Patterns and dynamics of rest-phase hypothermia in wild and captive blue tits during winter |
| |
Authors: | Andreas Nord Johan F Nilsson Maria I Sandell Jan-Åke Nilsson |
| |
Institution: | (1) Department of Animal Ecology, Lund University, Ecology Building, 223 62 Lund, Sweden |
| |
Abstract: | We evaluated biotic and abiotic predictors of rest-phase hypothermia in wintering blue tits (Cyanistes caeruleus) and also assessed how food availability influences nightly thermoregulation. On any given night, captive blue tits (with
unrestricted access to food) remained largely homeothermic, whereas free-ranging birds decreased their body temperature (T
b) by about 5°C. This was not an effect of increased stress in the aviary as we found no difference in circulating corticosterone
between groups. Nocturnal T
b in free-ranging birds varied with ambient temperature, date and time. Conversely, T
b in captive birds could not be explained by climatic or temporal factors, but differed slightly between the sexes. We argue
that the degree of hypothermia is controlled predominantly by birds’ ability to obtain sufficient energy reserves during the
day. However, environmental factors became increasingly important for thermoregulation when resources were limited. Moreover,
as birds did not enter hypothermia in captivity when food was abundant, we suggest that this strategy has associated costs
and hence is avoided whenever resource levels permit. |
| |
Keywords: | Body temperature regulation Corticosterone Energy conservation Food availability Heterothermy Life history trade-offs |
本文献已被 SpringerLink 等数据库收录! |
|