Parsa National Park was initially established as Parsa Wildlife Reserve in 1984 ( 2041 B.S. ) with a an area of 499km2 aiming to preserve Asian Wild Elephant (Elephus maximus ) and their remaining habitat of historical Char-Koshe-Jhadi which was spread over Terai from east to west of Nepal.
Winter (October-December) provide pleasant temperatures with clear skies. Night time temperatures can drop to 0°C. In spring (January-March) temperatures rise and water becomes scarce. In summer (April-June) the days become hot and humid with temperatures rising up to 40°C. Monsoon (July-September) brings cooling rains.
The typical vegetation of the park is tropical and subtropical forest types with sal forest constituting about 90% of the vegetation. Chir pine grows in the Churia Hills. Khair, sissoo and silk cotton trees occur along watercourses. Sabai
grass grows well on the southern face of the Churia Hills.
An estimated 919 species of flora have been recorded including 298 vascular plants, 234 dicots, 58 monocots, five pteridophytes, and one gymnosperm.
In May 2008, a census conducted in the reserve confirmed the presence of 37 gaurs. Gaur survey 2016 conductedby the Park shows that the number has been increased to 105. A survey combined with extensive camera-trapping conducted in 2008
estimated four adult Bengal tigers resident in the reserve.
A camera-trapping survey conducted in February 2017 for three months revealed the presence of 19 Bengal tigers. This indicates the rise in tiger population by three times in three years.