Clark L
Monell Chemical Senses Center, 3500 Market Street, 19104, Philadelphia, PA, USA.
Oecologia. 1987 Jan;71(2):233-238. doi: 10.1007/BF00377289.
The operative temperature of the environment was estimated for starlings using hollow, unheated taxidermic mounts. On average, adults foraging in full sun were characterized by shorter foraging bouts than those adults foraging in full shade. Simultaneous observations of air temperature, operative temperature, and the foraging duration of adults indicated that air temperature was a poor predictor of the maximum length of a foraging bout. The operative temperature of the environment was not correlated to the maximum and mean length of foraging bouts for temperatures below 31.5°C, but was negatively related to maximum and mean foraging duration for values above 31.5°C. I also found that foraging adults experiencing high thermal loads (T ≥31.5°C) were less likely to return to the nest with food. These results raise the possibility that adults may be limited in their utilization of foraging sites due to an inability to cope with heat load, and that much of the loafing behavior observed for breeding birds may be behavior to avoid heat stress. The implication for seasonal variation of clutch size is discussed.
利用中空、未加热的鸟类标本估计了椋鸟所处环境的有效温度。平均而言，在全日照下觅食的成年椋鸟的觅食时间比在全阴凉处觅食的成年椋鸟短。对气温、有效温度和成年椋鸟觅食持续时间的同步观察表明，气温并不能很好地预测觅食时间的最长长度。当温度低于31.5°C时，环境的有效温度与觅食时间的最长和平均长度无关，但当温度高于31.5°C时，它与最长和平均觅食持续时间呈负相关。我还发现，经历高热负荷（T≥31.5°C）的觅食成年椋鸟带回食物回巢的可能性较小。这些结果增加了一种可能性，即成年椋鸟可能由于无法应对热负荷而限制了对觅食地点的利用，并且观察到的繁殖鸟类的许多休息行为可能是为了避免热应激。文中讨论了这些结果对窝卵数季节变化的影响。
