A regionally informed abundance index for supporting integrative analyses across butterfly monitoring schemes

摘要: 1. The rapid expansion of systematic monitoring schemes necessitates robust methods to reliably assess species' status and trends. Insect poses a challenge where there are strong seasonal patterns, requiring repeated counts abundance. Butterfly (BMSs) operate in an increasing number countries with broadly the same methodology, yet they differ their observation frequency used compute annual abundance indices. 2. Using simulated observed data, we performed extensive comparison two approaches derive indices from count data collected via BMS, under range sampling frequencies. Linear interpolation is most commonly estimate series. A second method, hereafter regional generalized additive model (GAM), fits GAM within sites across climatic region. For methods, estimated bias statistical power for detecting trends, given different proportions missing counts. We also compared accuracy trend estimates using systematically degraded Gatekeeper Pyronia tithonus (Linnaeus 1767). 3. method generally outperforms linear method. When proportion increased beyond 50%, derived showed substantially higher estimation error as well clear biases, detect trends when was substantial. 4. Synthesis applications. Monitoring offers invaluable support conservation policy management, but requires analysis guidance new expanding schemes. Based on our findings, recommend approach conducting integrative analyses schemes, or analysing scheme reduced efforts. This enables existing be expanded developed within-year frequency, affording options adapt protocols more efficiently species large geographical scales.