The Siberian tiger also known as the Amur tiger, is a tiger subspecies inhabiting mainly the Sikhote Alin mountain region with a small population in southwest Primorye Province in the Russian Far East. In 2005, there were 331– 393 adult and subadult Amur tigers in this region, with a breeding adult population of about 250 individuals. The population had been stable for more than a decade due to intensive conservation efforts, but partial surveys conducted after 2005 indicate that the Russian tiger population was declining.By 2015, the Siberian tiger population has increased to 480–540 individuals in the Russian Far East, including 100 cubs. A more detailed census revealed a total population of 562 wild Siberian tigers in Russia.
Siberian tigers are known to travel up to 1,000 km (620 mi), a distance that marks the exchange limit over ecologically unbroken country. In 1992 and 1993, the maximum total population density of the Sikhote-Alin tiger population was estimated at 0.62 tigers in 100 km2 (39 sq mi). The maximum adult population estimated in 1993 reached 0.3 tigers in 100 km2 (39 sq mi), with a sex ratio of averaging 2.4 females per male. These density values were much lower than what had been reported for other subspecies at the time. In 2004, dramatic changes in land tenure, density, and reproductive output in the core area of the Sikhote-Alin Zapovednik Siberian Tiger Project were detected, suggesting that when tigers are well protected from human-induced mortality for long periods, the density of female adults may increase dramatically. When more adult females survived, the mothers shared their territories with their daughters once the daughters reached maturity. By 2007, density of tigers was estimated at 0.8±0.4 tigers in 100 km2 (39 sq mi) in the southern part of Sikhote-Alin Zapovednik, and 0.6±0.3 tigers in 100 km2 (39 sq mi) in the central part of the protected area.
Following a decrease of ungulate populations from 1944 to 1959, more than 32 cases of Amur tigers attacking both brown and Asian black bears were recorded in the Russian Far East, and hair of bears were found in several tiger scat samples. Tigers attack Asian black bears less often than brown bears, as latter live in more open habitat and are not able to climb trees. In the same time period, four cases of brown bears killing female and young tigers were reported, both in disputes over prey and in self-defense. Tigers can tackle bears larger than themselves, using an ambushing tactic and jumping on to the bear from an overhead position, grabbing it by the chin with one fore paw and by the throat with the other, and then killing it with a bite in the spinal column. Tigers mainly feed on the bear's fat deposits, such as the back, hams, and groin. Amur tigers regularly prey on young bears and sub-adult brown bears. Reports of preying on fully grown small female adult Ussuri brown bears by a big male tiger are common as well. Predation by tigers on dennis brown bears was not detected during a study carried between 1993 and 2002. Ussuri brown bears, along with the smaller Asian black bears constitute up to 40.7% of the Siberian tiger's diet. Brown bears alone constitute up to 18.5% of their diet depending on the locations. Certain tigers have been reported to imitate the calls of Asian black bears to attract them.
A broad genetic sampling of 95 wild Russian tigers found markedly low genetic diversity, with the effective population size extraordinarily low in comparison to the census population size, with the population behaving as if it were just 27–35 individuals. Further exacerbating the problem is that more than 90% of the population occurs in the Sikhote Alin mountain region, and there is little movement of tigers across the development corridor, which separates this sub-population from the much smaller sub- population found in southwest Primorye province. The winter of 2006–2007 was marked by heavy poaching. Poaching of tigers and their wild prey species is considered to be driving the decline, although heavy snows in the winter of 2009 could have biased the data.
The Amur tiger is listed in the Red Book of Russia. In April 2007, experts from the World Wildlife Fund (WWF) announced that the Amur tiger population reached a hundred years, and the maximum that the tiger is no longer on the verge of extinction. In he held a complex expedition staff IEE RAS in the framework of the "Amur tiger" in the Ussuri reserve the Far Eastern Branch of RAS in the Primorsky region of the Far East of Russia. We found out that in this area inhabited by six species of Amur tigers. With the help of satellite collars scientists monitor their routes, and marked the first female tiger for the year 1222 managed to get the location. According to published research animal uses an area of almost 900 square kilometers - despite the fact that the area of the reserve - only 400 square kilometers. This means that the Tigers are far beyond the protected area, undergoing high-risk. This data, according to the publication, give grounds to speak about the need for a buffer zone of the reserve and regulation of human activities beyond.