The queen is led? Bumblebee (Bombus spp.) nest-searching on sea wall banks may be influenced by cutting and sward height

Abstract

English sea wall flood defences support an important grassland habitat for bumblebees (Bombus spp.). However, annual cutting in midsummer (July–August) could negatively affect them. The mowing regime on a sea wall at Goldhanger Creek in Essex was changed to a late cut (after 15 September) and nest-searching behaviour was compared with an adjacent sea wall cut in midsummer (normal cut in August). Sward height and the number of queens nest-searching were significantly higher on the normal cut sea wall than on the late cut one. Tall grass swards resulting from a cut early in the previous summer may be important for nest-searching compared to those mown late, although there is probably an interaction with sea wall aspect and soil type. The landward slope was also more attractive for nesting than the flat folding (berm) due to the longer vegetation where nests under construction were located (of Bombus humilis and B. terrestris).