Where have they gone? Below-par butterfly migration, from Eastern to Western Ghats, witnessed this monsoon 

This phenomenon is observed during the current year too and the movement was observed from Kallar region towards Sirumugai and STR in the second week of November. 
Dark Blue Tiger, a butterfly species.
Dark Blue Tiger, a butterfly species.

COIMBATORE: The western districts of Tamil Nadu, especially Coimbatore,  witnessed below-par butterfly migration (Eastern Ghats to the Western Ghats) from the onset of northeast monsoon season. 

The Nature and Butterfly Society (TNBS) which has been observing the migration of butterflies since 2013 found that this year, there was a low-scale migration of species like Tigers and Crows, especially Blue Tiger, Dark Blue Tiger, Double-branded Crow, and Common Crow. Harsh climatic condition is cited as the top factor affecting the butterfly migration. 

“Many of the regular routes over which the migration is usually observed did not see any movement. However, a few routes by which the migration reached the hills of western districts saw congregations of Crows and Tigers,” said A Pavendhan coordinator of TNBS.

“The recent heavy rains in the Nilgiris pushed Tigers and Crows towards Anaikatti hills and further to Palakkad district of Kerala,” Pavendhan added. “This year, TN has recorded 92% of its normal rainfall (Jun-Sep 2023), while the districts involved in the migratory movement in the west zone, especially Salem and Namakkal had a deficit of 7% and 10%.

Though this is termed as normal, we see a good migratory movement when the rain is in excess. This could be one reason why we did not see much of Tigers and Crows which usually emerge from these districts en masse and make a southwest movement towards Coimbatore, Nilgiris and Northwestern border of Erode,” said H Ramanasaran a member of TNBS. 

Between October and December, Common Albatross emerges in large numbers especially from the low to mid-elevation ranging from Anaikatti hills to Nilgiris. These butterflies reach the lower elevation and move towards the Sirumugai forest range and Sathyamangalam Tiger Reserve. This phenomenon is observed during the current year too and the movement was observed from Kallar region towards Sirumugai and STR in the second week of November. 

S Gopalakrishnan of Tirupur TNBS said in 2020, during Coimbatore Forest Division Birds and Butterflies survey on Common Albatross emergence and movement similar observations were made from Karamadai hills towards Sirumugai region.

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