Hummingbirds are captivating creatures. Their high energy demands make their survival through the colder months a subject of curiosity. Understanding how these tiny birds manage when winter arrives reveals remarkable adaptations and behaviors.
Migration Journeys
For many hummingbird species, migration is a primary strategy to avoid harsh winter conditions. Ruby-throated Hummingbirds travel from the United States and Canada to Central America and Mexico. The Rufous Hummingbird makes one of the longest migratory trips, covering nearly 4,000 miles from Alaska and northwestern Canada to Mexico. These journeys are undertaken due to the scarcity of nectar and insects, and the onset of cold temperatures.
Hummingbirds prepare for migration by increasing body weight, sometimes by 25-40%, to build fat reserves for long flights. They fly during the day, using visual cues like blooming flowers to find sustenance. Some Ruby-throated Hummingbirds undertake a non-stop flight across the Gulf of Mexico, lasting 18 to 24 hours. Young hummingbirds navigate these routes without parental guidance.
Survival Strategies for Winter Residents
While many hummingbirds migrate, some species, like Anna’s Hummingbird, overwinter in colder climates along the Pacific Coast. These resident hummingbirds employ specialized strategies to endure the cold. Torpor is a survival mechanism, a deep sleep that conserves energy. During torpor, a hummingbird’s metabolic rate, heart rate, and body temperature decrease significantly. Heart rate can drop from over 1,000 to fewer than 50 beats per minute, and body temperature from 40°C to 9°C, allowing them to use up to 95% less energy.
Hummingbirds enter torpor, often nightly, when food is scarce or temperatures drop, helping them survive low resources. Even in this state, they can lose about 10% of body weight overnight due to their high metabolism. Beyond torpor, wintering hummingbirds rely on available food sources. They consume nectar from late-blooming flowers like hellebores, camellias, and primroses, and feed on tree sap from sapsucker wells. Insects and spiders are part of their winter diet, providing protein, vitamins, and minerals.
Supporting Winter Hummingbirds
For those hummingbirds that remain in colder regions, human assistance helps. Providing sugar-water feeders offers a consistent food source when natural nectar is limited. Maintain these feeders, especially in freezing temperatures. Nectar solutions can freeze, so strategies like rotating multiple feeders, bringing them indoors overnight, or using external heat sources like incandescent Christmas lights or feeder heaters are recommended.
The nectar solution should be a 1:4 ratio of white sugar to water, without added dyes, as higher concentrations harm them. Regular cleaning of feeders, at least once a week, prevents harmful bacteria or fungi. Beyond feeders, planting late-blooming, nectar-rich flowers or providing shelter in dense shrubs also supports overwintering hummingbirds.