The Batang Toru orangutan is now being described as a distinct species. (Photo courtesy of Tim Laman)

Erik Meijaard: A Sumatran Wonderland


DECEMBER 29, 2015

The forest was not like any other I had visited. Relatively short, thin, mossy trees, with many conifer-type species, an uncommon feature in tropical rainforests. And it was quiet and cool, unlike the oppressive hot humidity and constant buzzing and chirping normally encountered in these environments. I was back in Batang Toru, for the first time in 18 years.

In 1997 I had been asked to survey the forests south of Lake Toba in Sumatra. Common knowledge was that the Toba region divided Sumatra into two bioregions. To the north, species like Orangutans and White-handed Gibbons occur, while south of Toba you get the Tapir and Bearded Pig. Why these forest species don’t occur across the entire island is unclear. Something unusual apparently happened around Toba that ensured that species lived either north or south but not both.


Many people think that the Toba eruption was that unusual thing that happened. The Toba volcano exploded some 70,000 years ago in a blast so big that it deposited meters of volcanic ash as far away as present-day India some 4,000 kilometers to the west. Just think about the kind of ash cloud needed to achieve that! The massive Lake Toba is what now remains of the huge Toba volcano before it blew its top. In comparison, the much better known Krakatau eruption in 1883, which was one of the biggest volcanic events in recorded history and killed some 36,000 people, was microscopic compared to what happened in Toba.

The steep terrain in Batang Toru has created many waterfalls. (Photo courtesy of Tim Laman)

As said, the long-held assumption was that there were no orangutans south of Toba. After weeks of surveying I proved that assumption wrong with the discovery of orangutans in the Batang Toru area, a mountainous forest in the triangle between Tarutung, Padangsidempuan, and Sibolga. Orangutans are locally called Juhur Bottar, or “white meat,” also indicating that like elsewhere in Indonesia, the species has long been on people’s menu.

Mission accomplished and report written, I went home and focused on other things. But some people do real conservation rather than just writing about it like I do. Over 10 years ago, a group of dedicated conservationists decided that Batang Toru was worth saving. Most of the rugged and steep terrain had been given out as timber concessions in apparent conflict with Indonesia’s Basic Forest Law of 1980, which prescribes that such steep, highly erodible, and fragile terrains should be protect to prevent downstream flooding and soil erosion.

It sounds simple to point out to the government that a particular area had been wrongly allocated to commercial forestry, but more than 10 years of intensive lobbying were needed at the level of three districts, North Sumatra province and ultimately at the national level. Finally, in 2014, it was agreed that indeed Batang Toru should be protected in accordance with Indonesian law.

After years of listening to the people pushing for this status change, this was now an opportune moment for me to come back and enjoy the conservation benefits. There are not many places left in Indonesia where one could potentially encounter wild tigers, orangutans, tapirs, bears, serows, siamangs, and a range of other species, so off I went.

Not easy to get there, though. The terrain is seriously rugged. The walk to the Batang Toru basecamp at about 900 meters above sea level is a stiff six-hour hike along slippery muddy trails. And that basecamp is still on the periphery of the forest. Talking to the local Batak field team, no local people in living memory have ever walked across the Batang Toru area, simply because it is pretty much impossible to do so. That does really make me wonder what could be encountered deep in the interior of the area.

I really loved the five days I spent in this forest. After nearly 25 years in the tropics I still don’t like the heat and it was great to walk through primary forest at a pleasant temperature of some 25 degrees. One of these forest hikes took us to a stunning cave. Local Batak people, and more recently immigrants from Nias Island, come here regularly to catch and eat thousands of small fruit bats that live in these caves. The cave mouth was massive, and I am pretty sure that like in many caves in Southeast Asia, prehistoric people would have lived there.

We explored the cave, wading through the deep river and mountains of bat poo, and we managed to penetrate several hundred meters into its deep upper recesses. Quite an experience, in complete darkness with our head torches picking out large numbers of bats flitting around us, billions of cockroaches feeding on guano, large spiders feeding on cockroaches, and snakes feeding on bats. Very few people would have been there before us, and this ability to pioneer, is what makes Indonesia still such an exciting place to explore, at least for a naturalist like myself.

A forest stream in Batang Toru's upland forest.  (Photo courtesy of Tim Laman)

Being back in Batang Toru after nearly two decades was great. In the end I did not see orangutans, but that was more my own laziness. The field team had spotted an orangutan and had followed it to its night nest. The only thing I needed to do was to get up at 4:30 a.m. in the freezing cold, skip morning coffee, walk in the dark for 45 minutes, and, voilà, wait for the orangutan to wake up. I stayed in bed.

The conservation work here is not done. A hydropower project apparently financed by the ANZ bank and to be implemented by the state electricity company PLN, is being planned in the lowland part of Batang Toru which has the highest density of orangutans and several recently discovered species new to science. Also, the Martabe goldmine is digging a massive pit just outside the protected forest, but has started to explore inside the Hutan Lindung too. And, there are about 30,000 spontaneous migrants from Nias Island, who are presently cutting down the forest, and snacking on species like orangutans.

Batang Toru is one of the very few examples of serious conservation in Indonesia, where people really stick out their necks, and work and battle with government and communities to achieve positive conservation outcomes. It is an example anyone with conservation ambitions should pay attention to, because few groups have the commitment and skills to do what the Batang Toru team has done: Safeguarding a true Sumatran wonderland.

Erik Meijaard coordinates the Borneo Futures initiative: and