Department of Biology, Western Kentucky University, Bowling Green, KY 42101, USA.
Department of Biological Sciences, Simon Fraser University, Burnaby, BC, Canada, V5A 1S6.
J Exp Biol. 2021 Apr 1;224(7). doi: 10.1242/jeb.237198. Epub 2021 Apr 15.
Sleep loss impairs cognitive function, immunological responses and general well-being in humans. However, sleep requirements in mammals and birds vary dramatically. In circumpolar regions with continuous summer light, daily sleep duration is reduced, particularly in breeding birds. The effect of an anti-narcolepsy drug (modafinil) to putatively extend wakefulness was examined in two species of closely related arctic-breeding passerine birds: Lapland longspurs (Calcarius lapponicus) and snow buntings (Plectrophenax nivalis). Free-living adult males were implanted during the nestling phase on day 4 (D4; 4 days post-hatching) with osmotic pumps containing either vehicle or modafinil to extend the active period for 72 h. Nestlings were weighed on D2 and D7 to measure growth rates. Additionally, focal observations were conducted on D6. Male longspurs receiving modafinil made fewer feeding visits and spent less time at the nest but tended to spend more time near the nest than controls. We observed no change in longspur nestling growth rates, but fledging occurred significantly later when males received modafinil, suggesting a fitness cost. In contrast, modafinil had no measurable impact on male or female snow bunting behavior, nestling growth rates or time to fledging. We suggest male longspurs compromise and maintain vigilance at their nests in lieu of sleeping because of the increased predation risk that is characteristic of their tundra nesting habitat. Snow buntings are cavity nesters, and their nests do not require the same vigilance, allowing males to presumably rest following provisioning. These life-history differences between species highlight the role of predation risk in mediating behavioral modifications to prolonged wakefulness in arctic-breeding songbirds.
睡眠不足会损害人类的认知功能、免疫反应和整体健康。然而，哺乳动物和鸟类的睡眠需求差异很大。在有连续夏季光照的环极地区，每日睡眠时间会减少，尤其是在繁殖鸟类中。在两种密切相关的北极繁殖雀形目鸟类中，研究了一种抗嗜睡药物（莫达非尼）延长清醒时间的效果：拉普兰长趾百灵（Calcarius lapponicus）和雪鹀（Plectrophenax nivalis）。在雏鸟期（孵化后第 4 天，即 D4），自由生活的成年雄性被植入含有载体或莫达非尼的渗透泵，以延长 72 小时的活跃期。在 D2 和 D7 对雏鸟进行称重，以测量生长率。此外，在 D6 进行了焦点观察。接受莫达非尼的长趾百灵雄鸟进食次数减少，在巢中停留时间减少，但在巢附近停留的时间比对照组多。我们没有观察到长趾百灵雏鸟生长率的变化，但当雄性接受莫达非尼时，幼鸟的离巢时间明显推迟，表明存在适应代价。相比之下，莫达非尼对雄鸟或雌鸟雪鹀的行为、雏鸟生长率或离巢时间没有可测量的影响。我们认为，由于其苔原筑巢栖息地特有的捕食风险增加，长趾百灵雄鸟在巢中做出妥协并保持警惕，而不是睡觉。雪鹀是洞穴筑巢者，它们的巢穴不需要同样的警惕，因此雄鸟在喂食后可以休息。这些物种间的生活史差异突显了捕食风险在调节北极繁殖鸣禽对长时间清醒的行为改变方面的作用。
