Time for the majestic Sumatran tiger is running out. The island’s population crashed by 16.6 percent between 2000 and 2012, and with the ever-increasing threat of palm oil invading their land, the future doesn’t look good.
After setting up hundreds of camera traps and trekking through the Sumatran jungle for a year, a team of researchers found that tiger densities were 47 percent higher in healthy forests than in logged forests. However, they did observe a 4.9 percent rise in the number of tigers per square kilometer between 1996 and 2014, although the team is keen to point out that this news needs to be taken with a pinch of salt.
“We find that while tiger densities have significantly increased over the last decade, the disproportionate loss of higher quality lowland and hill primary forest habitat, in combination with severe fragmentation of remaining strongholds, has offset this important conservation achievement and led to an equivocal or higher threat of extinction,” the researchers wrote in their paper, which is published in Nature Communications.
The jungle of Sumatra isn't just home to tigers, it's an important habitat for a plethora of creatures, from orangutans and rhinos to clouded leopards and sun bears. Deforestation puts all of them at risk.
Unfortunately, habitat loss and fragmentation is occurring all over the world, driving many unique species to the brink of extinction. What’s more, it’s solely caused by us. It can result from all sorts of human activities, from building houses, towns, and cities to cutting down trees to make way for palm oil plantations and agriculture.
According to the World Wide Fund for Nature (WWF), “habitat loss is probably the greatest threat to the variety of life on this planet today.” It is the biggest danger to 85 percent of endangered and threatened species worldwide, and it’s putting everything from elephants to butterflies at risk.
Tigers are no exception. They have lost over 90 percent of their historical habitat, which is an issue because tigers need space. The team calculated that each Sumatran tiger requires about 390 square kilometers (150 square miles) of home turf.
There are various subspecies of tiger around the world, all desperately clinging on. The Bengal tiger of the Indian subcontinent is now the most numerous, although it covers just a tiny portion of its original range and less than 3,000 individuals are left in the wild. Three species – the Caspian tiger, the Javan tiger, and the Bali tiger – are already extinct.
Long ago, tigers were decimated by hunting. While habitat loss is now a bigger threat, they are still affected by illegal poaching due to their sought-after skins, perceived threat to humans, and demand for their body parts for use in traditional Asian medicine.
The researchers found that between 2000 and 2012, the Sumatran tiger’s habitat shrunk by 17 percent. Nevertheless, they describe the threats of deforestation and habitat fragmentation as “imminent and often irreversible”, highlighting the immediate danger the tigers are in, but also signifying a ray of hope by suggesting that something can still be done to save the Sumatran tiger.
To be viable in the long term, tiger populations need 30 breeding females. The researchers only found two areas big enough to sustain this number.
"The erosion of large wilderness areas pushes Sumatran tigers one step closer to extinction," said lead author Matthew Luskin, previously a graduate student at the University of California, Berkeley, in a statement. "We hope this serves as a wakeup call."
What is needed now is for logged areas to be reforested, so that Sumatran tigers can once again spread out into more of their natural range. However, the researchers fear that this probably won’t occur, so it is essential to protect the two sites viable for breeding populations.
"Large-scale reforestation is unlikely," said co-author Mathias Tobler of San Diego Zoo Global. "If we are going to save Sumatran tigers in the wild, the time to act is now."