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As Round as a Ball —But Fat?
Why did so many people say they saw fat hummingbirds last week? Here's a clue: Many people reported cold air temperatures at the same time:

"One fat female this morning on the feeder, haven't seen her the rest of the day. Probably on her way south. Only 48 degrees this morning."

"One plump female feeding on flowers and feeders from 9:30-11:30 am. Last night in the low 40's."

When it's cold, a hummingbird often looks fat because it's fluffing its feathers for extra insulation. A hummingbird's body temperature is about 105°F. By fluffing its feathers, the hummingbird is able to trap the warm air and protect its tiny body from the surrounding cold air.

Hummingbirds are also known for their ability to enter a state called torpor. Read more about this important adaptation hummingbirds have survive when it's cold.


Hummingbird with fluffed feathers.

Image courtesy of Anne Green