Lucas Jeffrey R, Freeberg Todd M, Egbert Jeremy, Schwabl Hubert
Department of Biological Sciences, 915 W. State Street, Purdue University, West Lafayette, IN 47907, USA.
Horm Behav. 2006 May;49(5):634-43. doi: 10.1016/j.yhbeh.2005.12.012. Epub 2006 Feb 3.
We tested for hormonal and behavioral differences between Carolina chickadees (Poecile carolinensis) taken from a disturbed (recently logged) forest, an undisturbed forest, or a residential site. We measured fecal corticosterone and body mass levels in the field, and fecal corticosterone, body mass, and caching behavior in an aviary experiment. In the field, birds from the disturbed forest exhibited significantly higher fecal corticosterone levels than birds from either the undisturbed forest or from the residential site. Birds from the disturbed forest also exhibited lower body mass than those from the undisturbed forest but higher body mass than those from the residential site. Our aviary results suggest that these physiological differences between field sites are the result of short-term responses to ecological factors: neither body mass nor fecal corticosterone levels varied between birds captured at different sites. Aviary sample sizes were sufficient to detect seasonal variation in fecal corticosterone (lowest in summer), body mass (highest in spring), and rate of gain in body mass (highest in winter). Under "closed-economy" aviary conditions (all food available from a feeder in the aviary), there were no site differences in the percent of seeds taken from the feeder that were cached. However, under "open-economy" conditions (food occasionally available ad libitum), significantly fewer seeds were cached by birds from the disturbed forest compared to the undisturbed or residential sites. On average, there was only a two-fold difference in population levels of fecal corticosterone. This difference is about the same as an increase in fecal corticosterone induced by a 2-h increase in food deprivation and cannot be considered to be an acute stress response to disturbance.
我们测试了从受到干扰（近期砍伐过）的森林、未受干扰的森林或居民区采集的卡罗来纳山雀（Poecile carolinensis）之间的激素和行为差异。我们在野外测量了粪便皮质酮和体重水平，并在鸟类饲养实验中测量了粪便皮质酮、体重和贮藏行为。在野外，来自受干扰森林的鸟类粪便皮质酮水平显著高于来自未受干扰森林或居民区的鸟类。来自受干扰森林的鸟类体重也低于未受干扰森林的鸟类，但高于居民区的鸟类。我们的饲养实验结果表明，野外不同地点之间的这些生理差异是对生态因素短期反应的结果：在不同地点捕获的鸟类之间，体重和粪便皮质酮水平均无变化。饲养实验的样本量足以检测粪便皮质酮（夏季最低）、体重（春季最高）和体重增加率（冬季最高）的季节性变化。在“封闭经济”的饲养条件下（所有食物都可从饲养笼中的喂食器获得），从喂食器获取并贮藏的种子百分比在不同地点之间没有差异。然而，在“开放经济”条件下（食物偶尔可随意获取），与未受干扰或居民区的地点相比，来自受干扰森林的鸟类贮藏的种子明显更少。平均而言，粪便皮质酮的种群水平只有两倍的差异。这种差异与食物剥夺增加2小时所诱导的粪便皮质酮增加量大致相同，不能被视为对干扰的急性应激反应。
