Interaction Between Wildfowl and Recreation at Llangorse Lake and Talybont Reservoir, South Wales
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Interaction between wildfowl and recreation at Llangorse Lake and Talybont Reservoir, South Wales C.H. TUITE, MYRFYN OWEN and DAVID PAYNTER Introduction recreation (walking, picnicking, etc). In recent years there has been growing General concern about the influence of eutro phication and recreation on the diversity This paper describes part of a three-year and welfare of the lake’s fauna and flora study into the effects of water-based (Cúndale 1980). Talybont was considered recreation on wildfowl populations (Tuite the control site, at which wildfowl use 1981). The other two parts involved an was largely determined by natural factors, extensive examination of wildfowl num such as migration, overall population bers and distribution on British inland levels in the region, weather and eco waters in relation to recreation in winter logical carrying capacity. Comparative (Tuite et al., in press) and in summer summaries of their morphometric features (Owen & Tuite, in press). Whereas it is and trophic status are given in Table 1 well known that water-borne activities and outline maps in Fig. 1. are disturbing to wildfowl (e.g. Cooke 1975, Batten 1977), the exact way in which this affects the welfare or move Llangorse ments of the birds is unknown. Effects may vary from gross distributional Llangorse is the largest natural lake in changes, in which sites are totally aband south Wales, a typical lowland eutrophic oned, to much more localised small-scale lake. There are fairly extensive areas of alterations in ranging, feeding or roosting reedbed, especially along the south and behaviour. This field study aimed to western shores (Fig. 1a), in which the examine some of the latter. commonest species are the common The main study site was at Llangorse reed Phragmites australis, reedmace Typha Lake, near Brecon, Powys, but the nearby latifolia and yellow water lily Nuphar Talybont Reservoir was also monitored lutea, while the only submerged macro- during the study winter of 1980-81. phyte present in 1982 was milfoil M yrio Both waters are within the boundaries phyllum spicatum — the only remnant of the Brecon Beacons National Park, are of the formerly abundant and diverse close to one another (about 6.5 km apart), community (Cragg et al. 1980; R. Hay and have a reasonable number and cock pers. com.). Palaeological analysis of diversity of waterfowl. Talybont supports the diatom flora of sediment cores little recreation, whereas Llangorse is suggests that eutrophication started in heavily used for recreation throughout Roman times with building of roads into the year, with sailing, windsurfing, coarse the area and the introduction of settled fishing, power-boating, water-skiing, row agriculture (Jones et al. 1979). The rate ing and canoeing, as well as informal of eutrophication has probably increased Table 1. Comparative morphometric features and eutrophic status of Llangorse and Talybont. Feature Llangorse Talybont OS reference SO 1019 SO 1326 Altitude (m) 155 200 Surface area (ha) 153 131 Mean depth (m) 1.8 9.0 Banks Shelving Steep Maximum length (km) 2.0 3.3 Trophic status Eutrophic Oligotrophic Surroundings Mixed farmland Largely forested 48 Wildfowl 34 (1983): 48-63 Wildfowl and recreation 49 LLANGORSE LAKE TALYBONT RESERVOIR Figure 1. Outline maps of Llangorse Lake and Talybont Reservoir showing the vegetation zones. recently, due to rapid growth in the is deeper and less productive than Llan application of agriculture fertilisers in the gorse, and is surrounded by fairly steep catchment area, and, until a new sewage hillsides rising to over 400 m. The lower treatment works was completed in 1981, slopes are mainly forested with upland to the sewage effluent from Llangorse sheep grazing above. The most important village. A sequence of algal blooms feature for wildfowl is the marsh area at occurs from spring to autumn (Tai & the south end (Fig. 1b), where the Benson-Evans 1977). Llangorse was Caerfanell river enters the reservoir. declared a Site of Special Scientific This provides the only feeding habitat Interest by the Nature Conservancy for most wildfowl species and this part Council in 1954 and was listed as a Grade has been designated a Local Nature 1 site in the Nature Conservation Review Reserve, managed jointly by the Brecon (Rat cliffe 1977). Naturalists Trust and the Water Authority. The region is not an important one for wildfowl; the sites are not on a major Talybont fly way nor are there any other substantial concentrations of wintering wildfowl in Talybont is a direct supply reservoir tlie vicinity. managed by the Welsh Water Authority, 50 C.H. Tuite, Myrfyn Owen and David Paynter Methods counts in each season) from the National Wildfowl Counts indicates that 1980-81 Waterfowl population monitoring was not atypical in the