Ova ptica spava dok leti

Fregata ptica može ostati u zraku iznad otvorenog oceana danima zaredom. Ne može sletjeti na vodu jer njezino perje nije vodootporno, pa jednostavno ne slijeće. To otvara očito pitanje. Kad spava?

A frigatebird can stay in the air over open ocean for days at a time. It cannot land on water, because its feathers are not waterproof, so it simply does not come down. That raises an obvious question. When does it sleep?

Istraživači su odgovorili tako što su fregatama pričvrstili male uređaje za snimanje moždane aktivnosti i pustili ih. Ptice su letjele i do deset dana bez prestanka. Doista su spavale u zraku, i to često samo pola mozga odjednom, dok je druga polovica bila budna i jedno oko ostajalo otvoreno. Kad su kružile uzlazeći na toplom zraku, polovica koja je pratila zavoj obično je ostajala budna.

Researchers answered it by fitting small brain recorders to frigatebirds and letting them go. The birds flew for up to ten days without stopping. They did sleep in the air, and often only half of the brain slept at once, with the other half awake and one eye still open. When they were circling upward on warm rising air, the half watching the turn tended to be the half still awake.

Iznenađujući je dio količina. Na moru su ptice spavale oko četrdeset minuta u cijelom danu, u kratkim naletima od nekoliko sekundi. Na kopnu su iste ptice spavale više od dvanaest sati. Tako mogu funkcionirati na gotovo nimalo sna cijeli tjedan, a onda se vrate kući i sve to nadoknade.

The amount is the surprising part. Out at sea the birds slept about forty minutes in a whole day, in short bursts of a few seconds each. Back on land the same birds slept more than twelve hours. So they can run on almost no sleep for a week, and then they go home and pay it all back.