DURING the months of December and January, a large congregation of crow butterflies occupies certain areas of the park, turning it into a carpet of wings. The butterflies, which are usually spotted around the plants of Crotalaria, Heliotropium and Senecio subdiscoideus, mysteriously vanish after January. "We have been observing this tendency of the crow butterflies for the past two years," said Rama Murty.
A recent study conducted by Sanctuary magazine notes that crow butterflies have a tendency to migrate in large groups from the Western Ghats to the Eastern Ghats during certain periods of the year. Their migrations have been observed in Bangalore, Tumkur and Mysore (in Karnataka), Palakkad and Kannur (in Kerala), Coimbatore, Udhagamandalam, Vellore and Chennai (in Tamil Nadu) and Tirupati (in Andhra Pradesh) and in wild life sanctuaries in the region.
Preliminary studies concluded that migratory habits of the crow butterflies could be attributed to a combination of climatic conditions, and availability of food and habitats in which they can breed. However, more data are needed to develop a clear understanding of their traits.
But why do the butterflies stick to only certain species of plants? Tiger and crow butterflies need pyrrolizidine alkaloids for the production of sexual pheromones, which they obtain from Crotalaria, Heliotropium and Senecio subdiscoideus.
Said Rama Murty: "We want to create a separate butterfly zone by identifying plants that attract these butterflies and segregating them to one section of the park, so that we can closely observe other behavioural traits of the butterflies."
NIVEDITA GANGULY
