Bihar has notified forest area of 6,764.14 kmÂ², which is 7.1% of its geographical area.The sub Himalayan foothill of Someshwar and the Dun ranges in the Champaran district are another belt of moist deciduous forests. These also consist of scrub, grass and reeds. Here the rainfall is above 1,600 mm and thus promotes luxuriant Sal forests in the area. The most important trees are Shorea Robusta, Sal Cedrela Toona, Khair, and Semal. Deciduous forests also occur in the Saharsa and Purnia districts. Shorea Robusta (sal), Diospyros melanoxylon (kendu), Boswellia serrata (salai), Terminalia tomentose (Asan), Terminalia bellayoica (Bahera), Terminalia Arjuna (Arjun), Pterocarpus Marsupium (Paisar), Madhuca indica (Mahua) are the common flora across the forest of Bihar.
The Ganges River dolphins, or “sois” are found in the Ganges and Brahmaputra.This river dolphin is the national aquatic animal of India. It is now considered amongst the most endangered mammals of the region. The dolphins range from 2.3 to 2.6 meters in length. They have impaired vision due to the muddy river water but use sonar signals to navigate.Vikramshila Gangetic Dolphin Sanctuary ,near Bhagalpur is set up to ensure the protection of this species.
Valmiki National Park, West Champaran district, covering about 800 kmÂ² of forest, is the 18th Tiger Reserve of India and is ranked fourth in terms of density of tiger population. It has a diverse landscape, sheltering rich wildlife habitats and floral and faunal composition, along with the prime protected carnivores.