Hummingbirds are remarkable little birds that have evolved to sustain themselves on a diet consisting primarily of nectar from flowers. Unlike other birds that migrate or hibernate during the colder winter months, many hummingbird species tough it out through the winter by adapting their feeding behaviors and physiological needs. But just how often do these tiny dynamos need to eat when flower nectar is in short supply? Let’s take a closer look at hummingbird winter feeding patterns and nutritional requirements.
Hummingbird Winter Feeding Patterns
During warmer months when flowers are abundant, hummingbirds feed every 10-15 minutes throughout the day, visiting hundreds or even thousands of blossoms. They consume more than their weight in nectar each day! However, winter brings scarcer food supplies.
There are two key ways hummingbirds adapt their feeding behavior in winter:
1. Lowering Body Temperature
Hummingbirds can lower their high metabolisms and body temperatures at night to conserve energy. Their nighttime body temperature drops from around 105°F to as low as 65°F, resulting in a 50-75% drop in metabolic rate. This allows them to slow their breathing and heart rate and reduce their energy needs.
2. Entering Periodic Torpor
Many hummingbird species use torpor intermittently during the day in winter, allowing them to conserve huge amounts of energy. Torpid hummingbirds go into a temporary state of decreased physiological activity characterized by a reduced body temperature and metabolic rate. Their heart rate slows from around 500 beats per minute to 50-180 beats per minute. Breathing also slows.
Torpor bouts may last a few minutes to a few hours. This gives the birds a chance to rest and rely on stored energy reserves. During torpor, they don’t need to eat as frequently.
Hummingbird Nutritional Requirements
So what are hummingbirds’ key nutritional needs, and how much food must they consume to meet those needs in the lean winter months? Let’s look at some key facts:
Calories
Hummingbirds have very fast metabolisms, requiring large amounts of energy. During active periods in winter when they are not in torpor, they may need to consume between 3,000 to 7,000 calories per day. Given their tiny size, this represents about 2.5 to 3 times their body weight in nectar.
Sugar
Nectar is the ideal fuel for hummingbirds because it is high in sugar. The main energy source hummingbirds derive from nectar is sucrose. During winter, they get most of their sucrose intake from any remaining flowers and feeders. Hummingbirds need to consume about 1 gram of sucrose for every 0.8 calories they expend while active.
Other Nutrients
Hummingbirds meet their needs for key nutrients like proteins, vitamins and minerals by consuming insects and tree sap. They do not get these nutrients from nectar. During winter when insects are scarce, they may get insufficient nutrition if nectar/sucrose is their only food source. Providing a complete nutritional formula in feeders is advisable.
Water
Like all living things, hummingbirds need water to survive. They get most of their water needs from the nectar they drink, but may also sip from rain drops, dew or bird baths. Supplying clean water is important during winter.
How Much Do They Eat in Winter?
During a typical winter day, a hummingbird’s food intake may include:
- Up to 1/3 ounce of sucrose-rich nectar or sugar water from feeders
- Tiny amounts of insects and tree sap for essential nutrients
- Water for hydration
However, torpor reduces these needs tremendously. Torpid hummingbirds may survive on just 1/10th of these amounts on a given day.
How Often Should Hummingbird Feeders Be Filled in Winter?
How frequently you need to fill your feeder depends on:
- How many hummingbirds are feeding
- Weather conditions
- Feeder capacity
As a general guideline:
- In mild climates, fill feeders every 2-3 days
- In colder climates, fill feeders daily or even twice daily if freezing occurs
- Check feeders often and refill when low. Don’t let sugar water freeze inside.
Tips for winter feeding success:
- Use a heated feeder if temperatures will be below freezing
- Use nectar formula with electrolytes
- Provide coconut oil for extra energy
- Have multiple feeders to give hummingbirds options
- Keep feeders clean to prevent mold
The Importance of Artificial Feeders in Winter
Natural food sources like flowers and insects can be scarce in winter. Artificial feeders provide an essential source of nutrition. Here are some key benefits of feeders for wintering hummingbirds:
- Provide concentrated sucrose nectar to fuel their metabolism
- Offer essential amino acids, vitamins, minerals
- Give hummingbirds the energy they need to periodically arouse from torpor
- Provide hydration and prevent dehydration
- Allow hummingbirds to conserve energy instead of foraging widely for scarce food
Winter feeding with artificial feeders allows hummingbirds to meet their nutritional needs with less foraging effort. This helps compensate for the lower availability of natural nectar sources and insects.
