Page 19 - Bumblebee Conservation Trust Buzzword magazine winter 2020

Get carder! Managing habitats are found on sea walls, which pollinator conservation in mind. Rotational

(different sections cut each year) and late
may be important corridors along which
sea walls for scarce bumblebees can disperse. The loss of (annual cut delayed until 15 September)
flower-rich habitats since the 1940s led
cutting are the main pollinator sensitive
to a steep decline in the distribution of
management regimes undertaken on the
bumblebees the Shrill carder bee until it was largely east coast by the EA in an effort to reverse
pollinator declines.
restricted to a few locations along the
Thames Estuary (Essex and Kent).
By Dr Tim Gardiner, Sea walls (vegetated earth embankments) are vital Once considered fairly widespread, the
ecologist, poet and engineered structures for the defence of low-lying Moss carder bee is now primarily a coastal
species in the English parts of its range.
children’s author areas along estuaries and along the coast of the UK. Queens usually emerge between March
As strong continuous linear features in the landscape,
there are over 2,000 km of sea walls in England and and May to search for a nest site. The
Wales, with the greatest length being in Essex (450 nest is built at ground level and usually
km). Comprising a range of habitats, sea walls lie at covered by moss, dry grass or leaf litter
the interface between the shoreline (estuary or open collected by the bees. This species may be
sea) and terrestrial habitats such as grazing marshes or restricted to extensive areas of flower-rich
agricultural land on the landward side. grassland in the heart of coastal grazing
marsh and sea walls where it forages on
Sea wall flood defences support some of the richest legumes such as red clover and bird’s foot-
modern bumblebee assemblages, with 14 social trefoil.
species capable of regularly exploiting this habitat and
up to 11 of these co-existing along sea banks within As carder bee nests can persist until
the Thames Estuary. This includes five UK Biodiversity August or September, there is a need for
Action Plan (UK BAP) ‘priority’ species such as the a continuous succession of flowers from
Shrill carder bee (Bombus sylvarum) and Moss carder spring through to autumn to ensure there
bee (Bombus muscorum). The Shrill carder bee needs is a continual food supply and this includes
extensive flower-rich areas and suitable nesting sites species such as thistles for new summer
Photos: Above: Shrill carder bee of long tussocky grass to survive. As a late nesting queens and males. Carder-bees, like Photo: the landward face of a vegetated sea wall
(Bombus sylvarum); below: folding other bumblebees, therefore benefit from in Essex by Andy Skinner
flowers By Tim Gardiner; Top: and foraging species (often into September), suitable management of a sward that maintains
Wallasea Island by Bex Cartwright Further reading
optimum levels of flowering plants.
Gardiner T., Pilcher R. & Wade
Historically, sea wall mowing regimes have M. (2015) Sea Wall Biodiversity
not been favourable for the conservation Handbook. RPS, Cambridge.
of rare bumblebees, where entire sea
walls were mown to a short sward height www.essexfieldclub.org.uk/portal
(<10 cm) in midsummer (July and August). /pSea+Wall+Biodiversity+
This removes available bumblebee Handbook
forage plants in one event. Rare and
endangered bumblebee species such as
the Shrill carder bee are likely to continue Follow us on:
to decline unless suitable flower-rich @Bumblebeeconservationtrust
foraging habitats, including sea walls, are
sympathetically managed. Over 132 km of @BumblebeeTrust
sea wall grassland in Essex is managed @Bumblebeeconservationtrust
by the Environment Agency (EA) with
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