Upslope migration is slower in insects that depend on metabolically demanding flight

Climate change is forcing species to migrate to cooler temperatures at higher elevations, yet many taxa are dispersing slower than necessary. One yet-to-be-tested explanation for inadequate migration rates is that high-elevation environments pose physiological barriers to dispersal, particularly in species with high metabolic demands. By synthesizing across >800 species, we find evidence for metabolic constraints: upslope migration is slower in insects that rely on nature’s most expensive locomotor strategy—flight. Upslope migration is a recognized climate change response, but which traits support this migration is unclear. The authors use a global dataset of 807 insect species—flying and non-flying—to show that lagging upslope migration in terrestrial animals may be linked to oxygen demands.