Peregrine falcons show signs of national decline, but not in Maine

Yahoo

27-05-2025

May 27—After rebounding from near extinction, Maine's peregrine falcons appear to be holding steady, producing more chicks than usual last year to remain seemingly unaffected by the avian flu that is killing peregrines in other shoreline states.
In 2024, about 35 years after their reintroduction to Maine, 33 peregrine falcon pairs raised 46 babies to their fledgling stage, or at least 28 days of age, resulting in a productivity rate of 1.39. That's better than 2023, when 30 pairs produced 37 fledglings, above the population's five-year productivity average.
A new state report documents the peregrine falcon's status, laying out the productivity numbers but also raising concern about the future of a crow-sized bird that's celebrated as the fastest animal on the planet, capable of diving at speeds of up to 200 miles per hour.
"Despite this relative stability in productivity in Maine, there is growing concern in other regions," said Erynn Call, state raptor biologist and report author. "In 2024, New Jersey and Virginia reported sharp declines in productivity and unusually high adult turnover, raising alarms among peregrine biologists."
The nest success rate in New Jersey fell from 83% in 2023 to 63% in 2024, with an exceptionally high adult turnover rate due to highly pathogenic avian influenza, or HPAI, according to the report. Virginia's adult turnover rate more than doubled to 40%, with rates as high as 63.2% along the coasts.
In other parts of the U.S., observers have documented significant drops in occupancy: 48% in Montana, 30% in New Mexico and 43% in Nevada. Steep declines have been reported internationally, in Denmark, France and Germany to Norway, as well as Sweden and Switzerland to as far away as Russia and Malaysia.
In the report, Call says the pace and scale of these worldwide losses represent the most significant threat to peregrines since the DDT era, when widespread pesticide use caused the peregrine to disappear from Maine. The population collapse prompted state and federal regulators to declare the falcon endangered.
Recovery began when DDT was banned. Peregrines were reintroduced to Maine in the 1980s, with 153 young birds released over a period of years. They began to nest here again in 1988, about 25 years after the last known breeding pair had been seen in Maine.
While HPAI has been found in other wild birds in Maine, including Canada geese, red-tailed hawks and great horned owls as well as ducks, gulls and shorebirds, no peregrine falcons have tested positive for it, according to Tegwin Taylor, a wildlife biologist at Maine Department of Inland Fisheries and Wildlife.
To date, five peregrines have been tested during treatment for injuries at a wildlife rehabilitation center.
"While it's limited information, it's generally good news for peregrines in Maine!" Taylor said.
Call and Taylor are not sure why Maine's peregrine falcons seem to have avoided the flu deaths of other coastal states, but say it could be because Maine peregrines tend to hunt songbirds, which are less likely to carry HPAI than the shorebirds and waterfowl favored by peregrines of other coastal states.
Both Call and Taylor warn against reading too much into the HPAI testing results, noting there are still fewer than 50 nesting pairs of peregrine falcons in Maine. With a population that small, the loss of one bird, much less a nesting pair, is meaningful.
Due to limited resources, state observers could not visit every potential falcon nesting site last year, nor locate every missing peregrine, so it is possible that a peregrine could have died from HPAI and remain undocumented, they warn.
Looking beyond the fledgling count and bird flu, Call points to other signs of a stressed state population.
Limited testing of injured peregrine fledglings and eggs shows high levels of lead and forever chemicals, contaminants that could hurt the peregrine's ability to successfully reproduce, Call said. More tests are needed to understand the exposure and risks.
The presence of single birds at four nesting sites could also mean the population was not big enough for all of Maine's peregrines to find a mate. In others, the mate was a young, second-year falcon who had a harder time successfully raising chicks because they are still developing their hunting and nesting skills.
But last year's count found other signs of hope, too, in newly discovered nests: at the Ripogenus Dam on the west branch of the Penobscot about 40 miles west of Millinocket, on Casco Bay's Cushing Island, and in a nesting box recently installed by Sappi Mill in Skowhegan.
The peregrine falcon was removed from the federal endangered species list in 1999, its numbers robust enough to allow permitted captures in small numbers for hunting purposes. But it's still on Maine's list because of the small size of the local population and its sensitivity to nesting disturbance.
Peregrines like to nest up high on cliffs, quarry walls, buildings, bridges or towers. They will defend the nest aggressively, which can pose problems for both people and birds. Eggs can get knocked out of nests, chicks can fall and fledglings take flight too early.
When a nest is found, Call works with landowners to minimize disturbances. Visitors to Acadia National Park may be familiar with the peregrine's nesting season due to the March-August closure of the popular Precipice Trail.
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