Birds of the Tywi Valley PDF Print E-mail

Llanelli Naturalists Newsletter - Summer 1992
Julian Friese

The Tywi valley, cut into an anticlinal structure of Lower Palaeozoic rocks, is some fifty-three miles or so from source to mouth, and it is regarded, with those areas on the Old Red Sandstone, as the most agriculturally productive area of Carmarthenshire. Much of it now is permanent pasture for livestock - dairy cattle and sheep, though in the past a more varied farming regime was in operation. For example, Arthur Young in 1760 mentioned the growing of potatoes, clover, turnips and cabbages on a rotational basis as well as areas of pasture.

The river is noted amongst fishermen for its salmon and the unpolluted waters and adjoining areas support healthy populations of otters and a range of birds. Rare invertebrates, more typical of northern Britain such as the five-spot ladybird Coccinella quinouebunctata, the impressively large wolf spider Arctosa cinerea and a rare "stilleto-fly" Thereva lunulata inhabit its shingle banks; there are also areas of interest to the botanist with pink purslane Montia sibirica for example, colouring some of its banks in summer. Pink purslane was only discovered in the county in 1956 (on the R. Bran at Llandovery), but since then it has also colonised much of the middle section of the Tywi. The main purpose of this article however, is to examine the birds inhabiting this river valley, species - as the following text will show, are a fascinating mix of those associated with both upland and lowland Britain.

During the breeding season the upper Tywi valley is rightly renowned for its typical Welsh upland avifauna. This usually consists of birds such as pied flycatchers, wood warblers, redstarts and tree pipits in and around the hanging oak woodlands; dippers and grey wagtails along the river courses and ravens, buzzards and possibly even a red kite soaring over the wild plateau of Mynydd Mallaen. The often heavily-grazed upland woods lack a dense shrub or herbaceous layer and so birds like the blackcap which occupy such habitats in the county's lowland woods are regularly absent; outside the woodlands, whinchats and redstarts are to be found on the brackeny slopes and grassy areas with scattered hawthorns ("ffridd"). A few pairs of ring ouzels nest on scrubby rock outcrops or in similar gullies; crags are the domain of kestrels and sometimes, peregrine falcons.

Below the market town of Llandovery, the nature of the Tywi changes, from a river that tumbles through a narrow steep-sided valley to a slower body of water that winds its way across a level green vale. Here, where the valley is broader, meanders form in the river and with them associated ox-bow lakes, water meadows and shingle shoals opposite exposed earth banks. Some aspects of the bird life now shows affinities which may be thought of as perhaps more "lowland English" in character than that found further upstream in the headwaters, but as well as this "lowland English element" there are species that are more typically associated with the hills of Britain - the goosander for example.

Perhaps the most noteworthy of the Tywi valley's birds is a relative newcomer to the county, which was only first recorded breeding in 1986 - the little ringed plover. A stroll near any extensive shingle shoal in summer will often induce a bird present to utter it warning call, a clear piping "pee-u". Seeing the bird, however, sometimes takes a little while due to its superb camouflage (merging with the pebbles) and its habit of standing completely still. Not until it runs along the ground will its precise whereabouts become obvious.

Since 1990 Barry Stewart and myself have been engaged in ringing the birds along the Tywi to study any movements between the sites used in different years. Also in 1991, a population survey for the National Rivers Authority (organised through the R.S.P.B.) was carried out. This, amongst other things, revealed that the majority of clutches were laid during the first two weeks of May and that unregulated shingle extraction by farmers is probably the biggest threat to the eggs at this time. (Trampling by livestock is the other major danger).

The rapid build up of breeding pairs found along the Tywi (and its tributaries the Cothi and the Bran) caught most observers off guard and this quick rise is illustrated in the following histogram.

Histogram showing the increase of breeding little ringed plovers on the Twyi and it tributaries

 

One could speculate that there is perhaps enough unused habitat for a potential maximum county population of around 55 pairs of little ringed plovers. Certainly, the numbers of this charming wader are flourishing at the moment -let's hope it long continues to do so.

