“Discover the Incredible Migration of 17 Million Insects Through a Pyrenean Pass”

In a stunning natural phenomenon, each year 17.1 million insects migrate through a 98.4-foot gap in the Pass of Bujaruelo, located between two Pyrenees peaks on the border of Spain and France. This migration was recently documented by a team of scientists from the University of Exeter over a four-year period.

The study, titled “The most remarkable migrants — systematic analysis of the Western European insect flyway at a Pyrenean mountain pass,” was published in the journal Proceedings of the Royal Society B. The researchers used video cameras and visual counts to track the migration of various species of day-flying insects as they traveled south along this well-established route.

Lead author of the study, Will Hawkes, described the migration as truly remarkable, with vast numbers of marmalade hoverflies and other insects making the journey from northern Europe, including the UK, to Spain and beyond for the winter. On some days, the researchers observed over 3,000 individuals per meter, per minute.

The team noted that insect numbers peaked during sunny, dry, and warm conditions with low wind speeds and a headwind, which kept the insects flying low over the pass, making them easier to count. The majority of the migrating insects were flies, accounting for 90% of the total number, while dragonflies and butterflies made up less than two percent.

These migrating insects play crucial ecological roles as pollinators and pest controllers. They carry genetic material between plant populations, improve plant health, transport nutrients, and assist with decomposition. However, their populations are believed to be declining due to habitat loss and climate change.

Dr. Karl Wotton, the team leader and co-author of the study, emphasized the importance of raising awareness about these remarkable migrants to protect their habitats. By spreading knowledge about these insects, there is hope that efforts can be made to ensure their survival and continued migration through the Pyrenean pass.