Wednesday, August 22, 2012

Declining Prey Species Could Endanger India's Tiger Population

Bengal tiger

Studies by environmental groups have recently shown that India's tiger population is declining as a result of decreasing numbers of prey species, especially deer, in the nation's tiger reserves. After a treatment of a tiger at the Alipore Zoological Gardens for starvation, the Wildlife Institute of India (WII) made a report saying that prey base in the Sunderbans Tiger Reserve of West Bengal is under investigation. The report, titled Population Estimation And The Ecology Of Tigers In Sunderbans Tiger Reserve (STR) was done by a joint collaboration of the National Tiger Conservation Authority (NTCA), WII, and the Sunderbans Tiger Reserve. It has found a very low prey density in the mangroves, Sajnakhali Wildlife Sanctuary, and the west range of the Sunderbans. According to WII's scientist Y.V. Jhala, a total of 187 kilometers of boat transects was conducted between February and May to get an idea of the prey density through visual detection. He further added that each transect was repeated three to six times, and that prey density along Sajnakhali's creeks and west of the Sunderbans was relatively low with only 13.3 spotted deer per square kilometer. He also stated that in an area of 2,500 square kilometers, the number of deer will only be a little over 30,000 making the prey density very low in such a large area of the Sunderbans.
Chital (spotted deer); favorite prey of tigers

An earlier study by scientists George Schaller and Ullas Karanth stated that there should always be a natural balance between the predators and their prey. While a total of 500 deer could provide adequate food base to one tiger, the breeding rate of the prey is always controlled by the predation rate of tigers. Going by that figure, the study said that the low density of deer could only support 60 to 65 tigers. The WII alerted that herbivores cannot salinity after a time point, which leads to the fall in prey base and eventually a likely decline in tiger numbers. This fact is now being enhanced by more detailed behavioral studies being carried out by the institute. Scientist and conservationist Ullas Karanth stated that a long term population dynamic studies being done in Karnataka will tell the WII whether Sunderbans' tiger population is increasing, decreasing, or stable. Biswajit Roy Chowdhury, a member of the West Bengal wildlife advisory board, stated that the decline in prey base in the Sunderbans was a result of Cyclone Aila. Another board member named Joydip Kundu added that if the study is to be trusted, there is a crucial need to increase Sunderbans' prey base by moving additional prey species from other sanctuaries. With a very low density of prey species such as deer and wild boar, experts have called for a detailed study to see whether any disease outbreak is behind the repeated straying of tigers in Sunderbans' villages.
Sunderbans during sunrise

I very much hope that conservationists and experts will come up with a solution to help revive India's tiger population from the declining of prey species, especially in the Sunderbans. The study by the WII has shown that the prey density in this delta is very low, which is why it is extremely crucial to investigate the cause(s) of the decline in prey species. At the same time, measurements to prevent tigers from straying into human settlements should be undertaken. The Sunderbans have long been infamous for being a major hub of tiger attacks. Usually this occurs when men from villagers would go into the forests to collect fish, firewood, and honey to support their families thus bringing them into close contact with these formidable felines. In response to such attacks, people have conducted strategies in hopes to prevent tigers from attacking them. The most common methods included wearing of masks behind their heads when venturing into the forests, or placing dummies resembling humans and laced with electric wires at a random spot. However, tigers have proven to be smart and calling the tactics a bluff. But now, with factors such as the rise in water levels because of climate change and declining of prey species, tigers have resorted to straying into villages putting lives of several people including children into jeopardy. This explains why it is absolutely necessary to take decisive action in determining what is causing the tigers' prey species to diminish, and undertake protection measurements to keep both people and tigers safe from each other. In 2009 and 2010, it was found that the reason tigers have been straying into Russian towns and villages is because they were infected with canine distemper. In addition to tigers, there is also a similar situation in southern India where elephants are becoming more defensive as a result of fragmentation in their habitat. This article gives a clear representation about why it is crucial to protect and conserve populations of our motherland's native species from both natural and man-made threats.

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