Thursday, November 11, 2010

The butterfly flutter

Researchers across the world wonder at the beautiful and mysterious butterflies. K. Jeshi meets experts who were in the city recently for a seminar hosted by Bharathiar University
Photos: S. Siva Saravanan & M. Periasamy

Butterfly effect Harvard University's Krushnamegh Kunte

It is a large congregation, millions of butterflies — dark blue tigers, double-banded crows, common crows and blue tigers. They can be found on the branches of evergreen trees in the Western Ghats, especially the Nilgiris and the Anamalais, during the months of October and November. In January, they disperse and breed. And, just before the monsoons set in, the progeny of the second or the third generation migrate back to the Eastern Ghats, the land of their ancestors.
Biologists marvel at the phenomenon. Who tells them it is time to go back? Where do they get the signals from? The mystery continues. “In South India successive generations of butterflies move back and forth,” says Krushnamegh Kunte, researcher at Harvard University. “We do not know how they know where to go.” The milk weed butterflies (derived from the plant family with toxic saps they feed on), the white yellowish and creamy white emigrants (common and mottled), can be spotted in thousands right in our backyard and urban gardens. They take several days to pass through an area.
Researchers say the phenomenon is driven by the monsoons. May be, they avoid the intense rains and humidity (unfavourable for breeding) and migrate to the plains. “It is like a relay race over a period of six months,” says Isaac Kehimkar of the Bombay Natural History Society. Another notable migration is that of the crimson rose butterflies from Rameshwaram to Sri Lanka during December and January.
Photos: S. Siva Saravanan & M. Periasamy

Common emigrant butterflies engaged in mud puddling

Sikkim and the Himalayas are considered a Mecca of Butterflies. “We have 18,000 species of butterflies in the world. In India, we have roughly 1,250 species. Of which, you have 800 species in the Eastern Himalayas, Sikkim, Meghalaya, Manipur and Mizoram. About 335 are endemic to the Western Ghats,” says Kunte.
Species such as the southern bird wing (the largest butterfly in India), Malabar banded swallowtail, Malabar tree nymph, and Tamil cat 's eye and Travancore evening brown are found only in the Western Ghats.
Another significant aspect is ‘mud puddling'— where male butterflies absorb minerals, salt and water content from the wet soil into their bodies. This is transferred to the females during mating. “Thousands of males elbow each other. The ‘saltiest' male gets the female,” Isaac adds.
Some butterflies can be distasteful prey and can teach their predators an unpleasant lesson. They feed on the toxic alkaloids found in certain plants. When a hungry bird pecks on them, it triggers a fearful physiological reaction in the predator's body. “A great deal of sexual selection happens based on this. Females select the most distasteful males to ensure a safety of the progeny.”
Declining numbers
It is important to protect their habitats, which are on the decline. “Hundreds of butterfly species were recorded at the Biladu Pumping station spot in Mussoorie. Now, thanks to construction work, there is devastation a decline in butterfly population,” says Avtar Kaur Sidhu who works with the Zoological Society of India in Himachal Pradesh and Jammu and Kashmir. Butterflies also serve as biological indicators, of a healthy environment. Partnerships with local people, especially the tribals, is a good way to begin, they say. “In Kenyan forests, butterfly farming helps communities stay inside the forests. The pupae are exported to butterfly parks across Europe. They don't cut trees, don't kill animals and save the forests for butterflies, as it gives them money,” Isaac says.
At Ultapani in Assam, a hot spot for butterflies, the Bodo tribals work closely with the tourism industry. Also, the Bagua Tribals in Arunachal Pradesh. “They serve you continental food and take you to watch birds and butterflies.”
“Conservation involving tribal communities is critical. India has a rich diversity and endemicity of flora and fauna in regions such as the Western Ghats, Assam, North east Himalayas and the Naga Hills,” says Roger C. Kendrick of Kadoorie Farm and Botanic Garden Corporation, Hong Kong.
The researchers were in Coimbatore to participate at the 3rd Asian Lepidoptera conservation symposium and training programme, organized by the Department of Zoology of Bharathiar University in collaboration with ZOO Outreach Organisation.


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