Sikkim is rich in avifauna and is considered to be a birdwatchers paradise. Its avian population extends to almost 550 species. The climate varies between the tropical heat of the valleys and the alpine cold of the snowy regions. The altitudinal zones of vegetation range from tropical, sub tropical, temperate to Alpine. In some places only 10 Kms in a direct line separate the warm valleys from perpetual snow. The telescoping of terrain has created marked altitudinal zonation in the humidity, rainfall, climate and vegetation. This factor is responsible for the great variety and abundance of the resident bird life, making this area arguably one of the richest areas of its size anywhere in the world.
West Sikkim offers great birding opportunities. Barsey, located at 3300 m, on a massive ridge covered with protected forests of Silver Fir, hemlocks, magnolia, and Rhododendrons is one of the best birding areas in Sikkim. Around Pemayangste and the nearby village of Pelling there are several excellent birding sites and hikes. Some important species like the Maroon-Backed Accentor, Red-faced Liocichla etc are found around these forests. The Khecheopheri Lake hosts migrant ducks and occasionally some rare species such as Black-necked Crane, Black-tailed Crane and many others.
For those who are enthusiastic about trekking in the high Himalayas, the best way to see higher altitude birds is to take the 10 day Dzongri. Some of the birds seen on this trip are Blood Pheasant, Himalayan Monal, Brown Parotbill, Fire-tailed Myzornis, Cutia, Sapphire flycatcher, White browned Bush Robin, Grandala, Rufous - breasted Accentors, White winged and collared Grosbeaks, Spot-winged Rosefinch, In South Sikkim is the Maenam Wildlife Sanctuary. The sanctuary starts from 2000m, with a sub-tropical forest, gradually taken over by moist temperate forest at around 2500-3000m and then sub-alpine conifer forests at altitude higher than 3000m. Rabongla to Maenam top is about 12km and a further 1km trek will take one to Bhaledhunga, a cockscomb shaped stone. Important birds in this trek include satyr Tragopan, Kalij pheasant, rusty-bellied Shortwing, Minivet, Yuhina, flycatchers etc.