The wide range of climate accounts for correspondingly marked contrasts in flora and fauna between different regions of the country. In the south, the sal (the wood of which is used for railroad ties), sisu, and other subtropical trees are abundant in forests; in the extreme north, junipers are seen even at the altitude of the glacial moraines. Many kinds of conifers also exist in the alpine zone, along with the yew, various hollies, birch, dwarf rhododendrons, and other alpine flora.
Dominant in the Langtang Valley are the chir pine, willow, alder, and evergreen oak. Blue pine and silver fir are frequent in the subalpine zone, which also supports tree rhododendrons— magnificent plants often reaching a growth of 12 m (40 ft). Ground orchids, lilies, yellow and blue poppies, and crimson anemones are prevalent in central Nepal. The profusion of wild flowers extends to very high altitudes; at 5,200 m (17,000 ft), several varieties of primula, pink and white cotoneaster, and white erica have been gathered, along with many kinds of alpine mosses and ferns.
The tiger, hyena, and jackal still exist in southern Nepal, although in decreasing numbers. Rhesus monkeys and a variety of other small jungle mammals and rodents are common. At middle altitudes are found the black bear, several species of cats, squirrel, hare, deer, and antelope. Higher in the mountains, wild sheep and goats, marmots, and a species of tailless mouse-hare are numerous. Small black spiders were found at 6,900 m (22,500 ft) on rocky ledges traversed by the Mt. Everest expedition of 1953. Birds of Nepal include the green finch, dove, woodpecker, nuthatch, warbler, flycatcher, bulbul, and other familiar species. At about 2,700 m (9,000 ft) are found the hill partridge, pheasant, yellow-backed sunbird, minivet, and many of the flowerpeckers; the redstart, pipit, wagtail, snow pigeon, snowcock, and golden eagle thrive in both the alpine and subalpine zones.