The Shrill Carder Bee on the Move?
1Ted Benton and 2John Dobson 113 Priory Street, Colchester COl 2PY; 2148 Main
Road, Danbury CM3 4DT
In the wake of evidence that some of the British bumblebee species were in steep decline
towards extinction, 5 of them were included in the UK's 'Biodiversity Action Plan'
(1994). Two of these 'BAP' species were eventually discovered to have strong populations
along the Thames estuary, in north Kent and south Essex. These were the Brown-banded
Carder Bee Bombus humilis and the Shrill Carder Bee Bombus sylvarum. Despite their
increasing rarity nationally, these two species were surprisingly abundant in the remnant
grazing marshes, flood defences and ex-industrial 'brown-field' sites scattered along
the estuary from east London through to Canvey Island and Hadleigh on the Essex side
of the river. Peter Harvey and others were able to demonstrate the exceptional
communities of bees, wasps, ants and other invertebrates in these localities, pointing to
the conservation value of despised urban 'waste land'.
Unfortunately for the wildlife, government had other ideas. The 'Thames Gateway' project
involves the building of over a quarter of a million new houses, together with transport
and other necessary infrastructures. To date, it seems that the standard priority of
developing 'brown field' sites first remains in place, threatening obliteration of these
unique assemblages of invertebrate species. Add to this the development pressures
associated with the successful Olympic bid, and the future looks very bleak.
However, there have been some slight grounds for hope. One is that at least one key site
(the Northwick site, on Canvey Island) has been largely saved from development as a
result of timely and energetic intervention by English Nature. Other sites have been
obtained by the RSPB, but the management strategy for these remains uncertain.
The problem for conserving the rare bumblebees, however, is that they require large
areas of suitable habitat to maintain viable populations. National bumblebee expert,
Mike Edwards, estimates that mosaics of habitat not less than 10 square kilometres are
necessary. So, saving a single foraging or nesting site might well save small, localised
populations of some solitary bees or wasps, but not so the bumblebees.
It began to seem as though the Thames estuary populations of the Shrill and Brown-banded
Carder Bees were doomed. A possible 'last-ditch' strategy to save them might be to use
agri-environmental schemes to provide suitable habitat in Essex and Kent outside the
'Gateway' development zone, but close enough to allow colonisation by the bees. However,
this seemed a rather remote and unlikely prospect - until this year....
The authors have been up-dating the Essex dragonfly distribution maps over the last
five seasons, and this year decided we needed more survey-work on the Dengie Peninsula.
Large parts of the Dengie are rather remote and quite difficult to access, and not
12 Essex Field Club Newsletter No. 49, January 2006