Twice a year, Chicago hosts a massive tweet-up for migrating birds.

Craig Taylor stoops to scan Lake Michigan's surface through his prized Swarovski spotting scope. Perched at the end of a pier locals call the Fish Hook, he pivots the instrument on its tripod, sweeping his line of sight past Canada geese and red-breasted mergansers.

Word has it a western grebe-rare for Illinois-was spotted days earlier just north of here near Montrose Point Bird Sanctuary on Chicago's North Side. And just before that, this spot set the social media birding world aflutter with an influx of snowy owl sightings.

Montrose Point Bird Sanctuary
Montrose Point Bird Sanctuary. Photo courtesy of Chicago Park District. 

It turns out that America's third-largest metropolis is also one of its most-birded locations. More than 7 million migrating birds pause in Chicago each spring and fall, drawn to the vast city park network as they congregate along Lake Michigan's shore.

"People don't think about a major metropolitan area as a place you would go to enjoy nature," says Geoff Williamson of the Illinois Ornithological Records Committee. "But it's absolutely fabulous."

A mix of location, amenities and wind patterns has landed Chicago its five-star status among winged travelers and their non-feathered fans. Chicago sprawls along the Mississippi Flyway, a migration route that birds use to travel from the tropics, up the Mississippi River Valley and along the Great Lakes to northwest Canada. The lake to the city's east and farmland to the west serve as fine flyover territory, but not as prime places to land for food and rest.

The city's green spaces offer the food and shelter birds need after a night of travel. Westerly winds help nudge them toward the city. Once there, they seek out parks and marshes-a funneling that gives some areas 10 times more migrating birds than others.

The Chicago Park District's focus on developing natural areas-planting cattails at the edges of beach dunes near Montrose Point Bird Sanctuary, for example-has helped re-establish the city as a friendly stopping place.

Spring migration runs from March through early June, with a sweet spot in the second to third weeks of May. "All their hormones are in high gear, and everybody is singing their heads off," says Greg Neise, founder of the Illinois Birding Network.

Blue-gray gnatcatcher
Blue-gray gnatcatcher. Photo courtesy of Chicago Park District.

Chicago has an active and inviting birding community that supports free bird outings, including a walk at Wooded Island every Saturday morning led by the Chicago Audubon Society. A guide and longtime participants will gladly share tips on where to look and what to listen for on this leisurely paced adventure.

About 21,000 Facebook users follow the Illinois Birding Network, where enthusiasts share sightings, tips and photos. You can also search for Bird the Preserves events held in Chicago-area forest preserves. And then, there's simply asking anyone with a scope trained on the sky and a field guide in hand. "Birders love new birders," says Judy Pollock with the Forest Preserves of Cook County. "It's a friendly crowd."