A European monitoring protocol for the stag beetle, a saproxylic flagship species

1. Developing protocols for threatened invertebrates is often challenging, because they are not only rare but also elusive. This is the case with the stag beetle (Lucanus cervus), a protected and flagship species for the saproxylic beetle fauna in Europe. 2. We applied a standard transect walk at a European scale (8 countries, 29 transects) to test its practicability and reliability as survey design.