Llanelli Naturalists Newsletter - Summer 1993 - No 55
MH Williams

Soon after December 1963, when we first moved to Wales from our native Kent, a start was made to visit localities in the Llanelli area which offered potential for the bird-watcher. One of these sites was "Swiss Valley" or Cwm Lliedi which holds two large water bodies - the Upper and Lower Lliedi Reservoirs. Whilst the Lower Reservoir (c.14.50ha) is open to the public and a footpath skirts most of its circumference, the Upper Reservoir (c.13.75ha) is only accessible to permit-holding fishermen and a restricted number of bona-fide naturalists; this relative lack of disturbance (and perhaps a shallower area with marginal vegetation at the top of this upper reservoir), make it seemingly more attractive to wildfowl and other birds.

The Lower Reservoir was constructed to provide adequate water for Llanelli's • burgeoning population and industry in the latter years of the nineteenth century; the Upper Reservoir was subsequently built when it was realised that even more water was required. Both occupy the deep, narrow Cwm Lliedi - ideal and conveniently located for reservoir construction. Most of these notes will refer to the Upper Reservoir which is, in any case, the one which I visit most frequently.

In the early 1970's, the Llanelli Naturalists Society was formed by Noel and Georgina Tallowin, assisted by a number of local naturalists, myself included, as it was felt that existing natural history societies in the county did not provide adequate attention to the Llanelli area, which is far the most populous area of Dyfed. Quite soon in the first few years of the Society, an informal agreement was reached with the water authorities, in which a portion of the Upper Reservoir would be managed as a nature reserve, I being appointed as the honourary warden.

One of the first tasks was the construction of a hide, using materials provided by the Water Authority and labour provided by Llanelli Naturalists members. I recall it was a solid two day effort! Nest boxes were also erected in adjacent woodland - to a maximum of 46 in one year (now down to a more manageable 30). These nestboxes have had to be positioned about 30ft up the trees, due to an unfortunate recurring problem with vandals and although safer for the birds, it does make the annual task of checking (and later, clearing out) the boxes more difficult, as it involves the carrying around of a two-tier ladder. However, one is rewarded by the occupation of these boxes by a range of tit species (mostly Great and Blue) and since 1987, Pied Flycatchers have utilised some boxes. Up to five boxes (1989) have been used, though only two are in occupation this year. Pied Flycatchers now occur elsewhere in adjacent woodlands and singing males can be heard in the valley north of the reservoirs as far as Horeb; in such areas nesting pairs utilise natural cavities rather than nestboxes. Other local ornithologists have commented that this attractive summer migrant has likewise colonised other local woods since the early/mid 1980's - for example, Stradey Woods and the woods on the western slopes of Mynydd Penbre. On 20 January 1977, I was delighted to find two dormice tenanting one box!

The Upper Reservoir regularly holds wintering (mid October to late March) flocks of Pochard and Tufted Duck, with mid-winter peaks usually around the 30-50 mark for the former species and 25-35 individuals of the latter duck; exceptionally larger numbers occur, for example, 183 Pochard and 77 Tufted Duck on 14 December 1991. The occurrence of these two species is expected for both are "diving ducks", able to exploit the deeper waters of this reservoir; whereas "dabbling" ducks such as mallard occur on the shallower margins. According to the "Winter Atlas" (Lack, 1986), the Tufted Duck is the commonest - and still increasing - diving duck in Britain, feeding mostly on animal food (eg molluscs or aquatic larvae) though it will eat seeds, particularly in autumn. It normally dives to about 2.5m (though down to c.5m) and the males often dive deeper than the females so there can be segregation of the sexes in feeding flocks. The same source (loc.cit.) remarks that the Pochard prefers larger waters to the previous species and is not such a deep diver (usually in the 1-3.5m range) and it principally feeds on plant food (eg pondweeds Potomogeton spp., or the algal Chara spp); sometimes animal matter is also consumed.

Great-crested Grebes now usually attempt to nest annually in the Reserve area (the northern extremity) of the Upper Reservoir, normally only pair though on occasion (eg in 1984), two pairs. Great-crested Grebes first nested in 1977, but no young were produced in 1985-92 due to fluctuating water levels. The breeding results are given below:

1979 -    4 young

1981 -

1983 -

1984 -    2

1985 -

1992 -

1993 -

In 1993, the Grebes had three attempts to nest. With the first attempt the water level dropped, leaving the nest "high and dry", the eggs in the second nest were submerged by flood water, but fortunately the third attempt was successful with four young being hatched. Little Grebes or Dabchicks have bred on the Upper Reservoir, their characteristic "whinnying" call sometimes heard before the bird is noticed.

