Four of the world's rarest rhinoceroses have been captured by camera traps installed in an Indonesian national park, according to an environmental group.
The footage from movement-triggered hidden cameras shows two female Javan rhinos and two calves in Ujung Kulon national park in November and December last year, said WWF.
Javan rhinos are among the world's most endangered species, with an estimated population of no more than 50 in Ujung Kulon. A few others live in Cat Tien national park, in Vietnam.
"This is good news to ensure that the population is viable," said Adhi Hariyadi, WWF project leader in the park.
The first "video trap" footage, recorded in November, showed a mother and calf, identified later as a male, walking steadily toward the camera. Several more shots of the family were obtained later.
In December, another 30-second video showed a larger calf with its mother. It was later identified as a female about a year old.
The national park's chief, Agus Priambudi, said the footage provided substantial information about population dynamics of Javan rhinos as well as feedback about survey and monitoring system of the survival of endangered species.
After camera and video traps have captured 14 rhino births during the past 10 years, the Javan rhino study will now focus on the animal's habits, distribution, genetic diversity, diet and nutrition, as well as pathology and cause of stress, WWF said.
"This female calf documentation is a breath of fresh air for us – and Javan rhino conservation in general – since the majority of calves we identified previously ware male," said Hariyadi. WWF last published video of Javan rhinos in 2009, when it released a clip showing a family of three in the southern tip of Java.
Rhino numbers in Indonesia over the past 50 years have been dramatically affected by rampant poaching for horns, which are used in traditional Chinese medicines, and by the destruction of forests by farmers, illegal loggers and palm oil plantation companies.
Last year, three Javan rhinos were found dead within the 297,881-acre (120,551-hectare) park, and one of them was suspected to be the victim of poachers.
