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 was then changed to a ‘late’ cut (September) on a sea wall and compared with an adjacent sea wall cut ‘normally’ (midsummer).
There were significantly more queens nest-searching in May compared to April. Sward height and the number of queens nest-searching were significantly higher on the normal cut sea wall than on the late cut one. No correlation between queen abundance and forage availability was significant. The nesting habitat therefore seems more important than forage abundance for queens.
The summer studies revealed the workers’ higher abundance on the late cut wall. However, this new spring study of queens reveals their preference for the normal cut wall. Having a mosaic of habitats seems the key to conserving sea wall grassland bumblebees.
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