Hummingbirds, known for their iridescent plumage and rapid wingbeats, embark on remarkable annual migrations. These tiny birds travel thousands of miles between their breeding grounds in North America and their warmer wintering habitats in Central America or Mexico. Understanding their migratory patterns offers insight into their impressive endurance and how they navigate vast distances.
The Annual Journey: When Migration Begins
Most North American hummingbird species begin their southward migration in late summer and early fall. This journey typically starts as early as late July, with a peak in activity throughout August and September. The migration is a gradual process, not a sudden mass departure, and continues with stragglers crossing the southern U.S. border into late October or even November. During this period, hummingbirds intensively refuel in the mornings, travel during midday, and forage again in the late afternoons to maintain their body weight. They often gain 25-40% of their body weight to fuel these long journeys.
Signals for Departure: What Triggers Migration
Hummingbirds initiate their southward migration in response to specific environmental cues. A primary trigger is the decreasing duration of daylight hours, known as photoperiod, which causes hormonal changes within the birds. Dropping temperatures also play a role, signaling the onset of colder seasons. A decline in the availability of natural food sources, such as nectar-producing flowers and insects, prompts them to seek more abundant resources in warmer climates. These innate signals guide hummingbirds, ensuring departure before harsh winter conditions or severe food scarcity.
Regional and Species Variations in Timing
Migration timing is not uniform across all hummingbirds; it varies depending on their geographical location and species. Hummingbirds in northern regions, such as parts of Canada and the northern U.S., typically commence their southbound journey earlier, sometimes as early as July for some Ruby-throated Hummingbirds. In contrast, those in more southerly areas may start their migration later in the fall. For example, Ruby-throated Hummingbirds, prevalent in the eastern U.S. and Canada, generally begin their fall migration in late August or September. Rufous Hummingbirds, found primarily in western North America, begin their southward movement as early as July, often following the Rocky Mountains back to Mexico.
Supporting Hummingbirds During Their Southern Journey
Supporting migrating hummingbirds involves several practical steps, primarily food availability. Keep hummingbird feeders clean and filled with a sugar solution well into the fall, even after most birds have departed. The recommended solution is a 1:4 ratio of refined white sugar to water, boiled and cooled before filling. Avoid red dyes, honey, brown sugar, or artificial sweeteners, as these can be harmful.
Leaving feeders up does not prevent migration; their departure is driven by changing daylight, not food scarcity. Feeders serve as refueling stations for birds on their journey. Continue to maintain feeders for at least two weeks after your last sighting to aid any late-migrating individuals. Planting late-blooming native flowers like Cardinal Flowers, Salvia, Columbines, and Bee Balm also provides natural nectar sources.