The Ruby-throated Hummingbird is the primary species observed in Virginia during the warmer months. They spend spring and summer utilizing the state’s abundant flowers and feeders. When seasons change, this species undertakes a long-distance migration to warmer wintering grounds. Understanding the timing of this departure is important for residents who host these energetic flyers.
The Critical Departure Timeline in Virginia
The southward migration from Virginia is staggered, spanning several weeks. The overall window for most Ruby-throated Hummingbirds to leave the state extends from late August through early October. This period allows different age and sex groups to depart when they reach biological readiness.
The first to initiate the journey are the adult males, typically beginning their solo flights south in late August or the first week of September. Having completed their reproductive role, they do not remain in the breeding territory. This early exit allows them to establish favorable stopover points ahead of the larger wave of migrants.
Following the males, adult females and juvenile birds start their migration throughout September and into early October. Females remain longer to ensure their young are fully fledged and independent before departure. While the majority of the population has left by early October, late-season stragglers or birds migrating from further north may still be observed in Virginia until mid-October.
Environmental Triggers for Migration
The decision to migrate is not driven by temperature, but rather by predictable biological and environmental cues. The most significant signal is the change in photoperiod—the steady decrease in daylight hours after the summer solstice. This change triggers hormonal shifts that initiate the migratory impulse, overriding the availability of food sources.
This internal biological clock prompts the birds to enter a phase called hyperphagia, a period of intense, increased feeding. Hummingbirds consume large quantities of nectar and small insects to build up their fat reserves, which serve as fuel for the long journey. During this time, a hummingbird may gain 25 to 50 percent of its body weight, accumulating fat essential for powering high-energy flight.
Stored fat is an efficient energy source, providing more than twice the energy per gram compared to carbohydrates or protein. This physiological preparation is a direct response to shortening days, ensuring the birds are physically ready to endure the taxing journey regardless of local weather. Once fat reserves are sufficiently built, the instinct to migrate takes over and the birds depart.
The Southern Journey and Return
After leaving Virginia, Ruby-throated Hummingbirds fly toward wintering grounds located primarily in Central America and southern Mexico. Some individuals travel as far south as Panama, seeking areas where flower nectar and insect populations remain abundant year-round. This route is solitary, as hummingbirds do not migrate in flocks, and juveniles must navigate the route on their own.
The most challenging portion of the migration is a non-stop flight across the Gulf of Mexico, a distance of 500 miles or more over open water. This leg requires a continuous flight of up to 20 hours, utilizing fat reserves accumulated before departure. While a direct trans-Gulf route is common, some birds may follow a circum-Gulf route along the coastlines of Texas and Mexico.
The birds remain in their southern habitat throughout the winter, preparing for the northward return trip. Spring migration begins as early as late February, with the first arrivals appearing in Virginia between late March and early April. Similar to the fall, the first birds to arrive are usually adult males, who quickly establish territories for the upcoming breeding season.
Preparing Feeders for the Final Departures
Residents can support these travelers by maintaining feeders appropriately during the fall. A common misconception is that leaving feeders full of sugar water will prevent hummingbirds from migrating. This is incorrect, as the impulse to migrate is driven by the immutable photoperiod, not the local food supply.
Keeping feeders clean and filled provides a crucial refueling station for Virginia’s resident birds and those passing through from further north. During hyperphagia, readily available sugar water helps them rapidly store the necessary fat for their journey. Continue to change the nectar every few days to ensure it remains fresh and free of mold or bacteria.
The recommended practice is to leave feeders in place for at least two weeks after the last hummingbird sighting. Since the main departure window closes in early October, this often means keeping feeders up through the end of October or even into early November. This simple action ensures that any late-migrating individuals have access to the high-energy fuel they need to complete their migratory flight.