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Control of insensible evaporate water loss by two species of mesic parrot suggests a thermoregulatory role

Authors :
Gerhard Körtner
Fritz Geiser
Philip C. Withers
Christine Cooper
Source :
Journal of Experimental Biology.
Publication Year :
2020
Publisher :
The Company of Biologists, 2020.

Abstract

Insensible evaporative water loss 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 (Psephotus haematonotus) and eastern rosellas (Platycercus eximius), measuring their evaporative water loss, 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 evaporative water loss with increasing relative humidity, rates of evaporative water loss were not fully accounted for by the water vapour deficit between the animal and its environment, indicating that the insensible evaporative water loss 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 (Melopsittacus undulatus). 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 evaporative may be involved, possibly via modification of expired air temperature and humidity, and surface resistance.

Details

ISSN :
14779145 and 00220949
Database :
OpenAIRE
Journal :
Journal of Experimental Biology
Accession number :
edsair.doi.dedup.....ca2406d8fec613a3b08305c9a6b22ecc
Full Text :
https://doi.org/10.1242/jeb.229930