How accurate are single site transect data for monitoring butterfly trends? Spatial and temporal issues identified in monitoring Lasiommata megera

摘要: Multiple transect counts following Butterfly Monitoring Scheme (UKBMS) guidelines and Jolly–Seber estimates of population size were used to monitor the abundance second generation Lasiommata megera on a single site in southern England. The two methods resulted different patterns emergence being detected. proportion (estimated by Jolly–Seber) recorded with depended time day weather afternoon best recording trend over flight period, but even then variable fraction (6.2–51.3%). Increasing frequency which are carried out per week reduced variation increased fit generated estimates. However, indices from randomly selected for L. within sampling weeks varied 4-fold other butterfly species also highly variable. For megera, count variability is attributed non-representative placement route changes behaviour spatial distribution relation season. We suggest that need be fully validated before data populations at individual sites.