title: Novel energy-saving strategies to multiple stressors in birds: the ultradian regulation of body temperature.
abstract: This study aimed to examine thermoregulatory responses in birds facing two commonly experienced stressors, cold and fasting. Logging devices allowing long-term and precise access to internal body temperature were placed within the gizzards of ducklings acclimated to cold (CA) (5°C) or thermoneutrality (TN) (25°C). The animals were then examined under three equal 4-day periods: ad libitum feeding, fasting and re-feeding. Through the analysis of daily as well as short-term, or ultradian, variations of body temperature, we showed that while ducklings at TN show only a modest decline in daily thermoregulatory parameters when fasted, they exhibit reduced surface temperatures from key sites of vascular heat exchange during fasting. The CA birds, on the other hand, significantly reduced their short-term variations of body temperature while increasing long-term variability when fasting. This phenomenon would allow the CA birds to reduce the energetic cost of body temperature maintenance under fasting. By analysing ultradian regulation of body temperature, we describe a means by which an endotherm appears to lower thermoregulatory costs in response to the combined stressors of cold and fasting.
authors.affiliation: Department of Biological Sciences, Brock University, St Catharines, ON, Canada L2S3A1 gtatters@brocku.ca.
authors.forename: Glenn J
authors.identifier: 0000-0002-6591-6760
authors.initials: GJ
authors.lastname: Tattersall
authors.affiliation: Université de Lyon, UMR 5023 Écologie des Hydrosystèmes Naturels et Anthropisés, Université Lyon 1, ENTPE, CNRS, 69622 Villeurbanne, France.
authors.forename: Damien
authors.identifier: 0000-0002-8865-5428
authors.initials: D
authors.lastname: Roussel
authors.affiliation: Université de Lyon, UMR 5023 Écologie des Hydrosystèmes Naturels et Anthropisés, Université Lyon 1, ENTPE, CNRS, 69622 Villeurbanne, France.
authors.forename: Yann
authors.identifier: 0000-0003-0572-7199
authors.initials: Y
authors.lastname: Voituron
authors.affiliation: Université de Lyon, UMR 5023 Écologie des Hydrosystèmes Naturels et Anthropisés, Université Lyon 1, ENTPE, CNRS, 69622 Villeurbanne, France.
authors.forename: Loïc
authors.identifier: 0000-0001-7779-7634
authors.initials: L
authors.lastname: Teulier
mesh_terms: D000818:Animals; D001833:Body Temperature Regulation; D003080:Cold Temperature; D004372:Ducks / Q000502:physiology*; D004435:Eating; D005215:Fasting
keywords: body temperature variability; fasting; homeothermy; nocturnal hypothermia; rhythm