The awesome flight of the peregrine
Just the term “bird of prey” commands a certain sense of respect. The Peregrine falcon (Falco peregrinus) is no exception. Due to federal support in the 1970s, and the efforts of conservation groups and state management agencies, they have come back from the brink of extinction and are steadily increasing in number each year.
Historically known as a “duck hawk” “Great-footed Hawk,” and “Wandering Falcon,” the Peregrine is a crow-sized falcon, adorned with a blue-gray back, barred white underparts, and a black head and mustache. This formidable bird has the ability to reach speeds over 200 miles per hour, making it the fastest animal in the world. Its hunting dive, “the stoop,” involves soaring to a great height and then diving steeply at high speeds, and hitting one wing of its prey so as not to harm itself on impact.
No stranger to strange lands, the Peregrine’s breeding grounds range from the tundra to the tropics. It is the world’s most widespread bird of prey. The scientific name comes from the Latin words falco, meaning hook-shaped (falcate) and may refer to the shape of the beak or claws, and peregrinus, alluding to its ability to migrate far and wide. They live on every continent except Antarctica. There are three subspecies of the Peregrine found in North America; the American Peregrine falcon (Falco peregrinus anatum) is what we see in our region.
The Peregrine nests are called “eyries,” and are hollow indentations rather than actually constructed nests; they are usually found on cliff edges, or in more urban areas, tall buildings and other cityscapes. Sometimes Peregrines take the nests of other birds, but they do not build them.
The Peregrine falcon made the Endangered Species List in 1970, when its population plummeted due to the use of pesticides and chlorinated hydrocarbons. By 1975, an estimated 324 nesting pairs were left in North America. In Idaho by 1974, Peregrines were essentially gone from the state. In Montana in the 1980s, not a single Peregrine eyrie was found. Things were not looking for the Peregrine.
The pesticide DDT was banned after a correlation was made with usage and impacts on bird reproduction. DDT softens bird eggshells, resulting in widespread nest failure. Because Peregrines are at the top of their food chain, feeding on birds who feed on invertebrates, and because they live quite long, DDT was slowly concentrated in Peregrines. They did not die, but the poison altered their calcium metabolism, thinning the eggshells that sheltered their young. The weight of a nesting mother was enough to destroy the shell, so the chick was never born. After the banning of these high-risk pesticides in the 1970s, the Peregrines made an impressive recovery; they were removed from the Endangered List in 1999. In 2002, there were over 2000 known nesting pairs in the United States, and an additional 400 pairs in Canada. Their numbers continue to grow.
“Since the reintroduction of the Peregrines through the captive breeding program, the species is doing very well—pretty much increasing every year,” reports Idaho Department of Fish & Game Senior Wildlife Research Biologist Colleen Moulton. “There are now 42 known Peregrine territories in Idaho, though they are still considered a Species of Greatest Conservation Need in the State.” This designation exists in Idaho for species of concern that may not necessarily be on the Endangered Species list, but have experienced dwindling numbers and need continued monitoring and protection.
In Montana, thanks to the efforts of groups such as the Peregrine Fund, the Montana Peregrine Institute, Montana Fish, Wildlife and Parks, and Avista, as well as other partners throughout the State, the Peregrines are also experiencing an increase in population. Between the years of 2003-2005, there was an average of 51 active territories (general area where eyries are found); that number grew to 69 in 2006-2008.
“While historic records showed that Peregrines had existed throughout lower Clark Fork River corridor, none had been observed in many years,” says Nate Hall, Avista’s Terrestrial Program Leader. “With this in mind, Avista worked with the Peregrine Fund and other partners throughout the 1990s to establish hacking sites [to release captive-bred birds] along the lower Clark Fork corridor in an effort to reestablish Peregrines in the area.”
The Peregrine Fund, located in Boise, Idaho, has been integral in the successful recovery of the Peregrine falcon and other birds of prey internationally (www.peregrinefund.org). Over 6,000 Peregrines bred in captivity have been reintroduced by the Peregrine Fund, created in 1970—an integral time for the species. The World Center for Birds of Prey is also housed at the Peregrine Fund, which probably has something to do with the State of Idaho adopting the Peregrine as the official state raptor and designating the bird a special place on the Idaho quarter that came out in 2007.
