Poaching, habitat loss, inbreeding and hybridization. These are just a few of the threats faced by many wild feline species around the globe. Here are six of the world's most endangered feline species and subspecies—some of which may not survive into the next century.

1. Amur leopards

Let's start with the good news: The population of critically endangered Amur leopards (Panthera pardus orientalis) has increased an amazing 50 percent in the past five years, according to new surveys by WWF Russia. But here's the bad news: Even with that increase in population, there are only 48 to 50 Amur leopards remaining in the wilds of Russia, with maybe eight to 11 more across the border in China.

Although much of the leopards' range in Russia is theoretically protected, the big cats still face a variety of perils, including poaching, the destruction of their forest habitats and climate change. Amur leopards were not recognized as their own subspecies until 2001, when genetic tests revealed their distinction from other leopards, which may have slowed efforts to protect them. Luckily, conservation efforts over the past 12 years have worked. According to WWF Russia, the leopards have not just increased their population, they have also increased their range, spreading out into habitat beyond the small pockets they have occupied over the past decade. The leopards may have even started crossing the border into North Korea, a country where they have not been seen for decades.

Unfortunately, another potential threat has arisen. Amur tigers (Panthera tigris altaica), also critically endangered, have doubled their population in the same region where Amur leopards live. The two big feline species will probably not compete with each other for food—they prey on different animals—but they do compete for space. At least three leopards have been killed by tigers in recent years. It's too early to tell whether the problem will grow in the future, but the situation will need careful monitoring.

2. Iberian lynxes

Habitat loss and two diseases that were introduced into Spain and Portugal by humans have taken their toll on the Iberian lynx (Lynx pardinus). Fifty years ago the species numbered about 4,000 animals. Today its wild population is between 100 and 200 cats.

Luckily, a few dozen additional lynx reside in a captive breeding program, which for the first last month froze the embryos and egg cells from two females for use in future breeding efforts. The two females—one of which had already given birth to 16 cubs—were both suffering from health problems and were about to be sterilized to preserve their quality of life. Before the operations scientists flushed their ovaries, preserving not just fertilized embryos that the cats would not have been able to bring to term but also other egg cells. This is the first time that embryos from this species have been cryopreserved, and the effort’s success increases the hope that Iberian lynxes will survive, at least in captivity.

3. Asiatic cheetahs

Asiatic cheetahs (Acinonyx jubatus venaticus) once roamed throughout the Middle East and central Asia before hunting all but wiped them out. Today the last 100 or so Asiatic cheetahs live in Iran, where they face habitat degradation, poaching and the loss of their prey from overhunting by humans. Scientists don't know exactly how many Iranian cheetahs remain, but a long-term camera-trap survey has so far managed to count 20 of the big cats, including seven females. Unfortunately, one of the females was killed by shepherds earlier this year, supposedly to protect their flock from predation.

Camera trapping is currently suspended during livestock season, but the Iranian Cheetah Society is still out with handheld digital cameras. This week it announced that the country's only known cheetah cubs are doing well in northeastern Iran. The four cubs are roughly a year and a half old and will probably leave their mother in the next few months. The survival rate for Asiatic cheetah cubs is unknown, but cubs in Africa have a 95 percent mortality rate during their first 17 to 18 months so this is great news for the Iranian subspecies.

The full counting effort is expected to continue, but it won't be easy. The few remaining cheetahs are spread out over thousands of kilometers, making it extremely difficult to track and locate them. The count is also hampered by a lack of equipment, funding and trained field members, although it has support from multiple international organizations.

4. Iriomote cats

The last 100 or so critically endangered Iriomote cats (Prionailurus bengalensis iriomotensis) live exclusively on the 284-square-kilometer Japanese island from which they get their name. These forest-dwelling felines—which aren't much bigger than domestic cats—probably didn't face many threats until the human population started to expand on the island. The modern age brought development, predatory domesticated dogs, diseases from domesticated cats, invasive cane toads and wild boars, new roads and, perhaps worst of all, automobiles. So many Iriomote cats have been killed by cars that the island is covered with signs warning drivers to watch out for them—which makes it kind of ironic that one of the few chances you'll ever get to see an Iriomote cat is in this 60-second video shot in 2010 by a passing motorist:

5. Scottish wildcats

A hundred years ago more than 100,000 Scottish wildcats (Felis silvestris grampia) roamed the Scottish Highlands. Fabled for their ferocity and often referred to as Highland tigers—although they are not much bigger than house cats—the wildcats are now almost completely gone. As I wrote last year, the native wildcats were done in by the introduction of feral and domesticated cats (Felis catus), which not only competed with the wildcats for prey but also bred and hybridized with them, diluting their gene pool to the point where few, if any, remain. Some scientists estimate that there may be fewer than 100 Scottish wildcats left. Even so, the scientists fear that only a handful of the remaining wildcats are genetically pure. A breeding program has been put in place, and new DNA technology might help identify the best and purest prospects for breeding, but in all likelihood the Scottish wildcat will fade away in another couple of generations, if it even takes that long.

6. South China tigers

It's hard to say how many South China tigers (Panthera tigris amoyensis) remain in the world. In the 1950s there were an estimated 4,000 members of this subspecies, but they didn't last long after the Communist government of China declared the cats an "enemy of the people" in 1959. Today the subspecies is considered "critically endangered, possibly extinct in the wild." No sightings of wild South China tigers have been confirmed since the 1970s, when the last known tigers were collected and brought into captivity. Although reports of wild tigers turn up from time to time, none of the sightings have yielded conclusive proof. The most noteworthy event occurred in 2007, when a farmer said he took several photographs of a wild South China tiger, but they were later proved to be frauds.

The only South China tigers that we can verify live in captivity. Breeding efforts over the past 40 years brought the subspecies' population up to around 100. A few of those cats actually live in South Africa at a reserve set up by the organization Save China's Tigers, which runs a program to breed and teach captive-born animals how to survive in the wild. Although the effort has successfully bred more than a dozen new tigers in South Africa, it has also earned its share of criticism, most recently in 2011, when one of its tigers broke through an electrified gate and killed another.

The Chinese government says it intends to eventually create a national reserve to allow these rare tigers to live in the wild, but whether that happens or not remains to be seen.

Next?

Sadly, several more cat species could easily join this list. The Javan leopard (Panthera pardus melas) and the Arabian leopard (Panthera pardus nimr) are both critically endangered, with populations of about 250 and 200 cats, respectively. The Asiatic lion (Panthera leo persica) numbers about 400, all of which live in a single forest in India. Only about 160 wild Florida panthers remain, although scientists today debate whether or not they should continue to be listed as their own subspecies. Indonesia's flat-headed cat (Prionailurus planiceps) was declared endangered in 2008, with no single population larger than 250 adults. As pressures increase, more felines will suffer. And as time progresses, we will probably have a few extinctions to report, because for too many of these species their nine lives are drawing to a close.