It has been three weeks since I watched the first teetering flight of the young peregrine falcon at the Precipice. Now all four of the young are flying, and they have traded their awkward adolescent flapping for smooth glides along the east face of Champlain. They are beginning to take longer and more daring flights from the cliffs, and their ventures are getting longer and more frequent.
Soon they will learn to hunt. Much of their time in the air is spent chasing and diving after one another. The young falcons are playing, but they are honing the skills they will need to become independent adults. We have already seen one of the youngsters dipping into an unsteady dive towards the bright blur of a goldfinch.
Peregrines are now nesting successfully in Acadia: the four Precipice young this year and the 150+ other chicks who have fledged from the park since 1991 are a testament to that. However, the current triumph of the species in Acadia and in the eastern US is shadowed by their 30-year absence during the mid-to-late 20th century.
In the 1930’s and ‘40s, there were an estimated 350 nesting pairs of peregrines east of the Mississippi. A site study in 1964 counted zero. While the falcons would attempt to nest, the eggshells they produced were abnormally thin: their eggs were weak enough to be crushed by the 1.5 pound weight of an adult female. Clearly, something in the environment of these eastern peregrines was preventing them from reproducing.
This environmental contaminant turned out to be DDT, a pesticide used to control disease-causing biting insects such as mosquitos. From the 1950s to the 1970s, this pesticide was sprayed liberally across the densely populated Eastern US. DDT was certainly a highly effective pesticide: populations of harmful insects were plummeting due to its use. Best of all, it appeared to be harmless to humans and other mammals.
However, the wide use of DDT had unforeseen consequences for birds. While the rampant spraying of DDT did not seem to injure or kill birds outright, a metabolite of DDT called DDE was causing the thinning of their eggshells by inhibiting their calcium uptake. Birds of prey faced the worst effects of DDT due to a process called bioaccumulation. An example of bioaccumulation a songbird eats insects exposed to DDT, the concentration of DDE will be higher in the songbird because it will eat many insects to meet its dietary needs. The concentration of DDE is even higher in birds of prey like the peregrine falcon, who will consume multiple songbirds in a day. Since they are at the top of the food chain, birds of prey are important bio-indicators of the overall health of an ecosystem.
While scientists in the 1950s and ‘60s were becoming more and more aware of the dangers of DDT, the general public remained largely uninformed until Rachel Carson, a scientist and writer, published the groundbreaking book Silent Spring in 1962. Silent Spring made scientific knowledge about the harmful effects of DDT accessible to non-scientists. People began to see for themselves the ecological damage DDT was inflicting on their communities, and what they saw inspired them to take action.
The companies responsible for DDT’s production still insisted the pesticide was safe. Despite their efforts to shut down the scientific and public outcry, DDT was finally banned in 1972. The next year the final Endanger Species Act was ratified with peregrine falcons on the list. While these were important steps in the conservation of peregrines, banning DDT and listing the species as federally endangered wasn’t going to bring the species back. The damage was already done.
In the mid-1980s, a collaborative effort between biologists and falconers began in order to reintroduce peregrines to the cliffs that were once theirs. The subspecies native to the Eastern US, Falco peregrinus anatum, was completely extinct in the wild, but some remained in captivity. These surviving birds were crossed with peregrines from the Western US and the far north, sparsely populated areas where DDT was seldom, if at all, sprayed. Acadia National Park was chosen as a prime spot to reintroduce the falcons due to its status as a protected area, the presence of rugged cliffs, and the historic presence of peregrines here.
In Acadia, the reintroduction effort began at Jordan Cliffs in 1984 and continued until 1986. 22 peregrines in total were raised in captivity and subsequently released. Another batch of nestlings was planned for 1987, but the hacking effort stopped abruptly when a wild falcon was spotted in the park for the first time since 1956. Park biologists fairly buzzed with excitement: here was living evidence of the hard work they’d done to reintroduce the species. The falcon, a sub-adult male, was identified as Ganesh, a peregrine hacked from Jordan Cliffs in 1986.
Though Ganesh’s first return to Acadia in 1987 was brief – he was only spotted in the park for a few weeks – he would return again the next year, this time with a female. This female, still in her first-year plumage, was still too young to breed. Ganesh was seen again in 1989, also with a younger female, and in 1990 with an adult female. While Ganesh and the 1990 female attempted courtship, no nest or chicks were ever seen.
Finally, in 1991, Ganesh and an adult female successfully hatched chicks at the Precipice. While Ganesh and his mate are long gone, peregrine falcons have been returning here to breed every year since. They also nest at two other locations in the park: Jordan Cliffs, where the original 22 peregrine nestlings were hacked in the 1980s, and Valley Cove.
The four Precipice young this year are a part of this legacy. They tumble through the sky, tearing at the air with talons they do not yet fully understand how to use. Watching their soaring flight, it is easy to forget the vulnerability of these wild creatures.
The story of the peregrines in Acadia National Park is an example of successful conservation and proof that, through awareness and action, we can restore the species and ecosystems harmed by human activity. Now, in the 21st century, we are beginning to glimpse the troubling reality of global climate change. Thousands of species, including the peregrine falcon, are at our mercy. Will we once again work to undo the damage we have already done to natural ecosystems, or – better yet – make an effort to prevent this damage from happening in the first place? Only time will tell.
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July 26, 2019
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Last updated: July 26, 2019