Delhi’s butterfly species count dips, experts say patchy rains to blame

This year’s count of 67 was lower than the 75 butterfly species found in 2021 and 74 in 2020. Their population density was lower as well, said experts.

This year’s Big Butterfly Count from September 1 to 30 has found 67 species of butterflies in the national capital region, including rare sightings of the Dingy Swift, Common Shot Silverline, Common Rose and Tailless Lineblue.

A common grass yellow butterfly. (HT Photo)

This years count was lower than 75 species found in 2021 and 74 in 2020, possibly due to low rainfall in the region during the monsoon, according to Sohail Madan, centre manager at the Bombay Natural History Society, which celebrates Butterfly Month in September.

While less rainfall is a key factor behind the low numbers, the bouncing back of activities after the pandemic is also likely to be impacting butterfly numbers, said Surya Prakash, a zoologist from JNU who covered areas like Gautam Buddha Nagar, JNU, Sanjay Van and Neela Hauz.

“We saw a very high number in 2020 and even in 2021. During both these years, there was less activity outside, be it vehicles, industries or construction activity, due to the lockdown and restrictions,” Prakash said. “Butterflies are very sensitive to the environment around them and they thrived most in the lockdown period as human interference was minimal, even in public parks.”

This year, butterflies such as Plain Tiger, all three varieties of the Grass blue, Lesser, Dark and Pale, and Common and Mottled Emigrant were all found in abundance, he said. However, numbers for other species such as the Danaid Eggfly, Great Eggfly and White Arab were lower.

Rain and puddles are important for butterfly breeding, with butterflies often carrying out puddling, an activity where they spend time around damp sand or mud in order to drink water and mineralize.