North America’s Most Endangered Animals

When Polynesians arrived at the uninhabited Hawaiian Islands thousands of years ago, they found an array of colorful tree snails, each less than an inch in length, across the island of Oahu. Those little snails—there are 41 species in the genus Achatinella—can now be found only on high ridges of the island’s two extinct volcanoes. All the snails in this genus are listed as endangered; many are thought to already be extinct. Their numbers were decimated by a combination of factors, including collectors who wanted the shells, the introduction of nonnative plants and animals, including rats, and loss of the native vegetation—the snails graze on fungus that grows on the leaves of native plants. A conservation project at the University of Hawaii, however, is breeding nine species of Achatinella snails in the lab in an effort to save the creatures.

The Hawaiian Islands, with hundreds of endangered plants and animals, are often called the “Endangered Species Capital of the World.” The islands’ remote location resulted in the evolution of thousands of species that live nowhere else in the world. That specialness, however, confers an added danger, because once a species disappears from Hawaii, it is usually gone forever. – SZ

More than 100 red wolves roam Alligator River National Wildlife Refuge in coastal North Carolina. That may not sound like many, but it’s the result of a successful reintroduction program. By the early 1980s only a few wolves remained in the wild—victims of hunting and habitat loss—and scientists captured the last 17, breeding them in captivity and then repopulating the refuge. But now there’s a new threat to the wolves: climate change and the resulting rise in sea levels may drown the wolves’ low-lying coastal home. But Alligator River scientists aren’t giving up. They’re using wetland-restoration techniques, including simple measures like planting soil-stabilizing trees, to protect the refuge from higher tides and stronger storms and give the area’s animals, including the wolves, time to move farther inland as the coastline shifts. – SZ

The smallest of the world’s sea turtles, Kemp’s ridleys are also the most endangered. In 1947, 42,000 of these turtles were filmed nesting on a single beach near Rancho Nuevo, Mexico. That film also captured people digging up the nests to collect the eggs, which number more than 100 per nest; the eggs are eaten and are considered an aphrodisiac. In the United States, all six sea turtle species are listed as threatened or endangered. As with other species, many Kemp’s ridleys have been killed after getting trapped in fishing gear as they travel up and down the East Coast. By 1985, only 702 turtle nests were found in their entire nesting range, which extends into Texas.

Officials in the United States and Mexico have been working to protect Kemp’s ridleys for decades. There is now a system of reserves, including the Rancho Nuevo beach, where turtles can safely nest. People as far away as Massachusetts help by rescuing turtles that take a wrong turn when moving south and getting stuck in Cape Cod Bay. Those efforts have seen success—an estimated 8,000 Kemp’s ridley sea turtles nested in 2009. – SZ

With its nine-and-a-half-foot wingspan, deep black feathers and bare pink head, the California condor is quite a sight. Before settlers rushed into California in the mid-19th century, lured by the discovery of gold, the condors soared peacefully through the skies. But then people starting shooting them and stealing their eggs. Birds that weren’t killed outright often died of lead poisoning from eating bullet fragments in the carcasses they scavenged. In 1985, when only 22 birds survived, the United States Fish and Wildlife Service captured the last nine in the wild and placed them in a breeding program. Seven years later, condors from that program were reintroduced into California, and that program has since been expanded to two more release sites in that state as well as sites in Arizona and Baja California, Mexico. About 150 birds have been released into the wild, and with normal breeding the population now numbers more than 300 birds. – SZ

As its name suggests, this furry herbivore, about the size of a large house cat, is found only on Vancouver Island in British Columbia, Canada. Small colonies of one to three family units live in high-elevation forests on the island. No one is quite sure how many marmots there were before counting began in 1979, but numbers dwindled from a high of several hundred in the mid-1980s to a mere 35, all in one spot, in 2004.

Researchers are still studying the reasons behind the marmot’s decline, but clear-cutting the island’s forests likely had some effect. Without the cover of trees, the marmots may have become more vulnerable to predation by birds, wolves, cougars or a combination of the three. A captive-breeding program has had some success, and dozens of marmots have been released on Vancouver Island since 2003. However, there are still some worries, as a recent study found that captive-born marmots are even more vulnerable to golden eagles than their wild-born brethren. – SZ

In waters along rocky reefs off the West Coast, from Northern California to Baja and the Gulf of California, swims the giant sea bass. These top predators, which can reach lengths of seven feet and weights of 500 pounds or more, live near kelp beds and feast on smaller fish such as anchovies and sardines, along with crabs, spiny lobster and even small sharks. Commercial fishermen started pulling giant sea bass out of the water with hand lines in 1870, but after they switched to gill nets, they quickly drove down the fish’s numbers: the fishery peaked in the 1930s at around a million pounds of giant sea bass caught in a year. By 1980 fishermen caught less than 40,000 pounds of the fish.

