Hummingbirds are among the smallest birds, with a tiny size that belies an incredibly high metabolic rate. They require vast amounts of nectar and small insects to fuel their constant activity. This high energy demand means they are always just a few hours from starvation if food sources are unavailable. A common question arises: where do these remarkable birds go when winter approaches?
The Migratory Journey
Most North American hummingbird species embark on migratory journeys south. They fly to warmer climates like Mexico, Central America, and Caribbean islands, where food remains abundant. The Ruby-throated Hummingbird, for example, travels from its breeding grounds in the eastern U.S. and Canada to wintering areas as far south as Panama. Migration is driven by decreasing availability of nectar and insects as autumn progresses, not solely by cold temperatures.
This annual movement is triggered by environmental cues like changing daylight hours. Hummingbirds do not travel in large flocks; instead, each bird follows its own instincts regarding departure times and routes. The Ruby-throated Hummingbird undertakes a non-stop flight across the Gulf of Mexico, a journey that can last 18-22 hours. While some Ruby-throats may winter along the U.S. Gulf Coast, the majority continue further south to their tropical destinations.
Survival Strategies for Migration
Preparing for migration requires significant physiological adjustments. Hummingbirds enter hyperphagia, increasing food intake to build fat reserves. These fat stores can constitute as much as 40% of their body weight, providing concentrated energy for long, uninterrupted flights. This fattening allows some Ruby-throated Hummingbirds to complete a 500-mile Gulf crossing without needing to refuel.
During migration, especially during cold nights or when food is scarce, hummingbirds employ an energy-saving state called torpor. Similar to a mini-hibernation, torpor involves a significant drop in body temperature and a reduction in metabolic rate by up to 95%. This allows them to conserve energy when not actively foraging, which is beneficial during migration. While in torpor, their heart rate and respiration slow.
Hummingbirds That Don’t Migrate
While many hummingbird species migrate, some, like the Anna’s Hummingbird, are year-round residents in colder climates, such as the Pacific Northwest. These non-migratory hummingbirds have developed specific strategies to endure winter conditions. Their survival depends heavily on supplemental food sources, including tree sap, small insects found in sheltered areas, and human-provided feeders. The availability of exotic flowering trees in urban areas has also contributed to their expanded winter range.
Anna’s Hummingbirds utilize torpor more frequently during winter nights to cope with prolonged cold and reduced food availability. They can lower their body temperature significantly, recovering rapidly in the morning to forage. This ability to enter and exit a torpid state allows them to conserve energy when temperatures drop or natural nectar sources are scarce.
Supporting Winter Hummingbirds
For hummingbirds that remain during winter, human assistance can be important. Providing sugar water feeders offers a reliable food source when natural nectar is limited. The recommended nectar recipe is one part white granulated sugar to four parts water, though a slightly richer mix of one part sugar to three parts water can be offered in cold weather to provide more energy. Avoid red dyes or other sweeteners like honey or brown sugar, as these can be harmful.
Maintaining feeders requires consistent care, especially in cold conditions. Feeders should be cleaned regularly to prevent mold growth, and the solution must be kept from freezing. Strategies to prevent freezing include using specialized feeder heaters, wrapping feeders with insulating materials like bubble wrap or holiday lights, or rotating multiple feeders. Positioning feeders in sheltered spots, such as under eaves or near a light fixture, can also offer some protection from wind and cold.