When the weather cools, many people wonder when hummingbirds will depart for the season. Their sudden disappearance is a predictable event tied to an ancient, internal schedule. Understanding this natural cycle, which governs their long journey south, explains why the feeder may suddenly stand quiet. The timing is a function of their biological programming and geographic location.
The Biological Clock: Why Hummingbirds Migrate
The primary signal prompting hummingbirds to begin their southward journey is the steady decrease in daylight hours, known as the photoperiod. This change triggers hormonal shifts that initiate a migratory state. This biological mechanism is a far more reliable cue than fluctuating weather or local food availability.
Once the internal clock signals migration, hummingbirds enter hyperphagia, dramatically increasing food intake to build fat reserves. This fat, which can nearly double their body weight, serves as the high-energy fuel required for their immense journey. Colder temperatures and reduced natural food sources are secondary signals that reinforce the initial light-driven trigger.
Regional Differences in Feeder Departure
The precise timing of departure is highly dependent on geographic location across North America. Hummingbirds begin their migration earliest in the northernmost parts of their range. For instance, in Canada and far northern states, adult male Ruby-throated Hummingbirds may start moving as early as late July or August.
The majority of the population begins traveling during September, which is the peak of the southward flow across the mid-latitudes of the United States. Further south, along the Gulf Coast, migrants may linger much later, sometimes remaining into October and November. The timing also varies by species; the Rufous Hummingbird, which breeds as far north as Alaska, begins its southward trek relatively early, often in late July and August.
Staggered Departure
Adult males of most species typically depart first, followed by adult females a week or two later. Juvenile birds are the last to leave their breeding grounds. This staggered departure means that even after summer residents are gone, feeders may see a temporary increase in visitors as migrants from further north pass through the area. This continuous movement can extend hummingbird activity well into the fall, especially in southern regions.
Managing Feeders During the Migration Window
A common concern is that leaving a feeder out will delay a hummingbird’s migration, preventing departure before winter. This is a misconception, as migration timing is governed by the unchanging photoperiod, not by the presence of a reliable food source. Providing fresh nectar actually assists the birds by offering a convenient energy boost for their demanding journey.
Post-Migration Feeding
It is recommended to keep feeders fully stocked for at least two to four weeks after the last hummingbird sighting. This practice provides an opportunity for late-migrating individuals or stragglers to refuel. During this fall period, maintain cleanliness by changing the nectar every few days to prevent fermentation and washing the feeder weekly to avoid mold and bacteria growth.
Year-Round Residents
In regions like the Pacific Coast, the desert Southwest, and the Gulf Coast, some species, such as the Anna’s Hummingbird, are year-round residents or overwinter in small numbers. In these areas, maintaining a clean, fresh feeder throughout the winter provides a valuable resource for birds that do not migrate or for unusual visitors that have traveled out of their expected range.