The Javan rhinoceros, one of the world’s most endangered species, continues to persevere in its last remaining sanctuary, the latest census from the Indonesian government has found.
In a statement issued Feb. 26, the Ministry of Environment and Forestry said the population of Javan rhinos (Rhinoceros sondaicus) as of the end of 2017 was a minimum of 67 individuals: 37 males and 30 females. All of the rhinos, once the most widespread rhino species in Asia, are now corralled into a single area, Ujung Kulon National Park on the westernmost tip of Java — an area spanning 480 square kilometers (185 square miles), or the combined size of the New York boroughs of Queens and Brooklyn.
The census showed the population holding steady from the previous year, park agency head Mamat Rahmat said in the statement.
“Our field surveys found no signs of Javan rhino death,” he said.
Four rhino protection units, or RPUs, comprising park authorities and representatives of conservation NGOs, regularly patrol the area. They are also helped by community members in joint patrols four times a year.
The report indicated that the rhino population included about 13 juveniles — a positive sign, given that Javan rhinos are typically solitary animals known to have a low reproduction rate. Females of the species reach sexual maturity at 3 or 4 years old, while the males mature much later, at around 6 years. The gestation period is 16 months.
“The findings reflect a healthy Javan rhino population that’s breeding well,” Widodo Ramono, executive director of the Indonesian Rhino Foundation (YABI), told Mongabay.
Despite the positive news, Widodo emphasized the importance of sustained protective measures for the animal, and research into the dangers of having only one surviving population of the species.
“The habitat eventually will hit its natural limit to provide for the population,” he said.
The latest reported number is short of a target, set in 2007, of raising the population to 70 to 80 rhinos by 2015. Some conservationists say they believe the park may not be able to support a larger population than at present.
While authorities have reported zero rhinos killed, threats from human encroachment into Ujung Kulon remain real. In September 2017, the park agency reported that dozens of people were caught engaging in illegal activities in Ujung Kulon’s core zone and jungles, including hunting wildlife, collecting wood and other resources, and even planting rice and other crops.
The threat of natural disaster is one that has long loomed over the population, whose habitat lies within the danger zone of Anak Krakatau, the ever-growing and active volcano that rose up after the catastrophic eruption of Krakatoa in 1883. That eruption generated a tsunami with 30-meter (100-foot) waves that hammered the Ujung Kulon coast.
Indonesian authorities and wildlife experts have since 2015 been scouting a second site to seed a new population of the Javan rhino. The current shortlist includes locations in western Java, but there have also been calls to look further afield at Sumatra, which is home to a distant cousin, the Sumatran rhino.
But the prospects of survival for the Sumatran rhino (Dicerorhinus sumatrensis) appear bleak. Experts believe the total population in the wild could be as low as 30 individuals. They live in fragmented packets of forest far away from each other, making breeding much more challenging.
Poaching and habitat loss have put the Javan and Sumatran rhinos on the IUCN’s list of critically endangered species, or a step away from vanishing from the wild.