The peregrine falcon is a remarkable bird of prey that can reach speeds of over 200 mph when diving for prey. However, due to the effects of pesticides, especially DDT, peregrine falcon populations plummeted in the middle of the 20th century. By the 1960s, the species was endangered throughout much of its range. Through dedicated conservation efforts, peregrine falcons have made an incredible recovery, although they are still rare in some areas.
The Natural History of the Peregrine Falcon
The peregrine falcon (Falco peregrinus) has one of the most extensive natural ranges of any bird species in the world. It can be found on every continent except Antarctica and inhabits a wide variety of habitats including coasts, mountains, and wetlands. Peregrines nest on tall cliffs and hunt other birds in flight. True to their name, which means “wanderer”, peregrines are highly migratory in many parts of their range. However, those that breed in the tropics tend to be non-migratory. There are 19 recognized subspecies of peregrine falcon throughout its widespread distribution.
Historically, peregrine falcons thrived in wilderness areas with ample nesting sites and prey. Before the mid 20th century population decline, there were believed to be around 10,000 nesting pairs in North America. Peregrines prey primarily on other birds up to the size of ducks and doves. The long, pointed wings allow the peregrine to reach speeds over 200 mph in its characteristic hunting stoop or dive, making it the fastest animal on Earth. Few prey species can escape a determined peregrine once it has laid eyes on its target. The peregrine was revered and used in falconry for centuries, especially by European nobility in the Middle Ages.
Population Declines
Starting after World War II, peregrine falcon populations began to mysteriously crash across North America and parts of Europe. Several theories were proposed such as disruption of nesting sites, overharvesting by falconers, or prey declines. However, researchers soon noticed that the main factor in the decline seemed to be linked to the peregrines themselves, rather than just their food or habitat resources. Very few young peregrines were surviving to adulthood and those that did often exhibited strange behaviors or deformities.
By the early 1960s, most biologists studying the species agreed the main cause of the population crash was the buildup of DDT and other toxic pesticides in the environment after World War II. Although DDT was initially hailed as an extremely effective tool to control insects that spread disease and damaged crops, it began to show deadly side effects as it built up in food chains. Since peregrines are at the top of the food chain, they received concentrated doses of DDT that interfered with their reproduction. The pesticide caused peregrine eggshells to be abnormally thin and prone to breakage before hatching. It also impaired courtship and parental behaviors needed for successful breeding. Several other species of raptors, such as bald eagles and ospreys, experienced similar population declines during this period.
Endangered Species Protection
By the 1960s, it was clear the peregrine falcon was in serious danger of extinction across the majority of its range. Conservationists lobbied for government protections for peregrines and other affected species. In 1970, the U.S. Department of Interior listed the peregrine falcon as endangered under the Endangered Species Conservation Act, a predecessor to the modern Endangered Species Act (ESA) passed in 1973. This made the peregrine one of the earliest species to receive protection under the ESA. Around the same time, peregrines became listed as endangered internationally by the International Union for Conservation of Nature (IUCN).
Listing the peregrine falcon as federally endangered provided a framework to guide recovery efforts. Endangered species listing banned direct persecution and disturbance of peregrines, although enforcement remained challenging. Most importantly, it required analysis of how government actions could impact the species. Researchers soon used this tool to make the case that banning DDT was essential for preventing peregrine extinction. After mounting evidence demonstrated the harm caused by DDT, the U.S. Environmental Protection Agency banned its use in 1972.
Peregrine Falcon Recovery Efforts
Banning toxic pesticides like DDT was the essential first step in allowing peregrine falcon populations to recover. However, researchers and conservationists knew they needed to take additional actions to help bring peregrines back from the brink of extinction in many areas. Numerous governmental agencies, universities, nonprofits, falconers, and other collaborators came together in a massive coordinated effort. Their innovation and dedication during the peregrine falcon recovery program saved the species and served as an inspiring model of effective endangered species conservation.
