One thing disturbing is occurring to Peregrine Falcons in North America. Their numbers are heading downward for the primary because the Nineteen Sixties and ’70s, when the birds had been teetering on the fringe of extinction as a result of widespread use of the pesticide DDT. Fortunately, a large Peregrine Falcon recovery effort was launched in response, producing 1000’s of captive-bred falcons and releasing them throughout North America. It was a spectacular success, with the birds’ numbers growing nationwide by greater than 5 % a 12 months for many years. In 1999, the Peregrine Falcon was lastly faraway from the Endangered Species Listing—a exceptional achievement within the annals of conservation.
I’m proud to say I used to be a part of the unique cohort of raptor lovers who helped save Peregrine Falcons all through the Nineteen Seventies. None of us ever imagined we might ever see this species declining in numbers once more in our lifetime. However sadly, greater than half a century since these heady days, the Peregrine Falcon is likely to be in hassle as soon as extra.
I just lately spoke with Kathy Clark, chief of New Jersey’s Endangered and Nongame Species Program, who advised me that the Peregrines nesting in her state have had an abnormally excessive grownup alternative fee for the previous couple of years. Wholesome raptor populations at all times have an excellent provide of floaters—non-breeding adults which might be able to step in if one or each birds at an eyrie die. But when the excess dwindles, a species can run into issues, which is what occurred when DDT induced the birds to put skinny shells that usually didn’t hatch. There have been simply not sufficient additional falcons to exchange the breeders when wanted.
This appears to be taking place now, and Clark would know. These New Jersey birds are a few of the best-monitored Peregrine Falcons on the planet. A lot of the nesting adults are banded, so researchers know when a falcon goes lacking. In lots of different locations, folks can solely do occupancy counts at identified Peregrine nests. A pair of adults is likely to be current, however there isn’t any means of understanding if it’s the authentic pair or some new arrivals.
“Of 44 nesting Peregrines, half of them had been lacking this 12 months,” says Clark. That’s a 50 % alternative fee, however for those who look simply at coastal eyries, it’s a whopping 63 %. “Our regular alternative fee is about 15 %,” she says.
Make no mistake: These lacking birds are useless.
Make no mistake: These lacking birds are useless. A falcon is not going to abandon its nest territory. Along with the turnover of adults, two New Jersey eyries had been unoccupied this 12 months, and a 3rd beforehand energetic nest web site was occupied by a first-year feminine and a second-year male. The nest failed. Youthful birds like this are not often as profitable at producing younger as older, extra skilled adults.
“A number of the banded birds are vanishing and being changed, often by birds which might be additionally banded, so we all know who they’re,” Clark says. “Previously, there have been at all times sufficient floaters {that a} lacking chook would get replaced immediately.”
Virginia has a monitoring program very similar to New Jersey’s, and many of the state’s nesting Peregrines are banded. Bryan Watts, director of the Middle for Conservation Biology at William and Mary School, has observed an analogous spike within the grownup turnover fee at Peregrines eyries in Virginia.
“We’ve had some turnover up to now, nevertheless it was nothing like this 12 months,” he says. “Right here alongside the Atlantic Coast, the birds are often changed shortly, sometimes inside days. However this 12 months we had two vacant territories on the coast and a few nests had second-year females, which is a priority. This implies that the floater pool is stretched skinny.”
What might be inflicting this? Some have recommended {that a} decline in prey species or contamination by neonicotinoid pesticides or flame retardants is likely to be guilty. However others, together with myself, suppose a likelier risk is that the useless falcons grew to become contaminated by Extremely Pathogenic Avian Influenza (HPAI), which has been hammering waterfowl, seabirds, and shorebirds for the previous few years. It’s fascinating to notice that the worst turnover charges in New Jersey and Virginia occurred in coastal areas, the place these species make up extra of the Peregrine’s prey base.
