South Gower Cliffs - Gower - page 93

atrequirements ofmanyofthespecies,whichmakethemverysensitive toenvironmental changes,andto
thelowpopulationlevelsatwhichtheynormallyoccur.Theecologicalandeconomicimportanceofthese
insect communities cannot be overemphasised. The decline of bees, wasps and ants in the countryside
is a reliable indicator of profound environmental poverty as they are a 'key piece in the environmental
jigsaw and as they decline or become extinct at local or national levels so does a myriad of other organ-
isms' (Fowles, 1996). It is therefore extremely important to conserve areas, such as Gower, that hold rich
invertebrate faunas. Many nationally rare species occur in the peninsula, as well as many others that are
extremely scarce in Wales. At the time of writing the Countryside Council for Wales and Liverpool Mu-
seum are about to complete a three-year study of the invertebrates of soft cliffs throughout Wales, ending
with selected sites in Gower. More information may therefore be forthcoming in the near future.
Thelowcliffsof'head'depositsfromthelasticeageareanoticeable featureofthecoastline between
RhossiliandOxwichandoccurlessfrequentlyfromPennardBurrowstoMumblesHead,wheretheytend
to support more scrubby vegetation. The importance of the cliffs for insects relates to their capacity to
provide a continuous supply of microhabitats rarely found elsewhere. The regular erosion of the crumbly
soils creates areas of bare ground and maintains pioneer plant communities which can include large num-
bers of plants such as bird's-foot-trefoil, horseshoe vetch, kidney vetch Anthyllis vulneraria and hogweed
Heracleum sphondylium. All these provide rich food sources for bees and wasps during the flight period
andsupportlargecommunitiesofplant-eatinginsectssuchasweevils.Thebareareassupplynestingareas
for bees and wasps and suitable hunting areas for ground beetles and spiders while seepages and pools
provide the wet mud required by some species for nest building and refuges for insects with an aquatic
stage in their life cycle such as craneflies. For instance the cranefly Dicranomyia goritiensis is known
from coastal cliff seepages at Longhole Cliff. It has been agricultural policy in the past to bring as much
land as possible into use and as a result the natural vegetation has in places been squashed into a narrow
coastal belt. A small number of clifftop fields have therefore been included within a Tir Cymen agri-en-
vironment agreement and are managed as fallow or spring cereal and stubbles as an experiment to see if
it is possible to increase the abundance and diversity of nectar sources in the vicinity of the soft cliffs.
Elsewhere in Gower there are few similar habitats, except for the west-facing solifluction terrace, 2
kilometres long, at the base of Rhossili Down. Despite its length it may be of less interest for insects,
certainly in the southern part where the soft cliffs are mostly vegetated and stable and extremely heavily
grazed by sheep. North of the Old Rectory, however, there is a rich leguminous sward, which is likely to
support a varied invertebrate fauna, but this may be more similar to that of Llangennith Burrows than the
typical Gower soft cliffs. The seepages and streams here provide a sharp contrast to the conditions on the
south coast.
Someoftheearliest invertebrate recordsarefromHortonandconcerntheminingbees Andrena rosae
and Andrena marginata noted in 1914 by Hallett, together with a nationally scarce 'nomad' cuckoo bee
Nomada flavopicta. Andrena rosae nestsinbaregroundonlightsoils,includingwell-usedpaths,andpos-
sibly shares a communal nest entrance to its burrow with other females, as closely related species do. Its
life history has not been studied in Britain and it is still unclear, for instance, which plant species are vis-
ited for pollen. The summer brood probably collects umbellifer pollen, but the spring brood might use a
variety of early flowering plants. First-brood adults are on the wing between late March and the end of
May, whilst the summer brood appears between mid-July and early September. The bee was found again
atHortonCliffinMarch2002,byP.M.PavettfromCardiffMuseum,buttodatetherehavebeennoother
records. Nomad bees, such as Nomada flavopicta , are wasp-like bees that are parasites of various mining
bees; they do not actually feed on their hosts, but merely take the food that was intended for the host lar-
vae. Like other cuckoo bees they have no pollen-collecting equipment.