The little owl in this part of the country is also probably near the edge of its British range. Records of breeding birds in the Tywi valley have been recently on the increase, with breeding noted at Dryslwyn, Court Henry, Ffairfach, Llandeilo, Llangadog and suspected at Rhosmaen in the last five years. It is quite conceivable that this is a frequently overlooked species throughout the valley as much suitable habitat exists (i.e. scattered old trees in open terrain). The best indications of breeding are the hunger calls of the young from the nest-site in late summer.

Allt-y-Gaer, a larch plantation on the slopes of Grongar Hill near Llangathen, holds Wales' largest heronry, with some fifty pairs of herons regularly nesting in recent years and because of its importance the heronry has been notified as a Site of Special Scientific Interest. Formerly, the herons nested in Allt-y-Wern, a short distance upstream, but felling operations forced the birds to move to their present abode. From this nest site, the birds range widely over the valley below stalking frogs, small mammals such as voles as well as various fish. An area of Dinefwr Park, Llandeilo is still called "The Heronry" strongly suggesting this was where the "splendid heronry" containing "scores of herons" was located in 1858 (Davies, 1858). "Rhiw'r adar" (or Birds-hill) nearby is also suggestive of occupation by the heron at some stage, but this too is now deserted for herons seemingly have a tendency to move site from time to time, perhaps in response to some adverse event at a critical stage of the breeding season. The fortunes of the heronries in the Tywi valley - and elsewhere in Carmarthenshire have been carefully documented by the County Bird Recorder, Mr Dilwyn Roberts to whose summary (Roberts, 1984) interested readers are directed.

Whilst the herons continue to thrive, the same cannot be said of the white-fronted geese, which winter on those river-side pastures principally between Cilsan Bridge and Dryslwyn Castle (they can usually best be seen from the latter site). Local naturalists who were bird-watching in the late 1960's or early 1970's will enthuse about the almost-magical sight of up to 3,000 loudly-calling geese in the air at once and such memorable experiences were not confined to the Tywi valley, for the geese regularly flew south, on some winter evenings over Llanelli, to (it is presumed) the Burry Inlet, returning to their Dryslwyn feeding grounds in the morning. Recent counts have been paltry (c30 or so) compared to the thousands seen some two decades ago. Yet the breeding population in Siberia (from where these geese come) is said to be increasing spectacularly, so why the continuing decrease at Dryslwyn? It has been suggested that the change from grazing cattle to sheep is responsible but the white-fronts prefer short sheep-grazed pastures. Recent research, including ringing, has shown that a much higher proportion of these geese are now wintering in the Netherlands and the Nord Rhein - Westfalia region of Germany where they are both fed and are afforded protection. So rather than wasting energy and flying further west to Wales, the geese remain on the Continent. This is said to be a phenomenon known as "short stopping", well known amongst geese in North America (Kirby et al, 1991). Sadly, because of conservationists success elsewhere in Europe we may see a further, perhaps even terminal, decrease in the numbers wintering in the Tywi. The birdwatcher will though be compensated by the flocks of wigeon, teal and mallard and the few Bewick's swans that still enliven the Tywi in the short days of winter.

The handsome goosander has only nested on the Tywi in recent years, in line with its similar colonisation of the rest of Wales. The first confirmed nesting in Carmarthenshire was only in 1980 when a pair bred near the RSPB Dinas Reserve on a tributary of the Tywi, though birds were present at an earlier date. This "saw bill" duck is now firmly established on the Tywi (and other major rivers), indeed the RSPB "Goosander Count" in 1985 gave a total of no less than sixty-six females and ducklings on the Tywi (Carms. Bird Report 1984-85).

