Continental-scale patterns in diel flight timing of high-altitude migratory insects

Area of Science:

• Ecology
• Entomology
• Bioacoustics

Background:

• Many insects undertake high-altitude migrations crucial for ecosystem services (pollination) and agriculture (crop pests).
• Understanding the diel (daily) timing of insect migratory flight is vital for effective conservation and pest management.
• Vertical-looking radars offer automated insect migration monitoring, but large-scale deployment has been limited.

Purpose of the Study:

• To quantify diel flight periodicity and geographical/seasonal variations in migratory insects.
• To generalize regional findings on insect migration timing to a pan-European scale.
• To assess the feasibility of using radar networks for large-scale insect biodiversity monitoring.

Main Methods:

• Utilized a network of 17 vertical-looking radars across Europe.
• Collected data on insect migration between 50 and 500 m above ground level.
• Analyzed data for diel flight periodicity from March to October 2021.

Main Results:

• Peak migratory flight activity consistently occurred around noon, during evening twilight, and occasionally in the morning.
• The relative intensity of insect migration remained largely consistent across different diel phases (morning, day, evening, night) from May to September.
• These patterns were observed across diverse locations throughout temperate Europe, irrespective of overall daily migration volume.

Conclusions:

• Diel migratory insect movement patterns are predictable and widespread across temperate Europe.
• Findings extend and generalize previous regional studies on insect migration timing.
• This study provides a foundation for utilizing radar networks in global insect biodiversity monitoring.