Saturday, February 27, 2010

Good News for the Siberian Tiger

In a world where many animals are under siege, the Amur tiger – popularly known in the West as the Siberian tiger – offers an encouraging message: the population of the huge cat is showing signs of recovery.

During the past 100 years, the Amur tiger population of the Russian Far East was decimated by forest destruction, trophy hunting and poaching for tiger body parts for use in traditional Chinese medicine. By the 1940s the number surviving had dwindled to an estimated 50.

Thanks in part to $611,131 in U.S. Fish and Wildlife Service grants that, combined with partner donations and in-kind contributions, push the total to more than $1 million, the big, distinctive cats appear to be rebounding in Russia.

Recent surveys indicate that between 331 and 370 adult tigers and 100 young – about 450 tigers in all -- are living in the Russian Far East, home to 95 percent of all Amur tigers in the world.

Service wildlife biologist Fred Bagley, long associated with Amur tiger conservation efforts, said a spike in tiger poaching in the early 1990s was subsequently met by a Russian government crackdown, and the intensified anti-poaching efforts have paid off.

The Amur tigers is one of five tiger subspecies in the world; of eight that once roamed the earth, three became extinct in the 20th century. While the majority of Amur tigers live today in the Russian Far East, a much smaller number are known to inhabit China, and a few may occur in North Korea. Some estimates place the global tiger population in the 3,900 to 5,100 range, down from perhaps 100,000 more than 100 years ago.

The demand for tiger parts for use in traditional Chinese medicine has played a major role in the decline of the Amur tiger population. Despite medical evidence to the contrary, belief persists that tiger parts can curb ailments ranging from impotence to arthritis, skin disease, fever, and more.

And during the last period of heightened poaching, Russian conservation workers estimated that as many as 60 tigers were killed each year.

But the tigers’ situation has shown marked improvement: local government in the Russian Far East, said Bagley, is firmly committed to helping rescue the tigers, and the Service has remained a firm partner in the effort. Service grants have helped pay for vehicles, uniforms, fuel and even salaries for Russian game wardens who have had success in deterring poachers. It’s a relationship that has had positive results.

“It’s hard to find another place in the world where tigers are doing as well,” Bagley said.

Left alone in the wild, the tigers do well, indeed. Amur tigers breed easily, and even though the number of young in the current decade has given cause for some concern, the number of cubs born to each litter has increased slightly, granting some stability to the gradual population increase.

Amur tigers, which can weigh up to 600 pounds at maturity, are loners that travel enormous distances in search of prey, such as elk and wild boar. While some of the tigers have been known to attack humans, they usually prefer to avoid people. The tigers have been known to kill wolves that venture into their territory.

Another threat to the tiger is Russia’s own healthy economy. Wildlife law enforcement jobs in the Russian Far East don’t pay well, and even the most dedicated Russian game wardens are often easily lured elsewhere by better pay, making it difficult to keep trained personnel on the job.

“In the scheme of international grants, the amount of money we’ve contributed to this effort has been relatively modest,” said Bagley. “But there is no doubt that we’ve had an impact. This is one of those times when you can point to something and say, yes, we’re making a real difference. Applied research, habitat protection, effective law enforcement and the support of local people made possible through conservation education, are advancing the survival of this tiger.”

Tuesday, February 23, 2010

Genetics

Several reports have been published since the 1990s on the genetic makeup of the Siberian tiger and its relationship to other subspecies. One of the most important outcomes has been the discovery of low genetic variability in the wild Far Eastern population, especially when it comes to maternal or mitochondrial (mtDNA) lineages. It seems that a single mtDNA haplotype almost completely dominates the maternal lineages of wild Siberian tigers. On the other hand, captive cats appear to show higher mtDNA diversity. This may suggest that the subspecies has experienced a very recent genetic bottleneck caused by human pressure, with the founders of the captive population being captured when genetic variability was higher in the wild. However, it may well be that the Siberian tiger population has always shown relatively low genetic diversity, due to a small number of founders colonising the Far East. Work with the preserved remains of the now extinct Caspian Tiger (P.t. virgata) has shown that the two subspecies share a comparatively recent common history, at least when it comes to mtDNA lineages. It appears that tigers colonised central Asia at most 10,000 years ago, and the modern Siberian stock may be the result of a few Caspian tigers subsequently wandering east via northern Asia.

New genetic analysis revealed that the extinct Caspian tiger lives on in the Siberian Tiger. Researchers from the University of Oxford in the United Kingdom collected tissue samples from 20 Caspian tiger specimens kept in museums across Eurasia. Afterwards, researchers from the U.S. National Cancer Institute (NCI) Laboratory of Genomic Diversity in Frederick, Maryland, sequenced parts of five mitochondrial genes. The Caspian Tiger's mitochondrial DNA is only one letter of genetic code separated from Siberian Tiger DNA, while it is readily distinguishable from the DNA of other tiger subspecies. This indicates that the Caspian and the Siberian subspecies are really one. The scientists have concluded that the two are so similar because both were descended from the same migrating ancestor. The ancestor colonized Central Asia via the narrow Gansu Corridor (Silk Road) from eastern China. The researchers suggest that through the early 1900s, Caspian and Siberian tiger populations intermingled, but hunters subsequently isolated the two groups. This resulted in the Siberian population splitting off from the Caspian population only in the past century.

Sunday, February 14, 2010

Reproduction

Siberian tigers reach sexual maturity at four years of age. They mate at any time of the year. A female signals her receptiveness by leaving urine deposits and scratch marks on trees. She will spend a week with the male, during which she is receptive for three days. Gestation lasts from three to 3½ months. Litter size is normally three or four cubs but there can be as many as six. The cubs are born blind in a sheltered den and are left alone when the female leaves to hunt for food.

Cubs are divided equally between genders at birth. However, by adulthood there are usually two to four females for every male. The female cubs remain with their mothers longer, and later they establish territories close to their original ranges. Males, on the other hand, travel unaccompanied and range farther earlier in their lives, thus making them more vulnerable to poachers and other tigers.

Friday, February 5, 2010

Siberian tiger pictures

We score web for most beautiful Siberian tiger wallpapers. Each wallpaper is handpick by my for quality and filter out the junk pictures so you do not have to worry about them here.

Just click on picture to enlarge: