3 Types of Falcons in Illinois: A Field Guide to Kestrels, Merlins, and Peregrines
September 21, 2026
The smallest falcon in Illinois has lost roughly half its population since the 1960s, even as its far more famous cousin has staged one of American conservation’s biggest comeback stories. Anyone researching the types of falcons in Illinois will find just three species that show up on a regular basis: the American Kestrel, the Merlin, and the Peregrine Falcon.
Two other falcons, the gyrfalcon and the prairie falcon, have had recorded sightings in Illinois, but they have proven extremely rare, as the state lies well outside their normal ranges. Falcons look and hunt differently than the state’s more common eagles and hawks. Compared to hawks, falcons have longer wings and are built for speed, while hawks typically fly slower and kill their prey with their talons rather than their beaks like falcons do.
All three Illinois falcons are protected under federal law, so watching from a respectful distance is the only way to interact with them. The table below breaks down how they compare before diving into each species in detail.
| Species | Length | Wingspan | Best Time to See in Illinois |
|---|---|---|---|
| American Kestrel | 9–12 inches | 20–24 inches | Year-round resident |
| Merlin | 9.4–11.8 inches | 20.9–26.8 inches | Spring and fall migration |
| Peregrine Falcon | 14–19 inches | 3.3–3.6 feet | Migrant, with year-round city residents |
1. American Kestrel
The American kestrel (Falco sparverius) is the smallest falcon in North America, measuring about 9 to 12 inches in length with a wingspan of 20 to 24 inches. Despite the tiny frame, this is a genuinely fierce hunter that punches well above its weight class.
Males and females look strikingly different from each other. Males exhibit striking slate-blue wings and a rusty-red back and tail, while females have a more subdued reddish-brown coloration with black barring, both featuring a distinctive double black stripe on their faces. That patch of blue coloring on the male’s wings and crown is one of the fastest ways to separate a kestrel from any other small raptor in an Illinois field.
American Kestrels are common year-round residents across the state, frequently found in open areas such as grasslands, farmlands, and even urban settings, often perching on wires or treetops along roadsides. Birders in the Chicago area have even found them nesting in laundry vents on old apartment buildings, proof of how comfortable this species is around people.
Pro Tip: Watch open fields and roadsides on calm, sunny afternoons. Kestrels hover with rapid wingbeats while scanning the ground, a hunting behavior that makes them far easier to spot than most other Illinois raptors.
On the menu, American Kestrels eat small creatures including insects, reptiles, amphibians, birds, and rodents. That diet regularly includes grasshoppers and dragonflies, along with the occasional bee or beetle plucked out of midair, plus small frogs found near field edges.
The population trend behind this small falcon is sobering. The colorful American Kestrel, the smallest and some say the fiercest falcon on the continent, has lost half its population in the past 50 years. According to the Cornell Lab’s All About Birds, kestrels are listed as endangered or threatened in four northeastern states, and 21 states list them as a species of concern, though Illinois has not yet added the bird to its own threatened list.
Scientists still disagree on the exact cause. “Birds like kestrels, they are such good conservation tools because they’re colorful; they’re charismatic; people love raptors,” says Chad Witko, Audubon’s senior coordinator of avian biology for the Migratory Bird Initiative, in comments reported by Audubon. Habitat loss and a shortage of nesting cavities are the leading suspects, which is why volunteer groups across the region have turned to a simple fix.
The American Kestrel is comfortable around people, and will quite commonly use human-made nest boxes to raise their young. In Kane County, that idea grew from a single college research project into a much larger effort. The effort began in 2012 when a Forest Preserve District of Kane County intern installed 12 nest boxes in six area forest preserves, with that first year rewarded by the successful fledging of five kestrels. Homeowners near open farmland or grassland can support the species the same way, by installing and monitoring a properly sized nest box.
2. Merlin
The Merlin (Falco columbarius) is a compact, muscular falcon that punches even harder than the kestrel relative to its size. Illinois hosts three species of falcons on an annual basis, and the Merlin is one of them, though it is far less commonly seen than the kestrel because it passes through mostly during migration.
Size-wise, Merlins measure 9.4 to 11.8 inches in length, weigh 5.6 to 8.5 ounces, and have a wingspan of 20.9 to 26.8 inches, making them only slightly larger than a kestrel but noticeably stockier. According to Biology Insights, Merlins are primarily seen in Illinois during spring and fall migration periods, though some may remain as rare winter residents, tending to frequent woodland edges and open areas, with their migration through the state typically occurring in March and then again in August.
