Dr. Lowman’s latest Nature’s Secrets column in newsobserver.com:
Every autumn, many millions of birds migrate from northern breeding grounds to equatorial locations. This annual flight is not only extraordinary in terms of time and energy but also raises questions about the physiological issue of sleep for birds. Some birds migrate long distances, and others only shift regionally. So how do birds rest during migration, and what are the consequences for sleep in migrating animals?
In 2011, the Swiss Ornithological Institute affixed electronic tags to the Alpine swift to monitor their movements. This bird spends the summer breeding in Europe, but winters in Africa, many thousands of miles away. Thanks to radio-tagging, scientists found that these birds were always in the air – and never alighted on land. The tags only recorded data every four minutes, so the birds could have landed intermittently. But this amazing discovery indicates that some birds almost never sleep in the conventional sense. In their aerial existence, swifts feed on insects in the air columns and do not need to be land-bound for feeding. However, they do need to breed, which undoubtedly requires some time on land, and the process remains a mystery. …
