A wind-sheltered twig is where hummingbirds sleep at night. In winter, they can slip into torpor. They normally do this on frigid nights, but sometimes during the day.
Despite their usual stance, hummingbirds sometimes sleep upside down. Their fast metabolism means these little birds may burn most of their energy when sleeping.
So they may enter torpor, where their heartbeat, respiration, and other functions slow down. Their toes cling to their perch while sleeping.
It looks scary, but the bird normally awakens up and can straighten itself. While sitting atop a feeder, they may appear upside down.
Torpor helps hummingbirds store energy and tolerate very cold temperatures. Metabolic rate drops 95%.
The bird wakes up from this profound sleep unharmed. Though frail, they're hardy little critters!
Therefore, don't panic if you observe a hummingbird in an unusual posture or appearing to be asleep. It's typical!
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