Butterflies are on the move as the planet warms: New research

Recent research reveals that a growing number of butterfly species are altering their geographic ranges due to environmental changes worldwide. This phenomenon, known as species range shifts or redistribution, results from shifts in temperature, rainfall, and habitat conditions forcing butterflies to relocate and seek new habitats.

The study analyzed data from over 6,180 reports from 565 scientific studies and expert assessments, covering 1,758 species across 105 countries. The findings indicate that 80% of documented butterfly species have expanded their ranges latitudinally (north to south) or longitudinally (east to west), while 27% have reduced their range, and 22% have shifted vertically up or down mountain slopes.

While the general perception is that species shift toward cooler temperatures at higher latitudes or up mountain slopes, the reality is more complex. Butterflies require specific host plants, nectar sources, shelter, and safe breeding sites in their new locations. Moreover, connected habitats are essential for butterflies to move, mate, and reproduce.

To illustrate, the tawny coster butterfly has expanded from the Indian subcontinent to Southeast Asia and Australia, while the Godartiana byses has shifted from Brazil's Rio de Janeiro and Bahia into São Paulo, largely driven by climate warming. Conversely, the small blue butterfly has lost 40% of its habitat in the UK during the past 150 years, and the Danube clouded yellow has experienced a severe range contraction in Romania due to agricultural expansion.

These examples demonstrate that butterflies' range shifts are not merely a tale of species moving toward the poles. The primary drivers of these shifts are climate change and extreme weather events, although agriculture, forestry, urban development, and habitat destruction also play significant roles by destroying host plants, breeding sites, and fragmenting habitats.

The study highlights that Europe and North America have extensive long-term butterfly monitoring programs run by expert volunteers and citizen scientists, documenting range shifts for more than half of their national butterfly species. However, in most countries, records exist for fewer than 10% of known butterfly species, particularly in Central Africa, Southeast Asia, New Guinea, and the Amazon Basin, which are biodiversity hotspots where many species may already be near their upper thermal limits.

To better protect butterflies in these regions, it is crucial to support the development of citizen science monitoring programs for experts and volunteers. The study underscores the importance of conservation efforts that not only protect past butterfly habitats but also include the areas where butterflies will relocate and the wildlife corridors they will use to reach these new locations.

If conservation efforts fail to account for these shifts, protected areas based on historical species distributions may become outdated, leaving butterflies and their ecosystems vulnerable.