When Congress passed the Endangered Species Preservation Act in 1966, many Americans understood for the first time the perils facing wildlife. Habitat loss, pesticide use, hunting, and other human activities were threatening iconic species, including the bald eagle, American alligator, Florida manatee, California condor, and dozens of others. The 1973 Endangered Species Act strengthened the earlier act’s provisions and laid out a framework for protecting many more plants and animals. As a result, some once-endangered species have made impressive comebacks. Here are just a few.
Our national symbol’s comeback from near-extinction is one of the best-known conservation success stories. Bald eagles have been protected from hunting and poaching under several U.S. laws, including the 1918 Migratory Bird Treaty Act, the 1940 Bald and Golden Eagle Protection Act, and the 1973 Endangered Species Act. But even these measures didn’t save eagles from the ravages of pesticides. In the mid-20th century, agricultural use of DDT led to contamination of waterways and the fish in them. Eagles ate the poisoned fish and laid eggs with extremely thin shells, which caused the eaglets to often die. In 1963, only 417 breeding pairs of bald eagles lived in the lower 48 states. Since then, bans on harmful pesticides and blanket protection of eagles and their nests — plus restoration of their habitats — have allowed bald eagles to rebound. They were removed from the Endangered Species List in 2007, with an estimated 316,700 in the lower 48 alive today, but biologists are still keeping a close eye on their recovery.
A population of these graceful seabirds spends the summer pretty far from the ocean. Interior least terns nest and raise their chicks on sandbars along the Great Plains’ major waterways, including the Mississippi, Missouri, and Arkansas rivers. During the 20th century, decades of development and damming along these rivers destroyed the birds’ nesting grounds. The inland population had shrunk to fewer than 2,000 individuals by the time it was added to the Endangered Species List in 1985. Following the designation, projects to restore the rivers’ natural flow and ecosystems helped the birds recover. The U.S. Fish and Wildlife Service delisted interior least terns in 2021, and they number about 18,000 today.
Lesser Long-Nosed Bat
These 3-inch-long bats are major pollinators of saguaro cactus and agave plants in their desert habitat. Some populations of these mammals migrate from Central America to southern Arizona and New Mexico by following a “nectar trail” of night-blooming flowers. They need safe places to rest together during the day, but the destruction of roosting sites along their route caused their numbers to plummet. By the time they were protected under the Endangered Species Act in 1988, there were fewer than 1,000 left. Conservationists in the U.S. and Mexico worked together to locate the remaining roosting sites and protect them from disturbance. The bats rebounded to an estimated 200,000 individuals. In 2018, the lesser long-nosed bat became the first bat species removed from the endangered list.
Delmarva Peninsula Fox Squirrel
Found only in Maryland’s Eastern Shore, southern Delaware, and a smidgen of Virginia, the Delmarva Peninsula fox squirrel is huge — about the size of a house cat with a super-fluffy tail. In the mid-20th century, much of its habitat — mature hardwood and pine forests — was cleared for farming and suburban development, reducing its range by roughly 90%. Its population dropped so drastically that the squirrel was designated for protection under the 1966 Endangered Species Preservation Act, the precursor to the 1973 Endangered Species Act. Efforts by government and private landowners to preserve large forest tracts, foster new squirrel populations, and limit hunting brought the cute critter back from the brink. Conservationists counted about 20,000 Delmarva fox squirrels at the time it was delisted in 2015.
This little minnow lives in the floodplains of Oregon’s Willamette River Valley, where it had evolved to survive in slow-moving marshes, beaver ponds, and oxbow lakes. Human infrastructure to control floods and dam rivers, straighten out waterways for navigation, and drain wetlands — as well as the introduction of non-native bass and bluegill — contributed to the fish’s decline in the 20th century. The Oregon chub landed on the Endangered Species List in 1993, which triggered efforts to help it recover. Government agencies worked with landowners to protect and restore its habitat. By 2014, when the Oregon chub became the first delisted fish, its population had rebounded from fewer than 1,000 fish in eight locations to more than 160,000 in 83 known places.
Channel Islands Foxes
Three subspecies of tiny foxes call California’s Channel Islands National Park home. They’re perfectly adapted to the unusual coastal Mediterranean climate, but the foxes have not had an easy time over the past couple of centuries. Ranchers and farmers altered the landscape and introduced sheep, pigs, and deer and the military set up defenses at the park during World War II. In the 1990s, golden eagles migrated from the mainland and preyed on feral pigs and foxes. By 2004, when the foxes were placed on the Endangered Species List, there were only 15 individuals each on Santa Rosa and San Miguel islands and 55 on Santa Cruz. An intensive plan to cull pigs, remove golden eagles, and breed the foxes in captivity led to the fastest recovery of an endangered mammal. All three fox subspecies were removed from the list in 2016, as the population grew to more than 2,800.
Concho Water Snake
Young Concho water snakes depend on riffles — fast-flowing shallow streams over a rocky bottom — for cover and to hunt small fish. But dams and reservoirs built in its central Texas range have eliminated these streams, caused silt to build up in the waterways, and allowed vegetation to take over the rocky outcrops in which the snakes hide. A program to restore native plant cover, reduce sediment buildup and improve water quality began in 1987 following the snakes’ designation as endangered. In 1989, conservationists built six artificial riffles to assist the juvenile snakes. All six were occupied within three years, a sign of the species’ comeback. When the Concho water snake was delisted in 2011, biologists estimated its population in the tens of thousands.