Photo by Steven Sachs, Audubon Photography Awards
By Steve Hampton
I saw a Peregrine Falcon recently. We were birding the farmlands south of Chimacum, Washington. Walking a big loop through the fields, we were just about back to the car when we saw it soaring on stiff wings, so high up our cameras struggled to focus on the little dot in the sky. After a few circles, it flapped once, tucked, and went into the longest, steepest power dive I’ve ever seen a peregrine make – at least 400 feet nearly straight down. It pulled out at the end, about 20 feet above the ground, but ready to hunt again. It was a good-sized bird, probably a badass female (which are bigger than the males).
This was the first peregrine I’ve seen all year, and it’s already late September. According to my eBird records, in 2024, I saw them seven times; in 2023, six times; in 2022, ten times; and in 2021, twelve times. That feels about right. So what happened this year?
It wasn’t just me. It has been the same story across North America and Europe. In fact, my tiny data set tracks with other more systematic surveys.
For decades, the Peregrine Falcon, along with the Bald Eagle, has been a poster child of recovery since DDT was banned in 1972. By 1999, they were removed from the federal endangered species list. I began to see them every year, often in fall, chasing sandpipers or ducks at a local wetland.
Then came avian flu. It reached North America in 2014, though big outbreaks weren’t detected until a few years later. The virus first spread among waterfowl and gulls — and then jumped to a wide variety of seabirds. These are all top of the menus for a Peregrine Falcon. One of its historic names is “Duck Hawk.”
Last December, the journal Viruses published this paper: Highly Pathogenic Avian Influenza Contributes to the Population Decline of the Peregrine Falcon (Falco peregrinus) in The Netherlands. It reported that, of 32 peregrine falcon carcasses analyzed, 28 were positive for the virus. They reported a steady increase in peregrines since 1990, to about 120 individuals by 2011. This number stayed level until a series of avian flu outbreaks, which began 2016. Since then, their numbers have nearly halved.
The Netherlands study compared the specific variants of avian flu from the dead falcons to potential prey items. They found that, in the 2016 outbreak, the infected falcons matched the infected swans and geese, suggesting the falcons acquired the flu after scavenging on carcasses. They recommended carcass collection to minimize exposure to raptors. In later outbreaks, the falcons were linked to a strain associated with Black-headed Gulls.
In Scotland, avian flu impacts on other raptors, such as Golden Eagles and White-tailed Eagle, have been well-documented. A recent study of 50-60 known peregrine eyries found that, after an avian flu outbreak in 2022, the number of pairs with a sub-adult quadrupled (from 4% to 16%), while the number of fledged young fell to an all-time low. The total number of active nests, however, only slightly declined.
In North America, National Audubon reported on declines across the continent. New Jersey reported a 50% decline in breeding pairs. Along the upper Yukon River in Alaska, a third of the nest sites were abandoned or had only one falcon present. In the San Juan Islands, Bud Anderson noted that the breeding population has fallen from 18 pairs to just two. Peregrine experts were unanimous – this all coincides with avian flu.
Looking at eBird data, observations of Peregrine Falcons follow a clear annual pattern, peaking in the last week of September thru the first two weeks in October. I focused on peak frequency for each year, 2015 thru 2024. Peregrine Falcon sightings have dropped 50%. Frequency (the percentage of eBird checklists that report a Peregrine Falcon) has fallen from 4% (at its annual maximum) to about 2%. I expect this year’s peak frequency to be even lower.
The decline frequency on eBird reports has been even more dramatic in Washington State, where peregrines eat a lot of waterfowl.
There is some hope. During their recovery, peregrines famously moved into cities. New York City alone has about 30 nesting pairs. Their nests on bridges and skyscrapers are often featured on live webcams. They often feast on regular old city pigeons. This has somewhat insulated these birds from avian flu, while their cousins feasting on ducks from coastal marshes have been heavily impacted.
The current decline in Peregrine Falcons has been so recent and quick that it’s easy to be fooled by maps and charts that don’t include the last few years. eBird’s trends map for the peregrine, which focuses on the breeding season, 2012-2022, shows a 10.3% increase during that time period in the US. In the Pacific Northwest west of the Cascades, where I live, all the dots on their trends map are blue (meaning an increase) or white (meaning no statistical change). But the eBird trends analysis doesn’t cover the last three years.
Last year, the Washington Department of Fish and Wildlife published their Periodic Status Review for the Peregrine Falcon, based on data up to 2021. The executive summary concludes:
“The species continues to increase in abundance and as of December 2021 there were 190 known breeding territories in Washington, far exceeding historical levels and estimates of future abundance presented in the 2002 status review. The population has continued to increase across its range in North America. The status of the Peregrine Falcon in Washington is secure, and we recommend that its current designated status as a delisted species be maintained.”
The WDFW webpage still reads today, “Peregrine falcons have experienced a remarkable recovery and the population continues to increase across Washington.”
For all of us, it’s time to update what we understand about this magnificent and iconic bird. Hopefully, they’ll recover again.
Steve is a writer, researcher, and retired from the California Department of Fish & Wildlife where he was involved in oil spill response, natural resource damage assessment, and habitat restoration. He was a program speaker for SSBA in December 2022 on birds and climate change and lives in Port Townsend. You can access the entire article with graphs at https://schampton.substack.com/p/where-have-all-the-peregrines-gone
