During Arctic summertime the sun stays up for 24 hours. One day lasts many weeks. How do birds cope with 24-hour daylight?

Lapland longspurs (Calcarius lapponicus), pictured above, rigorously adhere to their own internal clock. “If it ought to be night right now, we’re going to sleep.” They sleep during the day.

Other species have different strategies. Some have no clock at all. Others vary their clocks based on sex, male or female.

Find out how four species cope with 24-hour daylight in this vintage blog: Arctic Summer Bird Activities.

(photos from Wikimedia Commons; click on the captions to see the originals)