Article

Thermoregulation under semi-natural conditions in speckled mousebirds: the role of communal roosting

Published in: African Zoology
Volume 41, issue 2, 2006 , pages: 155–163
DOI: 10.1080/15627020.2006.11407350
Author(s): Andrew E. McKechnieSchool of Biological and Conservation Sciences, University of KwaZulu-Natal, South Africa, Gerhard KörtnerSchool of Biological and Conservation Sciences, University of KwaZulu-Natal, South Africa, Barry G. LovegroveSchool of Biological and Conservation Sciences, University of KwaZulu-Natal, South Africa

Abstract

Mousebirds (Coliiformes) exhibit well-developed communal roosting behaviour as well as a pronounced capacity for facultative hypothermic responses. We recorded body temperature (Tb)) in speckled mousebirds (Colius striatus) under semi-natural conditions in outdoor aviaries, and examined interactions between behavioural and metabolic thermoregulation by experimentally manipulating food availability and communal roosting behaviour. When food was available ad libitum, mousebirds roosting in a cluster maintained approximately constant rest-phase Tb, with 32°C < Tb < 42°C. By contrast, rest-phase Tb in single mousebirds decreased at 0.5°C/hr and minimum rest-phase Tb was significantly lower than when clustering. When food availability was restricted, the mousebirds exhibited facultative hypothermic responses that were less pronounced in clustering groups (minimum rest-phase Tb = 33.3°C, circadian amplitude of Tb = 9.5°C) compared to single birds (minimum rest-phase Tb = 30.7°C, circadian amplitude of Tb = 11.8°C). When clustering, rest-phase Tb was highly synchronized among individuals. Our data reveal that communal roosting has profound consequences for rest-phase thermoregulation in C. striatus, and provide further insights into the potential role of physiological constraints in the evolution of avian sociality.

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