Entomologist Gerard Talavera made a remarkable discovery on a beach in French Guiana when he noticed something unusual. “I couldn’t believe it, but it was a painted lady,” he said, referring to the painted lady butterflies (Vanessa cardui), a species not typically found in South America.
Remarkable journey
Talavera’s observation revealed that the butterfly had completed one of the longest insect migrations ever recorded, crossing the Atlantic Ocean. Researchers from the University of Exeter, in collaboration with citizen scientists, have been tracking the movements of painted lady butterflies. Their findings, published in the journal Nature, unveiled an astonishing migratory pattern.
Evidence of a transoceanic journey
The analysis of pollen on the butterflies’ wings matched plants found only in West Africa, indicating a transoceanic journey. Genetic sequencing and isotope tracing further confirmed that the butterflies originated from Europe and Africa, ruling out a route over land from North America. Combined with favorable wind data, this provided strong evidence for the first documented case of butterflies migrating across the ocean.
The painted lady’s migration begins in the deserts of North Africa, where the butterflies breed during the spring. As summer approaches, they embark on a northward journey, crossing the Mediterranean Sea and reaching as far as the United Kingdom and Scandinavia. This remarkable feat is often completed by multiple generations of butterflies, with each generation passing the baton to the next.
“This is a brilliant piece of biological detective work,” said David Lohman, an evolutionary ecologist at the City College of New York, who was not involved in the study. The painted lady’s migration is not only long-distance but also highly responsive to environmental conditions. The researchers found that the butterflies can adjust their routes and timing based on factors such as weather patterns, resource availability, and human-induced changes in the landscape.
Implications for conservation
The study of the painted lady’s migration has significant implications for conservation efforts. As a highly mobile species, the painted lady is vulnerable to threats such as habitat loss, climate change, and the use of pesticides. Understanding their migratory behavior can help inform strategies to protect this insect and the ecosystems it supports.