Hummingbirds embark on astonishing migratory journeys. These tiny, energetic birds are renowned for their incredible flight capabilities, including hovering and flying backward. Their small stature belies impressive endurance, allowing them to undertake extensive seasonal travels.
Why and When They Travel
Hummingbirds migrate primarily in response to seasonal availability of essential resources. Their diet is nectar from flowering plants and small insects, both of which become scarce in colder climates. As autumn approaches and daylight hours shorten, these birds instinctively begin southbound journeys toward warmer regions where food remains abundant.
Migration typically involves southbound movement in late summer to early fall, usually between August and October. Northbound spring migration begins as early as February in Mexico and Central America, with birds reaching northern states and Canadian provinces by April or May. This cycle allows them to access suitable breeding grounds with ample food during warmer months and escape scarce winter resources.
Remarkable Journeys of Specific Species
The distances hummingbirds cover during migration are remarkable, particularly for species like the Ruby-throated and Rufous Hummingbirds. The Ruby-throated Hummingbird, weighing little more than a penny, migrates annually from eastern North America to southern Mexico and Central America. This journey involves a non-stop flight across the Gulf of Mexico, approximately 500 miles, which can take 18-22 hours.
The Rufous Hummingbird has one of the longest migratory routes, traveling up to 4,000 miles from its breeding grounds in Alaska and northwest Canada to its wintering sites in Mexico. This species follows a clockwise loop migration pattern, moving up the Pacific Coast in spring and returning south through the Rocky Mountains in late summer and fall. While many hummingbirds migrate, species like the Anna’s Hummingbird are largely non-migratory, remaining year-round along the Pacific Coast.
The Science of Their Flight
The ability of hummingbirds to undertake extensive migrations is attributed to physiological adaptations. They possess an incredibly high metabolic rate, which powers their rapid wing beats—ranging from 15 to 80 times per second during migration. To fuel these demanding flights, hummingbirds undergo a period of intense feeding, known as hyperphagia, before migration, gaining 25-40% of their body weight, sometimes even doubling it, primarily as fat. This stored fat serves as a highly efficient energy source, providing more than twice the energy per gram compared to carbohydrates or protein, and also producing water which aids in hydration.
Hummingbirds also employ torpor, a short-term reduction in metabolic rate and body temperature, to conserve energy, especially during cold nights or when food is scarce. This mechanism helps them manage their energy reserves efficiently, both during daily cycles and in preparation for long migratory flights. For navigation, these birds utilize multiple cues, including the sun’s position, visual landmarks, and potentially Earth’s magnetic field, with some studies suggesting cryptochrome proteins in their retinas act as light-sensitive magnetic sensors. Their highly developed spatial memory also allows them to recall specific feeding locations year after year.