Across the Indonesian island of Java, suitable habitat for Javan leopards shrunk by more than 1,300 square kilometers, or 500 square miles, between 2000 and 2020. That’s according to a recently published study that sought to map the remaining living space in which the big cat can still survive.
Researchers looked at a set of variables that may affect the presence of leopards, such as the extent of primary and secondary forests, the presence of plantations, and distance from rivers and human settlements. They also looked at past monitoring data to build their habitat suitability model. In total they assessed about 12,900 km2 (5,000 mi2), which is around a tenth of Java’s land mass.
The research found that in 2000, an estimated 2,481 km2 (956 mi2) of land was classed as “highly suitable.” By 2020, however, this had shrunk by more than 40%, to 1,430 km2 (552 mi2). “Suitable” habitat fell by 251 km2 (97 mi2), while habitat deemed unsuitable increased by around 1,300 km2 (500 mi2). Primary forest loss accounted for most of these declines, the researchers note.
Javan leopards (Panthera pardus melas) are the sole remaining large predator on the island; poaching, loss of prey and habitat loss and fragmentation are among the drivers of its decline. The critically endangered subspecies is thought to number as few as 350 individuals. Remaining leopards live in heavily isolated forest fragments across the island.
Hariyo “Beebach” Wibisono, director of SINTAS Indonesia, an NGO, welcomed the findings from the new paper as yet more evidence of the perilous conservation situation facing the big cat. It echoes findings from research he conducted in 2018, which indicated habitat suitable for the leopard covered less than 9% of the island, with half of it occurring in unprotected areas.
“This paper actually concludes the same things; that the Javan leopard is endangered because of habitat degradation and heavily isolated habitat and populations,” Wibisono, who was not involved in the new paper, told Mongabay. Together, the research underlines that the Javan leopard’s conservation status “is much more critical than what we thought,” he said.
He added he’s uncertain, however, about the extent of the remaining “suitable” habitat, saying he believes it may be overestimated in the suitability mapping. In some instances, he noted, plantations can serve as habitat for Javan leopards, but that depends highly on other variables, such as the presence of roads. “If there are roads there, then it can become unsuitable habitat for the Javan leopard,” he said.
Erwin Wilianto, founder of SINTAS and the Javan Leopard Focus Group, said the paper highlights that the big cat’s habitat keeps “shrinking with no connectivity.” He also shared Wibisono’s concern that the ecology of the species is vital in estimating its suitable habitat.
“This paper only points out a suitable area based on statistical terms, not ecological terms,” Wilianto wrote, adding that to be viable, more than 10 breeding individuals are needed in an area. “Therefore, an area with less than 230 km2 [89 mi2] should be taken out from areas with ‘suitable’ status.”
Given the findings of his own study and this recent paper, Wibisono said there are key three steps to preserving the species: maintaining healthy leopard populations, strengthening them in low-density areas, and then repopulating forests where the species is no longer present. Prior to that, he said, conservation efforts must be underpinned by a thorough population assessment, something that is thus far lacking for the subspecies.
“What we would like to do is know which forests have the highest densities of Javan leopards,” he said. “But first we have to know the status of the Javan leopard.”
This article by by Sean Mowbray was first published by Mongabay.com on 4 May 2023. Lead Image: A juvenile Javan leopard in Baluran National Park. Image by Candra Firmansyah via Wikimedia Commons (CC BY-SA 4.0).
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