Global butterfly index could advance insect conservation

An international consortium compiled more than 45,000 population trends for over 1,000 butterfly species and found average declines, while monitoring covers only about five percent of species and is concentrated in Europe and North America.

Researchers coordinated an international consortium to evaluate whether a global butterfly index can track insect population trends. They compiled monitoring data from many programs across multiple continents to assess coverage and signal strength. Butterflies are among the more visible and monitored insect groups, yet global monitoring remains uneven. The work aims to inform how a global indicator could support biodiversity tracking. Key findings: - The consortium assembled a dataset of more than 45,000 population trends covering over 1,000 butterfly species. - Only about five percent of butterfly species worldwide have monitoring data, and records are heavily concentrated in Europe and North America. - On average the sampled populations showed declines, and species expected to be sensitive to global change tended to decline more steeply. - The authors report a need for support to expand monitoring in underrepresented regions, note planned Global Butterfly Week activities this year, and say conversations about a formal international organization are under way. Summary: The analysis indicates average declines among monitored butterfly populations and large geographic and taxonomic gaps that limit robust global conclusions. Developing a global butterfly index and expanding monitoring, especially in underrepresented regions, are identified as priorities, with early coordination efforts and public events planned to build momentum.