One bird that is the very essence of summer along the Tywi must be the sand martin, a colonial relative of the more familiar swallow, which nests in the eroding vertical banks of the river. A survey of its colonies was carried out by the author in 1987-8 (Friese, 1989), though monitoring of one colony (at Penybont, north of Rhandirmwyn) had taken place since 1979. This counting of the number of breeding pairs present had shown that a savage decline had taken place, which mirrored national trends, caused, it is thought, by adverse conditions in the sand martins' wintering quarters on the southern edge of the Sahara region. Recently, the Tywi's sand martin colonies have been the subject of a ringing study. In the two summers of 1989-90 for example, almost a thousand birds were ringed, including fifteen recoveries from other sites, and one of the Tywi birds was later recaptured in France (Stewart, 1990). Such studies enable ornithologists to build up a picture of the species' migratory patterns and which sites are important as staging posts or wintering areas, thus helping to determine which areas are important to conserve.

In Ingram and Salmon's booklet "A Handlist of the Birds of Carmarthenshire" published in 1954, the yellow wagtail is stated as "breeding at Laugharne, Nantgaredig, Llanarthne, Llandeilo and north of Llandovery." There was in addition proof of breeding near Carmarthen in 1969. Nowadays, its status has declined to a spring and autumn passage migrant in the Tywi valley (and also the coast where until recently it bred in the extreme south-east). However, the numbers on passage do seem to be increasing during the last few years and two juveniles, seen on the 10th of August 1989 at Dryslwyn, may have been reared in the area - adults were known to be here on several dates earlier in that season.

A pleasant surprise during fieldwork for the new British Trust for Ornithology "Atlas of Breeding Birds" in 1989, was the discovery of a family party of reed warblers at the far eastern end of the ox-bow lake behind Dryslwyn Castle. The birds chief habitat requirements are Phragmites - reed-beds. In Carmarthenshire, a pair with young were also found as far inland as Pensarn where the distribution of Phraqmites peters out. The birds at Dryslwyn however, where found in a mixture of reed grass Phalaris arundinacea, reed sweet-grass Glyceria maxima, great reedmace Typha latifolia and willows and osiers Salix spp. This warbler has been noted as nesting in plants other than common reed elsewhere in Britain, amongst other rank herbaceous species like willowherbs and nettles and on the Continent, even in cornfields. Perhaps the overriding factors which decide where the bird will breed is the structure and sturdiness of the plant stems and as a consequence their suitability as a site from which a nest can be woven around and hung.

Another warbler known to be on the increase in Carmarthenshire is the lesser whitethroat. Breeding was confirmed in sixteen 10km squares (with presence in another two). for the new B.T.O. Atlas in the years 1988-91. This compares with only one 10km square record of known breeding (and sightings in another 5) for the last Atlas during 1968-72. Many were located in the Tywi valley with around nine pairs found in 1989 - scrubby areas along the old railway line between Llandeilo and Carmarthen being a much favoured area. In May 1991, three males were heard repeating their characteristic rattling song in the hawthorns on the steep slopes of the hill directly below Dryslwyn Castle. Apart from the Tywi valley, this species is only frequent elsewhere in Carmarthenshire along the coastal belt.

 

When the adult lesser whitethroats have young with them, the whole family group will sometimes break out into an incessant "tac-tac" warning call, typical of other Sylvia warblers such as whitethroat and blackcap - but louder and more prolonged.

Records of tree sparrows in the Tywi valley have risen greatly in recent years, due, perhaps, to more vigilant observers than to any genuine change in the status of the bird itself, which is easily overlooked where numbers are low. It was thought to be restricted to the Dryslwyn locality, and later on, to the land lying between Golden Grove and Whitemill. Nowadays it can be found almost anywhere from Llandovery down to Carmarthen with sightings near Llanwrda railway station, Llangadog, Manordeilo, Rhosmaen, Ffairfach and just outside Carmarthen itself (along the disused railway track that runs parallel to Old Station Road below "The Esplanade").

