Ecological and anthropogenic covariates ... - GANGAPEDIA

Chapter 2
Photographic identification of wild gharials (Gavialis gangeticus Gmelin 1789)
for assessing feasibility of capture-recapture techniques for population
estimation.
Abstract
The Gharial is a critically endangered crocodilian, endemic to the Indian
subcontinent, and with populations facing severe declines across its range from both
direct and indirect causes. Available population estimates of gharials have been based
on direct ‘total counts’ and do not address uncertainty due to biological or
observation-related factors, especially detectability. The Chambal River in Northern
India is thought to have one of the last viable populations of the Gharial, and robust
estimates of population size, that incorporate uncertainty are necessary for informing
management and conservation decisions of this last surviving population. Individual
identification of Gharial, if demonstrated under wild conditions, can enable
abundance estimation within a capture-recapture frame-work, a technique that has
never been used for crocodiles anywhere. It will also enable regular monitoring of
their critically endangered populations. Photographic identification of individuals
offers several advantages employed within the sampling framework of capture-
recapture for estimating capture (detection) probabilities and population size. Photo-
identification has the advantages of being a non-invasive technique, with fewer
economic and logistic constraints of capture, handling, capture and post-capture
stress, tracking, altered behaviour and the demand for large sample sizes. Although
photographic identification of individual young gharials has been used in captive
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