Giant Pandas, like the National Zoo's Bao Bao, are among the endangered species surveyed in the World Wildlife Fund's Living Planet Report. (Abby Wood/Smithsonian Institution)

The past four decades have not been very good ones for the world’s animals.

Since 1970, the populations of vertebrate species have declined by more than 50 percent. For kids, that means there are half as many mammals, amphibians, reptiles, birds and fish around today as there were around the time their parents were born.

This news comes from the World Wildlife Fund’s Living Planet Report, which surveyed the health of more than 10,000 animal populations to understand the challenges facing living things on Earth today.

Most of these challenges, the report says, are caused by people. Humans have what is called an “ecological footprint” — a mark we leave on the planet’s environment by using up resources and burning fuels that contribute to climate change. And recently, that footprint has grown very big.

“The demands that we’re making on Earth are unsustainable,” said Keya Chatterjee, director of renewable energy for the World Wildlife Fund.

Through the Smithsonian's eMammal program, citizen scientists can install cameras that help conservationists learn about local wildlife, such as this deer. (eMammal/Smithsonian Institution)

This is bad news for animal species because it’s hard for them to adapt to changes in their environment. There are signs of these changes in the news every day, Chatterjee said.

She pointed to the story of 35,000 walruses that gathered on a beach in Alaska this autumn. Normally, the walruses would be resting on sea ice scattered throughout the Arctic. But global warming has caused most of that ice to melt, so the walruses must cram themselves onto the beach when they need to stop swimming, where they are at risk of dying from disease or stampedes.

Freshwater creatures — animals that live in lakes, rivers and streams — have suffered the most. Those populations are especially vulnerable to changes in their habitats (such as lakes becoming polluted or drying up) and have declined 76 percent during the time period of the report.

But the news from the World Wildlife Fund isn’t completely gloomy. The report also includes conservation success stories and ways to protect species and their habitats.

“Humans caused this, and so we know that humans can resolve it,” Chatterjee said. “This stuff can be turned around.”

Kids can get involved in the conservation effort as well. According to Chatterjee, most of humans’ ecological footprint comes from burning fossil fuels, such as the gasoline that runs cars. Anything you can do to use less energy — whether it’s installing efficient light bulbs or biking to school rather than having your parents drive you — makes a small difference.

“Kids are a really important part of this change,” Chatterjee said. “They’re the ones that are most affected by this because they’re the ones who are going to be living with this planet.”

“Citizen scientist” programs are another way for people to contribute to conservation efforts. Through the Smithsonian’s eMammal project, families can set up cameras in their back yards to help researchers keep track of endangered animals in our region. Another program, FrogWatchUSA, teaches kids how to recognize and report the calls of local frogs and toads so that scientists can better protect them.

These kinds of programs really work, said Don Moore, a senior scientist at the National Zoo and the Association of Zoos and Aquariums. Just look at the bald eagle: The famous bird almost went extinct in the middle of the 20th century, but a combination of government protection, monitoring from citizen scientists and programs to protect their habitat brought the bald eagles back. Now they are no longer considered endangered, and Moore often sees them in his own neighborhood.

“The bald eagle is a symbol of optimism,” Moore said. “It shows what we can do if we make individual choices to help animals.”

Glossary

Conservation: Protection of things found in nature — such as water, plants and wildlife — so that they will be available in the future.

Endangered species: A type of plant or animal that is at risk of disappearing forever, or becoming extinct.

Habitat: The place or environment where an animal lives and grows.

Sustainable: Capable of continuing for a long time. Sustainable practices make sure that resources can be used without being used up.

Vertebrate: A type of animal that has a backbone or spine, such as mammals, birds, reptiles, amphibians and fish.

Did you know?

The American bison, which has come back from near extinction, has a hump made of muscle, which supports its head as it plows through thick snow

Sarah Kaplan