The Endangered Species Act at 50

Ahead of the anniversary, experts from four schools across the University share their thoughts on the landmark legislation.

nixon at oval office desk
President Richard M. Nixon at his desk in the Oval Office, speaking with aide Kenneth Cole (left) and William Ruckelshaus of the Environmental Protection Agency (right), on Dec. 19, 1972. A year later, Nixon would sign the Endangered Species Act into law. (Image: Courtesy of the Richard Nixon Presidential Library and Museum)

After near-unanimous approval by Congress, the Endangered Species Act was signed into law by President Richard M. Nixon on Dec. 28, 1973. “Nothing is more priceless and more worthy of preservation than the rich array of animal life with which our country has been blessed,” Nixon said after the signing. “It is a many-faceted treasure, of value to scholars, scientists, and nature lovers alike, and it forms a vital part of the heritage we all share as Americans.”

As the 50th anniversary of the ESA approaches, Penn Today reached out to experts from four schools across the University to share their thoughts on the landmark law, its accomplishments, failings, and its outlook for the future.

Cary Coglianese, the Edward B. Shils Professor of Law and Professor of Political Science at the University of Pennsylvania Carey Law School and director of the Penn Program on Regulation

The Endangered Species Act (ESA), like most other major federal environmental statutes in the United States, was born in a much different era than today. Signed by Republican President Richard Nixon, the Senate had voted unanimously in favor of the ESA, while the House had passed it on an overwhelmingly bipartisan basis with near unanimity. The law’s passage came at a time of great optimism in government and science, when the country saw its astronauts landing on the moon. Legislators and the public had faith that the passage of clear, protective laws could solve big problems.

Reflective of that faith, the ESA’s key terms tend to be absolutist, placing strict bans on the “taking” of listed species and the destruction of its habitat. Yet today, 50 years later, the ESA’s record of accomplishment from these strong rules remains contested. It is true that certain megafauna such as the bald eagle and the gray wolf have seen restoration thanks in measure to the ESA’s protections. Other species that might have been extinguished by now continue to survive. But many of these species also remain listed as endangered or threatened.

bald eagle flying
manatee being cared for in pool
Left image: A bald eagle flies over a partially frozen Des Moines River in Des Moines, Iowa. Fifty years after the Endangered Species Act took effect, environmental advocates and scientists say the law is as essential as ever. Right image: Miami Seaquarium assistant animal care supervisor Jessica Schiffhauer prepares to bottle feed an approximately 7-month-old orphaned manatee named Junebug. The population of Florida’s iconic manatees has recovered enough that the species no longer meets the definition of “endangered” under the Endangered Species Act. (Left image: AP Photo/Charlie Neibergall. Right image: AP Photo/Wilfredo Lee)

As with other laws, the hopeful ambitions of the ESA at its adoption have dissipated with the passage of time and over the course of implementation. Some evidence suggests that the ESA has created perverse incentives for private landowners to “shoot, shovel, and shut up,” destroying habitat before endangerment determinations can be made, rather than affirmatively acting to protect species and their habitats. And strikingly, it was only five years after the ESA’s initial passage that Congress faced political pressure to amend the law to build into it an exemption process.

Although broad public support remains for species protection—and for environmental protection more generally—climate change poses one of the major threats to biodiversity today. The Biden Administration’s climate change efforts, including its climate-related legislative accomplishments, can thus be seen as some of the most hopeful recent legal steps to protect threatened plant and animal species. But unlike with the consensus that surrounded the ESA’s adoption 50 years ago, biodiversity-protective climate policies today do not enjoy anything close to unanimous support. In the end, it remains to be seen whether an ESA created a half-century ago will be up to the task of protecting species from the significant ecological disruptions that lie ahead.

Julie C. Ellis, adjunct associate professor of pathobiology, senior research investigator at the School of Veterinary Medicine and co-director of the Wildlife Futures Program

Born in 1971, only two years before the Endangered Species Act was passed, the ESA and I are practically the same age. In the first two decades after the ESA became law, the public, including myself, was increasingly aware and vocal about the conspicuous threats—pollution and loss of habitat—to wild species. As an avid audience member of the conservation-minded TV programs National Geographic and Mutual of Omaha’s Wild Kingdom in the 1970s and 1980s, protecting wildlife became a passion of mine. I am fortunate that the ESA was enacted in my lifetime allowing me the privilege of witnessing remarkable comebacks resulting from it, including that of the iconic peregrine falcon and bald eagle. 

As an adult, I channeled my passion for wildlife into a career as an ecologist and experienced the joy and challenges of implementing species recovery strategies during a summer spent on an island off the coast of New Hampshire. All summer, I patrolled the island perimeter to deter predatory gulls while keeping a lookout for the terns we hoped to attract. By the end of summer 1998, 45 pairs of terns had successfully nested. Now, over 3,000 pairs make the island their summer home. Species and habitat recovery efforts work. But threats to wild species persist and continue to grow in their complexity.

Such threats, including diseases and climate change, call for an all-hands-on-deck approach. This is why my colleagues and I launched the Wildlife Futures Program, a novel partnership between Penn Vet and the Pennsylvania Game Commission aimed at strengthening the resilience of the Commonwealth’s 480 species of birds and mammals. We leverage the diverse expertise of veterinarians, species biologists, ecologists, and others to discover innovative and proactive solutions to complex wildlife health challenges. It is our goal to ensure that all of Pennsylvania’s wild species, including those that are threatened or endangered, thrive for generations to come.

