Butterfly monitoring

Harker, R.J. & Shreeve, T.G. (2008) How accurate are single site transect data for monitoring butterfly trends? Spatial and temporal issues identified in monitoring Lasiommata megera. Journal of Insect Conservation, 12, 125–133.
Brereton, T.M., Roy, D.B., Middlebrook, I., Botham, M.S. & Warren, M.S. (2011) The development of butterfly indicators in the United Kingdom and assessments in 2010. Journal of Insect Conservation, 15, 139–151.