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Peregrine falcon monitoring remains relevant in Iowa due to threat of bird flu
The Iowa DNR reports that in 2025, four peregrine falcons died from the highly pathogenic avian influenza
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Peregrine falcon reproduction in Iowa “likely remains stable” following successful reintroduction efforts in the 1990s, but the Iowa Department of Natural Resources said monitoring still is warranted due to the threat of bird flu on the recovering bird population.
According to the 2025 peregrine falcon report, four peregrine falcons died from the highly pathogenic avian influenza outside of nesting season that year.
“Overall, Iowa’s nesting population of Peregrine Falcons appears to be stable, with birds generally returning to historic nesting sites each year, but this recovering population continues to warrant annual monitoring,” the report reads.
The highly pathogenic avian influenza, which has notably killed millions of commercial poultry and egg-laying birds, also spreads among wild migrating birds. The virus primarily infects waterfowl and shorebirds, but can also reach birds of prey like peregrine falcons, osprey and eagles that feast on the other birds.
Volunteers and trained surveyors monitored 20 nests in 2025, of which 13 were deemed successful, meaning the nests raised young birds to the fledgling stage. Volunteers, some of which are employees at power plants since the birds like to nest on energy plant towers, observe the nests several times throughout the year and record if the birds have mated and how many young are in the nest.
There were three more nests monitored in 2025 than in 2024, however the report said none of the 2025 nests were new nests. In 2024, DNR reported peregrine falcons had an above average year for reproduction with an average of 2.77 young per nest and a total of 36 young birds fledged, or surviving to the age of flying.
Reproduction statistics in 2025 were lower, with an average of 1.87 young per nest and a total of 28 fledged, but DNR said the 2025 statistics are similar to the three years prior, which indicates falcon reproduction is stable. Of the 20 monitored nests, one was inactive and four had an unknown outcome.
The birds of prey have dark colored caps, a stripe under their eye and slate blue colored backs with white, speckled chests. The crow-sized birds tend to be monogamous, according to DNR, and will reuse nest sites for several years.
Many peregrine falcon nesting sites in Iowa have their own livestreams, like the nest on the Dubuque County Courthouse.
In Iowa, the birds tend to nest primarily in Eastern Iowa on Mississippi River cliff faces, urban settings or on electrical towers.
Peregrine falcons disappeared from Iowa in the 1950s as they — like many other birds — were impacted by pesticides like DDT. A total of 169 peregrine falcons were released in Iowa between 1989 and 2003 in an effort to reintroduce the bird to the state.
Information on peregrine falcon and other wildlife monitoring programs can be found online.
This article was first published by Iowa Capital Dispatch.
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