Modelling of Metapopulation Dynamics and Distribution of Varanus Flavescens in Nepal Tarai: Implications to Conservation
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Department of Zoology
Abstract
Human presence within the Jagdishpur reservoir and associated wetlands has largely
fragmented the wetland habitats. In attempt to understand the metapopulation dynamics
of Golden Monitor Lizard (Varanus flavescens), these dynamics of the species were
modelled from surveys of two consecutive years in 2012 and 2013. A land cover
classification was performed to categorise land cover patterns and recognition of
landscape variables. Surveys to determine dynamic occupancy state of the species was
performed in 40 grids; 1 sq km each, enclosing Jagadishpur Reservoir and associated
wetlands and analyzed in Program PRESENCE. Impact of landscape variables on species
distribution and other factors used as covariates upon parameters were modelled in the
program. Available presence data were modelled for predicting potentially suitable
habitat using Program MAXENT. Land cover classification recognized five major
landcover types with greater proportion of forest and settlement areas. Other identified
classes were grassland, marshlands and bare lands distributed over the area. The study
revealed higher rate of recolonization probability over local extinction rate thus higher
occupancy in 2013. A patchy subpopulation type metapopulation in the study area was
documented. Occupancy of Golden Monitor Lizard was shown to be negatively affected
by distance to settlements while positive correlation existed between the state variable
and distance to nearest water source. MAXENT model predicted entire Tarai and some
river valleys as potential area but GIS analysis revealed a relatively less Extent of
Occurrence available for the species. The study concluded unstable metapopulation
existed as human disturbance increases. Identification and monitoring of other
metapopulation of the species, providing better protection or extension of PA networks,
landscape level conservation and enlistment of the species in national red data list as
endangered will help to conserve the species if implicated.