Captive Breeding and Hacking
One of the earliest strategies peregrine biologists employed was raising falcons in captivity to release back into the wild. They collected peregrine eggs from small remaining wild populations and raised the chicks by hand in indoor facilities. The young birds grew up associating with humans and depended on their caretakers to provide food. Before the birds were old enough to fly, researchers would place them in outdoor hacking boxes on cliffs and gradually wean them off dependence on humans. The boxes protected the juveniles while they learned to hunt live prey and survive outdoors. Once fully independent, the formerly captive-reared peregrines would disperse just as wild ones would.
This process, known as hacking, gave young peregrines the best chance at thriving in the wild. Between 1970 and 1997, recovery teams released over 4,000 hacked falcons across the U.S. Hacking was especially crucial for reestablishing peregrines in the eastern U.S. where the species had been completely extirpated. Without captive breeding, it’s likely the peregrine would have permanently vanished from east of the Rockies. Releases took place both near existing wild populations to reinforce them and in habitat far from remaining peregrines to found entirely new populations.
In addition to purposefully releasing falcons, recovery teams took action to help wild pairs succeed. If wild eggs or chicks were at risk, they would be taken into captivity temporarily and returned to the nest when able to survive. While controversial due to disruption, this strategy saved the lives of many wild peregrines that could then continue the recovery. Captive breeding and hacking became less common as wild populations rebounded and were able to sustain themselves.
Nest Boxes and Scrape Creation
Another method to aid breeding peregrines was providing artificial nest boxes or scrapes. Historic nesting locations on tall cliffs were abandoned in many areas as the population crashed. And newly released captive-reared birds often had trouble finding safe nest sites. To provide additional options, recovery teams installed nest boxes on buildings, bridges, and other structures imitating natural cliff habitat. They also created artificial scrapes (shallow depressions in substrate) on cliff faces using hand tools.
These measures gave peregrines accessible and protected sites to raise young. As the population grew, peregrines eventually found and returned to many historic cliff nests. But nest boxes and scrapes remain important in some regions such as the eastern U.S. where cliff habitat is scarce. They continue providing safe nesting options for peregrines that now thrive in urban and coastal environments.
Public Education
For the peregrine falcon recovery program to succeed long-term, public support was essential. People needed to understand why toxic pesticides had to be banned and other protections put in place. Peregrines also benefited when individuals made an effort to accommodate them. For example, building owners allowed access to install nest boxes, and rock climbers avoided crucial nesting cliffs during breeding season.
Therefore, education and outreach became a key focus of agencies and nonprofits involved in the recovery effort. National wildlife refuges offered peregrine-focused events and school programs. Recovery teams gave presentations on peregrines to community groups. News stories documented the species gradual population growth as a success story. Peregrine cams even allowed people an up-close view into nests. The public became enthralled with following the lives of both wild and released peregrines, giving them a meaningful stake in the recovery process.
Recovery Milestones
Within just a couple decades of initiating intensive recovery actions, peregrine falcon populations showed remarkable signs of rebounding. From an estimated low of 324 breeding pairs in North America in 1975, the number began rapidly increasing year after year. Here are some key events documenting the road to recovery for American peregrine falcons:
1999 – Peregrines Federally De-listed
In August 1999, the U.S. Fish and Wildlife Service officially removed the American peregrine falcon from the federal endangered species list. At this point, recovery objectives for sustainable population levels had been met across most of its U.S. range. From the 1975 low, the estimated number of breeding pairs had rebounded to around 3,000 by the late 1990s. The fast recovery pace slowed the need for many reintroduction programs. While no longer federally protected, state-level endangered species protections remained in place for some time in regions still lagging in recovery.
2003 – Arizona Delists Peregrines
Arizona was one site of intensive peregrine reintroduction in the Southwest. The state upgraded peregrines from endangered to threatened status in 1986 as the population improved. In 2003, Arizona removed state-level protections entirely for peregrines, joining several other states in delisting the recovered species.
2013 – Midwest Recovery
Midwestern states were the last region to recover viable peregrine falcon populations after their complete disappearance. In 2013, Ohio became the final state in the Midwest to delist peregrines at the state level. From zero nesting peregrines in 1975, over 250 breeding pairs were now present across the Midwest – a major victory.
2017 – California Delists Peregrines
California, along with the pacific Northwest, maintained higher peregrine numbers than other regions but still saw declines. After meeting recovery goals, the state fully delisted peregrines in 2017. Oregon and Washington had already removed state protections in 2004 and 2009. These actions showed the West Coast population had successfully rebounded.
