Conservation news

A trip on Borneo’s Mahakam River in search of forgotten wildlife

  • With funding from National Geographic we are retracing the footsteps of Henry Cushier Raven, a specimen collector who travelled extensively in East Kalimantan, Indonesia between 1912 and 1914.
  • We want to know which species Raven found and whether we can still find these species today.
  • In April 2016, we already covered the Berau and East Kutai parts of Raven’s journey. This is the story of his Mahakam travels.
  • The story is published in four parts. This is part II.
An impressionistic photo of magical moonlight reflecting on the Mahakam River. Photo by Gabriella Fredriksson

Continued from part 1.

We sail until 10 at night and tie up the boat near the mouth of the Kedang Kepala River in the town of Muara Kaman. This town has one of the few archaeological sites on Borneo, with building remains and unearthed artefacts indicating that in the 4th century AD this was the site of Martadipura, the first Hindu Kingdom in present-day Indonesia. The strategically chosen site, of which now little more remains than a few earthen ramparts, would have controlled the vast interior trade network. From this site, products like rhino horn, camphor and bird’s nests were exported to as far as China.

Muara Kaman is normally also a good site to see the highly threatened Mahakam dolphin, a river species of which only a few hundred animals survive. I saw a pod of this species years ago feeding in the confluence of the two rivers, where the black peaty waters from the north meet the brown silty waters of the Mahakam. This time we don’t get to see them, which might have been because it is dark when we arrive and I am still asleep when the boat engine starts up again just after the 4 am call for prayer from the local mosque. Later on, our team does see a mother dolphin and its baby from the observation deck, but I again manage to miss them as I am writing this below deck.

Sailing up the Mahakam towards the Mahakam Lakes. The slow glide along the river provides a great way to view wildlife. Photo by Gabriella Fredriksson

We enter the Mahakam Lakes area. Raven described this as “an enormous marsh” in which “birds of many varieties are abundant”. The most conspicuous were the white egrets, which “in many places simply swarmed, and from a distance they made the dark green trees have the appearance of being covered in white blossoms”. Also, “red-bodied hawks”, probably the Brahminy kites, “were abundant”.

Many of the species seen by Raven are still here, but what seems to have changed is their numbers. Surely, we see the various species of white egrets – little, intermediate, great and cattle – and pond and striated herons, but they are hardly swarming. We count three Brahminy kites, hardly a sign of abundance.

Brahminy kite. Normally a common species along Borneo’s rivers, including around cities, but now it took as two days before we saw the first one. Photo by Arie Prasetya

Of Raven’s common tree ducks, we see 10, we encounter neither of his two “common” species of rail, nor do we see the “fairly common” Oriental darters. Why have these species declined? One reason is obvious. As Raven noted, “the natives claim that they gather great numbers of birds’ eggs for food”.

The tree ducks are reportedly still heavily hunted to be sold as duck satay in Kalimantan’s restaurants. Also, since the 1970s, the area has lost a lot of forests in which these species would have bred, especially during the El Niño-induced long droughts of 1982, 1987 and 1997, when large areas of swamp forest were burned to a crisp. These forests were not just important for bird nesting but also crucial fish spawning sites. With the forests gone, birds have both lost their breeding sites, but also their food supply has dwindled along with declining fish stocks.

One thing Raven would certainly not have seen in the early 20th century are the many hundreds of edible nest swiftlet houses that are now a very common feature on the Mahakam’s banks. The nests of these birds are as highly sought after as 2000 years ago when this was still part of the Hindu Kingdom. The consumption of bird nests in the highly sought-after delicacy of bird-nests soup is an ancient tradition that does not seem to lose any of its popularity.

The swifts naturally build their nests in caves, but over-harvesting resulted in rapidly declining supplies and sky-high prices. One kilo of high quality nests can sell for as much as US$ 4000, and obviously competition for this product is high. Raven in fact travelled part of the way with a Dutch government officer whose sole task it was to check nest harvest levels to ensure that the local Sultan was paid the appropriate taxes.

One of the many swift houses encountered on our trip. Photo Gabriella Fredriksson

Of course, such unrelenting over-harvesting cannot be sustainable, but a few decades ago a smart local entrepreneur thought of a solution. He or she (no one seems to know this initial inventor) realized that it was possible to mimic the birds’ natural cave environment by building dark, window-less wooden houses. Birds were attracted to these nest sites by loudly playing their contact calls through a loudspeaker on top of the building, and for much of our way, we are accompanied by these amplified bird calls.

The invention of the swift house was a smart move, because this industry is now generating hundreds of millions of dollars in rural poor areas. One well-built swifts house can generate some US$ 1,500 to 3,000 per month, a vast amount of money in areas like the Mahakam River, where average per capita monthly expenditures in rural areas are about US$ 100.

Swift nests may give at least some people an escape route out of poverty. The popularity of swift houses is obvious and an entire industry has developed around them. Shops specializing in supplying the houses sell everything from special fans to keep the buildings cool to insect sprays for preventing outbreaks of bird lice and other harmful bugs.

The swift houses may even have boosted populations of the edible nest swiftlets, although no one has the data to prove this. Then again, these additional birds may compete with other even rarer insect-feeding swifts, endangering them even more. Damn, conservation is so difficult.

Rustam and Arie keeping an eye on a tropical storm that will soon catch up with us, lashing the boat with rain and gusts of wind, just when it gets dark, and threatening to run it on the rocks. I am checking out the escape routes and gather crucial things, but to our relief we get through ok and tie up for the night.

PART I | Part II of IV

Detailed species lists are available here.

Erik Meijaard coordinates the Borneo Futures initiative. Follow @emeijaard and @borneofutures.

Header image: Forest dragon in Borneo. Photo by Rhett A. Butler.