What are all these Chicago ducks and gulls eating this winter?

A look at the Lake Michigan fishery from an avian point of view.

Lake Michigan is a fishery that’s…..been through some stuff. Invasive species from sea lamprey to alewives to zebra and quagga mussels have altered the lake in innumerable ways. Those ecological changes have impacts on people and wildlife alike.

“It used to be that it almost all was commercial fishing for lake species,” says Tomas Höök, Director of Illinois Indiana Sea Grant and Professor in Purdue’s Department of Forestry and Natural Resources, “and that has changed dramatically to where with salmon stocking it is almost all toward recreational fishing. There’s really no commercial fishing in Illinois and Indiana at all any more.”

At this time of year one of the more apparent birding phenomena is the massive groups of wintering waterfowl on the Chicago lakefront. Gulls are right there with the ducks and geese, too. In a cold February like this year’s, waterfowl and gulls congregate around the few patches of open water. That was the case about a week ago at Chicago’s Jackson Harbor on the South Side. There Great Black-backed Gulls, Iceland Gulls and Herring Gulls stood on the edge of the ice, plucking fish from the water along Lake Shore Drive. Later in the year, we’ll see Double-crested Cormorants and Caspian Terns making the most of Lake Michigan’s fish stock. Here’s a recent video showing the scene in Jackson Harbor:

Höök told me that some open-water fish will move into harbors during winter, which may make them more vulnerable. The native gulls and waterfowl tend to prey on the invasive species, interestingly enough.

“The species that people tend to care about from a recreational fishery perspective are salmon and yellow perch,” Höök says. “We know from studies that birds tend to like alewife and goby. There’s some thought that there’s a preference for soft ray fishes, with soft fin rays, unlike the perch [which has spiny fins].”

When I began focusing on environmental work full-time in 2018, one of the first books I read was Dan Egan’s landmark “Death and Life of the Great Lakes.” One of the more obvious changes in Lake Michigan (actually Lake Michigan-Huron, which is one very large lake connected at the Straits of Mackinac) in the last four decades is the introduction of zebra and quagga mussels. The bivalves have filtered out zooplankton and increased water clarity. That has all sorts of impacts, including on the growth of Cladophora algae, another detriment to the ecosystem, and the source of avian botulism.

The Sea Grant program, a cooperative among NOAA (National Oceanic and Atmospheric Administration), Purdue University and the University of Illinois, uses research, outreach, and education to bring the latest science to Great Lakes communities and their residents. Höök’s outlook for the lake is more sanguine than I suspected. Several native lake species’ populations are increasing, in part due to re-stocking. Lake trout, cisco, grayling and sturgeon are on the comeback. Meanwhile, though, gulls and diving ducks are finding what they need in the lake.  

“That’s kind of cool,” Höök says of the native species. “Lake Michigan is never going to return to a natural state. It’s managing a number of different fish populations for a number of different needs, commercial, recreational and conservation and managing it for different purposes.”

An appreciation for the Great Blacked-backed Gull

Cornell Lab of Ornithology refers to the Great Black-backed Gull, the largest gull in the world, as the “king of the Atlantic waterfront.” All regal metaphors aside, these mighty members of the genus Larus are a thrill to see most any time, especially when they make their way to Lake Michigan in winter.

Great Black-backed Gulls are almost the same size as a Bald Eagle. The striking black-and-white predators tower over our local Herring Gulls, large birds in their own right. The Great Black-backed Gull is opportunistic and follows fishing boats, takes garbage from trash cans, harries other seabirds and preys on smaller birds, eggs and chicks.

They’re one of those birds that captures the imagination, and just uncommon enough to make every sighting a lot of fun.

The lakefront re-opens, finally

It’s the news many of us have been waiting for: the lakefront is re-open to vehicle traffic! It’s the latest and hopefully last chapter in the strange saga of lakefront closings and openings since the start of the pandemic. This is good news for birders and lakefront residents alike. One of our city’s greatest assets has been basically unavailable for the past year. With spring migration on the horizon, it’s great timing, too.

TWiB Notes

Two weeks ago, I wrote about the Brant that made its way from Wisconsin and Illinois to Indiana. Here is a video clip by Mitchell Wenkus featuring the Brant in Chicago, and other wintering waterfowl…..J. Drew Lanham wrote an amazing piece for Audubon Magazine about John James Audubon and what to do about his racist legacy. It’s worth a read, especially if you have been an admirer of Audubon…..The Chicago Park District has allocated $1.5 million in TIF funds to build a 3-mile trail as well as camping platforms at Big Marsh Park, a top birding site on the South Side…..Thursday’s installment of Birds & Bytes with Chicago Ornithological Society will feature Pam Karlson and the fabulous bird garden she’s created in her Chicago back yard. Register here.…..I’ll be showing “Monty and Rose” on Tuesday night with the Black River Audubon Society in my home state of Ohio…..I had a Common Grackle calling and flying around my neighborhood yesterday morning. It’s my first since late October.

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