Extinction

Once a koala population falls below a critical point, it can no longer produce the next generation, leading to extinction.

"We didn't start doing them to not do them," David Bernhardt said of his policies to limit protections for threatened animals and to factor the cost to corporations into protecting endangered species in an interview with The Washington Post published Friday.

There are only 144 kakapos left in the world.

Researchers have found that invasive birds play a critical role in the ecosystem of the Hawaiian island of Oahu, where native species have almost totally disappeared.

Insect numbers everywhere are declining—and scientists aren't exactly sure why.

The dinosaurs didn't have a chance.

Almost all animals of the 162 classified as threatened were in danger because of humans hunting the creatures for food or body parts.

Today some 500,000 bison have been restored in over 6,000 locations.

Data from Cassini's "death dive" reveals Saturn's rings could be just 10 million years old.

Warming waters around the world are turning turtles female on a massive scale.

Researchers link a supernova explosion 2.6 million years ago to the extinction of marine megafauna.

An estimated 70% of land animals and 96% of sea creatures were wiped out in Earth's biggest mass extinction.

Years of intensive fieldwork and meticulous museum study have revealed the new species in a case of mistaken identity.

"These predatory mice are pushing albatross, buntings, petrels and other seabirds towards extinction," said the Royal Society for the Protection of Birds.

National Science Foundation has given researchers over $200,000 to find out why Megalodon was wiped out.

"Killer whale populations found in the most polluted seas around Japan, Brazil, the U.K. or in the northeast Pacific, the authors report, are tending toward complete collapse."

The giant bird could grow up to 10 feet tall.

Humans were butchering giant animals on the island more than 10,000 years ago.

Ancient rocks suggest extreme temperatures drove their demise.

These sharks are now the most popular in the ocean.

Northern California, where the Humboldt martens live, has become popular for both legal and illegal marijuana cultivation.

Scientists simulated global warming inside bee nests to find out what happens if the Earth continues to warm at the predicted pace.

It didn't take long for dinosaurs to take over, according to new research.

But today's threats are far more intense than those of the past.

Tiny fish remains were time capsules of climate change.

Scientists hope their work highlights the disproportionately dominant role humans play on Earth.

"You haven't lived until you've put your arms around a mammoth femur trying to measure it," Smith said.

Focusing too much on your looks? That's what sent these species over the edge.

Some estimates say there are fewer than 30 vaquitas left in the world.

The species is "heading for catastrophe."