title: Body Temperature Regulation in Hot Environments.
abstract: Organisms in hot environments will not be able to passively dissipate metabolically generated heat. Instead, they have to revert to evaporative cooling, a process that is energetically expensive and promotes excessive water loss. To alleviate these costs, birds in captivity let their body temperature increase, thereby entering a state of hyperthermia. Here we explore the use of hyperthermia in wild birds captured during the hot and dry season in central Nigeria. We found pronounced hyperthermia in several species with the highest body temperatures close to predicted lethal levels. Furthermore, birds let their body temperature increase in direct relation to ambient temperatures, increasing body temperature by 0.22°C for each degree of increased ambient temperature. Thus to offset the costs of thermoregulation in ambient temperatures above the upper critical temperature, birds are willing to let their body temperatures increase by up to 5°C above normal temperatures. This flexibility in body temperature may be an important mechanism for birds to adjust to predicted increasing ambient temperatures in the future.
authors.affiliation: Department of Biology, Lund University, SE-223 62, Lund, Sweden.
authors.forename: Jan-Åke
authors.initials: JÅ
authors.lastname: Nilsson
authors.affiliation: Fauna & Flora International, 1000, Monrovia 10, Liberia.|A.P. Leventis Ornithological Research Institute, P.O. Box 13404, Jos, Nigeria.
authors.forename: Mary Ngozi
authors.initials: MN
authors.lastname: Molokwu
authors.affiliation: Department of Biology, Lund University, SE-223 62, Lund, Sweden.
authors.forename: Ola
authors.initials: O
authors.lastname: Olsson
mesh_terms: D000222:Adaptation, Physiological; D000818:Animals; D001717:Birds / Q000502:physiology*; D001833:Body Temperature Regulation / Q000502:physiology*; D005334:Fever / Q000378:metabolism*; D006358:Hot Temperature; D009549:Nigeria; D013816:Thermodynamics; D014329:Tropical Climate