‘Spatial Mark-Resight'(SMR) model to estimate Leopard population

What is the news?

Scientists from three organizations namely Aaranyak, Panthera, and WWF-India have developed a model called ‘Spatial Mark-Resight'(SMR). It will precisely estimate the population size of leopards.

Why ‘Spatial Mark-Resight'(SMR) model developed?

• Leopards can be identified like tigers with the help of their unique shape and size of the rosettes (black circular marks). It is present across their body coat.
• However, like many other wildlife species, leopards also exhibit phenotypic polymorphism (body colour variation determined by gene).
• Leopards are either rosettes (having black circular marks) or melanistic (full black, commonly called black leopard or Black Panther).
• The melanism presents a unique challenge in estimating and monitoring the leopard population. Natural marks (rosettes in case of leopard) are absent on these Leopards.
• This problem is more in the tropical and subtropical moist forests of south and south-east Asia. Here the frequency of melanistic leopards is high and leopards also face the greatest threat.
• Hence, the SMR model was developed. It will estimate the leopard population in areas having a mix of the rosette and melanistic individuals.

How Spatial-Mark-Resight (SMR) model used?

• The team used the three years of camera trapping data between 2017 and 2019. Info obtained from Manas National Park(Assam).
• The camera trapping data used to identify Rosette Leopards individually.  It also prepared the capture history (GPS locations, the individual ID of each unique photo-capture of leopard) information.
• They then borrowed the capture history information of the rosette leopards and applied the information to the melanistic leopards. It provided an estimate pf the entire population size of leopards.
• They found that the population density of leopards in Manas is 3.37 per 100 sq km. About 22.6% of images of the leopards were of the melanistic kind.

Significance of the model:

• The model can help assess the population of leopards across a great part of the species range from where population estimates are scant.
• This model can also be widely applied for other species that exhibit colour variation in nature.

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Source: The Hindu