R. Coley

The flood plain of the River Tywi between Carmarthen and Llandovery has long been an important wintering ground for several species of wildfowl. Most notably, the area around Dryslwyn Castle (SN554204) has been a destination for significant numbers of European White–fronted Geese, at least since the l920's, with 2, 500 birds (20% of the British flock) there in January 1971. However, since systematic counts started in 1968, numbers have steadily decreased, with only a few hard–weather fluctuations For the first time in living memory no geese were seen in the 1997– 1998 winter.

The European White–fronted Goose (ssp. albifrons), breeds almost exclusively in the Eurasian tundra zone Five discrete wintering populations are recognised (Ogilvie, 1978) the most westerly of these populations breed in north–western USSR and move through the Baltic regions to spend the winter in western Germany, the Netherlands, Belgium, Northern France and Britain (fig. I). The much darker, conspecific, flavirostris winters principally in Ireland, with small numbers using a few sites in western Britain – including the Dyfi Estuary (Fox & Stroud, 1986). In the latter half of the l960's the albifrons population began a spectacular growth phase, with numbers rising from a stable 50–60, 000 to a current total in excess of 200.000. It has been suggested that this increase may be caused by an influx of birds from the east European wintering grounds but it is more widely agreed that hunting restrictions in USSR and the Netherlands are responsible (Owen et al, 3986). Ironically, it is during this great expansion that numbers in Wales have declined.

Concurrent with this population increase has been the birds' demonstration of `short stopping" migratory behaviour. Increasing food supplies in both the Netherlands and (the former East) Germany, along with hunting restrictions, have seen greater numbers for longer periods at the more northerly wintering sites. Severe weather does push the birds further south into France (where there is still intense shooting pressure) and across the Channel into Britain, but the continuing mild winters of recent years have seen Britain's diminishing importance as a wintering area. The New Grounds, Slimbridge, continue to be Britain's most significant site but numbers have declined from 7, 600 in 1969–70 toc. 2, 600 in 1998–99.

The Dryslwyn flock, which can be considered a satellite of the New Grounds flock, has declined in a similar way (fig. 2), as have other traditional British sites – the Avon Valley, Hampshire (1, 500 in 1982. 0 in 1998 – J.M.Clark, pers comm); the Severn/Camlad marshes, Welshpool (1, 400 in 3958, 5 in 1996 – B Holt, pers comm). (One flock, on the Thames–Swale–Medway Estuary, has increased following RSPB protection.) Whilst we can cheer the positive fortunes of this species, it is impossible not to regret its passing from the Welsh avifauna and to wonder if local conditions have contributed to the desertion of the site. At the same time, it should be recognised that feeding grounds on the continent are finite, and subject to disruption by changing land–use; there is also increasing conflict with agricultural interests, and the possibility that flocks will be intentionally disrupted (Owen et al, 1986). It is not inconceivable that White–fronts may, at some future date, look again to the Tv–wi Valley, and it is against this background that the following brief observations, gathered between 1987–97, are offered.

The site was visited on 137 days, between early October and late March, from 1987–98 Geese were present on 56 occasions and were observed for some 110 hours The earliest arrival was 3rd November (1993) and the latest arrival date the 1st March (1997) departure (i.e last sighting) dates begin mid–February, with the 38th March being the latest recorded (1992). In only one winter (1987–88) were there fewer birds at the end of the winter than at the beginning, with Feb/March arrivals typically swelling numbers (>200%. four winters) (fig. 3). During five winters the earliest arrivals were 2/3/4 family parties (<12 birds), and in three winters, these birds remained the only residents until the New Year.

