Since 1620, when the Pilgrims landed on Plymouth Rock, an estimated 500 species and subspecies of plants and animals have gone extinct in the United States.

For another 1,300 other species, the risk of being vanquished is real. These imperiled creatures have been placed on the infamous endangered species list, where (the hope is) they are helped along until their populations recover to sustainable levels. Indeed, there are success stories, like America’s national bird, the bald eagle, which was taken off the list in 2007.

But for most endangered creatures, both here and abroad, their hard luck continues. Friday is Endangered Species Day. Below are some striking photos of extinction, endangerment, and even hope.

1. A 30-foot tall pile of bison bones

In 1871, a soldier named George Anderson wrote that it took his group six days to pass through a single bison herd on the plains of Kansas. “I am safe in calling this a single herd, and it is impossible to approximate the millions that compose it,” he wrote. But 13 years later, in 1884, the great American bison herds had been thoroughly annihilated – just an estimated 325 bison remained, mass-slaughtered for their skin. A century before the Endangered Species Act would come into existence, the bison were unarguably endangered. Yet, some farsighted Americans began creating their own private herds, giving the iconic American species a shot at survival. Whereas 30-60 million bison once stomped across the North American plains, 500,000 exist today, although they’re almost entirely domesticated livestock – less than 30,000 are wild beasts.

2. Lonesome George

With the death of Lonesome George (c. 1910 – June 24, 2012) came the death of his species. Lonesome George inhabited one of the Galapagos Islands, Pinta Island, and was the last known member of his tortoise species. Near the end of his life, there simply weren’t any females left for him to mate with, and Lonesome George never showed much interest in mating, anyhow. Other Galapagos Islands still have native tortoise populations, but it’s little surprise they’re endangered: European seafarers enjoyed this fresh tortoise meat, piling the shelled creatures into their ships. Even Charles Darwin enjoyed their buttery taste.

3. Living giants

In the 1870s, California’s sequoiasthe largest trees on Earth – were heavily logged. It’s a good thing that sequoia wood made for poor lumber, and these ambitious logging operations were abandoned. While still endangered, the sequoias haven’t been exploited in well over a century, so their numbers are increasing. It seems as if humanity will still be able to walk among the giants for some time, although the ancient plants now face threats from drought and rising temperatures.

4. Vulture strife

Without intensive assistance from humans, the California Condors, massive vultures with nearly ten-foot wingspan, would all be dead, just like the rotting carrion they eat. In 1982, there were only 23 known condors worldwide, but with conservation efforts, there were around 435 in 2015. The condors thrived during the last ice age, when there was a bounty of dead mastadons, mammoths, and buffalo lying out upon in the open, waiting for a vulture to plunge its bald head into their decaying flesh. Today, besides a lack of dead flesh, the condors also fall victim to lead poisoning. Most hunters use lead bullets, which fragment into thousands of pieces upon slamming into an animal, notably deer. The lead toxins remain embedded in deer flesh, and hungry, opportunistic condors unwittingly poison themselves.

5. Are you alive, Ivory-billed woodpecker?

There’s a drawing here, not a picture, for good reason. If the Ivory-billed woodpecker does exist, somewhere in the deep American woods, it is indisputably endangered. No one has found any conclusive proof of their existence in over 70 years, but Michael Collins, a mathematician and acoustics researcher with the U.S. Naval Research Laboratory, thinks that the lost birds still exist in the swampy forests of Louisiana and Florida.

5. De-horned

Rhinos are generally in bad shape, and some critically so. In large part, their horns – once an important defensive adaptation – are now an evolutionary detriment. Today, rhino horns fetch an incredible price: Between $100,000 and $300,000. Rhino horns are especially sought after in Vietnam, where some folks believe the horns, once ground up into powder and consumed, have cancer-curing and aphrodisiac properties. Here, Prince Harry inspects a poached and de-horned rhino in South Africa’s Kruger National Park.

6. What did the dodo actually look like?

The last dodo was spotted in 1662, so it’s difficult to know. Modern representations of this fat, flightless bird are based upon centuries-old drawings. The dodo once thrived upon the remote Indian Ocean island of Mauritius. But once Dutch sailors arrived, they found the naïve birds (who had never met a predator before) easy to catch, and ate them up.

7. Still here, still howling

In a human-dominated land, it’s hard to be a wolf: we occupy the same places and eat much of the same food. The gray wolf once roamed over most of the lower 48 states, but by the early 1970s, the animals had been exterminated from nearly every inch of this expansive region, save northern Minnesota. In some places, the U.S. Fish and Wildlife Service has concluded that the wolves have made an adequate recovery, and the animals have been locally removed from the endangered species list. Some people loves wolves, and some people hate wolves; endangered or not, it’s likely that this iconic symbol of the American wilderness will always be mired in controversy.

8. Trouble in (Hawaiian) paradise: The ‘Alala

Hawaii is the endangered species capital of the world. There are 44 native Hawaiian birds left. Of these, 33 are endangered. Ten of the birds haven’t been spotted in decades, so they’re probably extinct. The Hawaiian crow, the ‘alala, is hanging on — but just barely. In December, conservationists tried to release five crows into the wild. But just two weeks later, three of the birds were dead (for reasons unknown), and scientists pulled the plug on the reintroduction attempt. For now, the ‘alala will be kept in large cages and bred in captivity.

Photos via Wikimedia Commons, flickr user EU Webnerd, Library of Congress, Fish and Wildlife Service, Biodiversity Heritage Library, Getty Images, allispossible.org.uk, flickr user Patrick Bell, Getty Images / Carsten Koall