Line transect method apt for elephant count: Study (India)


The Statesman

Date Published

Researchers have strongly favoured the line transect method for estimating elephant population with greater accuracy in order to boost conservation efforts.

Line transect sampling is used for estimating population density of animals in the wild. In this survey, an observer moves along a transect line and notes the location of all animals detected relative to the line.

The study titled ‘Reliable monitoring of elephant populations in the forests of India: analytical and practical considerations’ has been conducted by researchers at Wildlife Conservation Society (WCS).

Researchers claimed that following line transect method can result in crucial information on the population status of elephants to help aid conservation in source sites across India.

The study reviewed different methods commonly deployed to arrive at elephant numbers in India and cautioned researchers against sources of bias and imprecision in these methods.

“A sound understanding of the distribution and abundance of a species is a prerequisite for devising appropriate policies at the national level and for implementing on-ground conservation actions at the level of each reserve,” said K Ullas Karanth, co-author and Director of Science in Asia, WCS.

Researchers said that reliable monitoring of key elephant populations have assumed great significance in the light of increasing poaching pressures, loss of forests, fragmentation and deterioration of remaining habitats.

However, they said monitoring methods used in many elephant habitats in India are not rooted in modern animal sampling and estimation theory.

The study authored by Devcharan Jathanna, Ullas Karanth, Samba Kumar, Varun Goswami, Divya Vasudev and Krithi Karanth was published in May edition of international journal– Biological Conservation.

“WCS India Program has been carrying out long-term monitoring of large mammals, including elephants in the Western Ghats landscape,” says Devcharan Jathanna, the lead author of the study.

He said they examined their own data derived from line transect surveys across a range of habitats, specifically focusing on improvements that were made to the survey design and analytical protocols over time.

“We discussed the consequences of these changes for the reliability of the resulting estimates. We believe it is practical to implement line transect surveys in many of the elephant reserves in the country where accurate estimates of elephant population size are important for conservation planning and action,” he said.

Using the line transect approach, the study estimated elephant population densities in Bhadra, Biligiri Ranganatha Temple, Bandipur and Nagarahole Tiger Reserves in Karnataka.

The results showed a range of densities from an average of 0.3 elephant per sq km in Bhadra to 2.2 elephants per sq km in Nagarahole.