In 1975, grizzly bears were listed under the Endangered Species Act as threatened—or “likely to become endangered in the foreseeable future.” Today, grizzlies are recovering in many parts of their range, with nearly 2,000 at last count.

On December 28, 1973, the Endangered Species Act (ESA) was signed into law. We’ll soon be celebrating the 50th anniversary of this landmark conservation legislation, which has saved hundreds of animals that once wavered on the brink of extinction. Today, without ESA protections, we might not have alligators patrolling our saw-grass marshes or bald eagles soaring in our skies or gray whales spouting off our coasts or grizzly bears lumbering through our Western mountains.

The ESA protects animals and plants at risk of going extinct, in part by mandating the creation of a list of endangered and threatened species. Species are considered for listing when federal scientists determine that ESA protection is needed or when the government receives a petition from an individual or organization requesting that a certain animal or plant be added. If scientists determine listing is warranted and the government adds the species to the list, then either the U.S. Fish and Wildlife Service (FWS) or, for most marine species, the National Marine Fisheries Service (also known as the NOAA Fisheries) must create a plan for aiding its recovery.

Now it’s hoped that another statute, the proposed Recovering America’s Wildlife Act, will augment the ESA in protecting species. And, today, we have more knowledge and tools than ever before to help us do so. For example, cutting-edge technology to more effectively locate polar bear dens across the Arctic is showing promising results. Finding dens—which are buried under snow and nearly invisible—will help efforts to protect mother polar bears and their cubs. And while animal welfare is rarely considered during national, regional and local policymaking, scientists have now identified methods for remedying this issue.


Reintroducing gray wolves to Yellowstone National Park sent beneficial ripples across the 22-million-acre Greater Yellowstone Ecosystem. Once the wolves rebounded, so did beavers, cutthroat trout and riparian vegetation.

ESA successes: gray wolves and bald eagles

One of the most celebrated ESA success stories is the reintroduction of gray wolves to the Northern Rockies, particularly Yellowstone National Park, where they had been missing since 1926. After the species was listed as endangered in 1974, the FWS, the National Park Service and state wildlife agencies partnered to relocate 41 wolves from wild populations in Canada and northwestern Montana into the park in the 1990s. By 2008, FWS biologists estimated that 1,639 wolves roamed through Idaho, Montana and Wyoming—five times higher than the minimum population goal in the species’ recovery plan.

The benefits from returning the wolves multiplied; reintroducing the keystone predator sent waves of positive effects rippling across the 22-million-acre Greater Yellowstone Ecosystem. The gray wolf’s absence, for example, had allowed Yellowstone’s elk to munch freely on aspens, cottonwoods and willows without fear of predation. This caused harm to beavers, which rely on riparian trees for food and shelter. In fact, just one colony of beavers remained in the park in 1995. Once wolves reappeared, however, they kept the elk on the move, riparian vegetation rebounded and habitats improved for beavers, cutthroat trout and other species.

Reintroducing gray wolves also produced more food for a wide array of animals that scavenge the predators’ kills. According to a 2003 study in the Journal of Animal Ecology, Yellowstone’s wolves consume only 40 to 80 percent of their elk kills, leaving plenty of leftovers to sustain other wildlife, from bald eagles, golden eagles, magpies and ravens to black bears, coyotes, grizzly bears and at least 57 species of beetles.


Victims of DDT, deliberate killing and habitat loss, bald eagles were down to just 417 breeding pairs in the Lower 48 by the 1960s. Protections inspired by the ESA allowed eagle numbers to increase; and in 2007, the birds were removed from the list of threatened and endangered species.

The story of bald eagles, too, has an ESA happy ending. An emblem of courage, freedom and strength, our country’s national symbol was once nearly extinct in the Lower 48. In 1776, when the country was founded, about a half-million bald eagles soared above what’s now the continental United States. But beginning in the late-1800s, the population steadily declined as eagles fell victim to deliberate killing, habitat loss and, starting in the 1940s, the widespread use of DDT—a synthetic pesticide that washed off the land into waterways and contaminated the fish that eagles eat. By 1963, only 417 breeding pairs remained in the country outside of Alaska.

Today, however, nearly 316,700 eagles once again glide across our nation’s skies—thanks in large part to the Endangered Species Act, which catalyzed a number of eagle conservation measures, including a ban on DDT, captive breeding and reintroduction programs, and protections for critical habitats.

ESA hurdles: black-footed ferrets and mountain caribou

Despite the ESA’s success at preventing extinctions, however, relatively few listed species have ever been declared sufficiently recovered to be removed from the list. Since the act was passed a half-century ago, just 54 species have been taken off, according to a 2022 study published in the science journal PLOS ONE.