Unique Adaptations for Winter Survival
Hummingbirds have many specialized anatomical and physiological adaptations to help them survive cold winters despite their tiny size, including:
Fat Deposition
Hummingbirds nearly double their weight before winter by storing fat reserves. This provides energy when food is limited.
Skeletal Muscle Adaptations
Their pectoral muscles are highly efficient at generating power and heat. This aids their ability to arouse from torpor.
capacious Storage Capacity
Their digestive systems can store up to 25% of their weight in nectar. This provides a reservoir of fuel.
Enhanced Kidney Function
Their kidneys efficiently concentrate urine to reduce fluid loss. This helps prevent dehydration.
High Hemoglobin and Capillary Density
Abundant hemoglobin and capillaries in their tissues allow for rapid oxygen and energy distribution.
Rapid Heat Generation
Their muscles have lots of mitochondria that can quickly ramp up heat production during arousal from torpor.
Feather Adaptations
Downy uppertail and thigh plumage create insulating air pockets. Feathers trap air to limit heat loss.
Behavioral Adaptations for Conserving Energy
Along with their physical adaptations, hummingbirds use various behavioral strategies to minimize energy expenditure in winter, including:
- Seeking sheltered roosting spots such as tree cavities or dense shrubs
- Huddling together in groups to conserve body heat
- Feather puffing to trap insulating air layers
- Orienting their bodies out of the wind
- Entering torpor to lower metabolic rate and temperature
The Critical Role of Backyard Bird Feeders
For hummingbirds wintering in northern climates, backyard feeders can truly be a lifeline. The nectar and nutrition they provide may determine whether hummingbirds can build up enough energy reserves to survive cold nights.
Feeders also give hummingbirds a reason to arouse from torpor periodically to feed. Access to feeders may enable northern populations to remain further north than they otherwise could by decreasing their risk of starvation.
By providing a reliable winter food source, backyard feeders likely boost winter survival rates and may even be extending hummingbirds’ breeding ranges northward over time.
Tips for Supporting Wintering Hummingbirds
Here are some tips for providing the best winter habitat for hummingbirds in your yard:
- Provide fresh nectar in multiple feeders placed in different sites
- Offer high calorie nectar formulas
- Include coconut oil or vitamins in the nectar
- Supply a protein-rich feeder made for hummingbirds
- Plant winter-blooming flowers and shrubs
- Provide insect feeders for essential amino acids
- Leave some leaf litter or mulch for insects to live in
- Set up a small “hummingbird haven” with a heated roost box
- Protect feeders from freezing
- Keep feeders clean to avoid mold
With some planning and effort, we can create a welcoming winter refuge for hummingbirds. Our yards may provide these tiny migrants with the sustenance they need to pull through until spring.
Key Facts Summary
- Hummingbirds have adaptations to reduce their metabolic rate and body temperature at night and enter torpor during winter days to conserve energy.
- They need to consume large amounts of nectar for energy and some insects for essential nutrients.
- During active periods, they may eat up to 1/3 ounce of nectar and tiny amounts of insects/sap daily.
- In torpor their needs are reduced to as little as 1/10th this amount.
- Artificial feeders provide essential nutrition not available from natural winter food sources.
- Feeders should be refilled often to ensure sugar water doesn’t freeze and is always available.
- Hummingbirds have specialized adaptations to survive winter despite their small size.
- Backyard feeders likely boost their chances of surviving winter in northern regions.
Conclusion
Hummingbirds are remarkable in their ability to make it through cold months despite their tiny, high-energy bodies. Periodic torpor allows them to conserve calories by lowering their temperature and metabolism for stretches of time. However, they still need to eat frequently when active, consuming large amounts of nectar for fuel along with some insects and tree sap for essential nutrients.
Artificial feeders can make all the difference by providing a reliable food source when flowers and insects are scarce. By refilling feeders often with nutritious sugar water, protecting them from freezing, and creating winter-friendly habitat, we can give wintering hummingbirds a better chance of getting the calories they need to survive until spring returns. Supporting these tenacious migrants through winter is incredibly rewarding.