Tree sparrows can sometimes be heard calling from hedgerows, the chirps sounding slightly more clipped than that of its common relative, the house sparrow. A too-rapid approach to the hedgerow will usually cause the birds to suddenly stop calling but a slow cautious stalk down to about five or six feet will often reveal them to be lurking in the foliage. After a few moments, their nerves will finally snap and the birds will shoot out from behind the hedge uttering the diagnostic flight-note, a hard "teck teck".

With late autumn and winter counts of 32 at Ffairfach, 39 at Dryslwyn in 1987 and 45 at Dinefwr Ponds in 1989 one can speculate that the Tywi populations of tree sparrows in spring may be perhaps 25-50 pairs. Although winter flock sizes do provide us with some idea of the breeding stock, it is a rough one and the figures given should at least be considered a "guesstimate".

This is not a complete summary of the birds of the Tywi valley and some species that are equally characteristic of the river and its environs have not been discussed - mute swans, coots, dabchicks, kingfishers for example. One can conclude however, that it provides (in a county context at least) an unique assemblage of birds with concentrations of certain species that are scarce or rare elsewhere in Carmarthenshire, as well as partly having a particular "feel" of lowland England in its distinctive assemblage of birds.

One concluding point perhaps worth mentioning is the fact that seemingly no longer are any appreciable marshy areas or new oxbows that are so favoured by wildfowl, being created by the River Tywi, perhaps partially due to the extensive anti-erosion measures and other works that have been undertaken by the National Rivers Authority (formerly Welsh Water). At some sites the removal of shingle is a cause for concern and the sudden controlled release of water from the Llyn Brianne dam in summer can devastate shingle nesters such as the little ringed plover. It is readily accepted that the agricultural community do not wish to see their land flooded too often or seriously eroded (though some individuals will gain by deposition of new areas on their side of the river). However, it could now be argued that the riparian land forms - tight meanders, oxbows and marshy areas are now too closely controlled. Eroding river banks are important for sand martins, shingle banks for little ringed plovers, and oxbows and their associated wet ground for a wide host of wildlife - wildfowl, otters, dragonflies etc. If there is now the prevention of erosion, by large scale engineering works (eg blockstones at meanders), then compensatory works, such as the creation of false meanders, screened by scrub and with marshy areas, should be also carried out to ensure that the Tywi valley remains a refuge for the widest variety of wildlife possible. FOr every scheme that potentially destroys an area of interest, compensatory measures, as advised by close liaison and agreement with conservation bodies, should be incorporated; otherwise a progressive and cumulative decline of certain habitats and their dependent species will take place.

 

Acknowledgements:

Thanks are due to Ian Morgan and Dilwyn Roberts for commenting on the draft of this paper and for offering amendments and additions to the text.

References

Davies, William (1855). Llandeilo-Fawr and its Neighbourhood. Llandeilo, 1858.

Friese, J. (1989). Sand Martin colonies on the R. Tywi and its tributaries,1987-88. Carms Bird Report, 1988:27-29.

Ingram, G.C.S. & Salmon, H.M. (1954). A Handlist of the Birds of Carmarthenshire.

Kirby, J.S. et al (1991). Wildfowl and Water Counts 1990-91. The Wildfowl and Wetlands Trust & the British Trust for Ornithology.

Roberts, D.H.V. (Editor). Carmarthenshire Bird Reports, 1982-1989.

Roberts, D.H.V.  (1984). Heronries in Carmarthenshire. Carms. Bird Report. 1983.

Roberts, D.H.V.  (1989). Scarce Carmarthenshire Birds: No8 Tree Sparrow. Llanelli Naturalists Newsl. Summer 1989:17

Sharrock, J.T.R. (Editor) (1976). The Atlas of Breeding Birds in Britain and Ireland. British Trust for Ornithology and Irish Wildbird Conservancy.

Stewart, B. (1990). Bird Ringing in Carmarthenshire, 1989-90. Llanelli Naturalists Newsl. Winter 1990-91:27-29.