The Sri Lankan leopard (Panthera pardus kotiya) is a leopard subspecies native to Sri Lanka that was first described in 1956 by the Sri Lankan zoologist Deraniyagala. In 2008, the Sri Lankan leopard was listed as Endangered on the IUCN Red List. The wild population is roughly estimated at 700–950 individuals as of 2015. The Sri Lankan leopard has a tawny or rusty yellow coat with dark spots and close-set rosettes, which are smaller than in Indian leopards. Seven females measured in the early 20th century averaged a weight of 64 lb (29 kg) and had a mean head-to-body-length of 3 ft 5 in (1.04 m) with a 2 ft 6.5 in (77.5 cm) long tail, the largest being 3 ft 9 in (1.14 m) with a 2 ft 9 in (84 cm) long tail; 11 males averaged 124 lb (56 kg), the largest being 170 lb (77 kg), and measured 4 ft 2 in (1.27 m) with a 2 ft 10 in (86 cm) long tail, the largest being 4 ft 8 in (1.42 m) with a 3 ft 2 in (97 cm) long tail. According to an article from BBC, the Sri Lankan leopard has evolved to become a rather large leopard subspecies, due to the fact that it is an apex predator without competition by other large wild cat species in the country. Sri Lankan leopards have historically been found in all habitats throughout the island. These habitat types can be broadly categorized into: arid zone with <1,000 mm (39 in) rainfall; dry zone with 1,000–2,000 mm (39–79 in) rainfall; wet zone with >2,000 mm (79 in) rainfall. Leopards have been observed in dry evergreen monsoon forest, arid scrub jungle, low and upper highland forest, rainforest, and wet zone intermediate forests. In 2001 to 2002, adult resident leopard density was estimated at 17.9 individuals per 100 km2 (39 sq mi) in Block I of Yala National Park in Sri Lanka's southeastern coastal arid zone. This block encompasses 140 km2 (54 sq mi), contains sizeable coastal plains and permanent man-made and natural waterholes, which combined allow for a very high density of prey species. The Wilpattu National Park is also known as a good place to watch leopards and currently a study is ongoing here conducted by The Leopard Project of The Wilderness and Wildlife Conservation Trust (WWCT).