"Cougars are very cryptic animals," says Michael Robinson from the environmental advocacy group Center for Biological Diversity.

He's referencing the fact that cougars often travel alone, often at night, and they're hard to track. When most people come across one in the wild, it's usually by accident.

To see one in the northeastern U.S. is even more rare, almost certainly a fluke.

Not since 1932 and 1938 in New Brunswick and Maine, respectively, were cougars officially recorded in the northeastern U.S.—at least in terms of breeding populations. But the big cats weren't always so scarce. Before the 19th century, cougars were abundant in this range.

However, on January 22, the Eastern cougar subspecies was officially declared extinct in the U.S. and removed from the endangered species list by the U.S. Fish and Wildlife Service.

Surprisingly, some scientists say, this removal could be a good thing. Cougars have a long, complicated history of existence in North America, but conservationists see a future where that's not the case.

Who's What and Since When?

The words cougar, puma, mountain lion, and catamount all refer to the same large cat, known scientifically as Puma concolor. When early European settlers first moved to North America, taxonomists began classifying the cats as different subspecies. Eastern cougars, Western mountain lions, the North American cougar, and the Florida panther, for example, were uniquely labelled.

"[Classification] was based on things like the fur coat of animals and nuanced differences in sizes," says Robinson.

A cougar living in the desert, for example, might look slightly different than one more adapted to a forest in Canada.

But advances in genetic testing have since proven that these differently named American cats are genetically the same.

Not on the List

Beginning in the 1800s, European settlers began rounding up and killing off cougars in the northeast. Some were trapped and killed for their fur while others were culled to prevent the cats from interfering with livestock.

In the past 100 years, they haven't been regularly spotted since, and Fish and Wildlife officials say there's no evidence of a sustained, breeding population in the area. The U.S. agency first began investigating the population in 2011, and officially recommended removal in 2015.

In a statement about the removal, U.S. Fish and Wildlife characterized eastern cougars as long extinct.

"There was never any real justification for giving it that status in the first place," says Mark Elbroch, the lead scientist for the puma program at the big cats conservation group Panthera. "There are even scientists arguing it should be removed for taxonomical error."

Whether or not this can be really characterized as an extinction, he says, depends on how loosely you use that term. While cougar populations in this region have declined to the point of non-existence, it's more accurate to say only a certain population of the North American cougar species overall has vanished.

(The de-listing did not impact the subspecies of Florida panthers, a big cat considered to be one of the world's most endangered mammals.)

What's Out West?

Both Robinson and Elbroch suggest that removing the Eastern cougars from the endangered species list could open up new conservation opportunities. As a whole, cougars across the U.S. are managed on a state-by-state basis. According to conservation organization the Cougar Fund, all Western states except Texas have at least some protections for cougars. In most places, cougars can legally be hunted with a permit.

In a statement about the de-listing, Robinson called on state governors to come up with local protections for the animals.

"It removes all those loopholes and complications of introducing a species where they're listed as endangered," notes Elbroch. "This will allow states to be in control of that process."

Watch: Cougar Comes Face to Face With Hikers

There's no doubt that Western cougar populations are heading east. Once documented only west of the Rockies, Western cougars have been popping up in the Midwest, and some males have even been found closer to the East Coast. Male cougars are known to roam large distances in search of territory or mates, but when females are spotted in the East, it would be one sign of a rebounding population, says Elbroch.

"We won't see it in the next 10 years," he suspects. "So therefore, reintroductions are good viable alternatives."

No current reintroduction plans are in place, except for Florida, where cougars from Texas have been introduced as a possible way to boost population numbers and diversity for the Florida panther subspecies.

A Valuable Part of the Ecosystem

In a recently published paper, Elbroch found that cougars are what he calls subordinate predators in the ecosystem, meaning they're carnivores, but also face threats from larger predators like wolves and bears.

"It's a harder way of living and then you tack on human management, and we don't know how those things interact," he says. Currently, the IUCN lists North American cougars as a species of least concern overall, but notes that their population is declining.

The animals face significant threats from habitat loss and fragmentation, and some down-the-line impacts from hunters killing younger males.

Robinson hopes to see more state-by-state conservation measures enacted to preserve the ecological balance these large predators provide.

"There is ecological havoc that has been created by deer not having any of their natural predators," he says of the rapidly growing white-tailed deer populations in the East. A decline in large predators is thought to be at least partially responsible for growing deer numbers. Deer carry ticks, and the growing threat of lyme disease has been a possible concern.

Additionally, Robinson adds, he would like to see the species protected for its own sake. He lives in the mountains of New Mexico and says it's thrilling to see one in the wild.