Ujung Kulon National Park has become the final refuge for which endangered animal?

The Javan rhinoceros (Rhinoceros sondaicus), also known as the Sunda rhinoceros or lesser one-horned rhinoceros, is a very rare member of the family Rhinocerotidae and one of five extant rhinoceroses. It belongs to the same genus as the Indian rhinoceros, and has similar mosaicked, armour-like skin, but at 3.1–3.2 m (10–10 ft) in length and 1.4–1.7 m (4.6–5.6 ft) in height, it is smaller (closer in size to the black rhinoceros of the genus Diceros). Its horn is usually shorter than 25 cm (9.8 in), and is smaller than those of the other rhino species. Only adult males have horns; females lack them altogether.

Once the most widespread of Asian rhinoceroses, the Javan rhinoceros ranged from the islands of Java and Sumatra, throughout Southeast Asia, and into India and China. The species is critically endangered, with only one known population in the wild, and no individuals in captivity. It is possibly the rarest large mammal on Earth, with a population of as few as 58 to 61 in Ujung Kulon National Park at the western tip of Java in Indonesia. A second population in Cat Tien National Park in Vietnam was confirmed as extinct in 2011. The decline of the Javan rhinoceros is attributed to poaching, primarily for their horns, which are highly valued in traditional Chinese medicine, fetching as much as US$30,000 per kg on the black market.