Hummingbirds, with their iridescent plumage and aerial agility, are captivating birds. These tiny creatures are renowned for their rapid wingbeats and ability to hover, making them a spectacle in gardens across North America. Many hummingbird species undertake remarkable annual migrations. This migratory behavior is a key aspect of their life cycle, allowing them to thrive by following seasonal floral blooms and insect availability.
The Long Journey South
Most North American hummingbirds embark on southward migrations to warmer climates for winter. Their primary wintering grounds span Mexico, Central America, and parts of the Caribbean. These regions offer a consistent supply of nectar-producing flowers and insects, essential for their survival during colder seasons.
The Ruby-throated Hummingbird, prevalent in eastern North America, typically migrates to southern Mexico and Central America. Many undertake a non-stop flight of up to 500 miles across the Gulf of Mexico. The Rufous Hummingbird, found primarily in western North America, travels one of the longest migratory routes, covering nearly 4,000 miles from its breeding grounds as far north as Alaska to wintering sites in southern Mexico. They often follow the Pacific Coast northward in spring and return south via the Rocky Mountains in late summer and fall.
Timing Their Departures and Returns
The timing of hummingbird migration is synchronized with environmental cues, particularly changes in day length. Most hummingbirds begin their southward journey in late summer to early fall, generally from August through October. Male hummingbirds often depart first, followed by females and then juveniles, allowing younger birds more time to develop and build energy reserves for their initial long flight.
Declining food sources, cooler temperatures, and shorter daylight hours stimulate this migratory urge. The return journey northward to their breeding grounds typically commences in early spring, from late February to May. Ruby-throated Hummingbirds, for example, start arriving in Gulf Coast states by late February to mid-March, progressively moving north to reach their northernmost breeding areas by April or May. The precise timing can vary year to year based on weather patterns and the availability of food along their routes.
Fueling the Epic Flight
Preparing for demanding journeys requires hummingbirds to accumulate substantial energy reserves. Before migration, they enter a phase known as hyperphagia, consuming excessive amounts of nectar and small insects. This intense feeding allows them to build up fat stores, their primary fuel source for long flights.
Hummingbirds can gain up to 25-40% of their body weight in fat, sometimes even doubling it, providing enough energy for non-stop flights of several hundred miles. Their high metabolic rate necessitates this efficient energy storage. During migration, they can also employ torpor, a short-term, hibernation-like condition where they lower their body temperature and slow their metabolism to conserve energy, particularly during cold nights or when food is scarce. While exact navigational mechanisms are not fully understood, hummingbirds instinctively follow established routes, possibly using cues like the sun’s position or the Earth’s magnetic field.
Hummingbirds That Stay Put
Not all hummingbirds undertake long-distance journeys. Some species, or individuals within migratory species, remain in certain regions year-round if local conditions permit. This is particularly true in areas with milder climates and consistent food availability.
Anna’s Hummingbird has the northernmost year-round range among North American hummingbirds. Found along the western coast from southern Canada to northern Baja California and inland in parts of Arizona, they often reside permanently in areas like the Pacific Northwest. Their ability to overwinter is attributed to abundant nectar from ornamental plants and human-provided feeders, alongside a diet that includes a significant amount of insects. These resident hummingbirds adapt to cooler temperatures, sometimes utilizing torpor to survive cold nights.