Hummingbirds are among the smallest creatures in North America, known for their iridescent feathers. These birds maintain the fastest metabolism of any warm-blooded animal, fueled primarily by flower nectar and small insects. Their presence in the United States and Canada is seasonal, as they are long-distance migratory species that must travel great distances to survive the winter.
The Primary Migration Triggers
The decision for a hummingbird to leave its northern breeding grounds is not based on local weather conditions or a sudden lack of food. Instead, the primary trigger is a subtle, internal clock mechanism known as photoperiodism. This biological process registers the consistent, daily decrease in the duration of daylight hours as the summer solstice passes. The shortening photoperiod initiates a chain of physiological changes within the bird’s body, including hormonal shifts. These hormonal signals prompt a phase called hyperphagia, where the hummingbird dramatically increases its food intake to gain 25 to 40 percent of its body weight in fat reserves, which will serve as the energy source for the long migration.
Regional Migration Timelines
Hummingbirds begin their southbound journey at staggered times, with the exact window depending largely on geography and species. For the Ruby-throated Hummingbird, the species commonly found in eastern North America, the first departures from northern breeding areas occur as early as mid-July for some adult males. The bulk of the migration from the northern states and southern Canada typically ramps up throughout late August and peaks in early September.
In central regions of the United States, the migration window stretches through mid-September as birds passing through join local populations. The final wave of migrants, often composed of females and juveniles, moves through the southern states and along the Gulf Coast well into late September and October. A similar pattern occurs in the West, where the Rufous Hummingbird begins moving south along the Rocky Mountains as early as July from its northern range in Alaska and the Pacific Northwest. These western species continue their passage through the western states until late September, with occasional stragglers appearing even later on the Gulf and Atlantic coasts.
Migration Destinations and Routes
The vast majority of North American hummingbirds travel to wintering grounds in Mexico and Central America. Species like the Ruby-throated Hummingbird winter in an expansive region stretching from southern Mexico down to the edge of Panama. Other species, such as the Black-chinned, Broad-tailed, and Rufous hummingbirds, primarily settle in various regions across Mexico.
The 500-mile nonstop flight across the Gulf of Mexico is undertaken by many Ruby-throated Hummingbirds. This immense journey across open water takes approximately 18 to 22 hours and is usually performed at night. Western species, including the Rufous and Calliope hummingbirds, tend to follow overland routes, often utilizing the mountain chains of the Sierra Nevada and the Rockies as a flyway. These mountain corridors provide a continuous source of late-blooming flowers and insects for refueling stops.
Preparing Your Yard for Departure
Supporting hummingbirds during the fall migration is a simple and effective way to help them complete their journey. Leaving feeders up will not delay departure, as their migration timing is governed by the unchanging photoperiod, not by food availability. Feeders simply provide a necessary energy boost for transient birds passing through the area.
It is recommended to maintain a clean feeder with a fresh solution until at least two weeks after the last hummingbird sighting. The standard nectar recipe is a simple mixture of one part white granulated sugar to four parts water, without any added coloring or artificial sweeteners. During the late summer and fall, you may need to refill feeders more frequently due to the intense feeding as birds prepare for flight. Regular cleaning is also necessary; feeders should be washed with hot water and a brush at least once a week, or more often in warm weather, to prevent the growth of mold and bacteria that can harm the birds.