Butterfly migration in the Western Ghats

Common Emigrants mud puddling in the Western Ghats   | Photo Credit: Theivaprakasham Hari

A surge of a million butterflies happens annually in the Western Ghats, as they migrate just before the onset of the Southwest Monsoon. “They move towards the plains and the Eastern Ghats to escape the rains. Sometimes, it is mere dispersal to cope with food scarcity, when there is a shortage of host plants. There is mass exodus to look for greener pastures,” explains Isaac Kehimkar, who spent a major part of his life studying these fragile creatures during his tenure at the Bombay Natural History Society (BNHS). Isaac is also the author of The Book of Indian Butterflies and a sequel, Butterflies of India, both published by BNHS.

“The annual butterfly migration happens across the Indian Peninsula,” says Kalesh Sadasivan, founder of Travancore Nature History Society. He adds that, between July and September, when the rains recede in the Western Ghats, they move back.

When the butterflies return, they do so with a new generation. “Butterflies have a short life span of four weeks,” says Isaac. Also called the ‘Butterfly Man of India,’ Issac has observed mass movements of butterflies at the Bombay Natural History Society campus in Mumbai, the Corbett National Park, Sanjay Gandhi National Park in Thane and parts of Maharashtra.

During the pre-monsoon,milkweed butterflies like the dark blue tiger, blue tiger, common crow and double-branded crow move swiftly towards the plains in a vivid streak of yellows, blues, and browns.

Dark blue tiger congregation

Dark blue tiger congregation   | Photo Credit: Arun Kumar Raju Urs

This time, a good number of common emigrants have been spotted, “forming strips of yellow on the ground as they engage in mud puddling (extracting minerals and water from the wet soil, which they transfer to females during mating). One can spot them along the Western Ghats,” says A Paavendhan, founder of Tamil Nadu Butterfly Society. His team has been tracking the migratory pattern for eight years. He recalls spotting thousands of lime butterflies in Kallar, near Ooty, an experience he describes as “unforgettable”.

Common Albatross at Grizzled Squirrel Wildlife Sancuary in Rajapalayam

Common Albatross at Grizzled Squirrel Wildlife Sancuary in Rajapalayam   | Photo Credit: Sharan Venkatesh

While tiger butterflies move like a river, others, like the common albatross, follow a single line. “The common albatross is a high altitude migrator from Coorg. As it has white wings, it is like an endless white string stretching into the forest,”says Kalesh.

Arun Kumar Raju Urs of Bengaluru Butterfly Club says he stood speechless when he saw the congregation of tiger butterflies for the first time, eight years ago in Mysuru. “There were millions hanging on the leaves, like a chunky necklace. Mysuru is a transit point during forward and reverse migration. They follow a pattern, depending on the weather conditions.”

More on butterflies
  • Striped Tiger closely resembles the monarch butterfly in appearance. It also has orange wings laced with black lines and white dots
  • In India, there are 1300 butterfly species, of this there is 330 plus in the Western Ghats and over 900 in the Northeast
  • The Regal Red Apollo butterflies fly above 10,000 feet in the drier cold desert regions of Ladakh
  • The milkweed butterflies get the name as the caterpillars feed on the latex-based sap produced by milkweed plants that contain toxic compounds. The toxins protect the caterpillars and adult butterflies from birds and other predators. That is why they have high survival rate
  • The milkweed is also the host plant of the monarch butterflies

Butterfly migration is one of the least studied natural phenomena in the country, says Kalesh. “Ask any school-going children about butterflies in your backyard, and you draw a blank. But, they are aware of the monarch butterfly migration that happens in the US as it is documented. We needed a platform.”

Right now, that platform is ‘Butterfly Migration India’, a WhatsApp group of 300 members from Kashmir to Kanyakumari, who track the movement at various points from the Western Ghats to the Eastern Ghats. “We are gathering data, for over three years now, to get a clear picture,” says Kalesh.

Striped Tiger

Striped Tiger   | Photo Credit: H.S.MANJUNATH

A scientific tagging method might help, adds Sammilan Shetty, founder of the model butterfly park at Belavai village in Mangaluru. The park is home to 150 species and works towards education and conservation. “Did you know that butterflies help study floral diversity?” says Samillan, adding, “Every butterfly species has a specific host plant. For example, if there is a profusion of the beautiful Malabar banded peacock butterflies, it indicates there is a flourishing number of Zanthoxylum trees.”

In countries like Taiwan, says Isaac, “They gently make a colour-coded mark on the wing and release the butterfly. In the US, a lightweight paper label is attached on the hindwing. But it is tough to do the same here. We have to label thousands and the recovery rate is low.”

Crimson Rose

Crimson Rose   | Photo Credit: Special Arrangement

Issac says butterflies are also monitored to study climate in many countries. “They are extremely sensitive to weather, and when it is too cold or hot, they just quit the place.”

There is a particularly pleasing visual as the pink rose and crimson rose butterflies flit from Kanyakumari to Sri Lanka. “A pink line dots the coast as they start their non-stop flight during December. It is an arduous journey,” says Isaac. “Many of them are on a one-way ticket. We have no idea about their return flight.”

Test your butterfly knowledge with a quiz designed by Sammilan Shetty on the MetroPlus Instagram page @thehindumetroplus. The quiz will be open from Saturday 8 pm, and answers will be revealed Live by Sammilan on Sunday noon, when he will also discuss the role of butterflies in the ecosystem.

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Printable version | Dec 4, 2021 2:11:54 PM | https://www.thehindu.com/sci-tech/energy-and-environment/it-is-that-time-of-the-year-when-butterflies-migrate-moving-en-masse-in-a-bright-dramatic-surge-experts-tell-us-what-to-look-out-for/article31701802.ece

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