To this point, the proof is circumstantial however compelling. Two useless grownup peregrines have been recovered at nests in New Jersey. One examined constructive for HPAI and the opposite was too decomposed for testing, whereas in Virginia two useless peregrines examined constructive this 12 months. In accordance with the USDA, avian influenza has been confirmed in additional than 50 useless Peregrines nationwide since 2023—however that is definitely a lot decrease than the precise determine. After a falcon feeds on a sick chook, the raptor often simply flies off to a cliff or different distant perch and finally ends up dying there inside a few days. It doesn’t depart behind an simply accessible corpse to check.
This isn’t simply an East Coast downside. I just lately spoke with Skip Ambrose, who started monitoring the Peregrines on the higher Yukon River of Alaska for the U.S. Fish & Wildlife Service in 1973 and has continued ever since—regardless that he’s been retired for a decade. He and his spouse, Chris Florian, have their very own boat now and cruise a 165-mile stretch of the river every year in late Could and June to find out nest-site occupancy, and once more in July to rely the variety of younger falcons the nests produced. He remembers effectively the low level in 1973 when solely 12 Peregrine Falcon eyries in his examine space had been occupied. By 2012, he counted greater than 60 pairs. However within the 2023 and 2024 breeding seasons, the numbers had been clearly falling.
“Adults had been simply lacking,” he says. “We had a bunch of singles.”
In 2024, a 3rd of the nest websites he visited had been unoccupied and a few solely had one falcon current, with no signal of breeding. “The truth that we’re seeing single birds at nest websites implies that the floating inhabitants have to be means down. When one thing occurs to an grownup, there aren’t sufficient replacements to fill in.”
Ambrose speculates that avian influenza is guilty. “I feel it’s too huge of a coincidence that Peregrine numbers are dropping after the arrival of HPAI,” he says. “Peregrines are the right go-look-for-sick-birds machine.” And it’s true—they’re at all times searching for weak, easy-to-capture people. That is nice ecologically, selling the survival and copy of the fittest. But when the prey they eat is affected by a lethal infectious illness, the falcon often dies.
I’ve additionally heard from researchers on the West Coast, reminiscent of Bud Anderson, director of the Falcon Analysis Group in Washington State. “The Peregrines within the San Juan Islands have skilled a calamitous drop,” he says. “We used to see 16 to 18 pairs there, however this 12 months we solely positioned 5 energetic eyries, and solely two of them produced younger.”
Apparently, the Peregrines within the jap a part of Washington State in addition to in cities don’t appear to be affected but. Might or not it’s their weight loss plan? Anderson thinks so. The birds within the jap a part of the state and concrete areas don’t eat as many waterfowl and shorebirds because the coastal birds. There have been huge waterfowl die-offs from avian influenza within the Puget Sound area within the final two years. To this point, seven useless Peregrines have examined constructive in Washington State.
“On the fee that is going, the birds is likely to be extirpated from some areas.”
“Puget Sound helps tens of 1000’s of waterfowl every winter,” he says. “We all know that the Peregrines nesting within the San Juans feed on enormous numbers of waterfowl, however that is much less so in jap Washington and within the cities.”
California can also be being affected. Grainger Hunt is a profession raptor researcher who labored with the Peregrine Fund for a few years. He has been checking 5 native Peregrine eyries close to his dwelling in northern California for 22 years.
“This 12 months, 4 out of the 5 nests failed, and we had our first subadult falcon at one nest,” he tells me. “I consider the birds are dying throughout incubation. That’s when the shorebirds are coming by on migration.”
Hunt additionally believes HPAI is guilty. “It’s simply too coincidental, and it appears extra lethal and chronic than something we’ve seen earlier than,” he says. “On the fee that is going, the birds is likely to be extirpated from some areas.”
There are nonetheless many questions at this level. Is avian influenza certainly inflicting the decline in Peregrine numbers, or is it one thing else? And whether it is HPAI, will it simply sweep by the chook’s inhabitants like a darkish wave after which fade away, leaving the birds to bounce again? Or will it proceed its lethal unfold, which is now infecting birds worldwide, and decimate Peregrine populations to the extent that we’ll want to avoid wasting them once more? It is too early to inform, however those that know the species finest are deeply involved, and that ought to increase alarms for everybody.
Tim Gallagher is a author primarily based in Freeville, New York, and the creator of Falcon Fever, The Grail Hen, Imperial Desires, and three different books.