Do Hummingbirds Sleep at Night? Here’s What Happens After Sunset

You’ve watched hummingbirds zip around your yard all day and may have wondered where they go when the sun sets. Hummingbirds are diurnal, which means that, like us, they settle down at night. They perch on a sheltered branch or twig. Then they may sleep. Or they may enter a remarkable energy-saving state called torpor, which looks similar but serves a very different purpose.

When sleeping, a hummingbird typically rests with its bill up and eyes closed, and it may make small movements, like fluffing or preening, as Anusha Shankar, Ph.D., an integrative biologist and physiological ecologist, explained in an interview with American Scientist.

During torpor, on the other hand, its body temperature, heart rate, and metabolism all drop, sometimes drastically. The tiny bird can remain motionless, hanging from a branch for hours.

It may seem strange, but this extreme state is important to a hummingbird’s survival, even helping it get through bitterly cold nights and conserve energy during migration and other demanding periods.

Here’s what you need to know about how hummingbirds spend their nights.

Deep Torpor, Shallow Torpor—and Sleep

Torpor is not ordinary sleep. Torpor primarily conserves energy, while sleep serves restorative functions. And in recent years, we’ve learned that torpor, at least in some hummingbird species, can range from shallow to deep.

In a 2022 multi-university study led by Shankar while she was a researcher at the Cornell Lab of Ornithology, researchers found that during deep torpor, hummingbirds’ body temperatures dropped about 50 degrees Fahrenheit below normal. But other times, their body temperatures dropped only about 20 degrees—a state of shallow torpor.

Body size seemed to play a role. While the smallest hummingbirds in the study entered deep torpor every night, bigger hummingbirds tended to have more flexibility, using deep torpor, shallow torpor, and regular sleep.

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A hummingbird in torpor

Deep torpor comes with trade-offs, not the least of which is the time it takes for birds to return to their normal body temperature and resume an active state—in the study, it took up to 30 minutes. Researchers suggest that some hummingbirds may have evolved the ability to enter shallow torpor to offset some of the potential costs of deep torpor.

Torpor is not an automatic nightly shutdown, however. On warm summer nights, a well-fed hummingbird may simply rest and sleep without dropping into deep torpor.

Why Hummingbirds Need This Survival Strategy

Hummingbirds have extraordinarily high metabolisms and must consume substantial amounts of energy during the day. Torpor can help them save energy overnight, especially during key times:

• When it’s cold—Maintaining normal body temperature overnight might require too much energy for a hummingbird, especially if normal daytime sources of nectar and insects are unavailable or reduced.
• During breeding season—When hummingbirds are spending large amounts of energy flying, feeding, and defending territory, torpor can help them conserve energy overnight.
• Ahead of fall migration—Some hummingbirds also use torpor as part of their energy-management strategy during fall migration, although how often they do so varies among species.

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The fuel-up before the wind-down

Hummingbirds That Use Torpor to Survive Cold Weather

In the Pacific Northwest, where beloved Anna’s hummingbirds reside, many backyard birders keep their nectar feeders up through winter. Unlike many other hummingbirds, Anna’s hummingbirds don’t migrate far and are spotted year-round as far north as the coast of British Columbia. Torpor helps these birds make it through winter: When temperatures drop, their breathing and heart rate slow, and their body temperature can fall dramatically to conserve energy.

Broad-tailed hummingbirds, too, are especially well adapted to surviving cold nights. The species breeds in mountain meadows and open woodlands at elevations reaching about 10,500 feet, where temperatures can fall below freezing at night, making torpor especially important.

Female broad-tailed hummingbirds build insulated nests using spiderwebs, gossamer, moss, lichen, and bark fragments. Males may leave their territories at night and move upslope when cold air settles into mountain valleys, where conditions may be warmer.

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An Anna’s hummingbird perched at night during a snowfall

What to Do If You Find a Hummingbird in Torpor

A hummingbird in torpor may appear completely motionless, but that does not mean the bird is injured or dead. It may simply be conserving energy until dawn.

Avoid disturbing a normally perched bird, but do not assume that every motionless hummingbird is merely torpid. If you find a hummingbird on the ground, visibly injured, unable to perch, or still unresponsive after it has had time to warm up following sunrise, contact a licensed wildlife rehabilitator.

After sunrise, hummingbirds gradually return to their normal daytime state, which can take up to half an hour. During this period, the bird may shiver or vibrate its muscles to generate heat before resuming normal activity.

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