Researchers have confirmed that common swifts in the air can pass most of the year, no less than ten months without ever touching the ground.
While there have been examples of birds in flight for months, including frigates and alpine swifts, evidence on common swifts sets a new record, according to the study published in Current Biology now.
“When common swifts leave their breeding site in August for a migration to the tropical forests of Central Africa through West Africa, never touch land until they return for the next breeding season 10 months later,” says Anders Hedenström of Lund University in Sweden.
“Some individuals may settle for short periods, or even whole nights in midwinter, but others literally never declined during this period.”
Hedenström says it’s likely to save energy during the day, slipping into the updrafts of warm air. But also they rise to great heights each day at dawn and dusk.
For their study, Hedenström and colleagues developed a new type of micro data recorder. These devices recorded acceleration to monitor the activity of bird flight. Later, researchers added light sensors for use in geolocation. The researchers placed 19 data recorders in common swifts that were captured again later.
The data showed that in flight Swifts spend more than 99 percent of their time during their reproductive period of 10 months no.
Hedenström says researchers do not yet know if these birds sleep or how. However, “the fact that some never fell for 10 months suggests that sleep on the wing”. Maybe find time for a nap during slow declines at dawn and dusk, he suggests.That’s a possibility that he and his colleagues hope to explore in future research.
Despite high energy costs associated with the flight, common swifts also manage to live a surprisingly long, contrary to popular notions about the hard life and die young life. There are documented cases of common swifts that live 20 years.
At that time, “the distance accumulated by the bird is equal to seven round trips to the moon,” says Hedenström.