Don’t let the small size fool you into thinking this bird is timid. Despite its diminutive stature, this falcon is an incredibly fierce bird that uses surprise attacks to bring down its prey, and it has even been seen attacking trains and cars that enter its territory. Listen for its voice near a nest site: it’s possible to hear a loud, high cackle that sounds like “klee-klee-klee,” typically made during courtship or when showing aggression.
Key Insight: Merlins hunt in pairs more often than most falcons.
Mated pairs have been known to work cooperatively, with one driving prey right into the claws of their partner, a tactic that makes them unusually effective at catching small songbirds on the wing. Unlike many raptors, Merlins rarely build their own nests from scratch. Like most falcons, Merlins don’t build their own nests but instead reuse other birds’ abandoned homes, favoring nests built by crows, jays, hawks, or magpies, and it’s also rare for them to reuse the same nest, instead opting to locate a new one each breeding season.
Merlins are also showing up in places they historically avoided. They tend to frequent woodland edges and open areas, and have increasingly been observed in urban and suburban environments, a pattern that mirrors the kind of birdwatching-friendly shift seen with other adaptable species that share Illinois neighborhoods, including some of the long-tailed songbirds that Merlins occasionally hunt.
3. Peregrine Falcon
The Peregrine Falcon (Falco peregrinus) is the headline act among Illinois raptors, and for good reason. Known for being the fastest bird on Earth, it can reach diving speeds exceeding 200 miles per hour when hunting, with Bird Feeder Hub noting that some sources claim speeds up to 240 mph during a dive.
Identification is fairly straightforward once you know the marks to look for. Adult Peregrines display a sleek, slate-gray back, white underside, and a sharply defined dark “mustache” mark on each side of their face, typically measuring 14 to 19 inches in length with a wingspan of 3.3 to 3.6 feet. According to Own Yard Life, those long, pointed wings let the bird “slice through the air with deadly precision” when striking prey in mid-flight.
The Peregrine’s story in Illinois is one of near-total loss followed by a genuine comeback. The peregrine falcon was extirpated from the state in the mid-20th century due to the rampant use of pesticides, but since then, they have been reintroduced, and their numbers have recovered. Historically, Peregrines nested on cliff faces along the Mississippi River, but following their reintroduction in the 1980s, many have adapted to urban life, and today they frequently nest on tall skyscrapers, bridges, and towers in major Illinois cities such as Chicago, where buildings mimic the high cliffs of their ancestral homes.
Important Note: The recovery of the Peregrine Falcon population, once endangered due to DDT poisoning, stands as a significant conservation success story. The species remains protected under federal law even though it has been removed from the endangered species list.
Chicago itself deserves special mention among peregrine hotspots. The city of Chicago is one of the best locations to find Peregrine Falcons, as the open spaces along the lake and tall buildings to nest on provide fantastic habitat. Beyond the city, AviBirds points to several other reliable spots: Illinois Beach State Park, where the diverse habitat of dunes, marshes, and forests attracts a variety of falcon species; the Mississippi Palisades State Park, which offers stunning bluffs overlooking the Mississippi River; and the Chautauqua National Wildlife Refuge, a hidden gem for birdwatching. Wetland-heavy sites like these also draw wading birds such as herons, so patient birders often come away with more than one good sighting.
Peregrines are not picky eaters, and their prey list is remarkably long. According to Bird Watching HQ, Peregrine Falcons primarily eat other birds, with at least 450 different types of birds documented as their prey, taking almost anything they can catch, including ducks, gulls, pigeons, and songbirds. These raptors have been observed killing individuals as small as a hummingbird, and as large as a Sandhill Crane, which says a lot about the size range this falcon is willing to tackle. Anyone curious about the tiny birds occasionally caught up in that prey list can learn more from this guide to hummingbirds in Illinois.
Peregrines aren’t especially vocal outside the nesting season. You won’t hear a Peregrine Falcon make much noise, except for around its nesting site as an alarm call, which sounds like “kack-kack-kack-kack”. During migration, they range far beyond their nest sites. They are spotted statewide, from suburban rooftops to expansive open habitats like lakeshores and river valleys, and while migratory, they can remain year-round in urban centers where food is abundant.
Illinois’s three resident falcon species cover a remarkable amount of ground between them, from farmland roadside perches to skyscraper ledges above the Chicago skyline. Kestrels reward patient roadside watching, Merlins are worth chasing during the March and August migration windows, and Peregrines can turn up almost anywhere with tall buildings or open water nearby. Birders who enjoy tracking regional raptor differences might also want to see how these same three species compare across state lines, with detailed guides covering the falcons found in Ohio, the falcons found in Florida, and the falcons found in Colorado.