The energy cost and lost feeding time caused by disturbance is often cited as a factor in site–desertion. Fox & Stroud (1986) suggest low–flying aircraft as a possible contributing cause of flavirotris desertion of Cors Caron in the late 1960's: the Hampshire Ornithological Society consider the activities of anglers and (nearby) wildfowlers may be implicated in albifrons' abandonment of the Avon Valley (J.M.Clark, pers comms) Dryslwyn certainly seems to suffer its share – surprisingly, perhaps, in the light of a low (human) population and lack of rights–of–way On eleven separate occasions the flock was put to flight. On ten of these occasions the flock relocated to "the other side" of the castle; on one occasion the flock disappeared in a south–easterly direction, after circling the valley for a little more than 20 minutes Low–flying aircraft wee the principal cause of flnck–flight (6 incidents): interestingly, high–speed jets were not seen to move the geese, despite yen' many attempts. but slow–moving, propeller driven planes (once) and helicopters (5 times) always caused the geese to take off Shooting parties (in pursuit of Wigeon) disturbed the flock into flight on three occasions on one of these occasions, gunmen were simultaneously active both up– and down–stream of the castle and the geese left the valley. Pedestrians initiated the other two observed disturbances – one walking dogs, a second walking his telescope. Free–range sheepdogs have frequently caused consternation among the (dwindling) Wigeon flock over the last two winters but have not been seen roaming whilst geese are present: this is, doubtless, a potential disturbance.Peregrine Falcon has been watched making repeated stoops at a family party of White–fronts prompting the birds to drop into the river; Red Kites have been ignored on the two occasions that they have been observed over–flying.

It is interesting to speculate on the destination of the birds seen leaving the valley. Before the population increases of the 1960's, the White–front was always associated with estuarine sandbank roasts, and the late Dilwvn Roberts (pers cornm) recalls regular "diurnal movements to and from the Buny Inlet" as "well known phenomena" in the 1930's and 1940's. Several birdwatchers resident in Lianelli also remember, in the 1970's – early l980's, overhead flights of geese (often large, noisy skeins) flying to the Burry Inlet to roost in the evening and back to Dryslwyn at first light. Prior to the building of the RAF airfield, in 1939–40, flocks occurred regularly on the Cydweli–Pembrey marshes, similarly; before the building of the steelworks In the early 1940's, Margam Moors (Glamorgan) held up to 2, 000 birds. On 17th January 1988, this author watched c120 White–fronts, in company with one Barnacle Goose, at Dryslwyn, and on 4th February 1988 counted 115 White–fronts plus one Barnacle, at dusk, on a tidal sandbank in front of Berges Island hide at Whiteford Point, Burry Inlet – a strong suggestion that such movements continued through the latter years of goose presence at Dryslwyn. At the same time, White–fronts have frequently been watched going onto the ox–bow lake (east of Dryslwyn Castle) at dusk, and have equally frequently been seen to emerge from the ox–bow at dawn.

Just 30 years ago it was possible to see both races of White–fronted Goose in a short winter day, by moving from the flavirosiris flock at Cars Caron to the albifrons flock at Dryslwyn. Today, the Greenland race is confined to the Dyfi Estuary and the Dryslwyn birds are becoming a memory. However, Dryslwyn remains an important wildfowl site, with its Whooper, Bewick's and Mute Swans, and even occasional Pink–footed Geese (1993). White–fronts will return, probably sporadically, perhaps, in the face of environmental change on the continent and continuing increases in numbers, in numbers, and the site should be valued accordingly.

Acknowledgements:

The author is grateful to the late Dilwyn Roberts for January–count data for Dryslwyn, to J.M. Clark for data about the Hampshire flock, to Brayton Halt for data about the Welshpool flock and to Louisa Huxtable for transcribing field–notes into a sensible format.

References:

Fox, AD. & Stroud, D.A. (1986) "The Greenland White–fronted Goose in Wales" in Nature in Wales – 4:1 & 2, pp 20–27: National Museum of Wales

Ogilvie, MA. (1988) Wild Geese. T & AD Poyser.

Owen, M., Atkinson–Wiiles. G.L. & Salmon, D G. (1986) Wildfowl in Great Britain, second edition; Cambridge UP