The main threats to the survival of the Amur tiger are poaching, habitat loss, and illegal hunting of ungulates, which are tigers’ main prey. Because they increase access for poachers, roads are another important threat to the Siberian tiger. Intrinsic factors such as inbreeding depression and disease are also potential threats to this big cat, but are less understood.
Poaching
WCS research has demonstrated that human-caused mortality accounts for 75-85% of all Amur tiger deaths. Current estimates indicate that 20-30 tigers are poached in the Russian Far East each year, although actual numbers may be higher. Population modeling based on Siberian Tiger Project field data suggests that poaching rates exceeding 15% of the adult female population could have dangerous repercussions, especially as tigers have fairly low population growth rates compared to other big cats. Analysis of mortality data in Sikhote-Alin Biosphere Reserve indicates that poaching rates may be at least this high in a significant area of Russian tiger range.
Tigers are most commonly poached for their fur and for their body parts, such as bones, that are used in Traditional Chinese Medicine. The opening of the border between China and Russia after the fall of the Soviet Union has made it possible to easily transport goods to Chinese markets and beyond. Although tigers are a protected species in Russia, enforcement agencies have very limited ability to catch convict poachers, and, even when this happens, fines are relatively small and disincentives insufficient. Poaching problems are further exacerbated by low incomes in many rural areas of the Russian Far East – sale of a tiger skin and bones represents a substantial source of income for poor people in remote villages.
It is also common for hunters to poach tigers to eliminate competition for ungulates and for locals to kill tigers in retaliation for depredations on domestic animals such as dogs and cows.
Figure 1. Causes of mortality detected by radio-tracking tigers captured in and near Sikhote-Alin Biosphere Reserve, 1992-2005. Sample sizes (number of dead tigers) are above each bar.
Habitat Loss
In Russia, human population growth does not threaten habitat as it does in many other tiger-range countries. However, activities such as logging, grazing, various development projects and uncontrolled fires are all resulting in direct habitat loss in the Russian Far East. Habitat is increasingly being divided into isolated patches, particularly at the southern edge of Amur tiger range.
Logging takes place in most of Amur tiger habitat. Although existing guidelines for timber harvest are actually quite sufficient, significant illegal logging and overharvest still occur. Selective logging, rather than clear cutting, is most common in tiger habitat, and does not seriously impact the quality of the habitat, if access to the extensive road system is controlled (thereby limiting poaching).
Fires are another important form of habitat loss. Many local residents consider fires to be the main cause of loss of forest habitat in parts of Primorsky Krai, and Amur tigers avoid areas that have burned, as they provide neither adequate cover for hunting, nor the habitat needed for prey.
Illegal Hunting of Ungulates
Illegal hunting of ungulates such as deer and wild boar significantly reduce prey availability for tigers. While official estimates continue to report stable numbers of ungulates, many hunters and wildlife biologists believe that abundance of ungulates in the Russian Far East has decreased considerably over past 15 years. Analyses from WCS’s Amur Tiger Monitoring Program clearly demonstrate that ungulate numbers are often 2-3 times higher inside protected areas, which are nonetheless impacted by poaching, though to a lesser extent.
Low ungulate numbers also foster a sense of competition between hunters and tigers. When ungulates numbers are low, it is easy to blame tigers, even when the root cause of population declines is overharvest by humans. When there is little prey available in the forest, tigers sometimes enter villages and prey on domestic animals, including dogs and livestock, which creates tiger-human conflict situations.
Roads
The number of roads in Amur tiger habitat is increasing steadily as logging activities and development push into even the most remote regions. Besides allowing greater access for poachers, roads increase tiger mortality from vehicle collision, and increase the probability of accidental encounters between tigers and people, leading to tigers being shot out of fear or opportunity. Roads also provide poachers greater access to ungulate habitat, which reduces tiger prey abundance.
Roads can be divided into two categories: primary roads, which are maintained year-round and provide access between villages and towns; and secondary roads, which are not regularly maintained but nonetheless allow access. From 1992 to 2000 WCS studied the fates of radio-collared Siberian tigers living in areas with no roads, secondary roads and primary roads. Our findings:
100% survival rate for adult tigers living in areas with no roads
89% survival rate for adult tigers living in areas with secondary roads
55% survival rate for adult tigers living in areas with primary roads
These results clearly demonstrate that the presence of both secondary and primary roads both greatly increase the odds of tigers being poached, and indicate the need for road closures and access control.