February 28, 2020
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Acadia falcons’ behavior watched

Contributed | BDN
Contributed | BDN

ACADIA NATIONAL PARK, Maine — There are signs of hope this spring along Precipice Trail and in Valley Cove.

The signs are typical for the season, even if they do not prove fruitful every year. Observers are waiting to see whether two other sites in the park, Beech Cliffs and Jordan Cliffs, also might show some promise of new life.

The four sites are where adult peregrine falcons have been known to nest in recent years in Acadia National Park. Over the past few weeks an adult pair on the east face of Champlain Mountain, where the aptly named Precipice Trail follows a steep, almost sheer path up the cliff, has been behaving as if they are preparing to lay eggs, according to park biologist Bruce Connery. So has another pair that nests at Valley Cove, on the western side of Mount Desert Island, where the east side of St. Sauveur Mountain plummets below the ocean’s surface into Somes Sound.

In keeping with an annual springtime practice, park officials have closed hiking trails near both nest sites in order to prevent human interference with the birds’ reproductive efforts. Park monitors have been visiting the sites, gazing up at the cliffs and scanning the rock faces through binoculars to see whether the falcons are copulating and staking out the areas around the cliffs as their own.

During a visit on an overcast day last week to the bottom of Precipice Trail, Connery said that falcons are fierce defenders of their nesting territories. The raptors can see other birds miles away, he said, and have been known to harass larger birds such as owls and eagles that get too close to their nests.

In a dive, he said, falcons can strike at speeds of up to 100 mph.

“They’re very fast and very aggressive,” Connery said, as one falcon sat atop a rocky outcropping several feet above its nesting site and the other perched in a tree about a hundred yards away. “They’ll go after [other birds] like ugly on an ape. There’s no tolerance at all.”

For decades there were no falcons in the park, or even in Maine. Before 1984, when peregrine falcons were reintroduced to the state, the last time any had been spotted in Maine was in Acadia in the early 1960s, according to Connery.

Charlie Todd, a wildlife biologist with the Maine Department of Inland Fisheries and Wildlife, said Monday that before the agricultural use of DDT and other pesticides began decimating bird populations after World War II, approximately 450 peregrine falcon nesting sites were thought to exist east of the Mississippi River. That had changed dramatically by the 1970s, he said.

“All of them were vacant,” Todd said. “This was one species that probably was headed toward extinction.”

As a result, several countries and states began a “monster effort” to bring falcon numbers back up, according to Todd. A genetic blend of falcons from other parts of the globe such as the Canadian Arctic, New Zealand and Spain were reintroduced to the eastern United States. Peregrines already had been reintroduced to other Eastern states before the first new generation of falcons was brought to the town of Amherst, Baxter State Park and Acadia in 1984, he said.

In 1987, the first falcons that had been brought to Maine returned on their own to Mount Kineo on Moosehead Lake, Todd said. A year later, an adult pair that returned to a site in southern Oxford County became the first pair of falcons to nest in Maine in nearly 30 years. Citing the property owner’s wishes, Todd declined to say where in Oxford County the nesting site is located.

According to Todd, 150 falcons were reintroduced in Maine between 1984 and the early 1990s. Now, the number of falcons that are believed to nest in Maine each spring is about a third of that, he said.

“We’re up to about 25 [pairs],” Todd said. “We had 23 last year.”

The federal government no longer lists peregrine falcons as endangered, but they still are considered endangered by the state of Maine, Todd said.

According to Connery, approximately 100 falcon chicks have been born and raised in Acadia since 1991, when the first falcons that had been reintroduced to the park returned and nested on their own. Of those, about 60 to 65 have been hatched and raised by their parents at the Precipice site.

Connery said that despite the number of chicks born in Acadia over the past 18 years, there still are reproductive failures.

Last year, all four chicks hatched at Jordan Cliffs died before they could fend for themselves, he said. The Patriot’s Day storm of 2007 resulted in the deaths of all of the falcon chicks on MDI hatched that spring.

In 2008, three of the four eggs that were laid at Precipice produced falcons that fledged, or grew old enough to fly away and find their own food. The fourth egg never hatched, Connery said. Scientists tested that egg and found it contained a high level of organochlorides, a toxin found in pesticides or flame-retardant chemicals.

“That egg indicates this female has been exposed to a lot of contaminants,” Connery said. “That egg was off the charts. That’s a concern.”

Even the number of successfully hatched and raised young birds might not be as good an indicator of long-term viability of the species as once thought, according to Connery. Park officials do not know how many of the falcons hatched in Acadia have grown old enough to have chicks of their own, he said, and adults might not produce as many offspring as once thought.

Researchers used to ascribe to the theory that, if a falcon reached reproductive age, it likely would produce a certain number of chicks during its lifetime, Connery said. Recent concerns about exposure to contaminants, as demonstrated by the unhatched egg tested last year, now suggest adults may lose their suitability for raising young, in terms of both biology and behavior, as they get older and toxins accumulate in their bodies, he said.

David Manski, head of the park’s resource management division, said Thursday that neither of the pairs at Precipice or Valley Cove is thought to have laid eggs yet this spring, but this is not necessarily a reason for concern.

“I think it’s still OK,” Manski said Thursday of the falcons’ reproductive chances this year. “I think it’s still early enough in the season.”

If a pair of Acadia falcons lay eggs, the trails near their nest likely will remain closed through the end of July, according to park officials.

Manski said balancing the needs of the birds and of park visitors can be tricky, especially along the popular Precipice Trail. As many as 40,000 people have been estimated to stop at the foot of the trail during the months it is closed to try to spot the falcons, he said.

From the park’s standpoint, protecting the falcons is more important than keeping the trails open, according to Manski. He said park visitors understand why this is the case.

“The Acadia birds are really important to the Northeast [falcon] population,” Manski said. “The birds take priority and the public has accepted it.”

If a nesting effort in the park is known to have failed, Manski added, the park is quick to open the surrounding trails back to the public.

According to Connery, it is OK that the falcon pairs in Acadia do not succeed in raising chicks every year. Just the fact that the birds now come back to Acadia each spring, after having disappeared from Maine for decades, is progress. The park’s falcon protection program certainly has helped, he said.

“I think it’s been a success,” Connery said.



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