A team of researchers has found that a species of bird called the common swift can remain in the air for up to 10 months, flying nonstop. Most common swifts don’t land at all during this period, only coming down when the next breeding season starts. The details are in a paper that was just published in the journal Current Biology.
Common swifts (Apus apus) are medium-sized birds with brown and black coloration. They breed throughout their homes in Europe and Asia, later undergoing a long migration to wintering grounds in Africa. The birds are adept at eating while in flight, consuming any flying insects they come across. Many scientists believed that the birds spent most of the year in flight, never landing, but there hadn’t been any conclusive evidence.
Researchers developed new micro data loggers that could be attached to birds without disrupting their flight. Each logger contained an accelerometer as well as a light sensor to help the scientists retrieve the device later in the experiment. The team attached the loggers to 19 individuals and then recaptured the birds over the next few years.
The researchers discovered that the swifts spent 10 months airborne during the non-breeding season. A couple of individuals rested briefly over one or a few nights but the others never landed. The birds appeared to be saving energy by gliding upwards in warm air currents when possible. The team isn’t sure how common swifts manage to sleep during these 10 months but they may sleep while in flight. A similar tactic was recently observed in another species, the great frigate bird. Frigate birds often spend one or two months in the air without landing, sleeping on the wing. The common swift goes much longer without resting, however, and scientists are already planning further research to figure out how the birds deal with sleep deprivation.
The team’s findings show that common swifts often fly for 10 months without landing. This is a new record for time spent in flight, beating out frigate birds and other swift species.
Hedenström et al. Annual 10-Month Aerial Life Phase in the Common Swift Apus apus. Current Biology (2016).