Thursday, January 31, 2019

Hairy Woodpecker -28 Degrees

-28 degrees Fahrenheit this morning, 30 January 2019, in Northfield, Minnesota. This Hairy Woodpecker might appear to be suffering, but probably not. Small birds have a number of adaptations to extreme cold. They often fluff their feathers to trap body heat and can also practice regulated hypothermia, thereby surviving drops of 15% of their normal body temperature. Woodpeckers cache food supplies for mornings like these. Some food-caching birds can increase their brain size in the winter, thereby increasing their memory of the locations of cached food. Dr. David Swanson, who studies cold tolerance in birds at the University of South Dakota, wrote me that almost all small birds show increases in maximum capacity for heat production in winter compared to summer.

This bird appears to be cleaning its bill against the tree bark, perhaps after caching a bit of suet from our bird feeder. Its closed eye may be just blinking or may be closed to avoid hitting the tree trunk. I don’t think that the eye is injured.

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