Anna’s hummingbirds (Calypte anna) are small, colorful birds found along the west coast of North America. While many hummingbird species migrate for the winter, Anna’s hummingbirds are well adapted to thrive year-round in their native range which extends from southern British Columbia to Baja California. Their ability to survive the winter depends heavily on finding adequate food sources. This article will explore what these tiny birds eat during the colder months when flowers are not in bloom and insect populations dwindle.
Nectar
Anna’s hummingbirds meet most of their daily energy requirements from drinking nectar. Their long slender bills and tongues are specially adapted for accessing nectar from flowers. During winter when fewer flowers are in bloom, Anna’s hummingbirds seek out any available flower sources and also shift to drinking more tree sap.
Some key winter flower sources include:
- Salvias – These tubular flowers bloom from fall through winter in coastal California gardens and chaparral habitats.
- Australian fuchsias – These epacrids bloom through winter and are an important nectar source.
- Tree tobacco – In the southwest U.S. these plants bloom from fall into winter.
- Hybrid Christmas cactus – The flowers open in winter and attract hummingbirds.
Anna’s hummingbirds use their bill like a straw to sip nectar from these flowers. They prefer red tubular flowers which are rich in sucrose-dominated nectar.
In addition to flowers, Anna’s hummingbirds drink sap from wells excavated in tree bark. They use their bills to pierce through the bark to the vascular layer which oozes sugary sap. Favored sap trees include alders, maples, and cottonwoods. Drinking sap provides an important source of carbohydrates in winter when flower nectar is limited.
Insects and Spiders
While nectar comprises the majority of their winter diet, Anna’s hummingbirds also consume small insects and spiders to meet their nutritional needs.
Insects caught during winter include:
- Gnats
- Aphids
- Mosquitoes
- Flies
- Beetles
- Leafhoppers
- Caterpillars
Anna’s hummingbirds hawk flying insects in midair and glean dormant insects from foliage and bark. Favorite spider prey includes small orb weavers, crab spiders, and jumping spiders which they pluck from webs and vegetation.
Consuming insects provides these birds with essential protein and nutrients to survive the challenging winter conditions. Fatty insects also help meet their high energy demands.
Sap Feeders
In natural habitats, Anna’s hummingbirds often feed on the sap of sapsucker wells. These sap wells are holes drilled in tree bark by yellow-bellied sapsuckers and other woodpecker species. The sapsuckers feed on the oozing sap as well as trapped insects. Anna’s hummingbirds opportunistically come along later to drink the sap.
At backyard feeders, people mimic this sap feeding behavior by making their own artificial sap wells. These homemade sap feeders consist of small holes drilled into trees, branches, or wooden planks. The holes are filled with a sugary liquid solution which artificially oozes out, simulating a sap well. Anna’s hummingbirds readily feed on these artificial sap sources. The sugar water is made by mixing 1 part white sugar with 4 parts water. No food coloring, honey, or other additives are necessary.
Providing an artificial sap feeder is an excellent way to attract and feed wintering Anna’s hummingbirds. The feeders should be cleaned and refilled regularly to prevent fermentation or mold.
Commercial Nectar Feeders
Many people use store-bought hummingbird feeders to provide supplemental nectar for Anna’s hummingbirds overwintering in their yards. These feeders are filled with commercially available premixed “nectar” fluids. While artificial nectar is not a complete substitute for natural food sources, these commercial feeders undoubtedly help sustain wintering hummingbird populations.
There are a few considerations for successfully feeding Anna’s hummingbirds with commercial nectar feeders in winter:
- Use a nectar solution with 20-25% sugar content to provide sufficient energy.
- Avoid red food coloring, which is unnecessary and potentially harmful.
- Change nectar every 2-3 days to prevent spoilage in winter weather.
- Clean feeders thoroughly before refilling to deter mold.
- Place feeders in protected areas out of direct wind, rain, and snow.
- Hang multiple feeders to accommodate territorial behaviors.
With proper care and maintenance, commercial nectar feeders can help supplement the diet of Anna’s hummingbirds throughout the lean winter months.
Backyard Plantings
In addition to nectar feeders, another way to support wintering Anna’s hummingbirds is providing flower gardens with winter-blooming plants. Some suitable hummingbird-friendly plants include:
- Coral honeysuckle
- Cape honeysuckle
- Aloe
- Red-hot poker
- Firecracker plant
- Winter-blooming salvias
- Flowering maple
- Fuchsia
Landscaping with these plants extends the availability of live flowers for hummingbirds. It also draws in more insects which the birds can prey on. Planting native species adapted to winter blooming in your region is recommended. Even non-native ornamental species can provide essential food.
Does Survival Depend on Human Feeders?
Anna’s hummingbirds evolved to thrive in western North America long before the introduction of commercial nectar feeders. However, human-provided feeders may help compensate for some limitations of urban environments.
