The adrenocortical responses to stress in breeding Willow Warblers Phylloscopus trochilus in Sweden : effects of latitude and gender

摘要: 1. In the present study we tested hypothesis that birds suppress their adrenocortical response to stress when breeding in a severe environment. 2. We measured increases circulating levels of corticosterone following capture and handling populations Willow Warblers, Phylloscopus trochilus, rich deciduous forest southern Sweden Warblers subarctic environment Swedish Lapland. Data from an 8-year on survival rates nest predation northern are also included. 3. By comparing changes immediately capture, restraint, then up 1-h post-capture across gender latitude, were able assess possible ecological influences. 4. had about same (0·27 0·30, respectively). Depredated clutches normally replaced (72%), but not (1%). 5. A reduced was found both sexes where conditions more nesting season shorter than Sweden. At site, males significantly robust females, whereas at site identical females. Maximum generated by protocol higher all other groups. 6. There marked individual variations patterns groups, there no significant relationships dynamics body mass or fat score males. However, females maximum level rate increase during positively correlated with mass. contrast, showed negative correlations increase. These differences may reflect different bases for modulation gender.