Portugal Steven J, Green Jonathan A, Butler Patrick J
Centre for Ornithology, School of Biosciences, The University of Birmingham, Edgbaston, Birmingham B15 2TT, UK.
J Exp Biol. 2007 Apr;210(Pt 8):1391-7. doi: 10.1242/jeb.004598.
Many different physiological changes have been observed in wild waterfowl during the flightless stage of wing moult, including a loss of body mass. We aimed to determine whether captive barnacle geese (Branta leucopsis) would show the characteristic decrease in body mass during their wing moult, even though they had unlimited and unrestricted access to food. Fourteen captive geese were weighed at 1-2-week intervals for two complete years. During the flightless period of the moult, body mass decreased by approximately 25% from the pre-moult value. To understand the basis of this change, the rate of oxygen consumption was measured during daytime and nighttime at six points in the second year, and at three points (before, during and after wing moult) behavioural observations were made. Measurements of the rate of oxygen consumption showed an 80% increase above that of the nonmoulting periods of the year. We propose that metabolism was increased during moult because of the cost of feather synthesis. Although food was available, the captive birds chose not to forage and instead increased the proportion of time spent resting. It is likely that this behaviour in response to wing moult is a strategy to avoid predation in the wild. Thus, the innate nature of this behaviour has potential survival value for wild birds of this species. We conclude that the increase in metabolism led to the use of endogenous energy reserves because the birds reduced rather than increased their food intake rates, and as a result, the barnacle geese lost body mass during wing moult.
在野生水鸟换羽的不能飞行阶段，人们观察到了许多不同的生理变化，包括体重减轻。我们旨在确定圈养的白颊黑雁（Branta leucopsis）在换羽期间是否会出现体重特征性下降，尽管它们可以无限制、不受约束地获取食物。对14只圈养的大雁连续两年每隔1至2周称重一次。在换羽的不能飞行期间，体重比换羽前下降了约25%。为了了解这种变化的基础，在第二年的六个时间点测量了白天和夜间的耗氧率，并在三个时间点（换羽前、换羽期间和换羽后）进行了行为观察。耗氧率测量结果显示，比一年中不换羽时期高出80%。我们认为，换羽期间新陈代谢增加是由于羽毛合成的成本。尽管有食物，但圈养的鸟类选择不觅食，而是增加休息时间的比例。这种对换羽的行为反应很可能是一种在野外避免被捕食的策略。因此，这种行为的先天性对该物种的野生鸟类具有潜在的生存价值。我们得出结论，新陈代谢的增加导致了内源能量储备的利用，因为鸟类降低而非提高了它们的食物摄入率，结果，白颊黑雁在换羽期间体重减轻。
