Semarang. Indonesia's tiger population is considered to be on the brink of extinction, with only a few hundred specimens remaining in the wild.
The Sumatran tiger (Panthera tigris sumatrae) is the only surviving subspecies of the archipelago's three tiger species, with the Bali tiger (panthera tigris balica) having gone extinct in the 1940s and the Javan tiger (panthera tigris sondaica) having disappeared in the wild during the 1980s.
But despite the International Union for Conservation Nature (IUCN) having classified these big cats as critically endangered 10 years ago, they are still being killed regularly.
Reuters reported on Monday (05/03) that a one of these top predators was brutally killed after it injured a person at Mandailing Natal village in North Sumatra. This prompted residents to call on rangers to kill it.
Before the news of the killing broke, the Jakarta Globe spoke with Wulan Pusparini, a tiger expert at the Indonesian chapter of the Wildlife Conservation Society, who explained why the preservation of these top predators in their natural habitat is so important for an ecological balance.
Wulan explained that the Sumatran tiger population is significantly decreasing due to poaching, habitat loss and human-wildlife conflict. She said a population viability analysis conducted by the WCS showed that there are currently only an estimated 600 Sumatran tigers remaining.
She said the Sumatran tiger is categorized as an apex predator in its natural habitat and its extinction will result in a trophic cascade – an ecological phenomenon triggered by the removal of top predators, which results in reciprocal changes in the relative populations of predator and prey in the food chain, resulting in dramatic changes to an ecosystem.
"If an ecosystem loses its top predators, the population size of animals under them would soar due to the absence of natural controllers. As a result, the ecological landscape would change as the increased population of herbivore species would consume the young plant population. The natural succession of the forest would get disrupted," she explained.
Wulan said trophic cascades occur when, such as in the case of tigers, their population is greatly reduced, while its prey, such as wild boar, would greatly increase in number.
"Wild boars are also a nuisance in plantations around forests, so the likelihood of human-wildlife conflict further increases," she said.
Wulan cited Yellowstone National Park in the United States as an example, where a decline in its gray wolf population resulted in an uncontrolled increase in herbivores, which affected vegetation.
This occurred because there were no other apex predators in the park, beside the gray wolf.
She said if Sumatran tigers should disappear from the wild, humans would have to deal with a massive increase in the population of prey animals.
"The tiger's prey would then have to be controlled by humans," she said. "Because the loss of tigers can lead to forest degradation due to over-grazing by their prey animals."
She said this phenomenon has a negative impact on the food chain.
"It's just like when we play jenga [a classic block-stacking game]. When a crucial block is removed from the bottom of the stack, the whole structure collapses," Wulan said.