The population of the endangered great Asian one-horned rhinoceros in Nepal's biggest wildlife reserve has fallen to 372 from 544 five years ago, mainly due to poaching say officials. In a census the Royal Chitwan National Park, home to the second largest number of single-horned rhinos in the world after India, showed their numbers had fallen to the lowest level in more than a decade. Environmentalists and officials say poaching became easier after small security posts in the reserve were merged with bigger ones because of Maoist threats.