TY - JOUR T1 - Ambient temperature effects on stress-induced hyperthermia in Svalbard ptarmigan JF - bioRxiv DO - 10.1101/594614 SP - 594614 AU - Andreas Nord AU - Lars P. Folkow Y1 - 2019/01/01 UR - http://biorxiv.org/content/early/2019/03/31/594614.abstract N2 - Stress-induced hyperthermia (SIH), which apparently involves elevated set point temperature, is a commonly observed response to handling in a range of animals. However, in small birds, handling in cold environments typically elicits hypothermia. It is unclear whether this indicates that SIH is differently regulated in birds, or if it is due to size (small birds being more likely to suffer higher heat loss rates when handled), because thermal responses to handling in low temperature have not been measured in birds > 0.03 kg. We studied SIH in the intermediate-sized (0.5-1.0 kg) Svalbard ptarmigan (Lagopus muta hyperborea) in 0 °C and −20 °C, in winter and spring. Handling consistently caused back skin vasoconstriction and elevated Tc. Tc increased less and back skin temperature decreased more in −20 °C than in 0 °C, probably because of higher heat loss rate in the cold. Our study confirms the generality of the thermal responses to stress in endotherms, and suggests that body size and thermal environment must be taken into account when evaluating SIH in birds. ER -