Tilgar Vallo, Saag Pauli, Moks Kadri
Department of Zoology, Institute of Ecology and Earth Sciences, University of Tartu, 51014 Tartu, Estonia.
J Comp Physiol A Neuroethol Sens Neural Behav Physiol. 2009 Aug;195(8):799-803. doi: 10.1007/s00359-009-0452-5. Epub 2009 Jun 9.
Birds respond to unpredictable events by secreting corticosterone, which induces various responses to cope with stressful situations. However, the evidence is still elusive whether altricial nestlings perceive and respond to external stressors. We investigated the development of adrenocortical stress response to handling-related stressor in nestlings of a small passerine bird, the pied flycatcher (Ficedula hypoleuca). Nestlings were held in isolation from their parents during the experiment to ensure that they indeed respond to handling, not to parental alarm calls. We found that both 9- and 13-day-old nestlings were able to elicit hormonal stress response. Although baseline as well as stress-induced corticosterone levels rose slightly with age, the magnitude of difference between the control and stress-induced levels remained similar in both age groups. However, comparison with adults showed that the stress response of nestlings prior to fledging was still incomplete and significantly lower than in adults. Overall, our results indicate that altricial nestlings do respond to acute stressors, but on the contrary to previous predictions the development of corticosterone stress response during growth period is not gradual and varies remarkably between different passerine species.
鸟类通过分泌皮质酮来应对不可预测的事件，皮质酮会引发各种反应以应对压力情况。然而，关于晚成雏是否能感知并应对外部应激源，证据仍然难以捉摸。我们研究了小型雀形目鸟类斑姬鹟（Ficedula hypoleuca）雏鸟对与处理相关的应激源的肾上腺皮质应激反应的发育情况。在实验过程中，雏鸟与它们的父母隔离饲养，以确保它们确实是对处理做出反应，而不是对父母的警报叫声做出反应。我们发现9日龄和13日龄的雏鸟都能够引发激素应激反应。虽然基线以及应激诱导的皮质酮水平都随着年龄略有上升，但两个年龄组中对照组和应激诱导水平之间的差异幅度仍然相似。然而，与成年鸟的比较表明，离巢前雏鸟的应激反应仍然不完整，且明显低于成年鸟。总体而言，我们的结果表明晚成雏确实会对急性应激源做出反应，但与之前的预测相反，在生长期间皮质酮应激反应的发育并非渐进式的，并且在不同雀形目物种之间有显著差异。