2020 – Full Species Recovery
In 2020, the IUCN Red List downlisted the peregrine falcon from vulnerable to least concern. This signified the global peregrine population is now secure and restoration efforts successful worldwide. While still faced with some localized threats, the species as a whole is in little danger of extinction.
Current Status and Threats
The massive coordinated recovery initiatives succeeded in saving the peregrine falcon from likely extinction. Populations increased more quickly than many biologists thought possible. Here is a look at the current status and ongoing threats for American peregrine falcons:
Current Population
From zero birds in some regions, the total North American peregrine falcon population is now estimated at over 3,500 breeding pairs. Several states have over 200 resident pairs, with robust populations in Texas, California, Nevada, and the Pacific Northwest. Urban centers like New York City and Chicago also host flourishing groups of peregrines.
While no longer endangered overall, peregrine numbers are still recovering in parts of the Northeast and Midwest. Ongoing releases and monitoring take place in areas with habitat but low natural recolonization. Maintaining high genetic diversity and preventing inbreeding depression remains a concern for some small isolated populations.
Banning Toxic Chemicals
The EPA ban on DDT proved essential for allowing peregrine recovery. The pesticide is now mostly eradicated from the environment. However, researchers have realized other chemicals may pose risks. For example, peregrines exposed to flame retardants showed thinner eggshells and lower chicks survival reminiscent of DDT effects. Thankfully, new regulations have been passed to restrict use of the most harmful flame retardants.
More recently, lead ammunition has become a focus. Scavenging lead bullet fragments in hunter-shot prey can cause lethal poisoning in peregrines. A planned transition to non-lead ammunition and fishing tackle will further reduce unintended poisoning risks. Overall, banning highly toxic and persistent chemicals remains a top priority for protecting peregrines.
Habitat Protection
Preserving suitable habitat for peregrines to nest and hunt continues to be essential now that populations have recovered. Development near cliffsides displaces some breeding pairs. Conservation of wetlands and riparian areas gives peregrines ample prey options. The species also increasingly relies on urban habitat like skyscrapers and bridges.
Many private landowners voluntarily restrict disruptive activities near peregrine nests. But additional habitat protections may be needed in the future. Climate change and shifting prey populations are likely to further alter peregrine habitat use in the coming decades. Maintaining connectivity between subpopulations will be key to preserving genetic diversity.
Reducing Disturbance
Peregrines remain sensitive to disturbance, especially during breeding season. While no longer illegal, activities like rock climbing and drones near nests can still cause abandonment. Many public agencies have voluntary seasonal restrictions on suitable cliffs. As recreational use of natural areas increases, managing human impacts will become more relevant.
Educational programs help reduce disturbance by making the public aware of peregrines. Nests on buildings or bridges are also more prone to accidental disruption. Signage and nested boxes help protect urban pairs while allowing human activity to coexist.
Monitoring and Research
Ongoing monitoring provides key data on peregrine population trends and reproductive success. Banding and tracking individuals also reveals details about migration routes, habitat use, and survival rates. If new issues emerged, researchers could detect problems early before they caused declines.
Major knowledge gaps still remain around peregrines exposure to contaminants, adaptations to climate change, and other threats. Field studies and modeling offer insights into how best to manage this still rare species. Funding for monitoring and research must continue even with delisting.
Conclusion
The story of the peregrine falcon offers hope for species recovery. In just decades, collaborative efforts brought North American peregrines back from the brink of extinction. Thanks to innovative conservation strategies and widespread support, the species has rebounded tenfold. While vulnerabilities still exist, the outlook for peregrines is exponentially brighter.
The peregrine’s plight also contains lessons for preventing future crises. Recovering an endangered species requires time, resources, and binding protections. Banning DDT demonstrated the power of environmental regulation to heal wildlife. Continued habitat conservation and public education are necessary to safeguard recovered populations.
This magnificent falcon’s speed and grace now again grace skies across the continent. By prioritizing coexistence with rare species, humans have given the peregrine falcon another chance to thrive for generations to come. The peregrine recovery program sets a gold standard in overcoming daunting odds to bring a species back.