Tamil Nadu has 2,961 elephants as per the Forest Department’s synchronised elephant population estimation done from May 17-19 in the four southern States. This is an increase from the figure 2,761, recorded in the survey done in 2017.
This survey was conducted in 26 forest divisions of Tamil Nadu, among which elephants were sighted in 20 divisions using the block count method. Six forest divisions (Madurai, Theni, Salem, Tirupattur, Vellore, and Tiruvannamalai) did not report elephants, as per the report. A total of 2,099 persons, including department staff and volunteers, were involved in the study, covering a distance of 8,838.4 km.
The figure 2,961 was arrived at by averaging the lower limit of 2,772 and the upper limit of 3,150 elephants. Among the five elephant reserves, the Nilgiris Eastern Ghats (Nilgiris) reserve had the highest estimated density followed by Nilambur Silent Valley (Coimbatore) reserve, Anamalai elephant reserve, Srivilliputhur elephant reserve and the Agasthyamalai elephant reserve.
For every male elephant, there are approximately two female elephants. The four major classes of age considered were calf (less than a year old and 120 cm in height), juvenile (1–5 years old; 121–180 cm tall), sub-adults (5–15 years old; 181–210 cm tall for female and 181–240 cm for male) and adults (15 years; more than 210 cm tall for female and more than 240 cm for male). Of the total elephants estimated, 27% are adult female, 13% are adult male, 21% are sub-adult female, 12% are sub-adult male, 8% are juvenile female, 5% are juvenile male, and 14% are calves.
“There is a good mix of elephants of all age groups. If the age-wise distribution was skewed, it means something was wrong with the ecosystem. But we can see a healthy mix,” said Srinivas R. Reddy, Chief Wildlife Warden. He further said that the increase of 200 elephants from the 2017 survey indicated that the population was stable. “Our landscape is saturated. Close to 3,000 is a good number. ...We might have missed out on some elephants, but we definitely don’t have fewer than 2,961 elephants.”
The Forest Department used two methods to estimate the elephant population — direct sighting using ‘sample block count’ and indirect estimate using line transect (dung count).
Each forest division was divided into several small blocks (up to 5 sq. km) and a team of three to four persons covered each block. “Upon sighting elephants, care was taken to count all individuals first and then age-sex them wherever possible,” said the report. A total of 690 blocks (total area of 3496.81 sq.km.) were selected for estimation. In each block, a transect of 2 km was laid across and walked on once to enumerate dung piles for estimating their density. This dung density was then converted into elephant density through calculations.
To study the structure of the population, the waterhole count method was deployed, for which data was collected during the sample block count. Waterholes were monitored as age-sexing elephants was easier due to better visibility. As many as 654 waterholes were selected for assessing the population structure.
