A Canada goose attempts a landing on the ice on Union Grove Lake in rural Gladbrook back on Jan. 1. The lake is part of Union Grove State Park in Tama County. Dozens of dead geese probable for avian influenza have been discovered in the park since December 2024. PHOTO BY RUBY F. MCALLISTER

Avian influenza (bird flu) is impacting wild birds worldwide and causing outbreaks in U.S. poultry and dairy cows, with human cases mainly reported in dairy and poultry workers. Presumptive positives have been reported in Tama and Marshall counties. But says Rachel Ruden, wildlife veterinarian at the Iowa DNR, who is based in Ames, the threat to the public is relatively low.

“The lion’s share of human transmission of this current strain have been associated with close contact to either sick poultry or sick dairy cattle,” she said.

Last week, the U.S.’s first bird flu death was reported in Louisiana. There have been 66 reported human H5N1 cases since the start of 2024. (Editor’s note: Since this story was first published in the Times-Republican newspaper, the number of reported human H5N1 cases has increased to 67.)

At Marshalltown’s Riverside Cemetery in December, a small number of visiting Canada geese died while stopping over at Lake Woodmere.

“We do not have a specific diagnosis for their illness and deaths. We worked with DNR wildlife biologists and followed their recommendations on containing the spread of any contagious disease: as soon as we noticed a bird that wasn’t moving, our team removed it and disposed of it according to DNR recommendations,” Interim General Manager Deirdre Gruendler said. “Local wildlife experts recommended that we not attempt to relocate our resident birds during this time period as that was likely to cause greater stress to them than anything contagious. We didn’t see any evidence that the flu spread to our flock.”

These birds, says Ruden, are presumptive positives for bird flu based on symptoms, and not actual testing, as she worked on the case at Riverside.

“If we can see sick birds displaying classic influenza signs visually — neck twisting, head tremors, and cluster or accumulating mortality of birds — those are presumptive positives for bird flu,” she said.

She added that reports of suspected bird flu peaked in Iowa from Dec. 8-21.

“It’s been tapering since then, which is good news, and what we would expect, as the Canada goose migration peaks in mid-December,” Ruden added. “Migration is a really stressful time in a bird’s life and with how cold it’s been, water sources have been closed off, meaning lots of birds congregated around open water sources. This is the case everywhere and not (just Iowa).”

She said while testing has been done across the state, it’s not done in every case.

“After documenting that first wave, we’re focusing on species that are less represented like raptors, hawks, owls and eagles scavenging on carcasses,” she noted. “Younger birds have a higher risk of contracting disease.”

She also responded to presumptive positive bird flu in Union Grove State Park in Tama County, alongside DNR wildlife management biologist Rodney Ellingson.

“I went up to view the site. There were approximately 40 dead geese at Union Grove throughout December/January that I’m aware of,” Ellingson said.

He added that he gets several calls per week on suspected bird flu. He responds mostly by phone, as cases have been widespread in the counties he represents including Marshall, Tama, Iowa and Poweshiek.

“I have visited a few sites if they have had higher numbers of dead birds, Canada geese mostly,” he added.

Ruden said the best way to dispose of a bird carcass is to double bag it for the landfill or your normal trash stream. But be sure to wear gloves. Note, some city ordinances do not accept animal carcasses in the garbage. Check before doing so.

She said people should continue to put out bird feeders.

“The species that are impacted by avian influenza do not include those that would be the regular attendees at bird feeders, so we do not recommend taking down bird feeders related to influenza unless they are waterside properties with waterfowl in attendance,” she noted. “Your standard backyard birds wouldn’t encounter the species that might be harboring influenza to be able to bring it back to the feeder. There are so few reports of songbirds that have been impacted.”

She recommends cleaning bird feeders every two weeks with a diluted bleach solution — 10% bleach to 90% water.

Cleaning will also help protect against other highly contagious illnesses such as conjunctivitis (also known as Finch Eye Disease).