环境温度和体内储备物共同影响煤山雀夜间体重的下降(英文)

Nocturnal body mass loss in coal tits Periparus ater:the combined effects of ambient temperature and body reserves

环境温度和体内储备物水平被认为是鸟类在静止状态下能量利用的重要调节因子(夜间体重降低)。然而,以往的研究没有把环境温度和体内储备物对夜间能量维持加以明确的区分。为了研究环境温度是否是为煤山雀(Periparus ater)夜间体重调节的直接因子,在自由取食条件下,实验室控制日-日和日-夜环境温度。温度变化模拟西班牙中部地中海山区秋季日-夜温度的变化。夜间体重取决于黄昏时的体重以及前一天体重的增加值。当前一日白天煤山雀体重增加最大时,记录夜间体重最大降低的比率。然而,环境温度的不可预见性没有影响煤山雀夜间体重降低,可以解释煤山雀内在的生理能量平衡。这些结果提示,当一些环境因子如温度变得不可预见时,鸟类在狭小范围内保持体内储备物。

The environmental temperature and the level of body reserves have been described as important regulating factors of the amount of energy used at resting （i.e. nocturnal body mass loss）. However, because these variables are associated in natural conditions, previous studies have not made a clear distinction between the separate effect of ambient temperature and body reserves on nightly energy management. To investigate whether ambient temperature acts as a proximate factor on nocturnal body mass regulation in captive coal tits Periparus ater, the day-to-day and day-to-night changes in environmental temperatures were experimentally manipulated, under unrestricted food availability. The experiment was conducted within the normal autumn range of temperature variation in a mountain area of continental Mediterranean climate in Central Spain. Nocturnal body mass loss depended on the level of body mass at dusk and daily body-mass gain in the previous day. The largest rates of body mass loss at night were reeorded when birds ended the previous day-time period with the highest levels of body reserves obtained after high rates of diurnal body mass increase. However, unpredictable changes in current environmental temperatures did not influence night body mass loss in the coal tit, as it would be expected following a pure physiological energetic balance. These results suggest that birds try to maintain budy reserves within narrow ranges when some environmental factors, as the ambient temperature, become unpredictable