Until a small group was found in 1981, black-footed ferrets were thought to be extinct. Today, thanks to captive breeding and reintroductions, a few wild populations remain. ©USFWS Mountain Prairie, Wikimedia Commons

An illustrative case is the story of the endangered black-footed ferret. Decimated by habitat loss and landowners killing off their prairie dog prey, these little carnivores were thought to be extinct until a small population was discovered in Wyoming in 1981. A few years later, that group formed the core of a captive-breeding colony; and since 1991, thousands of ferrets have been reintroduced to 33 sites in eight Western states, Canada and Mexico. But while the animals’ numbers peaked at about 700 in 2008, the FWS estimates there are only a few hundred now.

Newer threats include inbreeding and non-native sylvatic plague. To fight the disease and the fleas that spread it, biologists are experimenting with insecticides and vaccines. To increase the ferrets’ genetic diversity from inbreeding, in 2020 the FWS cloned a female ferret from another female that had never given birth (and therefore never passed on her genes), but the cloned female also was unable to reproduce. Biologists now say that ferrets might not ever fully recover. Without the ESA, however, the animal would already be extinct.

Scientists have examined several possible causes of low species recovery rates. Focusing on 970 species listed between 1992 and 2020, they concluded that, unfortunately, most species are not receiving protection until they have reached dangerously low population sizes. A case in point is mountain caribou in the Lower 48. Once roaming northern Idaho, northwestern Montana and northeastern Washington, the continent’s southernmost herds had dwindled to fewer than 50 individuals by 1983 when the population was listed as endangered.

In 2019, two mountain caribou subpopulations in the Lower 48, the South Purcell and the South Selkirk, were designated as extinct. Emergency measures came too late to save them. ©Watts, flickr

Three decades later, Canadian wildlife officials captured the last four caribou from the herds and moved them to join larger groups in British Columbia. Members of the Kalispel tribe in Washington say they hope to eventually relocate the caribou—which are an important part of the tribe’s traditional culture, diet and spirituality—back to this country.

Another hurdle for the ESA is inadequate funding. For its endangered species work, the FWS receives $70 to $80 million in federal funding a year—compared to the $766 billion the government spent on national defense in fiscal year 2022. Sadly, like the black-footed ferret, many listed species, from California condors to right whales, will remain conservation reliant; they will always need our care to survive. And even when recovery is possible, it’s expensive and takes a long time. Funding for the ESA is not commensurate with what is needed.

Not surprisingly, limited federal funding often prioritizes charismatic animals, such as bald eagles. Cash-strapped state wildlife agencies, meanwhile, focus much of their funds on game species that bring in fishing or hunting license revenue that can be used for those particular species’ conservation or for those on state endangered lists. That leaves hundreds of endangered species—from insects to wildflowers—with little to no funding, making them more vulnerable to extinction.

Although not on the list of endangered and threatened species, monarch butterflies are battered by climate change, habitat loss and pesticides. Luckily, conservation organizations and the public have stepped in to help these charismatic insects survive. ©Fernando Romo

ESA helpers: Recovering America’s Wildlife Act and science

One way to protect a broader array of species and increase funding for all at-risk animals and plants would be to pass the Recovering America’s Wildlife Act (RAWA). Introduced in the U.S. Senate in March 2023, the bipartisan bill would provide $1.3 billion a year to state wildlife agencies to fund wildlife conservation efforts. That funding would cover costs for 75 percent of activities outlined in state wildlife action plans, benefiting more than 12,000 species of concern. Many of those species also are on the states’ own lists of endangered species or protected under the ESA.

In addition, the law would provide $97.5 million annually to Native American tribes, which historically have been left out of reliable sources of funding for wildlife conservation. Passing the act would be a step toward co-stewardship and ensure that tribes have footing to meaningfully engage in and implement conservation decisions that impact their fish and wildlife relatives.

The RAWA would also do more to help at-risk species before they need ESA protection. Monarch butterflies are a good example of how the law’s proactive conservation could work. Battered by climate change, habitat loss and pesticides, these much-beloved insects have declined by 90 percent east of the Rocky Mountains and by 99 percent in the West since the mid-1990s. Although an FWS assessment in 2020 concluded that federal listing was warranted, further action was put on hold while the service focused on “higher-priority listing actions.”


Thousands of students and state transportation departments have planted native milkweed in gardens and along interstate highways to help with monarch butterfly conservation.

