Butterflies’ Epic 2,600-Mile Ocean Flight

Scientists recently uncovered groundbreaking evidence of butterflies embarking on a remarkable ocean flight across the Atlantic Ocean, covering a staggering 2,600 miles (4,200 kilometers). This discovery was made by Gerard Talavera, an evolutionary biologist from the Botanical Institute of Barcelona, during an expedition in French Guiana in 2013. Talavera observed a group of painted lady butterflies (Vanessa cardui) resting on the sandy shores, their wings worn and punctured.

The presence of these butterflies in South America baffled researchers, as this species is typically not found in that region. After a decade-long investigation, scientists have pieced together how these butterflies managed such an extraordinary ocean flight — marking the first recorded instance of an insect undertaking a transoceanic flight.

The findings, published in the journal Nature Communications, underscore the remarkable abilities of butterflies beyond their beauty, challenging perceptions of their fragility. According to Roger Vila, a researcher at the Institute of Evolutionary Biology in Barcelona, there remains much to uncover about the capabilities of these insects.

While insect migrations are known, tracking them poses significant challenges. Scientists primarily rely on sporadic reports from amateur observers and radar coverage, which are often incomplete and unreliable.

In unraveling the mystery of how painted lady butterflies reached French Guiana, researchers synthesized various lines of evidence. They sequenced the genomes of the butterflies, revealing close relationships to European and African populations. Analysis of pollen DNA found on the insects’ small bodies pointed to plant species unique to tropical Africa. Additionally, isotopic analysis of hydrogen and strontium on their wings indicated origins from western Europe.

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Collectively, this evidence discounted a North American origin, suggesting instead that these butterflies likely began their journey in Africa or Europe.

According to Clément Bataille, a professor at the University of Ottawa, the butterflies traveled over 4,200 km from West Africa to South America, potentially covering a migration path exceeding 7,000 km. This journey, he noted, showcases an extraordinary ocean flight for such diminutive creatures.

Painted lady butterflies are renowned for their extensive migrations, regularly traveling up to 9,000 miles between Europe and Africa, including traversing the challenging terrain of the Sahara Desert. However, their typical journeys involve nightly stops for rest and nourishment. In contrast, to reach French Guiana from West Africa, these butterflies would have had to sustain continuous flight for up to eight days without respite.

To uncover this part of the mystery, scientists examined wind currents originating from the Sahara Desert, which transport dust particles from Africa to the Americas. They determined that painted lady butterflies utilized these atmospheric streams to complete their impressive journey.

The butterflies employed a strategic approach, alternating between gliding with minimal effort to avoid falling into the sea, aided by upward air currents, and periods of active flight (Ocean flight) that required higher energy expenditure. According to Eric Toro-Delgado, a doctoral student at the Institute of Evolutionary Biology, this strategy allowed them to conserve energy while traversing vast distances.

In the absence of these wind currents, the butterflies would have been capable of flying a maximum of 780 km before exhausting their fat reserves and energy.

This finding highlights the incredible flight (Ocean flight) capabilities of insects and suggests that scientists may have previously underestimated their ability to disperse over long distances, including across oceans. Gerard Talavera, the study’s lead author, emphasized that understanding these migratory patterns is crucial for comprehending how species’ distributions are shaped over time.

1. ^{ONLINE NEWS} Turner, B. (2024, June 26). Butterflies cross Atlantic ocean on 2,600-mile non-stop flight never recorded in any insect before. livescience.com. [livescience.com]
2. ^{ONLINE NEWS} CSIC. (2024c, June 25). Scientists demonstrate for first the time that a group of butterflies flies across the Atlantic Ocean. EurekAlert! [EurekAlert!]
3. ^JOURNAL Hu, G., Lim, K. S., Horvitz, N., Clark, S. J., Reynolds, D. R., Sapir, N., & Chapman, J. W. (2016). Mass seasonal bioflows of high-flying insect migrants. Science, 354(6319), 1584–1587. [Science]