Data for <b>Insects can harness thermally driven slope-winds to disperse across mountainous landscapes</b>

<p dir="ltr">Many insects use prevailing winds in the upper atmosphere to travel hundreds of kilometres in particular directions to reach desired locations. To date, there are no studies showing whether small-scale wind systems, such as thermally driven slope-winds (upslope anabatic and downslope katabatic winds) are harnessed by insects. Here, we exploit previously collected data on >130 species of flying, aquatic insects (Trichoptera), some of which had dispersed to catchment ridgelines; other species had not and thus moved only locally. We tested whether dispersers responded differently to environmental factors (air temperature, sky clarity, wind gust and direction) compared to species that did not disperse. Dispersing caddisflies were affected strongly by the clarity of the skies, which increases the strength of downslope, katabatic winds and makes the stars and moon visible for navigation. Prevailing winds that were aligned with katabatic winds increased the numbers of dispersers, whereas it had no effect on non-dispersing caddisflies. The results suggest that dispersing caddisflies can harness katabatic winds to disperse downslope from catchment ridgelines. Feasibly, dispersers also exploit upslope anabatic winds during the day to reach ridgelines. These outcomes have profound implications for understanding the effect of dispersal on population dynamics and species richness of insect assemblages.</p>