Vertical-Looking Radar: A New Tool for Monitoring High-Altitude Insect Migration

Many insect species engage in high-altitude, wind-borne migration, often several hundred meters above the ground. At these heights they can use the wind to travel tens or hundreds of kilometers in a single flight, and hence a knowledge of their movements is essential to understanding their ecology and population dynamics. Direct observation of high-flying insect migrants is very difficult, especially at night, but the remote sensing capabilities of entomological radar provide a solution to this seemingly intractable problem. We describe a novel, nutating-beam, vertical-looking radar with autonomous data analysis software. This system routinely extracts data on size, shape, alignment, and displacement vectors from individual targets, allowing long-term monitoring of migrant insect populations. We discuss the capabilities and limitations of this system and describe some of its applications in the study of insect migration behaviour.