Butterfly bait traps versus zigzag walks: What is the better way to monitor common and threatened butterflies in non-tropical regions?

Trapping live butterflies using bait traps is a traditional monitoring method used in tropical regions. We compared the utility of bait traps with zigzag walks in temperate Central Europe where butterfly bait traps have not been systematically tested yet. We focused on butterfly communities in steppes, forest steppes and open woodlands. We carried out the research in seven localities during 2–4 consecutive days in summer 2013. We observed far fewer specimens using zigzag walks (538) than bait traps (2115), but more species (34 vs. 23), genera (27 vs. 18), as well as families (8 vs. 5). However, overall species composition was not influenced by monitoring method but only by locality. For 8 of 37 detected diurnal species bait traps were more efficient than zigzag walks. Most of the trapped species and individuals were sampled from the Nymphalidae and were attracted to both types of bait in various ratios. Pieridae and Papilionidae were not attracted to the traps. Also, some of both common and rare species of the Nymphalidae were detected only using zigzag walks. We recorded eight species from the Czech Red list of threatened species as well as one priority species of European Union interest by combining both methods. We are convinced that using a combination of the standard monitoring procedure and butterfly bait traps would lead to an improvement in species detectability and provide a more accurate estimation of actual species abundance.