Jared Farmer, Walter H. Annenberg Professor of History, School of Arts & Sciences

From my perspective as a U.S. environmental historian—and as someone who turns 50 in the coming months—the 50th anniversary of the ESA is a moment to reflect on the polarization of science in my lifetime. In 1973, there was bipartisan consensus that environmental harms, as measured by scientists, demanded governmental solutions. Back then, most Republicans and Democrats shared an understanding of the public role of science.

It’s lamentable that we’ve gotten to the point when U.S. partisans on one side pronounce, as part of a secular catechism, that they “believe” in science, while their political opponents reject scientific authority as antithetical to God, progress, and the American way of life. The environmental historians James Morton Turner and Andrew C. Isenberg, and the historians of science Naomi Oreskes and Erik M. Conway, have analyzed this divergence, which now prevents sensible revision of the ESA. To continue my religious analogy, environmentalists have worked to enshrine the act like a scripture, whereas anti-environmentalists still hope to burn it like a heretical book. 

peregrine falcon with trainer
polar bear walking on ice glacier
Left image: An adult Peregrine falcon prepares to dive at Christopher Nadareski, a research scientist at the New York City Department of Environmental Protection, participating as a volunteer cooperator with the New York State Department of Environmental Conservation’s Peregrine Falcon Program. Right image: A polar bear dries off after taking a swim in the Chukchi Sea in Alaska. (Left image: AP Photo/John Minchillo. Right image: Brian Battaile/U.S. Geological Survey via AP, File.)

Reasonable biologists, ecologists, and environmental managers would agree, notionally, that the ESA should be rewritten. Its regulatory emphasis on heroic recovery plans for charismatic single species in fixed habitats can be costly, burdensome, and inefficient. Moreover, this approach is inconsistent with current understanding of ecosystem management—especially given climate change—and inconsistent with the changed meaning of “species” after genomics. However, reasonable people would be fearful to see the current House majority—full of anti-science, and, paradoxically, anti-government legislators—rewrite anything, much less a law as important as the ESA. All the while, biodiversity continues to lessen.

Sarah E. Light, Mitchell J. Blutt and Margo Krody Blutt Presidential Professor, Professor of Legal Studies & Business Ethics, the Wharton School

On the 50th anniversary of the Endangered Species Act, it is worth taking a moment to celebrate the ESA’s many success stories. From the recovery of the bald eagle and the peregrine falcon to the reintroduction into the wild of the California condor, to the listing of the polar bear as threatened in light of climate change, the ESA has created a powerful set of tools to address risks to both endangered and threatened species. The case of Tennessee Valley Authority v. Hill exemplifies this power. In that case, the Supreme Court in 1978 enjoined the construction of the Tellico Dam by the Tennessee Valley Authority—despite its having been almost completed and nearly $80 million spent on its construction—because construction would destroy the habitat of the endangered snail darter, a small fish. But that case galvanized critics and exemplified the ESA’s political limitations. Congress ultimately passed a law exempting the construction of the dam from the ESA.

While the ESA remains necessary, in some ways the conversation is moving beyond the conservation of individual species to a focus on more cross-cutting issues like the preservation of biodiversity, such as in the Kunming-Montreal Global Biodiversity Framework (GBF), which was adopted at the 15th Conference of the Parties to the U.N. Convention on Biological Diversity in 2023. The GBF sets many goals, including the setting aside of at least 30% of the world’s lands and waters for conservation, with the goal of protecting biodiversity and the functioning of critical ecosystems with their services. And, the conversation is likewise moving beyond government alone, with business firms beginning to account for risks to their business and their impacts not only on the climate, but also on water, forest, and other ecosystems. A beta version of the Task Force on Nature-Related Financial Disclosures, modeled on the successful Task Force on Climate-Related Financial Disclosures, seeks to build on this momentum. Collectively, these developments have the potential to ensure greater focus on preserving our essential ecosystems, species, and habitats.

Ann Norton Greene, adjunct assistant professor and historian in the department of History and Sociology of Science whose research looks at environmental history and animals

The Endangered Species Act of 1973 is a landmark in the history of environmental policy. It protected plant and animal species before they reached the point of imminent extinction. It laid out a process of defining and protecting the critical habitats of endangered species and any adjacent ecosystems that supported a critical habitat.

The ESA provides a window into the environmentalism and politics of mid-20th century America. The emphasis on protecting systems rather than preserving individual plants and animals reveals the growing influence of ecological science. The ESA reflects the confidence of mid-20th century liberal politics that any problem can be fixed with legislation based on scientific data.

Most of the ESA details how protection will happen, navigating between different levels of government, government agencies, and treaties with other countries. It contains numerous compromises, such as excluding insect pests and permitting Native American hunting. However, ecosystems operate according to different rules than political systems or international relations. Ecosystems and natural forces do not recognize property lines or political boundaries. Biological forces favor survival of species, not individuals. A species threatened with extinction needs its whole ecosystem, not a partial one resulting from compromises hammered out between human stakeholders.

In the decades that followed, the ESA led to considerable conflict between stakeholders within ecosystems. Some thought that ecosystems defined relative to endangered species excluded human concerns and needs. Protecting the spotted owl threatened lumbering jobs, protecting wolves caused loss of livestock to farmers, protecting wild areas limited recreational and commercial activities.

The word ecology comes from the idea of the household economy encompassing all the residents of the places we call home. This interpretation places humans within the natural world, humans and nature shaping and being shaped by each other throughout history. The ESA reminds us that we need to think more expansively about ecosystems. What would an ecosystem look like that includes both jobs and owls? What would an ecosystem look like that sustains the health of natural systems, socioeconomic systems and American democracy?

herring swimming
(On homepage) River herring, also known as alewives, swim in a stream in Franklin, Maine. The fish were once headed for the endangered species list but have been making a comeback in some U.S. states. (Image: AP Photo/Robert F. Bukaty)