JAKARTA, Sept. 2 (Xinhua) -- The World Wide Fund For Nature (WWF) and biologists announced Friday they have found indications of the birth of four Javan rhinos in Ujung Kulon National Park, in Indonesia's Banten province, raising hopes for the survival of what many consider the rarest large mammal in the world.

The population of the mammal (rhinoceros sondaicus), also known as the Asian lesser one-horned rhino, is believed to be fewer than60 worldwide, the Jakarta Post daily reported on Saturday.

It is estimated that between 26 and 58 of the species live in Ujung Kulon and no more than eight of its subspecies are likely to survive in Cat Tien National Park in Vietnam.

Ujung Kulon National Park director Puja Utama said a WWF team, including park rangers and local people, discovered signs of the rhino calves in July in the park located on the far western tip of Java.

He said that the team found three sets of small footprints, ranging from 16 to 21 centimeters, together with larger ones of 24 to 28 cm, believed to belong to their mothers, in three different parts of the 120,000 hectare park.

The team also directly encountered a female rhino along with a calf. However, no photographs were taken.

The WWF concluded that the finding was evidence of four different calves because of the distance between the four areas where the discoveries were made and differences in the sizes of the footprints, he said.

"Javan rhinos are on the brink of extinction," said Director General of Forest Protection and Nature Conservation at the Forestry Ministry Arman Malolongan.

"Discovering they are breeding, even at a slow rate, gives us hope for the species' future."

The birth of the four rhinos, if the observations are correct, was the first known in three years, he said.

The WWF also is urging researchers to conduct a comprehensive study on the possibility of establishing a second habitat of rhinos outside the park to protect them from diseases or natural disasters that could wipe out their entire population.

"We are trying to minimize risk factors that could endanger the species. We can't just put all eggs in one basket," WWF Executive Director Mubariq Ahmad said.

To reduce threats against Javan rhinos, WWF recommends that park authorities take conservation measures, including reducing the number of banteng wild cattle in the park and invasive vegetation that hinders the growth of rhinos' favorite plants. Enditem