Hummingbirds, with their rapid wingbeats and iridescent plumage, are captivating creatures. Their presence often signals summer, but their appearances are seasonal due to migration. These tiny birds undertake journeys spanning hundreds to thousands of miles, moving between breeding grounds and warmer wintering habitats.
Timing of Departure
Hummingbirds typically begin their southward migration from late summer into early fall. In northern regions, Ruby-throated Hummingbirds may start their departure as early as late July, with peak movements throughout August and September. Their journey can extend into October for those departing from more southern U.S. areas. This is a gradual process, not a single mass exodus.
Male hummingbirds often initiate migration earlier than females, sometimes by several weeks, to reduce competition for dwindling food. Adult females follow, with juveniles typically making their first migration a week or two later. This staggered departure ensures resources along the migratory route are available for all birds. Rufous Hummingbirds, for example, may begin their southbound journey as early as July.
Factors Influencing Migration
The primary environmental cue for hummingbird migration is the change in daylight hours, specifically the shortening photoperiod as summer transitions to autumn. This alteration in light triggers hormonal shifts within the birds, prompting their instinctual drive to move to warmer climates. They rely on internal biological clocks synchronized with the changing seasons.
Decreasing temperatures also contribute to the migratory impulse, as colder weather makes conditions less favorable for survival. Concurrently, their main food sources—nectar from blooming flowers and small insects—begin to decline with cooler weather. This reduction in food acts as a reinforcing signal, compelling them to seek more abundant sustenance.
Preparation for the Journey
Before migrating, hummingbirds undergo significant physiological changes. They enter hyperphagia, a period of increased feeding activity. During this phase, they consume large quantities of nectar and small insects, often doubling their body weight. A Ruby-throated Hummingbird, for example, might increase its weight from about 3 grams to over 6 grams.
This stored fat is a concentrated energy source, providing more than twice the energy per gram compared to carbohydrates or protein, and is essential for sustaining their long-distance flights. Ruby-throated Hummingbirds can fly non-stop across the Gulf of Mexico, a journey of approximately 500 to 600 miles that can take 18 to 22 hours.
Hummingbirds also exhibit pre-migratory restlessness, an increased urge to fly as their bodies prepare for the journey. They typically fly during the day, often at lower altitudes, allowing them to spot food sources along their routes. While many follow general south-bound routes, such as the Gulf of Mexico crossing or overland routes, each bird may follow its own instincts regarding specific paths.
Supporting Migrating Hummingbirds
Supporting migrating hummingbirds involves providing reliable food sources as they prepare for and undertake their journeys. Keep hummingbird feeders clean and consistently filled, even into late fall. This practice does not prevent migration, as their departure is primarily triggered by changes in daylight hours, not food scarcity. Leaving feeders up for at least two weeks after the last sighting ensures late stragglers or passing migrants have access to sustenance.
A simple nectar solution is one part refined white sugar mixed with four parts water. Avoid adding red dye, as it is unnecessary and potentially harmful. Beyond feeders, planting nectar-rich flowers that bloom in late summer and fall provides natural food sources. Good options include:
- Cardinal Flowers
- Salvia
- Columbines
- Bee Balm
- Penstemon
- Coral Honeysuckle
- Milkweed
- Valerian
- Ironweed
- Goldenrod
- Aster
- Pineapple Sage
Additionally, avoiding pesticides helps protect insect populations that also serve as a food source for these birds.