Pills, Pools and Marshes - Gower - page 229

and common goby Pomatoschistus microps can be found in the lower reaches of the Gower streams, to-
gether with a variety of estuarine animals.
Rivers and streams can also support rich and varied wildlife communities well away from the aquatic
zone.Riparianareasinthepeninsula,thatismargins,banksandadjacentlandnexttothewatercourse,are
very important for many plants and animals, including otter Lutra lutra , water shrew and water vole Ar-
vicola amphibius . Many more species of terrestrial invertebrates also live beside rivers and streams than
in them. The banks of streams passing through woodland are especially rich and have their own particu-
lar faunas, with giant lacewings Osmylus fulvicephalus , or moss-breeding craneflies such as Dactylolabis
transversata and Tipula yerburyi .
The otter was very common in Gower until the early 1960s when, along with other species such as
peregrine, they were affected by pesticides entering the food chain. These pesticides, used in seed dress-
ingsandsheep dips,caused the otter tobecome extinct overmost ofits range inBritain. Duetothis otters
were absent from the area for over twenty years. There was a slow recovery following the prohibition of
the chemicals concerned and by the time the third Welsh otter survey was carried out in 1991 signs of
otters were found once again on the Loughor and Tawe rivers and one spraint (dung sample) was found
in Oxwich Marsh close to the coast. Since that date otters have become abundant again and are almost
certainly now making use of every stream, river and wetland. As they are at the top of the food chain the
presence of otters indicates the high quality of these habitats. The animals also make extensive use of the
coast and have been observed hunting in the sea close to Oxwich Point.
Although the streams are relatively small the habitats on the bank sides and adjacent areas are good
and there are many potential breeding sites available in the extensive reedbeds, scrub thickets and rush
pasture. A number of tree-root holts have also been found, mostly in ash and oak trees. Despite initial
impressions, all the signs are that Gower is able to support quite a large and thriving otter population, and
the animals are certainly breeding. Typical signs of breeding activity have been recorded at suitable sites
and small otter prints, obviously made by young animals, have been found on the lower reaches of the
Burry Pill. Additions to the population also come from animals travelling into Gower along the estuary.
OttersfromtheTaweriversystemmayalsobeabletoreachthepeninsulaviatheAfonLlan,whichshares
a watershed with some of its tributaries.
Mink Mustela vison are occasionally seen in and around Oxwich Marsh and its main feeder stream.
Onetookupresidenceinaholeinthemainsluicewallin1982andanotheradoptedthecabinofafloating
reedcutter in 2000. Both were shot by reserve staff, as was another in 2001. The expansion of mink popu-
lations has been mirrored in many parts of Britain by a reduction in the range of water voles, though they
havealways beencomparatively scarce inSouthWales. Researchers atOxfordUniversity have,however,
found evidence that as otters increase along rivers and streams mink decline, so the increased number of
ottersmaybehavingabeneficialeffectinotherways.Therehavealsobeeninstancesinwhichottershave
killed mink.
Possible water volesigns,suchasholesinthebank,areoftenseenalongGowerwatercourses, though
the animal itself is more elusive. In Britain as a whole, it has been calculated that 94 per cent of formerly
occupied sites may be lost, with an even greater reduction in actual numbers, making this the most dra-
matic population decline of any British mammal in the twentieth century. On the other hand there is good
evidence that the population decline had begun well before mink became widespread, probably due to
pollution and habitat degradation, and so a number of factors, probably interacting, have played a role in
the decline. Gower with its generally high-quality habitats has therefore, by default, become a stronghold
for water vole.