In a narrow passage in the Pyrenees, locals and visitors witness a spectacular aerial ballet. The Bujaruelo Pass, located on the Spanish border, becomes a veritable traffic jam of insects at this time of year, explains
The Dispatch. This annual migration, observed for decades, yet never ceased to amaze with its scale and beauty.
The first to note this migration were researchers David and Elizabeth Lack in 1950. Their discovery, made by chance, opened the way to numerous studies on the subject. Years later, a team of researchers led by Will Hawkes went there to quantify the scale of this migration. In September 2018, they installed a monitoring system to precisely measure the number of insects crossing the pass each day.
A veritable blizzard of butterflies and insects of all kinds
Every day, more than three million butterflies, dragonflies, flies and midges flock to a corridor 30 meters wide and two meters high. “It’s a blizzard of yellow and white butterflies, like a storm of petals“, describes one of the researchers. This natural phenomenon combines grandeur and novelty, with millions of insects making their way south to escape the harsh winter.
Researchers have estimated that no less than 17.1 million insects pass through this pass each year.
A massive migration encouraged by still warm and sunny days, with a headwind, low wind speed and little precipitation. These ideal conditions create a real “highway” for these little winged travelers, transforming the Bujaruelo pass into a crucial crossing point.
Why is this migration important for biodiversity?
This migration is not only an impressive visual spectacle, but it also has major ecological importance. Insects play a crucial role in pollinating plants and composting organic matter. Their journey through the Pyrenees contributes to the health of ecosystems on both sides of the mountain range.
Will Hawkes shared his personal experience whenhe found himself enveloped in a cloud of buzzing insects. “It was like a living carpet at my feet. The determination with which these insects crossed the pass was impressive.“, he explained. This determination underlines the vital importance of this migration for the survival of the species involved.
Billions of insects on the move
Beyond the Pyrenees, researchers estimate that billions of insects migrate each year through various crossing points.
Compared to the migrations of vertebrates, that of insects is much more massive in terms of biomass and abundance. This highlights the importance of continuing to study and understand these movements to preserve biodiversity.
Scientists are now preparing to watch the insects return in spring. This observation will allow us to better understand migratory cycles and the factors that influence these massive movements. The knowledge gained can then be used to inform conservation efforts and environmental policies.
