A recently conducted assessment of butterfly trends across the contiguous United States from 2000 to 2020 found declines at every scale: reductions in total numbers of butterflies, falling species richness, and large decreases in many individual species.
Giant Swallowtail (Papilio cresphontes) Photo : Martin Partridge
Using records of 12.6 million individual butterflies from >76,000 surveys across 35 monitoring programs, we characterized overall and species-specific butterfly abundance trends across the contiguous United States. Between 2000 and 2020, total butterfly abundance fell by 22% across the 554 recorded species. The equivalent of losing 1 in 5 butterflies over 20 years.
Species-level declines were widespread, with 13 times as many species declining as increasing. The prevalence of declines throughout all regions in the United States highlights an urgent need to protect butterflies from further losses.
Pipevine Swallowtail (Battus philenor) Photo : Martin Partridge
The scope and scale of butterfly declines suggest multiple and broadly acting threats, including habitat loss, climate change, and pesticide use.
The decline of butterflies has been linked to rising temperatures and changing climates in the US and other countries. Concordantly, the researcher’s found that species generally had stronger declines in more southernly parts of their ranges.
However, butterflies do have the potential for rapid population growth under the right circumstances, making species recovery a distinct possibility. Expansive efforts in conservation planning and action for insects could prevent widespread future losses and create and maintain the environment in which butterflies and other at-risk species can thrive.
The research was recently published in Science
