The Ruby-throated Hummingbird (Archilochus colubris) is the only species commonly found in Illinois, as it is the sole hummingbird that regularly breeds east of the Mississippi River. Their presence is entirely seasonal, defined by an annual migratory cycle dedicated to breeding and preparing for their long journey south to Central America or southern Mexico.
The Spring Arrival in Illinois
Ruby-throated Hummingbirds begin arriving in Illinois starting in mid-April, with the main wave of migrants appearing throughout May. Their northward movement is guided by environmental cues. The males arrive first, seeking to establish feeding territories and prime breeding locations.
The primary biological trigger for this spring migration is the lengthening of daylight hours, known as photoperiod. This timing corresponds closely with the blooming of early-season nectar sources, such as native columbine and red buckeye trees. These birds often remember the exact location of reliable food sources, sometimes returning to the same feeder location year after year.
Summer Residency and Breeding Activity
Once settled, hummingbirds dedicate the summer months (May through early August) to nesting and raising their young. Females independently construct tiny, cup-shaped nests using plant materials bound with spider silk and camouflaged with lichen. They typically lay two eggs, which are incubated for approximately two weeks, and the chicks fledge about three weeks later.
During June, feeder activity may slow down as females incubate eggs and conserve energy. Activity picks up again in mid-to-late July when the young birds leave the nest and join the adults. This period of peak summer residency sees the highest number of birds, as both local adults and juveniles forage heavily to meet high metabolic demands.
Tracking the Autumn Departure
The southward migration begins early, with the first adult males starting their journey toward wintering grounds in August. Females and juveniles follow later, typically beginning their departure in September. This long-distance flight requires the birds to gain 25 to 40 percent of their body weight in fat reserves for fuel.
The primary signal for this fall departure is the shortening of the day length, or photoperiod, not the onset of cold weather or food scarcity. Hummingbirds instinctively know when it is time to leave, departing well before the first hard freeze. While the bulk of the population is gone by the end of September, stragglers and late migrants from points further north may continue to pass through Illinois until mid-October.
A common misconception is that leaving feeders up will prevent hummingbirds from migrating, but this is untrue. Providing a consistent food source helps them build the necessary fat reserves for their flight across the Gulf of Mexico. Maintaining feeders into the late season ensures that any passing migrants have the fuel they need to complete their journey.
Maximizing Your Observation Time
To maximize observation time, ensure feeders are ready by mid-April to greet the earliest arrivals. Planting native, late-blooming flowers, such as cardinal flower and trumpet vine, extends the availability of natural nectar sources into the late summer.
It is helpful to keep feeders clean and stocked throughout August and September to support pre-migration feeding. You can safely remove the feeders only after you have not observed a hummingbird for approximately two weeks, which often means leaving them in place until the end of October.