Unraveling Population Trend of a Critically Endangered Freshwater Crocodylian, Gharial ( <scp> <i>Gavialis gangeticus</i> </scp> ) in the National Chambal Sanctuary, India

The gharial (<i>Gavialis gangeticus</i>), an endemic freshwater crocodylian species, has shown signs of recovery following a severe population decline, primarily due to concerted conservation efforts initiated in the mid-1970s. However, despite decades of sustained conservation initiatives, critical information on population trends, nesting success, and winter habitat use remains lacking, which is essential for guiding and refining future conservation strategies. The present study assesses the population trend, size class composition, nesting success and factors influencing gharial distribution in the National Chambal Sanctuary, which harbours ≈80% of the global gharial population. The population trend analysis indicated a positive growth rate ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mrow><mml:mover><mml:mi>r</mml:mi> <mml:mo>¯</mml:mo></mml:mover> </mml:mrow> </mml:mrow> </mml:math> = 0.032) and a finite rate of population increase (<i>λ</i> = 1.032), reflecting a steady increase in the gharial population in the Sanctuary. Nesting efforts also showed an increasing trend, from 402 nests in 2017 to 486 nests in 2019. Habitat use analysis revealed a preference for sandy substrate and a negative association with clay and rocky substrates, suggesting habitat selectivity that influences gharial distribution across the river. Overall, findings highlight the urgent need to reassess and strengthen current gharial conservation programs by integrating habitat-specific management, enhancing protection of prime nesting and basking sites, and sustainable use of river resources.