Habitat Suitability Assessment for Tiger in Trijuga Forest, East Nepal
Historically, tigers were distributed across the lowland forests of Nepal, but surveys between 1987 and 1997 documented only three isolated sub-populations: Chitwan-Parsa, Bardia and Shuklaphanta, with no reported occurrence east of the Bagmati River. According to the Tiger Conservation Action Plan (2008-2012), preliminary findings of research on tigers outside protected areas suggested that potential habitats in Kailali, Jhapa and Trijuga could hold about 5-7 tigers.
The tiger population is currently increasing in Nepal, with numbers having gone up from 98-123 (1999/2000) to 235 (2017/018). This number has soared in the last four years, as indicated by 2017/2018 tiger count. As the tiger population continues to rise, habitats become narrower, and the need for immediate expansion and management of future habitats seems apparent. Establishment of Banke National Park in 2010 was one step towards this, and tiger numbers boomed from 4 adults in 2013 to 21 in 2017/018. Similarly, on-going conservation efforts have led to expansion and status update of Parsa National Park where, according to ZSL, the numbers have nearly tripled in three years. A similar habitat which may support another viable population is Trijuga and adjoining forests in eastern Nepal. Tigers inhabited Trijuga forest until a few decades ago but were extirpated due to habitat degradation, fragmentation, lack of connectivity with source population, and excessive poaching of prey base and the tiger itself. The forest is now a national forest with several sections divided into community forests managed by local people. This area is also important for resident species like the Gaur and Sloth Bear, as well as wild elephant populations that use this forest as a corridor. Trijuga forest also lies within the proposed conservation landscape, Eastern Terai Chure Complex, which would be an eastern annex to Terai Arc Landscape. Therefore, assessment of habitat suitability was important, so that possibility of forest occupancy by tigers in the future could be understood. A team of biologist from Himalayan Nature surveyed the Trijuga Forest.
The major activities carried out included vegetation survey, tiger prey base survey, determination of threats to local biodiversity, status of human-wildlife conflict, exploration of water source, assessment of local people's dependency on the forest, understanding the local people's perception towards returning of tiger to the area and identify critical areas of improvement.