Improving our science: the evolution of butterfly sampling and surveying methods over time

Abstract

Butterflies are consistently the focus of conservation research because they contribute to ecosystem services, act as biological indicators, and are in decline worldwide. Land managers and researchers use many methods to measure butterfly populations, but this creates issues for standardization and production of comparative, rigorous data. To promote methods more appropriate for research-based conservation, we conducted a literature review focusing on the implementation and advancement of butterfly monitoring methods over time. We identified four main methods that are most frequently used in butterfly research and monitoring: (1) trapping and netting, (2) mark-recapture, (3) transects (Pollard walks), and (4) distance sampling. Although a progression of method development has occurred over time, all methods are still currently used in butterfly research, with trapping, netting, and mark-recapture used in 85% of studies. Over the last century, the amount of butterfly research has steadily increased, so it is vital to select methods that produce accurate, and comparable data. However, we found that method selection was not solely based on the type of data needed for accurate interpretation and extrapolation of results. Instead, land context, species abundance, and historically-used methods are driving method selection. As butterflies remain a high conservation priority, researchers must provide rigorous data that are necessary for creating effective conservation plans and policies by using a framework for method selection.