Chennai

Spotting many butterflies in Chennai? The city’s plants help!

“I was welcomed into Adyar Poonga park by common limes, and was bid goodbye by a painted lady when I was leaving,” laughs naturalist and author R Bhanumathi, fresh from a stroll around the park on a sultry Chennai evening.

She says she saw around 26 or 27 butterfly species in one evening alone, including “lots of lime butterflies busy in their breeding season. They were mating, there was courtship going on, some were even laying eggs.”

Sights like these are something the city’s dedicated band of butterfly observers was not expecting this year. A number of factors play a part in the reappearance of our winged friends in the aftermath of peak summer. Most of these factors are rain and moisture-dependent, hence the low expectations. However, the city’s local thickets have turned out to be tougher than presumed.

Each butterfly species needs two separate plant species to be available, before breeding can begin: one for its flowers and another for its leaves. “They need flowers for nectaring and new shoots and leaves on particular local plants — that we call larval host plants — for the catterpillars to eat,” explains Bhanumathi. The latter plants are where they lay eggs, she adds.

The extended drought left Nature enthusiasts with little hope of most of these plants flowering well, especially considering that the June drizzles, which usually mark the start of butterfly season in Chennai, have been somewhat light this year.

Yet, fresh shoots have doggedly emerged, buds have managed to bloom and the city’s butterflies now seem to have enough to frolick upon.

“The host plants haven’t missed their flowering cycle inspite of drought. With their little reserve resources, they are doing well,” observes Pauline Deborah, associate professor, Department of Plant Biology and Plant Biotechnology at Women’s Christian College, adding, “I observed them [the butterflies] on campus too. They are back in good numbers. Their host flowers are in bloom.”

There is a rebellion in the act of blooming, in quantities enough to support breeding season, that has taken Nature lovers by surprise.

In Chennai, ixora, peacock flower, lantana, coat button flower, premna, curry plant flower, Rangoon creeper and bougainvillea are some of the local plants and shrubs that different butterfly species depend on. Some require a significant bit of care: “like ixora and peacock flower... they are ornamental and found in homes, offices and public gardens,” says Pauline. Others flower throughout the year and “are wild weeds that do not require any care or attention, like the coat button flower or lantana.”

So how did Chennai’s natural vegetation manage to withstand the summer? Each has its own internal mechanisms, and even reserve resources, to cope with water shortage. Pauline elaborates: “Herbaceous plants or their propagules turn dormant and revive at the slightest touch of rain. Atmospheric moisture helps. Some lower their rate of transpiration and prevent water loss.”

So pioneers, dark blue tigers, lemon pansies, common crows, double-branded crows, striped albatrosses and more have been observed in the usual city hotspots, including Theosophical Society, Semmozhi Poonga and IIT campus. Painted ladies, in fact, have been in numbers much higher than usual, with some observers even saying that their migration from coastal areas to the Eastern Ghats has begun earlier this year. The migration usually takes place in October-November.

Painted ladies aren’t the only butterflies whose numbers have exceeded expectations. Says enthusiast Vikas Madhav, “Dark blue tigers have been seen in larger numbers this year compared to other years. They were seen migrating northwards.”

The image isn’t rosy all around though: not every plant can thrive in this weather. The white alder flower, for instance, is not abound. “Turnera subulata’s leaves are eaten by caterpillars of the tawny coster butterfly. Right now, tawny costers are not breeding at Adyar Poonga because that plant comes only after a good monsoon.”

In the last two-three years, mid-June has marked the beginning of active butterfly season, adds Bhanumathi. “The dormancy stage ends when fresh shoots come out, and butterflies are confident that there are enough tender leaves for larvae to feast on,” she says. If the leaves are succulent, larvae will feed enough, and pupate to emerge as butterflies in all their winged glory.

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Printable version | Nov 29, 2020 2:36:40 PM | https://www.thehindu.com/news/cities/chennai/spotting-many-butterflies-in-chennai-the-citys-plants-help/article28319676.ece

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