Shifting Baselines in North America's Longest Running Butterfly Monitoring Program

Eroding perceptions of biodiversity present a significant challenge for conservation. If younger generations see current degraded states as “natural,” goals for conservation actions may not be ambitious enough, and public support may be compromised. Historical data can provide context for fully appreciating the extent of biodiversity loss. We utilize the most species-rich day of each year in North America's longest running butterfly monitoring program's most diverse site to examine how perceptions of peak butterfly richness could shift over time. In early monitoring years, days with over 50 observed species were standard, but now peak richness days have shifted over time, such that these days now see ten fewer species. High-diversity days shape perceptions of biodiversity, and we provide an example of how long-term monitoring data can be utilized to study shifting baselines in observer perceptions of biodiversity and to contextualize current observations.