Hummingbirds, with their shimmering colors and rapid wing beats, undertake impressive annual migrations spanning thousands of miles. As summer fades, many in Chicago wonder about the departure of these aerial marvels, signaling a shift in the seasons.
Chicago Hummingbird Departure Timeline
Ruby-throated hummingbirds, the species commonly seen in Chicago, begin their southward migration as early as late July or early August, with males often departing first after breeding duties conclude. Most hummingbirds typically leave Illinois by the end of August or early September, heading for wintering grounds in southern Mexico and Central America by mid-September. While the majority are gone, “stragglers” can be observed passing through Illinois as late as the end of September or even the second week of October, especially those migrating from farther north. These birds migrate in waves, a strategy believed to protect the population from encountering severe weather all at once.
Factors Driving Migration
Hummingbirds undertake their extensive migrations primarily in response to environmental cues that signal the changing seasons. A key trigger is the decreasing duration of daylight hours, known as photoperiod, which instigates hormonal changes in the birds. This instinctual response prepares them for the long journey ahead. As days shorten, the natural food sources, such as flower nectar and insects, also begin to diminish in northern regions like Chicago. The dropping temperatures associated with late summer and early fall further reinforce the need to move to warmer climates where food remains abundant. These collective environmental signals prompt hummingbirds to build up necessary fat reserves for their flights. The search for consistent food and favorable weather conditions drive their annual departure from the Chicago area.
Supporting Hummingbirds Before Departure
Chicago residents can assist hummingbirds as they prepare for their migratory journey. Maintaining hummingbird feeders with fresh nectar is beneficial, especially during late summer and early fall when the birds are actively fueling. Ensuring the nectar is clean and changed regularly, every few days or more often in hot weather, supports bird health. A simple solution of one part white sugar to four parts water is appropriate, avoiding red dyes or honey. Planting late-blooming, nectar-rich flowers also provides a natural food source. Flowers like jewelweed, cardinal flower, salvia, and trumpet creeper are attractive to hummingbirds, helping them accumulate fat reserves for migration. Leaving feeders out until late October will not delay migration, as their departure is driven by instinct and daylight changes, not the presence of feeders.