use of either site. For Mallard Anas platyrhynchos, Total waterfowl counts were carried out Tufted Duck Aythya fuligula, and Poc at both sites on Wednesday and Sunday hard A. ferina, numbers at Talybont were of each week from September to March. substantially higher than at Llangorse in Each water was divided into zones as all months. It would be expected that the shown in Fig. 1. The numbers of birds latter would hold many more ducks of in each zone were recorded separately. all these species, since it is larger, con Zones 1-5 of Llangorse, which include tains a much greater area of suitable open water, were observed from the top habitat, and has a mixed farmland in the of the Llangasty Tallylyn church tower vicinity. Talybont is, in all these respects, on the southern shore, using a telescope less suitable for wildfowl. There seems, and binoculars. Zone 6 , an area of flooded therefore, to be some factor restricting fields to the west of the lake, was counted the carrying capacity of Llangorse for from a vanatge point on the road from these species, and recreation is a likely Bwlch to Pennorth. Talybont was counted candidate. from suitable points on the road running Goldeneye Bucephaia clangula, while along its west shore. more capable of exploiting deeper waters than the above three species, are also generally more abundant on productive Recreation and waterfowl monitoring at areas. Their numbers are, nevertheless, Llangorse consistently higher at Talybont. This species was found to react to the presence Detailed monitoring of recreational act of boats at great distances (Hume 1976), ivity and of waterfowl numbers and and is the most sensitive to recreational distribution was carried out. At the half disturbance in winter (Tuite et al., in hour of each daylight hour the numbers press). of birds in each zone were counted and Teal Anas crecca and Wigeon A. recorded. The position of each boat was penelope were present in similar numbers plotted, using different symbols for at both sites and showed very similar different types of craft. The position and patterns of temporal change through the number of people involved in lakeside winter. However, if zone 6 , which is activities were also mapped. Sampling outside the lake proper, were excluded, days were randomly selected, dividing numbers of both species would be con them between weekends and weekdays. siderably lower than at Talybont. In Days of poor visibility were replaced, contrast numbers of Coot Fulica atra, wherever possible, by the next approp Great Crested Grebe Podiceps cristatus riate day. A total of 63 all-day watches and Mute Swan Cygnus olor were higher were kept, 31 at weekends and 32 on for most or all of the winter months at weekdays. Full details of days and Llangorse. All these species are com amounts of recreation are given in Tuite monly associated with more eutrophic (1981). waters. The stands of submerged macro- phytes and emergents at Llangorse are likely to be particularly important for Results Coots and Mute Swans. The total count showed that Bewick’s Wildfowl counts Cygnus columbianus and Whooper Swans C. Cygnus observed at the two sites were The twice-weekly censuses are sum undoubtedly the same birds moving marized for the commoner species in between the two. Talybont was used for Fig. 2 in terms of the mean monthly feeding and roosting and Llangorse only numbers at each site. The monthly as a daytime feeding site. The preference means for all except vagrant species are of Goosanders Mergus merganser for presented in Table 2. A comparision of Talybont is almost certainly related to these means with the 1 2 -year regular stocking with trout, and the existence mean (the average of the three highest of a breeding population of brown trout Wildfowl and recreation 51 M UTE SW A N TUFTED DUCK GOLDENEYE Figure 2. The seasonal pattern of numbers of the nine commonest wildfowl species at Llangorse (squares) and Talybont (triangles). Salmo trutta. ducks in all zones. The vegetarian ducks The distribution of birds in the diff and swans are most frequently found in erent zones, from the twice-weekly the flooded marshland of zone 6 , whereas bird counts, is shown in Tables 3 and 4. of the open water areas, zone 5 holds At Talybont the vast majority of wild most birds. fowl were associated with the shallow water and marshland in zone 4, only the diving species spending significant Recreation at Llangorse amounts of time in other areas, with Goldeneye showing a preference for the Llangorse is privately owned and although zone nearest the dam. All the zones of there are water-ski and sailing clubs Llangorse were used substantially by there is little control on the water and one species or another, reflecting the access is freely available. A group called wider availability of usable habitat. PGL Holidays, which caters for children The bottom is within reach of diving adventure holidays, has a camp on the Table 2.