I surveyed 17 million insects flying through a Pyrenean mountain pass – here’s what I learned about these ‘remarkable migrants’
Despite only being in the pass for a single day, they labelled these insects “the most remarkable migrants of all”.
- Despite only being in the pass for a single day, they labelled these insects “the most remarkable migrants of all”.
- Our new study highlights that, across the autumn field season throughout September and October, more than 17 million insects migrate through this pass.
- In the intense late September heat, even the hardy mountain sheep were lying with their heads under rocks for shade.
- The insects flying south from mainland Europe and Britain total tens or hundreds of trillions – of which 17 million travel through this pass, according to our calculation.
- Alongside quantifying their numbers, I’ve been working hard to identify the entire insect assemblage migrating through this mountain pass.
Long-distance influencers
- Most (nearly 90%) of these insects are pollinators – including the tiny marmalade hoverfly and much larger hummingbird hawkmoth.
- Because they are migrants, these insects can move pollen – and the genetic material stored inside – many kilometres, linking geographically isolated plant populations.
- This improves the genetic diversity of the plants, and can even transfer genes for dealing with more adverse conditions such as drought.
- However, due to the climate crisis and habitat loss, some of these insect migrants – particularly pollinators – are declining.