Hummingbirds are fascinating creatures. They are the smallest birds in the world, yet they have incredibly high metabolisms that require them to eat frequently to sustain their energy. While they are very active and energetic during the day, many people wonder what happens to hummingbirds at night, especially when temperatures drop.
Where do hummingbirds go at night?
Hummingbirds don’t actually migrate long distances like some other bird species. Instead, they primarily go into a deep sleep state called torpor at night to conserve energy. They will choose a protected roosting spot where they can become nearly motionless to slow their metabolic rate and drop their body temperature significantly.
Preferred roosting spots include:
- Sheltered tree branches
- Dense shrubs
- Niches in rocks
- Cavities in trees
- Human-provided nest boxes or sugar feeders if available
By choosing these protected locations, hummingbirds can avoid wind exposure and hold their body heat in, allowing them to enter torpor quickly.
What is torpor?
Torpor is a state of decreased physiological activity with reduced body temperature and metabolic rate. It is similar to hibernation in other animals but occurs every night for hummingbirds. Entering torpor helps hummingbirds conserve a massive amount of energy when food sources are not available.
Here are some key facts about torpor in hummingbirds:
- Their body temperature can drop by 50-60°F/10-15°C.
- Breathing and heart rate are both slowed dramatically.
- They can reduce their metabolic rate by 95% compared to daytime activity.
- Energy expenditure is reduced to just 1/25th of their normal active rate.
Without the ability to enter torpor, hummingbirds would not be able to survive nights when cold temperatures and lack of food threaten their energy reserves.
How do hummingbirds survive the cold in torpor?
In torpor, hummingbirds allow their body temperature to fall as low as it takes to prevent starvation. Surprisingly, they can tolerate body temperatures even below the freezing point of water if necessary!
A few adaptations help them survive extreme cold while torpid:
- Increased blood sugar acts like antifreeze to prevent freezing.
- Slowed heart rate allows blood to be warmed as it circulates before returning to core.
- Feathers fluffed up to trap body heat.
- Body positioned on roost to reduce surface area exposed.
Their small body size and fast metabolic recovery also help hummingbirds bounce back quickly from torpor before daylight when they must feed again.
How long do hummingbirds stay in torpor?
Hummingbirds only remain in torpor as long as overnight temperatures require it. They will arouse from torpor as soon as it becomes warm enough or daylight cues trigger their bodies to resume normal functioning.
The length of torpor may last:
- 8-12 hours overnight in moderate temperatures
- Up to 48 hours in extreme cold
Arousing from torpor also requires plenty of energy, so hummingbirds do not want to spend any more time in this state than is necessary. As soon as the sun comes up, they prefer to start looking for food again to replenish their reserves.
What do hummingbirds eat at night?
Hummingbirds get essentially zero nutrition at night while in torpor. They rely completely on their body’s fat reserves to make it through until morning.
Their cravings for food are what rouse them from torpor very early in the morning, often before sunrise. At first light, they immediately begin seeking out nectar from flowers and human feeders to refuel.
A quick morning meal helps hummingbirds:
- Boost body temperature back to normal
- Raise metabolism to active daytime levels
- Power their wings for a busy day of feeding and flying
The high-energy food they prefer in the morning is sucrose-rich nectar. This rapidly digesting sugar provides quick energy.
Do hummingbirds sleep at night?
Hummingbirds do have all the normal brainwave patterns associated with sleeping in addition to torpor. Their sleep is much lighter while in torpor though.
Evidence they can sleep in torpor:
- They assume a typical sleep posture on their roost.
- It takes stimulation or loud noises to arouse them from torpor.
- If they do wake up, they fall back into torpor quickly.
Their sleep is very fragile and intermittent though. Their metabolism slows so far that they are somewhat deprived of REM and deep sleep stages. As soon as daylight triggers their bodies to bounce back to alertness, they become very active again.
Do hummingbirds hibernate in the winter?
Hummingbirds do not truly hibernate through winter. Hibernation requires animals to go days or weeks with complete inactivity and no food consumption.
Hummingbird survival depends on periodically arousing from torpor to feed. This allows them to get critical nutrition to sustain basic body functions all winter long when food is scarce.
However, hummingbirds in more temperate regions do go into much longer torpor bouts at night and lower their daytime activity levels in winter. Their behavior in winter includes:
- Taking advantage of winter warming from the sun’s heat during the day to become active and feed.
- Conserving energy with long torpor periods at night.
- Lower body temperatures than summer (but not as low as true hibernators).
- Slowed heart rate and breathing even during their active periods.
This partial hibernation or “hibernoid” state helps hummingbirds adjust to reduced food and harsh weather from late fall through early spring.
Do hummingbirds migrate for winter?
Most hummingbird species in the U.S. and Canada do not migrate far south for winter. However, they may move shorter distances based on food availability.
Their migration habits include:
- Western hummingbirds may fly to Mexico or Southern California.
- Hummingbirds along the Eastern U.S. may fly to Florida or Gulf Coast states.
- Ruby-throated hummingbirds travel from Eastern Canada to Southern U.S. for winter.
- Anna’s and Rufous hummingbirds that breed farthest north migrate the longest distances.
- Many hummingbirds do not migrate but can expand their home territory to track down food.
In these southern wintering grounds, warmer weather allows hummingbirds to maintain their normal active schedule and metabolism during daytime hours.
How can I help hummingbirds survive cold nights?
Hummingbirds appreciate any extra support bird lovers can provide to help them save energy on cold nights and find food first thing in the morning.
A few tips to help hummingbirds out:
- Provide cover for roosting like trees, shrubs, or a sheltered porch.
- Hang insulated feeders or bring feeders inside at night to prevent freezing.
- Use feeder heaters, extra sugar concentration, or indoor storage to keep nectar liquid.
- Make high-energy nectar available first thing in the morning.
- Supplement natural nectar sources with feeders full of sucrose-dominant commercial nectar.
- Place feeders in sunny spots to provide warmth and attract hummingbirds.
With a little help to get through frigid nights and fuel up in the morning, hummingbirds can continue charming us all winter long with their aerial acrobatics!
Conclusion
Hummingbirds have remarkable adaptations that allow them to survive cold nights through torpor. While they appear small and delicate, they are actually incredibly resilient birds capable of withstanding freezing temperatures overnight by entering a hibernation-like state. Their energy reserves get fully depleted each night, making the quick nourishment of early morning nectar critical to rebuilding their capacity for another busy day of hyperactive feeding. With suitable roosting spots provided, extra food sources, and occasional migrations, hummingbirds can get through winter despite the challenges of thermoregulation and starvation risks that the darkness and cold present.
