Javan rhinos: numbers on the upswing?

(This article was originally published in The Horn, autumn 2014. Author: Bill Konstant - Program Officer, International Rhino Foundation)


The Sumatran and Javan rhinos are possibly the rarest and most endangered large mammals in the world. Their combined populations probably number less than 175 animals. Sumatran and Javan rhinos were once bountiful and ranged over many hundreds of thousands of square miles stretching from India to Indonesia. Today, however, they survive almost entirely as relict populations in a handful of scattered tropical forests; the future for both species lies almost entirely in the hands of Indonesian wildlife authorities; and continued support for intensive monitoring and protection efforts is the last hope for avoiding extinction.

Though Javan rhino numbers may be only half those of Sumatran rhinos – 50 versus 100 – some experts contend that the Javan rhino is not as seriously threatened. That’s because, while the Javan rhino population does not appear to have lost ground in recent years, the Sumatran rhino seems almost to be in freefall.

Ujung Kulon National Park is the final stronghold for the Javan rhino, and the most recent evidence suggests that its numbers may be slowly increasing. A video camera-trap census conducted in 2011 yielded estimates of 35-44 animals, while a similar but more robust study in 2013 appears to indicate a resident population closer to 50 animals or more. That would be incredibly good news, especially if the increase is shown to include new infants and not just animals that might have been missed in the earlier study.

Just as they do on Sumatra, RPUs patrol and survey Java’s tropical forests for rhinos and other wildlife, including 25 species of threatened amphibians, reptiles, birds and mammals. There are no elephants on Java and the last of the island’s tigers was killed sometime late in the last century. Endangered Javan leopards still roam the landscape, however, as does the elusive Javan banteng (a wild form of cattle) and rare silvery gibbon.

One major way in which rhino management practices differ on Java is the effort currently being put into habitat restoration, all of which are focused on an invasive palm known locally as langkap and as Arenga obtusifolia to the scientific community. Langkap is a fast-growing species that can quickly dominate the lowland forest canopy, crowd out other trees, and suppress plant growth on the forest floor. Since the langkap’s fruit and leaves are not favoured food for wildlife, its dominance correlates negatively with healthy populations of several threatened species, including the Javan rhino. This observation led to a formal programme for removing the Arenga palm to establish alternative native plant communities, preferably containing a high percentage of Javan rhino food species. This work has been underway for almost two years now, during which approximately 70 hectares of langkap are rapidly being replaced by regenerating forest. The project is based in a 4,000-hectare section of Ujung Kulon designated as the Javan Rhino Study and Conservation Area (JRSCA).

JRSCA encompasses the eastern boundary of Ujung Kulon, abutting the burgeoning human population of Banten Province, for which the Javan rhino is an official symbol. Although only a small portion of the study area has been cleared of the invasive palm thus far, researchers are already documenting some encouraging project results. First of all, the growth of recolonising plants is rapid, with some species towering above a man in a year or less. Secondly, the percentage of rhino food plants represented in the regrowing forest is exceptionally high – above 90%. Lastly, the rhinos are responding well to the effort, seemingly beating a path to JRSCA. Forests through which only a couple of rhinos trod a year or so ago, recently yielded the tracks of nine distinct individuals that are presumably venturing into unfamiliar terrain to partake of the new “salad bars”. And only a couple of months ago, one adventurous rhino nonchalantly walked right through the yard of the newly-built RPU base camp, perhaps admiring its unique construction.