Inside a remote cave den, cameras film the world's newest Amur leopard cubs

The Amur leopard, the world's rarest big cat, has some welcome new reinforcements for its dangerously small population – and a brand-new chapter in a unique multigenerational saga.

Camera traps have revealed that a well-known leopardess known as "Berry" has given birth to two cubs in a cave den in the Kedrovaya Pad Nature Reserve, part of the 262,000-hectare Land of the Leopard National Park in the Russian Far East's Primorsky Krai (Maritime Province).

For a species whose total numbers are estimated at only around 80, a pair of newborns is a big deal. Scientists are particularly excited given that Berry's cubhood was documented in the popular 2014 online documentary series Spotted Family, which focused on her mother Kedrovka.

In a statement released by World Wildlife Fund-Russia, ecologist Yury Darman called the series "a real breakthrough" in understanding and publicising the Amur leopard. "For the first time the audience has seen something that no one has seen before – the real life of a real family of leopards in their natural habitat without any visual effects," he said. "I'm happy to know that a little cub with the injured paw from the series is now having her own happy family."

Berry is not shy around motion-sensor cameras: check out this 2015 WWF video of her blissful riverside cavorting (hypnotic soundtrack of loud birdsong and muffled organ music optional).

Now four years old, the feline mom has her work cut out rearing her impressively fluffy progeny. Researchers have identified the tracks of an Amur tiger in the vicinity of the cave den, and as you might imagine, a tiger isn't the most pleasant of neighbours for a mother leopardess.

At least Berry calls home the most important protected stronghold for her critically endangered kind. Established in 2012 in the far southwest of Primorsky Krai, Land of the Leopard National Park preserves 60 percent of the Amur leopard's remaining range and all of its known breeding habitat.

Extending from the shores of Amur Bay west to the Chinese border and from the Poltavsky Wildlife Refuge south to the Tumen River along the North Korean line, the park also serves as an essential refuge for an important population of Amur tigers. Separate from the main Amur tiger range in the Sikhote-Alin Mountains to the north, this transborder population "represents the 'source' for recovery of tigers in Northeast China," according to the Wildlife Conservation Society.

Long-legged and bushy-tailed, Amur leopards are ravishing in appearance, with ornately tattooed coats that appear short and orange-yellow in summer and heavy and pale in winter. Along with the Persian leopard, this is the northernmost subspecies of leopard, and it favours temperate mixed-hardwood forests where it hunts sika, roe and musk deer, as well as smaller quarry such as raccoon dogs, badgers and hares.

Also called Far Eastern or Manchurian leopards, these cats once ranged across southern Primorsky Krai as well as northeastern China and the Korean Peninsula. Logging, mineral development, road-building, overhunting of prey and direct persecution have steadily forced the leopard into an increasingly tiny shred of its former domain.

In 2007, only 30 Amur leopards were thought to survive. Conservation efforts, not least the creation of Land of the Leopard, have seen encouraging dividends since then: in 2015, a census showed the population had better than doubled, with 57 cats identified in the national park and as many as a dozen recorded in adjoining China. In recent years, Russia and China have stepped up collaboration to coordinate leopard and tiger conservation efforts on both sides of the border. (The status of Amur leopards in North Korea, meanwhile, is unclear.)

As in other parts of Asia where their kin overlap with tigers, Amur leopards normally appear to avoid direct conflict with their bigger relatives by selecting different prey and habitat. When red deer, boar and other preferred tiger eats are lacking, however, competition may heat up: researchers have found evidence of Amur tigers killing leopards, though impressive tree-climbing abilities often keep the spotted cats one step ahead.

Here's hoping Berry's cubs put in some practice in arboreal scrambling. There's a lot riding on their dappled shoulders – a family legacy, for one thing, not to mention the survival of their kind.