At a Glance

Scientists announced that three bird species vanished from the Earth for good in 2018.While 2018 didn't see much wildlife extinction, the Earth is losing animal species at 1,000 to 10,000 times the natural rate.Below are species that we lost last year, and some that we're on the brink of losing.

In 2018, scientists announced that three bird species vanished from the Earth for good, and more species on the brink could disappear forever in 2019.

Dissimilar to mass extinctions in the past, our current extinction crisis is almost solely caused by humans — specifically activities that cause loss of habitat, introduce alien species and contribute to the changing climate.

While last year in particular didn't see much wildlife extinction, the Earth is losing animal species , and as many as 30 to 50 percent of the planet's species may be extinct by 2050, the Center for Biological Diversity describes. The natural rate is around one to five species lost each year.

"Our planet is now in the midst of its sixth mass extinction of plants and animals — the sixth wave of extinctions in the past half-billion years," the center stated. "We're currently experiencing the worst spate of species die-offs since the loss of the dinosaurs 65 million years ago."

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Here is a list of the species that we lost last year, and some that we're on the brink of losing:

Alagoas Foliage-gleaner and Cryptic Treehunter

The Alagoas foliage-gleaner was declared extinct in 2018. The species was endemic to Brazil.

(Carlos Gussoni)

A pair of songbirds, the similar species called a sliver of the dense forest in northeastern Brazil home before deforestation ran wild in the region. The Alagoas Foliage-gleaner , Neotropical Birds lists, and was a new species of its own, according to BirdLife International.

When the treehunter was discovered, it was immediately placed into the "Critically Endangered" category, like other unique birds in the region.

The last sighting of the Cryptic Treehunter was in 2007, while the Alagoas Foliage-gleaner was last seen in 2011.

Spix's Macaw

The Spix's macaw, made famous by the movie "Rio," were declared extinct in the wild 2018. Around 100 birds still exist in captivity.

(Patrick Pleul/picture alliance via Getty Images)

The list's most vibrant bird, Spix's Macaw — a blue parrot native to Brazil and known for its onscreen role in 20th Century Fox's "Rio" — is believed to have gone extinct in the wild.

The creation of a dam, trapping for trade and deforestation drove the decline in the Spix's Macaw wild population, but an , BirdLife International says.

A 2016 sighting brought hope that the then-critically endangered species was still alive in the wild, but it was later believed to be one that escaped captivity.

Po'ouli

A small songbird native to Hawaii, the Po'ouli was discovered over 45 years ago. In 1981, its population topped some 150 birds, but , according to the U.S. Fish and Wildlife Service.

Habitat destruction by feral pigs, being hunted by mongooses, cats and rats, mosquito-spread diseases and competition with birds introduced in the area all were factors in the Po'ouli's extinction.

The last wild sighting of , according to BirdLife International.

On the Brink

Vaquita

The tiny vaquita porpoise will likely go extinct in the next few years, as less than 30 are left in the world.

(David Schneither/Getty Images)

Discovered in 1958, the and could go extinct any day, according to the World Wildlife Foundation. A small porpoise, the vaquita is the smallest cetacean species and calls the northern Gulf of California home.

The vaquita's decline in population largely stems from being caught and drowned in illegal gillnet fishing equipment.

Vaquita are the only of seven porpoise species that live in warm waters of the eastern Pacific Ocean, sporting dark circles around their eyes and mouth.

Less than 30 vaquita remain in the wild.

Northern White Rhino

The last male northern white rhino died in 2018, leaving behind just two females.

(Arun Roisri/Getty Images)

In March 2018, Sudan, the last remaining male northern white rhino, died at the age of 45. With Sudan's passing, the total number remaining northern white rhinos dropped to just two — both of which are female , according to the Ol Pejeta Conservancy in Kenya.

Scientists have found that assisted reproduction is possible, but the fate of the subspecies relies on expensive and difficult procedures never before used in rhinos.

The population's decline was , the World Wildlife Foundation says.