Is the world on the verge of losing the majority of its animals? It might sound absurd, but it’s not as far-fetched as you might think when you consider the earth’s history.

In the past 540 million years there have been five mass extinctions. A mass extinction is when more than three-quarters of the world’s species become extinct in a short frame of time. Total up the numbers in these five mass extinctions and we have lost 99 percent of the Earth’s species – and that’s without human intervention. Now, experts are concerned that a sixth mass extinction has begun, and could take a mere 1,000 years to complete.

Whether we are in the midst of a mass extinction or not, it’s clear that we are losing species at an alarming rate. Here are five recently extinct animals that left our world over the past decade:

5. Javan Tiger

Javan Tiger

Javan Tiger

Declared Extinct in 2003
The Javan tiger was a big cat, but not in comparison to other tiger species. The males weighed in at 220 to 310 pounds and the females averaged 170 to 250 pounds. Their small size was thought to be attributed to the size of the available prey in their native land of Java, Indonesia. The theory is that the smaller the prey, the smaller the predator.

At one point, the Javan tigers inhabited all of Java. In the mid 1800s to mid 1900s the native people viewed these tigers as pests and chased them off to the remote mountainous areas. By 1972, the remaining tigers were sectioned off to the Meru Betiri National Park Reserve. Unfortunately, the protection of the reserve was not enough.

Due to hunting, loss of forest habitat and lack of prey, the number of Javan tigers dwindled. The last members were spotted in the reserve in 1976 and the Javan tigers were officially declared extinct in 2003, joining the ever growing list of recently extinct species.

4. Western Black Rhinoceros

Western Black Rhinoceros

Western Black Rhinoceros

Declared Extinct in 2017
Rhinos have been around since prehistoric times and are the second largest land mammal, second in size only to elephants. in 2017, the Western Black Rhinoceros was officially declared extinct, leaving only four remaining rhino sub-species, all of which are endangered.

Despite the Western Black Rhino’s large size, they were actually extremely fast runners and could reach speeds of 40 miles per hour when they needed to intimidate other animals or humans. However, these big guys had extremely poor vision and had been known to accidentally run into trees and other objects. Besides their scary intimidation tactics, they were actually quite gentle and strict vegetarians. These giants had tough black skin that protected them from predators, but it was also quite soft to the touch and sensitive to sunlight, so the rhinos would wallow in mud to give them some UV protection.

Loss of habitat and poaching was the downfall for the Western Black Rhino. They had two horns that were valued on the black market for their beauty and supposed medicinal value. The last known members of this rhino sub-species were known to live in Cameroon, West Africa.

3. Southern Gastric Brooding Frog

Southern Gastric Brooding Frog

Southern Gastric Brooding Frog

Declared Extinct in 2002
Scientists had hoped the Southern Gastric Brooding Frog could provide a solution for stomach ulcers in humans. Why? Because this frog delivered it’s young from its mouth, temporarily turning off its stomach acid to do so. Scientists thought the ability to turn off the production of stomach acid could be useful to humans. Before scientists were able to discover the Southern Gastric Brooding Frogs’ secret, the species became extinct.

The Southern Gastric Brooding Frog was an aquatic species that lived in rainforests, wet forest communities and near freshwater streams in Australia. The last living member of this species was spotted in the wild in 1981 and the Southern Gastric Brooding Frogs were officially declared extinct in 2002. The cause of extinction is unknown. Their demise could have been caused by timber harvesting, habitat changes, non-native species of plants and animals, by disease or something else.

2. Pinta Island Tortoise

Lonesome George

Lonesome George – the last Pinta Tortoise (Mike Weston / Flickr)

Last Survivor Died 2012
The Pinta Island Tortoise has long been considered extinct in the wild. The last known member of the species was found in 1972 and transferred to the Charles Darwin Research Center. Being the last of his kind, he was named “Lonesome George.”

Researchers had hoped to find George a mate, but never succeeded. In 2012, Lonesome George died and the Pinta Island Tortoise was no more. George was 200 pounds and five feet long and was in the prime of his life at the time of his death. Pinta tortoises are thought to have a 200 year lifespan. The cause of his early death is not known, but a heart attack is suspected.

Where had George’s relatives gone? Why was he the last of his kind? Well, whalers and Galapagos Island (the native area of the Pinta Island Tortoise) settlers ate them. Because of the big size of these tortoises, they provided a lot of food to humans. In addition, because the tortoises could live a long time without food and water, the whalers liked to bring these tortoises with them on long excursions as a source of fresh meat.

1. Baiji River Dolphin

Baiji Dolphin

Baiji Dolphin

Functionally Extinct as of 2006
The Baiji River Dolphin have been considered critically endangered since 1996. Conservationists have made efforts to save these beautiful river dolphins, but have been unsuccessful. The last confirmed sighting of this freshwater river dolphin was in 2001. Since then, researchers have scanned the Yangtze River in China — the Baiji River Dolphins’ only habitat — in search of any survivors and have found none. In 2006, researchers declared the species had likely joined the long list of animals that are extinct, and stated that if there happened to be any survivors, they likely would not survive.

The Chinese regarded the Baiji River Dolphins as a national treasure. According to Chinese legend, the first Baiji River Dolphin was the reincarnation of a drowned princess. But, legends and treasures could not save these graceful freshwater dolphins from industrialization. Heavy ship traffic, over-fishing, dam building, dredging and water pollution produced an environment that was impossible for the Baiji River Dolphins to survive in.

The loss of these species should be a reminder about the importance of taking conservation seriously. We may not be able to save every species, but if we don’t take quick and serious action, we may one day lose them all.