Most putative subspecies described in the 19th and 20th centuries were distinguished on the basis of fur length and colouration, striping patterns and body size – characteristics that vary widely within populations.

[8] Samples of 95 wild Amur tigers were collected throughout their native range to investigate questions relative to population genetic structure and demographic history.

Despite their well-documented 20th century decline, the researchers failed to find evidence of a recent population bottleneck, although genetic signatures of a historical contraction were detected.

[26] In 2005, a group of Russian, American and Indian zoologists published an analysis of historical and contemporary data on body weights of wild and captive tigers, both female and male across all subspecies.

The reduction of the body weight of today's Siberian tigers may be explained by concurrent causes, namely the reduced abundance of prey because of illegal hunting and that the individuals were usually sick or injured and captured in a conflict situation with people.

[31] A wild male, killed in Manchuria by the Sungari River in 1943, reportedly measured 350 cm (140 in) "over the curves", with a tail length of about 1 m (3 ft 3 in).

[10] During the late Pleistocene and Holocene, it was likely connected to the South China tiger population through corridors in the Yellow River basin, before humans interrupted gene flow.

The ungulate complex is represented by seven species, with Manchurian wapiti, Siberian roe deer, and wild boar being the most common throughout the Sikhote-Alin mountains but rare in higher altitude spruce-fir forests.

Siberian musk deer and Amur moose are associated with the conifer forests and are near the southern limits of their distribution in the central Sikhote-Alin mountains.

[37] In 2005, the number of Amur tigers in China was estimated at 18–22, and 331–393 in the Russian Far East, comprising a breeding adult population of about 250, fewer than 100 likely to be sub-adults, more than 20 likely to be less than 3 years of age.

[3] An unknown number of tigers survive in the reserve areas around Baekdu Mountain, on the border between China and North Korea, based on tracks and sightings.

[2] In August 2012, a Siberian tiger with four cubs was recorded for the first time in northeastern China's Hunchun National Nature Reserve located in the vicinity of the international borders with Russia and North Korea.

[41] Camera trap surveys between 2013 and 2018 revealed about 55 Siberian tigers in four forested landscapes in northeastern China: Laoyeling, Zhangguangcai Range, Wandashan and Lesser Khingan Mountains.

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.

[46] Between January 1992 and November 1994, 11 tigers were captured, fitted with radio-collars and monitored for more than 15 months in the eastern slopes of the Sikhote-Alin mountain range.

In the same time period, four cases of brown bears killing female tigers and young cubs were reported, both in disputes over prey and in self-defense.

Numerous publications on these species there are mainly episodic and survey data on this issue are collected by different authors in selected areas which do not give a complete picture of the nature.

In areas where wolves and tigers share ranges, the two species typically display a great deal of dietary overlap, resulting in intense competition.

Today, wolves are considered scarce in tiger habitat, being found in scattered pockets, and usually seen travelling as loners or in small groups.

[44] 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.

[3] In northern China’s Huang Ni He National Nature Reserve, poachers set up foremost snare traps, but there is not sufficient personnel to patrol this 75 km2 (29 sq mi) area throughout the year.

Local hunters had access to a formerly sealed off lucrative Chinese market, and this once again put the region's tiger population at risk of extinction.

[76] In 2010, Russia exchanged two captive Siberian tigers for Persian leopards with the Iranian government, as conservation groups of both countries agreed on reintroducing these animals into the wild within the next five years.

[77] In 2005, re-introduction was planned as part of the rewilding project at Pleistocene Park in the Kolyma River basin in northern Yakutia, Russia, provided the herbivore population has reached a size warranting the introduction of large predators.

[10][61] Numerous cases of attacks on humans were recorded in the 19th century, occurring usually in central Asia excluding Turkmenistan, Kazakhstan and the Far East.

In China's Jilin Province, tigers reportedly attacked woodsmen and coachmen, and occasionally entered cabins and dragged out both adults and children.

[87] In January 2002, a man was attacked by a tiger on a remote mountain road near Hunchun in Jilin province, China, near the borders of Russia and North Korea.

The group found tiger tracks and blood spoor in the snow at the attack scene and followed them for approximately 2,500 meters, hoping to catch a glimpse of the animal.

[91] It was successfully tranquilized and taken for examination, which revealed that the tiger was anemic and gravely injured by a poacher's snare around its neck, with the steel wire cutting deeply down to the vertebrae, severing both trachea and esophagus.

[99] In September 2013, a tiger mauled a zookeeper to death at a zoo in western Germany after the worker forgot to lock a cage door during feeding time.