Great reed warblers were caught in reed beds using mist nets from April to August 2015. Birds were measured (body mass and wing length), aged, ringed and sexed. Additionally, we sampled approx. 30–50 µl blood from a brachial vein for blood smears, measured haemoglobin content (mg ml–1) using a HemoCue Hb201, and the remainder was stored in 0.5–1 ml SET-buffer (0.15 M NaCl, 0.01 M Tris, 0.001 M EDTA, pH 8.0) for subsequent genetic analyses of parasite types.