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Author Smit, B.; Boyles, J.G.; Brigham, R.M.; McKechnie, A.E.
Title Torpor in dark times: patterns of heterothermy are associated with the lunar cycle in a nocturnal bird Type Journal Article
Year 2011 Publication Journal of Biological Rhythms Abbreviated Journal J Biol Rhythms
Volume 26 Issue 3 Pages 241-248
Keywords Animals; *Biological Clocks; Birds/*physiology; *Body Temperature Regulation; Ecosystem; *Feeding Behavior; Insects; *Moon; Seasons; South Africa
Abstract Many studies have shown that endotherms become more heterothermic when the costs of thermoregulation are high and/or when limited energy availability constrains thermoregulatory capacity. However, the roles of many ecological variables, including constraints on foraging opportunities and/or success, remain largely unknown. To test the prediction that thermoregulatory patterns should be related to foraging opportunities in a heterothermic endotherm, we examined the relationship between the lunar cycle and heterothermy in Freckled Nightjars (Caprimulgus tristigma), which are visually orienting, nocturnal insectivores that are dependent on ambient light to forage. This model system provides an opportunity to assess whether variation in foraging opportunities influences the expression of heterothermy. The nightjars were active and foraged for insects when moonlight was available but became inactive and heterothermic in the absence of moonlight. Lunar illumination was a much stronger predictor of the magnitude of heterothermic responses than was air temperature (T(a)). Our data suggest that heterothermy was strongly related to variation in foraging opportunities associated with the lunar cycle, even though food abundance appeared to remain relatively high throughout the study period. Patterns of thermoregulation in this population of Freckled Nightjars provide novel insights into the environmental and ecological determinants of heterothermy, with the lunar cycle, and not T(a), being the strongest predictor of torpor use.
Address DST/NRF Centre of Excellence at the Percy FitzPatrick Institute, Department of Zoology and Entomology, University of Pretoria, Pretoria, South Africa. smitbe@gmail.com
Corporate Author Thesis
Publisher Place of Publication (up) Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0748-7304 ISBN Medium
Area Expedition Conference
Notes PMID:21628551 Approved no
Call Number IDA @ john @ Serial 59
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