The Ruby-throated Hummingbird (Archilochus colubris) is the only species of hummingbird that breeds and spends the summer in Ohio. These tiny birds, weighing only slightly more than a penny, undertake a migratory journey every year, traveling thousands of miles to their wintering grounds. They spend the non-breeding season in a narrow strip of territory extending from southern Mexico to Central America. Their departure from Ohio is tied to an internal biological calendar that prepares them for this annual flight.
Peak Migration Timing
The southward migration for Ruby-throated Hummingbirds in Ohio begins in late August and peaks throughout September. September represents the core departure window for the state’s summer residents. By the end of September, the majority of the local population has started the journey south.
The departure is a staged process based on the birds’ sex and age. Adult males, having completed breeding, are typically the first to leave. Females and the young of the year follow, with juveniles often lingering the longest as they build up energy reserves for their first long flight. While most birds are gone by the first week of October, stragglers and late migrants passing through from northern areas may still be observed well into the middle of the month.
Factors Driving the Journey
The trigger for the hummingbirds’ departure is the decreasing duration of daylight hours, a phenomenon known as photoperiod. This shortening of the day length initiates hormonal changes within the bird, signaling preparation for migration regardless of local weather or food supply. This internal timing mechanism ensures the birds leave with enough time to complete their journey to their wintering grounds in Central America or Mexico.
Once the migration signal is received, the birds enter a period of intense feeding called hyperphagia, where they rapidly consume food to accumulate fat reserves. Fat is the ideal fuel for migration because it provides more than twice the energy per gram compared to carbohydrates or protein. Furthermore, its metabolism produces water, aiding in hydration during long flights. A typical hummingbird, which weighs about three grams, can nearly double its body weight by adding two grams of fat, enough to fuel a non-stop flight of almost 600 miles.
Managing Feeders During Fall Migration
Ohio residents often worry that leaving feeders out will prevent hummingbirds from migrating, but this misconception is unfounded. The departure is driven by the photoperiod, not the food supply. Feeders serve as refueling stations, providing a high-energy source of sugar water for both local birds preparing to leave and transient birds migrating through the state. The birds’ internal clock compels them to move south once their fat reserves are sufficient.
To ensure late travelers have the necessary fuel, it is recommended to keep feeders in place until at least mid-October. A specific guideline is to leave the feeders up for approximately two weeks after the last hummingbird sighting. Maintaining a consistent supply of clean, fresh nectar supports any juveniles or stragglers completing their journey.