metabolism (M), respiration, body temperature (Ta) and water budget were examined with regard to physiological adaptations to these extreme environmental conditions. The zone of thermal neutrality (TNZ) extended from +34° C to at least +45° C. Basal metabolic rate (BMR) was 34.10±4.19 J g-1h-1, corresponding to the values predicted for a typical columbid bird. Thermal conductance (C) was higher than predicted. Geopelia cuneata showed the typical breathing pattern of doves, a combination of normal breathing at a stable frequency (ca. 60 min-1) at low Taand panting followed by gular flutter (up to 960 min-1) at high Ta. At Ta> +36° C, Taincreased to considerably higher levels without increasing metabolic rate, i.e. Q10=1. This enabled the doves not only to store heat but also to save the amout of water that would have been required for evaporative cooling if Tahad remained constant. The birds were able to dissipate more than 100% of the metabolic heat by evaporation at Ta≥ +44° C. This was achieved by gular flutter (an extremely effective mechanism for evaporation), and also by a low metabolic rate due to the low Q10value for metabolism during increased Tb. At lower Ta, Geopelia cuneata predominantly relied on non-evaporative mechanisms during heat stress, to save water. Total evaporative water loss over the whole Tarange was 19-33% lower than expected. In this respect, their small body size proved to be an important advantage for successful survival in hot and arid environments.
authors.affiliation: AK Stoffwechselphysiologie, Zoological Institute, Johann Wolfgang Goethe-University, Siesmayerstrasse 70, W-6000, Frankfurt/Main 1, Federal Republic of Germany.
authors.forename: Elke
authors.initials: E
authors.lastname: Schleucher
authors.affiliation: AK Stoffwechselphysiologie, Zoological Institute, Johann Wolfgang Goethe-University, Siesmayerstrasse 70, W-6000, Frankfurt/Main 1, Federal Republic of Germany.
authors.forename: Roland
authors.initials: R
authors.lastname: Prinzinger
authors.affiliation: Department of Zoology, University of Western Australia, 6009, Nedlands, WA, Australia.
authors.forename: Philip C
authors.initials: PC
authors.lastname: Withers
keywords: Avian ecophysiology; Deserts; Geopelia cuneata; Respiration; Thermoregulation