While some extended warm weather has made September feel like an extra month of summer in many ways, hummingbirds are preparing to migrate from the area before the cold weather hits.
Well-versed in migration, the colorful, nectar-loving birds have a tendency to leave Illinois by a certain time every year.
It's hard to blame the birds, with a forecasted La Niña in the upcoming months leaving the Chicago area and northern Illinois prone to lengthy cold snaps and heavy snowstorms, despite the La Niña generally producing an overall warmer winter.
The Chicago Botanic Garden has written about hummingbird migration habits for several years. The experts at the living plant museum say hummingbirds usually leave the Chicago area "by about the second week in October."
The garden's experts note that bird-lovers needn't worry about leaving out hummingbird feeders later than the scheduled departure: "They will not delay the birds’ migration—they instinctively know when it’s time to leave."
Typically the birds are already on their way out by September as part of their "great fall migration."
"On their fall migration south, they either cross the Gulf or follow the Texas coast back to Mexico," an online post on the topic reads.
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And while there are more than two dozen hummingbirds in the United States, it's the ruby-throated hummingbird that you might find in your Chicago-area backyard.
"The ruby-throated is the only hummingbird regularly found east of the Mississippi River," the garden says. "During the summer, they are frequent residents at the Chicago Botanic Garden. Right now, many more are coming from Canada, stopping in search of nectar and insects. They’re building up energy for their long journey south" for the winter season."
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Hummingbirds are typically in Illinois from May to October, though a scattering of them have been seen as early as March, according to the Forest Preserve District of DuPage County. You might have noticed them by the "hum" of their flapping wings, or their chatter, which sounds like high-pitched dolphin chatter," the Forest Preserve says.
As for looks, they're hard to missed. "Ruby-throated hummingbirds are bright emerald or golden-green on the back and crown, with gray-white underparts," the Forest Preserve continues. "Males have a brilliant iridescent red throat that looks dark when it’s not in good light."
Hummingbirds aren't the only Chicago residents heading south for the winter. Butterflies are, too.
Typically, an abundance of butterflies can be spotted throughout September, with peak monarch migrations typically occurring earlier in September.
Chicagoans will be able to make out bundles of butterflies well into October, too, as groups of stragglers are expected to round out the migration.
