Have you ever heard of the okapi? How about the white-winged flufftail or the red-belly toad? Most likely not, but if the International Union for Conservation of Nature, or IUCN, has its way, you'll be hearing much more about these and other endangered species. According to the IUCN, there are currently more than 21,000 animal and plant species whose existence is threatened. This April 22, get involved in Earth Day by learning more about this important organization and one of its biggest conservation efforts: the Red List.   

What Is the IUCN?

Founded in 1948 and headquartered in Switzerland, the IUCN is the world's largest global conservation network. Comprising more than 1,200 member organizations in more than 160 countries, the IUCN monitors, reports and manages the health of the world's plant and animal species. Almost 11,000 volunteer scientists and other experts review the latest research and develop standards to protect the world's natural resources.

The IUCN's overarching goal is to help governments understand how conserving nature ultimately supports their country's people. By combining the latest science with specific knowledge about local communities, the IUCN works to protect ecosystems, bring back lost habitats and improve the well-being of people around the world.

The Red List

One of the largest efforts of the IUCN is its Red List of Threatened Species, a comprehensive inventory assessing more than 71,500 plant and animal species. Updated yearly, the Red List helps guide conservation efforts by providing information about population size and trends, geographic range and habitat requirements of each species.

Its latest report, released in November 2013, labeled 21,286 species as "threatened" with extinction. This category is broken down into vulnerable species (10,549), endangered species (6,451) and critically endangered species (4,286). Threats to individual species vary widely, but can include destruction or loss of habitat, hunting, the introduction of new local predators as a result of human activity, and economic conditions in a given area.

The Bad News

Topping the list of threatened animal species is the okapi, which looks like a mix between a zebra and a horse but is actually related to the giraffe. The okapi population, found only in the rainforests of the Democratic Republic of the Congo, is dwindling dangerously, largely as a result of poaching and habitat loss.

Among the nearly 200 species of birds that are considered critically endangered is the white-winged flufftail, a small, secretive bird seen in parts of Africa. Its decline has resulted from deterioration of the bird's habitat thanks to overgrazing by livestock, wetland drainage and removal of marsh vegetation.

Red bellied toad

Another bird that has seen massive population and range decline in recent decades is the red-headed vulture. Native to parts of Asia, this avian species is now critically endangered, likely as a result of feeding on the carcasses of livestock that had been treated with diclofenac, a drug that is toxic to vultures.

Native to a very small area in Brazil along the Forqueta River, the red-belly toad also makes the critically endangered list. This species' rapid decline has been the direct result of a new hydroelectric power plant that was installed along the river near where the toads are found.

In the United States, the New England cottontail population has declined by 50% since 1994. Destruction and fragmentation of this rabbit's habitat has largely resulted from urbanization/suburbanization as well as industrial development throughout the region.

The Good News

It's certainly not all bad news when it comes to the health of animals and plants around the world. Conservation efforts are paying off for a number of species once considered endangered.

Leatherback Sea Turtles

Leatherback sea turtles, found in the United States and around the world, were once on the decline due to coastal development, pollution, poaching of beach-laid eggs and bycatch (being accidentally caught and drowned in industrial fishing nets). Today, these turtles are experiencing a resurgence, thanks to long-term conservation efforts to protect nesting areas and reduce leatherback bycatch.

Also making a comeback are California Channel Island foxes, which had diminished from the Southern California islands they call home. Conservation efforts to save this species included relocating golden eagles, which prey on the fox; instituting a captive breeding and reintroduction program; and providing much-needed vaccinations against canine diseases such as rabies.

Two species of albatross are rebounding as well. Thousands of black-browed albatross, found primarily around the Falkland Islands, and black-footed albatross, which make their home in Japan and the islands of Hawaii, were lost each year after becoming ensnared on the hooks of longline fishing fleets. Those same fisheries were also taking away some of the birds' vital food supply. Today, both species are growing in number because of restrictions placed on the fisheries.

The red-cockaded woodpecker — which builds its nests in the cavities of old-growth trees in the southeastern United States — once faced extinction because of clearance of forested areas for agriculture and construction through the mid-1900s. They were also threatened by the Southern pine beetle, which infests the cavities and kills nesting trees. Relocating female birds and building artificial cavities that are fitted to prevent beetle damage have helped to replenish this woodpecker population.

Efforts Must Continue

The Red List has brought awareness and action in preserving vulnerable plant and animal species around the world by highlighting species that are declining rapidly and engaging governmental and nongovernmental agencies to do their part. But for every species whose numbers improve, other species' numbers diminish.

"This year we're seeing some recoveries, which are a strong indication that conservation works," says Russell A. Mittermeier, president of Conservation International and chair of the IUCN's Species Survival Commission's Primate Specialist Group. "But the many species' declines mean we need to do much more."

To contribute to conservation efforts or learn more about how you can help spread the word, visit the IUCN Red List, the IUCN Red List Facebook page or Conservation International.