The Ruby-throated hummingbird, a small bird three to three and three-quarter inches long, is the primary hummingbird species found across Illinois. These birds are recognized by their rapid wing beats, exceeding 50 times per second, allowing them to hover while feeding. They primarily feed on nectar, but also consume small insects and spiders. As migratory birds, their presence in Illinois is seasonal, spending winters in warmer climates.
Spring Arrival in Illinois
Ruby-throated hummingbirds begin their journey north from Central America and Mexico as spring approaches. Spring migrants start arriving in Illinois around mid-April, with the majority appearing by May. Males precede females by about a week, seeking out territories and food sources. Upon arrival, they establish feeding territories and find early nectar sources.
Summer Residency and Activity
During the summer months, Ruby-throated hummingbirds are common residents throughout Illinois. Nesting activities take place from May through July, with females constructing small, cup-shaped nests made from plant materials and spider silk. These tiny nests, about the size of a golf ball, hold two pea-sized eggs.
Females alone incubate the eggs for 14 to 16 days, and the young fledge after 22 to 24 days. Throughout this period, hummingbirds feed on nectar and small insects, which are crucial for their high metabolism and for feeding their young. Their presence contributes to the pollination of various plant species.
Fall Migration and Departure
As summer transitions to fall, decreasing daylight and cooling temperatures signal the start of the southward migration for Ruby-throated hummingbirds. Their departure from Illinois begins in late August and continues through September, sometimes extending into early October. Females and juveniles depart before adult males, who may linger longer to continue feeding and building fat reserves. Before their long journey, these birds increase their food intake to accumulate fat, which fuels their non-stop flights, including across the Gulf of Mexico.
Factors Influencing Their Schedule
The precise timing of hummingbird arrivals and departures in Illinois can vary from year to year due to several environmental factors. Local weather patterns play a role; an early spring or unusually warm fall can lead to earlier arrivals or later departures. Conversely, late frosts or prolonged cold spells may delay their spring return. The availability of food sources, such as nectar plants and insect populations, also influences their migratory schedule. While general timeframes exist, these environmental variables mean that the exact dates of their seasonal presence can shift.