Old river loops that became a refuge
The Chitwan valley is shaped by moving rivers. Over centuries the Rapti and smaller streams changed course after floods, leaving behind curved lakes cut off from the main channel. Bishazari Tal is a cluster of these oxbows, fed by rain and groundwater, with marsh, grassland and sal forest between them. Water levels rise in the monsoon, when the lakes join into wider sheets of water, and fall through the dry season, leaving muddy margins where waders and crocodiles gather.
As settlers cleared Chitwan in the 1950s and 1960s, the forest around Bishazari became one of the last links between the lowland jungle and the hills. The Barandabhar forest, in which the lakes sit, now forms a corridor that tigers, rhinos, leopards and deer use to move north and south across the valley. Without such links, tigers and other wide-ranging animals would be trapped in isolated patches of forest, unable to find mates or new territory.
In August 2003 the lakes were designated a Ramsar site, recognising their value for waterbirds and threatened species such as the lesser adjutant, Pallas's fish-eagle and the ferruginous duck. Today the wetland is managed within the park's buffer zone, and local community groups help with patrols and visitor fees. Like many Terai wetlands, the lakes face siltation, invasive water plants and heavy use, and keeping them open takes constant work.
