For Some Arctic Birds, Time of Day Is Irrelevant

[Chris Merkord]

A red phalarope paddles between chunks of ice in the Arctic. Ralph Lee Hopkins

When the sun never sets, breeding birds show several daily activity patterns.

 

Arctic summers mean migrating animals, a bounty of breeding opportunities, and 24 hours of sunlight. Many plants and animals experience 24-hour cycles telling them when it's time to rest and when it's time to get up—called the circadian rhythm—that are often tied to light cues. So what happens when the sun never sets?

 

For four species of migrating birds that breed in the Arctic, new research shows that "anything goes," said Bart Kempenaers, a behavioral ecologist with the Max Planck Institute for Ornithology near Munich.

 

Lapland longspurs (Calcarius lapponicus) exhibit a 24-hour cycle, while semipalmated sandpipers (Calidris pusilla) and pectoral sandpipers(Calidris melanotos) are active around the clock. Red phalaropes (Phalaropus fulicarius) shift from a roughly 21-hour cycle to a 29-hour cycle.

 

The type of cycle each displays depends on the species, an individual's sex, and their social circumstances.

 

Read more: http://news.nationalgeographic.com/news/2013/06/130618-circadian-rhythm-arctic-bird-migrating-science/