Does control of insensible evaporative water loss by two species of mesic parrot have a thermoregulatory role?

Author(s)
Cooper, Christine Elizabeth
Withers, Philip Carew
Körtner, Gerhard
Geiser, Fritz
Publication Date
2020-10
Abstract
<p>Insensible evaporative water loss (EWL) at or below thermoneutrality is generally assumed to be a passive physical process. However, some arid zone mammals and a single arid zone bird can control their insensible water loss, so we tested the hypothesis that the same is the case for two parrot species from a mesic habitat. We investigated red-rumped parrots (<i>Psephotus haematonotus</i>) and eastern rosellas (<i>Platycercus eximius</i>), measuring their EWL, and other physiological variables, at a range of relative humidities at ambient temperatures of 20 and 30°C (below and at thermoneutrality). We found that, despite a decrease in EWL with increasing relative humidity, rates of EWL were not fully accounted for by the water vapour deficit between the animal and its environment, indicating that the insensible EWL of both parrots was controlled. It is unlikely that this deviation from physical expectations was regulation with a primary role for water conservation because our mesic-habitat parrots had equivalent regulatory ability as the arid habitat budgerigar (<i>Melopsittacus undulatus</i>). This, together with our observations of body temperature and metabolic rate, instead support the hypothesis that acute physiological control of insensible water loss serves a thermoregulatory purpose for endotherms. Modification of both cutaneous and respiratory avenues of evaporation may be involved, possibly via modification of expired air temperature and humidity, and surface resistance.</p>
Citation
The Journal of Experimental Biology, 223(19), p. 1-10
ISSN
1477-9145
0022-0949
Pubmed ID
32747451
Link
Publisher
The Company of Biologists Ltd
Title
Does control of insensible evaporative water loss by two species of mesic parrot have a thermoregulatory role?
Type of document
Journal Article
Entity Type
Publication

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