Bird "Goosebumps"

Goose bumps appear on many mammals when they are cold or afraid. Bumps appear at the base of the body hair making it stand up straight. The medical term for goose bumps on a person is cutis anserine. The reflex of producing goose bumps is known as horripilation, piloerection, or the pilomotor reflex.

The common name probably came from the similar appearance to a goose after all of its feathers have been plucked. The term "goose bumps" is misleading because the bumps on a goose’s skin do not qualify as piloerection, though birds do have the same reflex of extending their feathers out to keep warm.

In the winter birds can also grow twice as many feathers. The outer feathers protect them from wet weather and wind. The downy feathers underneath are fluffed up to trap air creating a natural layer of insulation. They can also scrunch down to cover their feet or pull a leg up close to the body and sleep with their bills under their wing feathers to breathe in warmer air.

Staying warm requires a lot of energy, even for the most insulated bird. That’s why they look for high-energy food especially right before they turn in for the night and when they break fast in the morning.

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