live in the tropical lowland and hardwood forests in the south. In the temperate zone, grey langur, tiger, goral and serow are found in mixed conifer, broadleaf and pine forests. Fruit-bearing trees and bamboo provide habitat for the Himalayan black bear, red panda, squirrel, sambar, wild pig and barking deer. The alpine habitats of the great Himalayan range in the north are home to the snow leopard, blue sheep, Himalayan marmot, Tibetan wolf, antelope, Himalayan musk deer and the takin, Bhutan's national animal. The endangered wild water buffalo occurs in southern Bhutan, although in small numbers. More than 770 species of bird have been recorded in Bhutan. The globally endangered white-winged duck has been added recently in 2006 to Bhutan's bird list. Plants More than 5,400 species of plants are found in Bhutan, including Pedicularis cacuminidenta. Fungi form a key part of Bhutanese ecosystems, with mycorrhizal species providing forest trees with mineral nutrients necessary for growth, and with wood decay and litter decomposing species playing an important role in natural recycling. Conservation The Eastern Himalayas has been identified as a global biodiversity hotspot and counted among the 234 globally outstanding ecoregions of the world in a comprehensive analysis of global biodiversity undertaken by WWF between 1995 and 1997. According to the Swiss-based International Union for Conservation of Nature, Bhutan is viewed as a model for proactive conservation initiatives. The Kingdom has received international acclaim for its commitment to the maintenance of its biodiversity. This is reflected in the decision to maintain at least sixty percent of the land area under forest cover, to designate more than 40% of its territory as national parks, reserves and other protected areas, and most recently to identify a further nine percent of land area as biodiversity corridors linking the protected areas. All of Bhutan's protected land is connected to one another through a vast network of biological corridors, allowing animals to migrate freely throughout the country. Environmental conservation has been placed at the core of the nation's development strategy, the middle path. It is not treated as a sector but rather as a set of concerns that must be mainstreamed in Bhutan's overall approach to development planning and to be buttressed by the force of law. The country's constitution mentions environmental standards in multiple sections. Environmental issues Although Bhutan's natural heritage is still largely intact, the government has said that it cannot be taken