Hummingbirds sleep at night just like we do, but they can also enter a deeper state called torpor. In torpor, hummingbirds drastically lower their body temperature and metabolism to conserve energy. This special adaptation allows hummingbirds to survive cold nights without using up all the energy reserves they gathered during the day. While hummingbirds typically sleep perched on a small branch or twig, during torpor they may be seen hanging upside down.
How Hummingbirds Sleep
Yes, hummingbirds do sleep, even though they never seem to sit still! Hummingbirds are typically active from dawn till dark, spending as many daylight hours as they can eating. However they don’t have specialized eyesight that would allow them to easily find food after dark, so they spend the night sleeping rather than being active.
Hummingbirds don’t sleep for a set number of hours, but base their sleep on sunrise and sunset. They will generally sleep from dusk till dawn, which can range from 8 to 12 hours or more depending on season and location.
In fact if you swear you saw a hummingbird hovering and feeding at your flowers during the night, you were probably seeing a sphinx moth.
Hummingbirds usually sleep perched on a small branch or twig. If possible, they will choose a location that has some protection from wind and weather, such as in a shrub or tree. Their feet can maintain a firm grip even when sleeping, so they aren’t likely to fall off.
Hummingbirds have the ability to enter a normal sleep state like we do, or to enter a shallow or deep energy-saving state called torpor.
Do hummingbirds sleep upside down?
Yes, hummingbirds do sometimes sleep while hanging upside down. While their normal sleep position is to perch upright, if the perch is particularly smooth they may slip forwards or backwards and end up upside down.
While in the “deep sleep” of torpor, this movement will not wake them up. But that’s okay because their feet are gripping so strongly that they won’t fall, and will continue to sleep hanging upside down.
If you see a hummingbird hanging upside down from your feeder, just let it be. It is most likely in torpor and will wake up on its own. If it falls to the ground, which is unlikely, you may want to move it to a safer spot.
Scientists aren’t yet sure why some hummingbirds choose to go into torpor while sitting at the feeder. It may be a strategy to have food available immediately upon awakening. This would ensure they start the morning with enough energy for the day.
What Is Torpor?
While many people describe torpor as a state of deep sleep, it isn’t really sleep. Torpor is a state of inactivity marked by reduced metabolism and body temperature. Animals that are able to enter a torpid state do so to conserve energy. The most well known example of this is hibernation.
Hibernation is a type of torpor that takes place over long periods of time. Like a bear hibernating throughout the entire winter. Hummingbirds, however, don’t hibernate. They can go into torpor any day of the year, for just a single night at a time. This is called “daily torpor” or noctivation.
What happens to hummingbirds during torpor?
The normal daytime body temperature of a hummingbird is over 100°F. During torpor, body temperature falls dramatically, controlled by the hummingbirds internal thermostat. The average body temperature of hummingbirds in torpor is between 41-50 degrees F. That’s quite a drop!
Researchers have recently discovered that hummingbirds can actually enter a shallow or deep torpor. By entering shallow torpor, hummingbirds can drop their body temperature by about 20°F. If they enter deep torpor, their body temperature drops up to a whopping 50°F.
In comparison, if your body temperature fell by just 3°F degrees below the normal 98.5°F you would be considered hypothermic and require outside sources of heat to warm you back up.
To achieve this low body temperature, their metabolism decreases up to 95%. Their heartbeat slows from the normal flying rate of 1,000 – 1,200 beats per minute to as low as 50 beats per minute.
Why do hummingbirds go into torpor?
Hummingbirds have an extremely high metabolism, about 77 times higher than us humans. This is why they must eat constantly all day long. They have to consume 2-3 times their body weight in nectar and insects daily. Nectar has a lot of high-energy sugar calories, while insects provide additional fat and proteins.
Since they don’t feed at night, the overnight hours are a long period of time where they are not replacing the energy their metabolism is using. Their body has to rely on its energy reserves until the next morning when they can find food again. On a warm night, this is usually manageable.
However it gets cold after the sun goes down. To keep their body temperature up they will use even more energy than they do during the day. Hummingbirds don’t have a layer of insulating downy feathers that many other birds have, making it even harder for them to retain body heat. If it gets too cold they just won’t have enough energy to keep warm, and will basically starve to death using up all their reserves.
The solution is torpor! Their ability to drastically reduce their metabolism and body temperature saves them huge amounts of energy. Torpor can lower their energy usage by