Green Sandpipers, distinctive with their prominent white rump and loud "tu EET-wit-wit" flight call, are quite regular on autumn passage and as winter visitors, frequently the overflow channel (the "By-Wash"), as well as the margins of the reservoir itself. Common Sandpipers occur on passage and have bred, in 1984 and 1985, when three young were raised in each year. Woodcock are found in the surrounding damp woodland, lurking in bracken stands or brambly areas whilst roosting in daytime; they emerge at dusk to feed.

Herons are regularly seen and are strongly suspected to have bred on at least one occasion, whilst Ravens breed annually in a clump of towering pines alongside the redundant mineral line which once served the now-closed Cynheidre Colliery. Kingfishers do not breed and are only irregularly noted, but Buzzards and Sparrowhawks are often seen, and they certainly nest in the vicinity. Green, Great-spotted and Lesser-spotted Woodpeckers are all found in the oak-birch-willow woods which flank much of the reservoir, but the last-named is not often observed due to its unobtrusive habits and canopy-feeding tendencies..

Amphibians are represented by Toads, Frogs and Palmate Newts, all of which breed, whilst Lizards occur on dry banks and walls. Badger setts are found in surrounding woodland but have suffered in the past from illegal digging. Otter tricks have been occasionally found, but it is not certain how regularly they utilise the reservoir: perhaps they are just transient visitors? Two water plants of note have been recorded by visiting botanists in the Upper Reservoir - Three-leaved Water Crowfoot Ranunculus trichophyllus and Perfoliate Pondweed Potomogeton perfoliatus.

Over the years, the Upper Lliedi Reservoir has provided a host of unusual records, some of which are listed below. Unattributed records are my own, otherwise the name of the recorder is given.

Jan 1970    -    14 Whooper Swans filmed on the reservoir.

18 April 1970 -    No less than 12 Great-crested Grebes (three birds have been the maximum in recent years).

11 May 1974    -    An immature Little Gull flying gracefully low over the water's surface (I.K. Morgan & E.J. Smith).

(12 Feb 1978 -    Upper Reservoir completely frozen over).

14 Jan 1979    -    A Glaucous Gull watched standing on the frozen reservoir.

14 Feb 1979    -    A Red-throated Diver (with evidence of oil on its breast); it had left by 26 Feb.

11-12 Dec 198 -    Three Green Sandpipers.

8-16 Jan 1982 -    Deep snow for a week. Found a dead starling which had been ringed in Norway in May 1981.

17 Jan 1982    -    Eight Bewick's Swans.

23 Feb 1982    -    A female Ruddy Duck put in an appearance.

15 Nov 1983    -    A male Scaup was recorded by Clive Jones.

8 Nov 1984    -    A female Scaup turns up!

Jan 1985    -    53 Pochard (C.Jones).  A female Goosander on the Lower Reservoir (CJ).

May 1985    -    Four passage Whimbrel.

27 April -    -    An adult Little Crake (Rob Hunt, Clive Jones et al).

2 May 1985    Watched at close range from the hide. A new county record.

6-10 Apr 1986 -    A passage Osprey delights local birdwatchers who watch it fishing at relatively close range - no less than seven trout were caught in nine attempts. (R.O. Hunt). The bird (a male) was also noted displaying and an Osprey (possibly the same individual) summered at Llyn Brianne in N.Carmarthenshire in this year. Migrating Ospreys have also been reported on the Lliedi Reservoirs on several other occasions eg in 1978, 1987 and 1991.

15 March 1987 -    Three Goosanders.

10 Jan -    -    A drake Ring-necked Duck is another rarity to turn up and

17 Feb 1988 again local birders were able to achieve excellent views of this bird which subsequently moved (until 21 April) on to the Old Castle Pond near Llanelli town centre.Water Rails were also observed feeding in front of the hide in this period.

25 March 1988 -    Three male and one female Shoveller.

26 Nov 1988    -    A Green Sandpiper bearing colour rings noted (J.R. Ellis & R.O. Hunt), it having been originally ringed at Reservoir in Jan.1985).

References

Lack, P. (1986). The Atlas of Wintering Birds in Britain and Ireland BTO/IWC. Poyser.