快猫短视频

EACH year, migrating songbirds complete an epic journey, migrating thousands of kilometres to new wintering and breeding grounds. And even more startling, they do it with little, if any, sleep.

How the birds manage to stay awake for so long is a mystery, but it doesn鈥檛 appear to make them ill or impair their cognitive performance. This unparalleled ability also explains how migrating songbirds can fly through the night, while spending most of the day feeding to refuel.

Niels Rattenborg and Ruth Benca of the University of Wisconsin-Madison made the discovery while studying captive white-crowned sparrows, which still attempt to migrate by hopping and flapping their wings inside their cage. By monitoring the sparrows鈥� brain activity, Rattenborg and Benca found that they spend 63 per cent less time sleeping during their migrating season than at other times (PLoS Biology, DOI: 10.1371/journal.pbio.0020212).

Despite being sleep deprived, the birds remained alert and performed just as well at behavioural tests as they did during the rest of the year. They did not send one half of their brain to sleep while the other half remains awake, as some other animals do. Dolphins and some seals, for instance, manage to rest one half of their brain while the other performs basic functions such as breathing. Similarly, ducks rest one half while the other watches for predators. In the sparrows, however, 鈥渂oth halves were completely awake鈥�, Rattenborg told 快猫短视频.

Birds have sleep patterns similar to those of mammals, with both REM and non-REM phases. But in other animals sleep deprivation causes profound deficits in neurobehavioural and physiological function. So the sparrows鈥� ability to stay awake and alert for so long during migration is a real puzzle 鈥� especially because at other times of the year, sleep deprivation impairs the birds鈥� mental performance.

There is evidence that other songbirds have a similar ability. 鈥淲e are finding pretty much the same thing in Swainson鈥檚 thrushes,鈥� says Thomas Fuchs, a graduate student studying avian sleep at Bowling Green State University in Ohio.