In natural habitat, Anna’s hummingbirds meet winter food needs by:
- Seeking out any remaining flowers and flowering shrubs.
- Drinking sap exuding from tree wells.
- Gleaning small insects from foliage and bark.
- Consuming spiders snared in webs.
- Competing for access to sapsucker sap wells.
In urban settings, landscaping often eliminates native vegetation and sapsuckers may be scarce. But gardens with winter-blooming plants and human-provisioned nectar feeders can replicate essential food sources. Supplemental feeding likely supports higher overwinter densities than natural habitats alone could sustain.
Do Anna’s Hummingbirds Store Food for Winter?
Anna’s hummingbirds do not hoard food or store caches for wintertime. Instead, they meet nutritional demands by shifting day-to-day food sources as the seasons change.
Their high metabolism requires visiting flowers or feeders every few hours when awake. To sustain this constant foraging, Anna’s hummingbirds rely on fat deposits and nightly torpor.
Torpor is a short-term hibernation which cuts their metabolic rate up to 95%. Each night, they enter torpor to conserve energy. By reducing their metabolism, the fat stored in their chest muscles can sustain them overnight until the next day’s foraging.
So winter survival depends on both finding adequate daily food and having enough fat reserves to enter nightly torpor. The fat provides some buffer during extreme cold spells when adequate flowers or insects may be temporarily unavailable.
How Do They Get Water in Winter?
Like food, Anna’s hummingbirds also require a reliable winter source of water. Their high metabolism leads to excess body heat that must be dissipated, often through panting. This breathing pattern results in high rates of water loss.
Anna’s hummingbirds meet their water needs in winter by:
- Drinking droplets from leaves and branches after rain or fog.
- Eating snow to get frozen water.
- Consuming sap, nectar, and juice from moist foods.
- Visiting dripping outdoor faucets.
- Using bird baths heated by solar fountains or lights.
Providing a heated bird bath or fountain is a great way to supply winter water for hummingbirds in your yard. Moving water helps prevent freezing and provides humidity. Include perches for the birds to conveniently drink.
Do Males and Females Have Different Winter Diets?
There are no major differences between male and female Anna’s hummingbird diets in winter. Both genders rely primarily on nectar and sap as energy sources and small insects and spiders to provide protein.
However, adult males may be better positioned to monopolize prime feeding locations. Their dominance hierarchies give them priority access to the best sap wells and the most protected nectar feeders.
Juveniles and subordinate females are forced to the margins and must locate sufficient alternate food sources. This competition means controlling limited quality food sources is key to winter survival, especially for breeding males. Providing multiple dispersed feeders helps reduce competition pressure.
How Does Diet Vary Across Their Range?
The winter diet of Anna’s hummingbirds varies somewhat across their expansive range:
- In Canada and Alaska, they are restricted to areas with sufficient winter-blooming plants, sap flows, and insects through mild periods.
- In Washington and Oregon, they depend more on landscaping plants, tree sap, and feeders in urbanized areas.
- In California, natural food is abundant but irrigation and exotic flowers have allowed dramatic expansion.
- In Arizona, bumblebee-pollinated hybrid plants provide important food sources.
- In Baja California, columnar cacti flowers and arthropod prey sustain them in the desert.
At the northern extreme limits, Anna’s hummingbirds’ winter diet is constrained by harsh conditions. But across much of their range, they flourish on a combination of native foods and human-provided feeders.
How Do Hummingbirds Survive Cold Nights?
Surviving freezing nights is one of the greatest winter challenges for Anna’s hummingbirds. They have adapted specialized strategies to make it through:
- Torpor – They reduce their metabolic rate and body temperature by entering torpor. This uses up less energy overnight.
- Nestling – They fluff up their feathers while roosting to trap heat.
- Shelter – They retreat to protected microclimates in thick vegetation, cavities, or under eaves.
- Shivering – If needed, they rapidly contract their massive pectoral muscles to generate heat.
- Small Body Size – Their tiny bodies cool off and warm up quickly, reducing energy needs.
- Fat Reserves – Excess body fat provides insulation and energy reserves.
During extreme freezes, their survival depends on accessing shelter in built structures or hidden microhabitats. Backyards with winter feeders become critical refuge when temperatures drop dangerously low.
Conclusion
Anna’s hummingbirds survive winter through behavioral and physiological adaptations that allow them to obtain enough food and water in challenging conditions. While native plants provide essential natural food sources, human-provisioned feeders likely facilitate higher overwinter densities, especially in urbanized habitats. Providing winter-blooming flowers and clean nectar feeders can help sustain resident Anna’s hummingbird populations. Their persistence even in cold climates is a testament to the impressive resilience of these tiny birds. With some support from backyard habitat, they can continue to brighten western winters with their iridescent colors.