In 1981 California severely limited giant sea bass fishing in its waters. While there is no hard data showing that the fish’s population has recovered, scuba divers say there are more of the fish in the waters at popular dive spots off La Jolla and Anacapa and Catalina Islands. Mexico, however, is a different story, as giant sea bass fishing continues there unfettered. – SZ

The chytrid fungus has been found on at least 287 species of frogs in 37 countries around the world and is suspected to be a major cause of amphibian die-offs. Among its victims is the Rabb’s fringe-limbed treefrog, which inhabited the tropical forest canopy of central Panama. With its big webbed feet, the frog could glide, limbs outstretched, from high branches safely to the ground. The species wasn’t discovered until late 2005, when a team of scientists visited the region to collect frogs and save them in captivity before the chytrid fungus arrived. Chytrid was detected in the area the following year, and the last known wild individual, a male, was heard calling in December 2007. Researchers at Zoo Atlanta and the Atlanta Botanic Garden attempted to breed the frogs but were unsuccessful. As of April 2011, there was only one lone male surviving at the botanic garden. – SZ

Pygmy raccoons can be a common sight among the mangroves on the northwest tip of Cozumel, an island off the coast of the Yucatán Peninsula in Mexico. They live nowhere else in the world, however, and there are likely fewer than 250 mature animals. Their island home is being increasingly developed for tourism, and scientists worry that the raccoons’ habitat may become more fragmented by roads and that hotels and golf courses may use up the fresh water needed by the island’s animals. Feral cats and dogs are also a threat; they carry diseases and prey upon the raccoons. But the biggest danger may be one that humans have little control over—hurricanes. A major storm can wipe out as much as 60 percent of the raccoon population in one blow, according to a study of two hurricanes that swept through the area in 2005. – SZ

In the past 30 years, the Caribbean has lost 80 percent of its corals. Among the hardest hit is staghorn coral, a species responsible for building much of the reef in shallow water around the Florida Keys, the Bahamas, the Caribbean islands and Venezuela. Since 1980, populations of the branching coral have declined by as much as 98 percent in some areas.

The threats to staghorn coral are the same affecting corals worldwide. Poor water quality, resulting from the runoff of pollutants from land, breeds coral diseases. (Staghorn corals have been plagued by white band disease.) Overfishing has removed important predators and herbivores, leaving more small fish and snails to prey on corals, and more algae and seaweed to smother them. The rampant burning of fossil fuels has resulted in the ocean absorbing more carbon dioxide from the atmosphere. Water temperatures have increased by 1.3 degrees Fahrenheit since the late 19th century, and the ocean’s acidity has increased by 30 percent since the start of the Industrial Revolution. As a result, corals are bleaching and struggling to deposit calcium-carbonate exoskeletons that form reefs. Nancy Knowlton, a coral reef biologist at the Smithsonian Museum of Natural History, compares the dissolving of the exoskeletons to that of teeth in Coca-Cola.

On one of Knowlton’s annual trips to Bocas del Toro, Panama, to study a mass coral spawning in 2009, she shared her bleak forecast: “If we don’t do something, we could lose coral reefs as we know them by 2050.” – MG

Franklin’s bumblebee lives in a narrow, 190-mile stretch of southern Oregon and northern California, between the Sierra-Cascade and the Coast Mountains. The population began to decline in the late 1990s, and no one has spotted the bumblebee, named after early 20th-century entomologist Henry J. Franklin, since 2006.

The decline of the Franklin’s bumblebee may be due to the spread of a disease introduced by bumblebees imported from Europe to pollinate commercial crops of tomatoes, peppers and other plants, says Robbin Thorp, an entomologist at the University of California, Davis. Populations of three other closely related bumblebee species are also dwindling, probably for the same reason. Bumblebees are not the only endangered bees in North America. In the past five years, beekeepers have lost up to 90 percent of their honeybee colonies to colony collapse disorder, a mysterious phenomenon whose cause is not yet known; pesticides, pathogens and stress are possible culprits.

But Franklin’s bumblebee could make a comeback. If at least some immune individuals survived the disease, they could repopulate the area, Thorp says. This summer he plans to search for survivors in the bumblebee’s territory. -- EW