Our work at Garnswllt was originally targeted at obtaining planning permission for the installation of a solar panel array in place of a small patch of mixed woodland to the north of the Welsh Water site. Although the ecological submissions were approved, and planning permission agreed, the customer postponed the project whilst consideration was given to installing additional waste-water treatment plant instead of the solar panels. The ecological work included several surveys, as outlined below, with most effort being expended on proving that there were no Hazel dormice being supported by the wooded area that would be affected.
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Dormouse Surveys. A combination of survey techniques, outlined below, enabled a firm conclusion that the wooded area was not occupied by Hazel Dormice.
Habitat Assessment. The proposed development site was a patch of mixed deciduous woodland which had been planted about 30-40 years ago on ground that had been used for the disposal of solid waste generated by the water treatment plant. The wooded area covered an area of about 1.4ha and had a seasonal pond in the south-western corner, where the surrounding ground was also often quite wet. Based on national averages for dormouse population densities, this site might have been capable, all else being well, of supporting 2-4 adult dormice, which was assessed as unlikely to be sufficient for a long-term population.
The trees within the proposed location were a mix of broad-leaf species, including ash, oak, willow, birch and elder with patches of hazel, particularly in the south-eastern corner; hawthorn and sycamore were also present. The proportion of hazel and other trees that were fruit bearing was low. The understorey was a mix of bramble and nettle with some regenerating saplings. Tree canopies provided about 75% cover, and the understorey at about 1.5m above ground restricted visibility to between 5 and 10 metres in late spring and summer, although considerably further outside this period. The northern section of the area had a higher proportion of dead and fallen trees and was also infested by Himalayan Balsam and Japanese Knotweed. The vegetation within the site was not therefore an optimum one for supporting dormice.
Habitat Isolation. The proposed site was isolated from the rest of the neighbourhood by the combination of a railway track, 2 rivers, the waste water plant itself and a large area of open farmland. The closest recorded populations of dormice were between 4 and 10 km away, and all were isolated from this site by the River Loughor, the banks of which had large breaks in the shrub and tree cover, with no opportunity for migrating dormice to cross the river using tree canopies. This assessment demonstrated that there was an extremely low probability that any resident dormouse population could be reinforced or replaced by migrants from other populations if required.
Nest Tube Survey. Fifty nest tubes were deployed around the survey site and monitored for usage between July and November with no signs of occupation by dormice throughout this period, considered to be the most active one for dormouse foraging. Many of the tubes had evidence of temporary use by small birds, probably as overnight refuges, and a couple of trail cameras detected a few visits by wood mice and wrens. These results suggested an extremely low probability that dormice were living in the area.
Nut Survey. Three different locations under the canopies of nut-bearing hazel trees were thoroughly checked in October and November for the presence of discarded nuts or shells bearing the tell-tale tooth marks of dormice. The results demonstrated that almost all hazel nuts had been eaten by squirrels or birds, with a small number of shells bearing teeth marks associated with wood-mice and voles. Again, this nil result for dormouse tooth marks suggested a very low probability that the area was populated by this species.
Otter Surveys. In-river checks of both the Rivers Loughor and Cathan revealed no field signs associated with the presence of otters, and inspection of the river banks also revealed no indications of recent presence. Similarly, the edges of the woodland patch revealed no signs of holts or resting locations, even though some areas seemed likely places.
Water Vole Surveys. The banks of the Rivers Loughor and Cathan were also inspected for the presence of water voles. In some locations, the banks were too stony for suitable burrows, whilst in others rock armour installations, to reduce bank erosion, offered no suitable sites. Other, seemingly more promising stretches of bank, also contained no sign of burrows or other field signs, such as latrines, food piles or cropped vegetation.
Badger Foraging. During our many visits to undertake the principal surveys, we recorded the presence of badger foraging signs, latrines and footprints. In addition, our deployed trail cameras also captured images of badgers wandering through the site occasionally, but no setts were found within the proposed development area.
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JP Ecological Services 