June 27, 2013
Rare Sumatran Tigers Threatened By Human Development
Brett Smith for redOrbit.com - Your Universe Online
A new study from Indonesian and American researchers in The International Journal of Conservation indicates that tigers on the Indonesian island of Sumatra have been highly susceptible to human development."Tigers are not only threatened by habitat loss from deforestation and poaching; they are also very sensitive to human disturbance," said study co-author and Virginia Tech researcher Sunarto, a native of Indonesia, where people typically have only one name. "They cannot survive in areas without adequate understory, but they are also threatened in seemingly suitable forests when there is too much human activity."
The most optimistic assessments peg the island's tiger population at about 400 individuals, and past research has put the Sumatran tiger density at about one cat per 40 square miles. According to a statement by the researchers, this is the first study to examine the population density of Sumatran tigers across different forest types - including the island's peat land, which was previously unstudied.
The team used widely accepted spatial estimation methods to refine their figures that were based on camera traps set up around Sumatra.
"Getting evidence of the tigers' presence was difficult," said study co-author Marcella Kelly, an associate professor of wildlife in the College of Natural Resources and Environment. "It took an average of 590 days for camera traps to get an image of each individual tiger recorded."
"We believe the low detection of tigers in the study area of central Sumatra was a result of the high level of human activity - farming, hunting, trapping, and gathering of forest products," Sunarto said. "We found a low population of tigers in these areas, even when there was an abundance of prey animals."
The researchers concluded that the legal protection of a designated reserve and intense management of this area could potentially reduce the amount of human disruption and ease the revival of tiger habitats. With the successful maintenance of a protective area, the research team said the tiger population should recover. To support their argument, the researchers noted a relatively stable tiger population in the region's Tesso Nilo Park, where human activities have been significantly reduced by legal measures.
The Sumatran tiger is a rare subspecies of the animal that is considered critically endangered by the International Union for Conservation of Nature (IUCN). The tiger is described as having darker fur and thicker stripes than other tigers. The Sumatran tiger also tends to be smaller than similar cats found in India.
Experts say Sumatran tigers strongly prefer living in the center of forested area with higher elevations and lower annual rainfall. Their preferred forests contain dense cover and steep slopes, and they have been found to avoid forested areas that have a large human presence.
Conservationists tend to blame the expansion of palm oil and acacia plantations for the tigers' habitat loss. Despite being granted full protection by the Indonesian government, tiger parts are still openly sold in Sumatra and other areas of the island nation. Many of these parts are also being smuggled into other nations.