On a more local level, the Montana Peregrine Institute is a non-profit scientific research institute dedicated to the study of the Peregrine falcons and other cliff nesting raptors in Montana and the surrounding states. They have coordinated 10 years (1999-2008) of intensive surveys designed to monitor the status and health of the Montana Peregrine falcon population. They also post federal delisting and travel over 18,000 miles a year to assist in monitoring efforts. See here.
Avista and their stakeholders signed the Clark Fork Settlement Agreement for the continued operation of the two dams on the Lower Clark Fork River in 1999. Part of the protection, mitigation, and enhancement plan calls for monitoring and protection of Peregrine falcons, among other sensitive species. The goal of this monitoring plan is to maximize opportunities to locate Peregrine eyries and protect them from human-caused potential negative impacts.
“The annual monitoring efforts were focused on areas where we knew Peregrines had nested historically,” Hall said. “While it was known that there were active eyries near Noxon and Cabinet reservoirs, it was not until 2007 that a pair of Peregrines were found to have successfully established an eyrie along Noxon reservoir, with another site identified in 2008.” Hall noted that these breeding territories are likely a direct result of the hacking efforts that occurred in the 1990s.
The Peregrine mostly feeds on medium-sized birds, with its favorites being pigeons, doves, songbirds, and waterfowl, but it will also eat the occasional mammal, reptile, fish, or insect. They hunt at dusk and dawn primarily and require open space in order to hunt therefore often appearing over open water, marshes, valleys, fields and tundra. In North American, known Peregrine prey comprises over 420 bird species and 23 mammals, including 10 bats!
The Peregrine searches for prey either from a high perch or from the air. Once prey is spotted, it begins its stoop, folding back the tail and wings, and tucking its feet. Prey is struck and captured in mid-air; the falcon strikes its prey with a clenched foot, stunning or killing it before turning to catch it in mid-air. A bit of a picky eater, the Peregrine plucks its prey completely before consuming.
The Peregrine reaches sexual maturity at or around age one, and mates for life. The pair returns to the same nesting spot annually. The courtship flight includes a mix of aerial acrobatics, precise spirals, steep dives, as well as ledge displays with the male and female bowing to each other. Ever the show-off, the male passes prey it has caught to the female in mid-air. To make this possible, the female actually flies upside-down to receive the food from the male’s talons.
The Peregrine predominately lives along mountain ranges, river valleys, and coastlines, though increasingly, it can be found in cities. In mild climates, the Peregrine can be a permanent resident.
“Most Peregrines migrate,” says IDFG’s Moulton. “But if their territory is in a place where they can get food, particularly in cities, they may stick around.”
Once an eyrie is made or discovered, females lay one clutch per year, which usually is composed of three or four eggs. In our region, Peregrines lay their eggs in April and May.
“Both adults incubate the eggs, so mom actually gets a break,” reports Moulton. “Survival rates are variable, depending on how good a prey year they have, how bad the weather is, and if both parents make it through the season. Up until the young are fledging (about 40 days old), they are completely reliant on the parents, so exposure or starvation is generally the cause if they don’t make it. After that, it could be anything.”
As with many other birds of prey, the female is generally larger than the male, in fact, the female averages 30 percent greater mass than her male counterpart. Peregrines’ life span in the wild can reach 20 years.
The Peregrine ranges in body length between 15 and 20 inches, with an average wing span of 3 and one-half feet. Quite large, yet they only weigh 1 and a quarter to 2 and three-quarter pounds. The adults have long, pointed wings, sometimes bluish black and sometimes slate gray, the same as their backs. The underparts of the Peregrine are white to rust-colored, with thin bands of brown or black. The tails appear much like the backs of these birds, but have thin stripes and are narrow and rounded at the end with a black tip and white band at the very end. The cere (fleshy swelling found at the top of the beak), as well as the feet are yellow, but the claws and beak are black. The upper beak is notched, an adaptation from severing the spinal columns of its victims. The immature Peregrine is browner, and has streaks instead of clean, thin bars.
“Thanks to the Peregrine Fund here in Idaho, the Peregrines are doing quite well,” says Moulton. “Banning DDT was the long-term solution. The captive breeding program is what got them back out there. The combination of the two is what saved the Peregrines.”
The public can get involved in continuing to monitor and protect Peregrines by learning to identify the species, as well as reporting active eyries to the Montana Peregrine Institute or IDFG. As budgets and dollars get tighter and tighter, public participation and volunteer efforts will help sustain management efforts to conserve and safeguard our exceptional native species—especially ones as notorious as the fastest animal in the world, harbored right here in our sleepy valleys and snowy mountain ranges.