The state is divided into 5 major altitudanal zones or Eco-regions :-
Tropical (300m-1200m)
Rufous-necked Hornbill , Great Indian Hornbill , Chestnut-
breasted Partridge, Black-breasted Parrot bill, Grey-crowned
Prinia and Ward’s Trogon. Peafowl, Python, Geckos, Porcupine,
Assamese Macaque and Barking deer, as well as many butterflies
and other invertebrates, fish, frogs and toads.
Sub Tropical (1200m -3000m)
Rusty-bellied and Lesser Short wing, Kalij and Satyr Tragopan.
Japalura lizards, Cobra, Krait and Himalayan Pit Viper, Himalayan
Bullfrog and many species of butterflies.
Temperate (3000m -4500m)
Red Panda, Common Langur, Himalayan Black Bear, Lesser cats,
Goral, Serow, Monal Pheasant, Fire-tailed, Sunbird, Blue Magpie
and various species of reptiles and amphibians. Musk Deer,
Himalayan Tahr, Blood Pheasant, and Ibis bill
Trans-Hymalayan(4500m -5500m)
Tibetan Gazelle, Tibetan Wolf, Tibetan Snow cock,
Lammergeier, Raven, Golden Eagle and Ruddy Shelduck
Alpline (>5500m)
Snow Leopard, Wild Yak, Blue Sheep