Coppack Timothy, Becker Simon F, Becker Philipp J J
Institute of Avian Research, Vogelwarte Helgoland, 26386 Wilhelmshaven, Germany Max Planck Institute for Ornithology, Vogelwarte Radolfzell, 78315 Radolfzell, Germany.
Biol Lett. 2008 Dec 23;4(6):619-22. doi: 10.1098/rsbl.2008.0388.
Many species of migratory birds migrate in a series of solitary nocturnal flights. Between flights, they stop to rest and refuel for the next segment of their journey. The mechanism controlling this behaviour has long remained elusive. Here, we show that wild-caught migratory redstarts (Phoenicurus phoenicurus) are consistent in their flight scheduling. An advanced videographic system enabled us to determine the precise timing of flight activity in redstarts caught at a northern European stopover site during their return trip from Africa. Birds were held captive for three days in the absence of photoperiodic cues (constant dim light) and under permanent food availability. Despite the absence of external temporal cues, birds showed clear bimodal activity patterns: intense nocturnal activity alternating with diurnal foraging and resting periods. The onset of their migratory activity coincided with the time of local sunset and was individually consistent on consecutive nights. The data demonstrate that night-migrating birds are driven by autonomous circadian clocks entrained by sunset cues. This timekeeping system is probably the key factor in the overall control of nocturnal songbird migration.
许多候鸟物种以一系列单独的夜间飞行进行迁徙。在飞行之间，它们会停下来休息并为旅程的下一段补充能量。长期以来，控制这种行为的机制一直难以捉摸。在这里，我们表明，野生捕获的迁徙红尾鸲（红尾鸲）在飞行安排上是一致的。先进的视频系统使我们能够确定在从非洲返程途中于北欧中途停留地捕获的红尾鸲飞行活动的精确时间。鸟类在没有光周期线索（恒定暗光）且食物供应充足的情况下被圈养三天。尽管没有外部时间线索，鸟类仍表现出明显的双峰活动模式：强烈的夜间活动与白天觅食和休息期交替出现。它们迁徙活动的开始与当地日落时间一致，并且在连续的夜晚个体表现一致。数据表明，夜间迁徙的鸟类由日落线索校准的自主生物钟驱动。这种计时系统可能是夜间鸣禽迁徙整体控制的关键因素。
