CHICAGO — Avian flu has likely killed hundreds of double-crested cormorants nesting at Baker’s Lake near Barrington.
Wildlife biologist Chris Anchor said this is the largest outbreak of disease in wild birds he’s seen in Cook County.
“I’ve never seen anything like this since I started working here 41 years ago,” said Anchor, of the Forest Preserve District of Cook County. “Chances are this is happening in other places, and we’re not aware of it because no one is looking.”
The outbreak, which affects wild, backyard and commercial bird populations, was likely caused by the same highly infectious strain of avian flu that is sweeping the country.
Since early February, more than 23 million birds in commercial flocks have been killed by avian flu or euthanized due to the outbreak, mostly outside Illinois, according to the U.S. Department of Agriculture.
Cases have been reported in 24 states this year, with Iowa the hardest hit, The Associated Press reported. While poultry remains safe to eat as long as it’s properly cooked, the prices of eggs and other poultry-related foods are soaring.
Federal and state officials said this is the worst avian influenza outbreak in the United States since 2015, when more than 50 million birds died from the flu or were euthanized.
In Illinois, officials closed Emiquon National Wildlife Refuge and Emiquon Preserve in west-central Illinois from March 16 to March 25 after a likely outbreak among migratory geese. According to the USDA, avian flu was detected in a handful of wild birds found dead in Will, Champaign and other counties in March.
The outbreak at Baker’s Lake, which is about 40 miles northwest of Chicago, appears to be the first large die-off of wild birds from the disease in Illinois, Anchor said. The state pathologist confirmed that seven double-crested cormorants discovered dead at the rookery tested positive for avian flu, he said.
Anchor collected the birds a few days ago after wading into the lake near the rookery where he discovered hundreds dead, some of them floating among the cattails and vegetation.
Though bird flu typically does not infect people, there have been some rare cases of human infection, according to the Centers for Disease Control and Prevention.
Anchor cautioned the public to avoid getting near or touching wild birds that look sick or are dead, especially aquatic birds and birds of prey.
Lincoln Park Zoo, Brookfield Zoo and other institutions recently brought their birds in exhibits indoors to protect them from wild birds that may be passing along the disease. “It’s a precaution,” Anchor said.
Avian flu, in particular, shows up in wild raptors, shorebirds, geese, ducks and other aquatic birds such as cormorants, as well as domestic chickens, turkeys, ducks and geese. And there are many different strains, some less lethal than others.
“The recent one is very deadly,” said Michael P. Ward, senior ornithologist with the Illinois Natural History Survey. “If the bird gets it, it dies.”
That’s one reason many cormorants may have succumbed to the disease at Baker’s Lake. These birds are colonial nesters, breeding closely together, making transmission of the disease easy, Ward said.
“There’s always avian flu going around, but this highly pathogenic version of it doesn’t show up often,” he said. “It’s usually found with waterfowl in tight areas and can cause a mass mortality event.”
“It often burns itself out quickly,” Ward said, adding he hopes that’s what will happen with the birds at Baker’s Lake.
Officials are remaining watchful because birds like cormorants are still migrating this time of year and can carry it with them to different areas.
“Herons, egrets, cormorants all get together in these rookeries where the disease can spread rapidly,” Ward said.
Though the chances of humans getting avian flu are very rare, Ward said, “It’s something we’re more concerned about these days, given that COVID (likely) jumped from wildlife to humans.”
Avian influenza spreads through direct, bird-to-bird contact. It can also spread to birds via contaminated surfaces and materials, including people’s clothing, shoes or hands, according to the USDA.
Birds that live in close quarters, like ducks and colonial nesters, are also susceptible to other diseases. Each summer, about a dozen of the birds at Baker’s Lake are found dead from a fungal disease called histoplasmosis or a viral disease called Newcastle disease, said Anchor. Both diseases affect domestic birds, and histoplasmosis can be transferred to humans.
Anchor learned about the dead cormorants after being notified by Tom Regan, of Barrington, who was watching birds at Baker’s Lake.
“I saw one dead bird and thought, ‘Oh, that’s not unusual with a big colony on the island. Then I see these others dying — about 10 or 20 — seeming to be writhing in pain,’” Regan said.
Great egrets, which also nest at Baker’s Lake, were flying around and seemed OK, he said. Great egrets and double-crested cormorants were at one time listed as endangered breeding birds in Illinois.
“When you see a large percentage of a population of birds disappear, it’s very dramatic and many people think it’s tragic,” Anchor said. “The birds become disoriented. They become uncoordinated. It’s part of nature.”
Reporting these sightings is important, according to the Illinois Department of Natural Resources. If people encounter five or more dead wild waterfowl, water birds or raptors in one location, they should contact their local IDNR district wildlife biologist (www.wildlifeillinois.org/sidebar/contact-an-idnr-district-wildlife-biologist) or USDA Wildlife Services at (866) 487-3297.
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