It was an overcast morning on the island of Sumatra, Indonesia last Saturday when conservation officers for the Way Kambas National Park came upon the newest member of a nearly extinct species resting next to his mother on the forest floor. Just four hours old, the hair-covered newborn, would soon become an international sensation representing a glimmer of hope for the most ancient – and perhaps most threatened – lineage of surviving rhinoceros: the Sumatran rhino.
A similar birth likely took place about four million years ago in the forests of the northern Indochina and South China region, when the original member of the Sumatran rhino genus, Dicerorhinus, took their first stumbling steps. Since then, the story of this species has been one of radical change and uncertainty, finally culminating in the existential vulnerability we see today.
Beginning in the early Pleistocene, about two million years ago, the Sumatran rhino population suddenly increased dramatically. Researchers believe this was the point when the rhinos began expanding their range from north Asia into south Asia and Sundaland – an emergent landmass comprising of the areas around Sumatra, Java, and Malaysia. After this initial spread – about 950,000 years ago – Sumatran rhino numbers peaked at about 60,000 individuals.
Various estimates place the current Sumatran rhino population at less than 80 individuals, of which there is perhaps only one reproductively viable group living in the wild. As an IUCN critically endangered species, efforts are being made to save them from extinction. The successful birth of this latest international star, who is now five days old, is the result of an undergoing re-population initiative by the Sumatran Rhino Sanctuary (SRS) – a 250-acre semi-wild facility in the middle of the Way Kambas National Park. At the SRS, 10 Sumatran rhinos are cared for around the clock and are part of a core program to produce a genetically diverse source of rhinos which can eventually repopulate Indonesia’s forests and lowland swamps.
A research paper published in 2017 suggests that the decline in Sumatran rhino populations is the result of a continuous decrease in their genetic diversity. Once the rhinos had spread throughout their maximum range during the Pleistocene, volatile climatic conditions isolated different groups. As forest-dwellers, various rhino populations were separated from one another when a savannah-like belt stretching through the middle of Sundaland, between what are today the islands of Borneo and Sumatra, emerged. This barrier-effect was compounded by periods of rising sea levels which submerged great expanses of land. When populations become fragmented and are unable to exchange genetic material, mutations increase in prevalence and reproductive viability declines.
The genetic diversity of today’s Sumatran rhinos is worryingly low. In fact, it is comparable to the levels of recently extinct mammals like the mammoths of Wrangel Island. SRS is tackling this issue by breeding individuals from different populations. For example, Rosa, who gave birth in the sanctuary last year, was a wild rhino living in Bukit Barisan Selatan National Park before she was transported to SRS after repeatedly visiting local villages in search of food. Harapan, the father of the most recent newborn, was born in the Cincinnati Zoo in the United States. In fact, he was the last Sumatran Rhino to live in the western hemisphere. Delilah, the calf’s mother, was born at SRS, daughter to Ratu, a ‘local’ from the Way Kambas National Park (and who gave birth for the third time two months before her daughter!). The SRS program is essentially mixing genetic pools which have likely been isolated from each other for quite some time.
It wasn’t only a changing climate which contributed to the threatened existence of Sumatran rhinos we see today, although it definitely set the groundwork. There is evidence that already in the late Pleistocene (which ended 11,700 years ago) humans were hunting the Sumatran rhino. They began clearing forests – the preferred habitat of these rhinos – soon after. Most recently, poaching served to almost eradicate the species entirely.
Happily, this little calf’s birth is the latest in a string of hopeful news. It's the second birth in less than two months at SRS and now the fifth which has taken place at the facility. The new arrival confirms the reproductive viability of one more breeding pair, bringing the total to six. Given the species densely vegetated habitat and the exceeding low population numbers, poaching does not seem to pose a significant threat to the species.
Whether or not the newest Sumatran rhino will manage to reverse a trend which has been progressing for hundreds of thousands of years remains to be seen. Nevertheless, he is raising important awareness and support for the imperiled species and likely reinforces the Indonesian government’s support for his species' conservation.
Header image: Stephen Belcher
Endangered
Endangered
Endangered