But when knowledge of the monarchs’ plight became public and widely known, dozens of states and nonprofits engaged in vital monarch conservation efforts. From Minnesota south to Texas along the U.S. portion of the monarch’s central flyway between Canada and Mexico, state transportation departments worked to promote pollinator habitat in the rights-of-way along interstates. More than 1,000 U.S. mayors have taken the Mayors’ Monarch Pledge, committing to foster pollinator habitat in their cities. Locally, many organizations have helped participants create pollinator-friendly, outdoor green spaces at businesses, homes and schools. Collectively, these and other efforts have helped create, protect and restore millions of acres of habitat for the iconic insects.

Supporting scientific research, too, can be a powerful tool in conservation. For example, researchers are now testing new technology that will more effectively locate polar bear dens across the Arctic, and they’re getting promising results. Researchers from British Columbia’s Simon Fraser University and Brigham Young University in Utah hope that improving tools to detect dens will help in efforts to protect mother polar bears and their cubs.

Denning is the most vulnerable time for polar bears. Cubs are born blind with only a light layer of fur to protect them from the cold. Totally dependent on their mothers, cubs live in winter dens under the snow. They are only able to emerge from the den in spring when they have grown enough to withstand harsh Arctic conditions. With increased industrial activity in the region, there is a need for more accurate tools that can detect polar bear dens to avoid disturbing them during this critical time. A mother bear’s inability to successfully raise cubs contributed to the 40% decline of the Southern Beaufort Sea subpopulation between 2000 and 2010.

A critical part of polar bear conservation is keeping mothers and cubs safe while also addressing other threats, such as climate change. ©Mike Hillman

Using ARTEMIS Inc., an imaging system that relies on Synthetic Aperture Radar (SAR), a recent pilot study was conducted in Churchill, Manitoba, Canada. The system can “see” the top snow surface, the den roof surface and inside the den cavity. The research team conducting the study found that SAR raised den detection to 66%, compared with the industry’s current 45% accuracy rate using the aerial Forward Looking Infrared (FLIR) system as a den-detection tool.

A third tactic we can use to help the ESA have more success would be to incorporate animal welfare into policymaking. An article, published in the journal Science in July 2023 and written by researchers at Rutgers University in New Jersey, notes that animal welfare is rarely considered during policymaking and the need for doing so.

There are several areas where animal welfare matters, such as when governments aim to improve farm productivity while reducing land use and greenhouse gas emissions. Unfortunately, some of the most straightforward ways of doing this have negative implications for animal welfare. Policymakers should ask “When, if ever, is it better to increase environmental sustainability if it reduces the well-being of animals?”


Animal welfare should be considered when making policies, such as when governments attempt to improve farm productivity while reducing greenhouse gas emissions and land use.

According to the scientists, there are well-developed tools for incorporating human welfare into policy analysis, but comparable tools for incorporating animal welfare are in their earliest stages of development. They suggest conducting interdisciplinary research to develop and refine methods for quantifying interspecies welfare, utilizing measurable correlations between animals and humans, and ensuring animal welfare is included in policy debates.

The bottom line is that it’s a mistake to ignore the effect of our public policies on domestic and wild animals. Our decisions affect other species, and in turn other species affect us, whether it’s through diseases that can be transmitted back and forth, through the productivity of our food supply or through many other interconnections.

ESA hitches: varied species and healthy ecosystems

According to a 2019 study published in the science journal PeerJ, the ESA has prevented the extinction of approximately 291 species since its inception. Species whose extinctions were averted range from large, well-known animals such as the California condor and Hawaiian monk seal to a host of lesser-known species, such as the diminutive Oregon chub, a minnow.

Since it was enacted, the ESA has prevented the extinction of nearly 291 species, including the Hawaiian monk seal, which has been listed as endangered since 1976. ©MarkSullivan, Wikimedia Commons

That’s a pretty good track record, but it’s not enough. The pending RAWA, the most significant federal investment in wildlife conservation since the ESA was signed 50 years ago, would bring together the energy and expertise of states, territories and tribes and provide them with the resources they need to assist the ESA in keeping species from becoming endangered and going extinct.

Because endangerment isn’t good. When an area’s species start to become endangered, it’s a sign that the ecosystem they live in is slowly falling apart. Each species that is lost triggers the loss of other species. As conservationist and naturalist John Muir once wrote, “When we try to pick out anything by itself, we find it hitched to everything else in the universe.”

We humans depend on healthy ecosystems to live. That means that when we strengthen and protect the Endangered Species Act, we also strengthen and protect ourselves.

Here’s to finding your true places and natural habitats—and the next 50 years of the ESA,