Dunlin - 2020 WeBS

Peak counts of dunlin are erratic, but generally in the range of 2,500 to 5,000 birds.  Numbers were higher on average in the 1990s, including a peak of some 8,500 birds in 1996-97 which mirrored an influx seen across the whole UK in that year only.  Numbers have been lower since 2000-01.

To be of national importance for a species, a site must hold a five-year average count above the threshold level.  With numbers fluctuating widely, the Cleddau occasionally achieves this figure

Most of the dunlin on the Cleddau are found on the large open mudflats of Pembroke River, Carew-Cresswell and Hook-Sprinkle.  Decadal averages indicate that most of the decline has occurred on the Pembroke River and the Carew-Cresswell.

Very few dunlin are counted on other Pembrokeshire WeBS sites - usually around 200 on the Nevern and Teifi combined, occasionally nearer 300.

Monthly indices show that, throughout the UK, numbers are now generally lower all through most of the winter.  This is mirrored by a rise in the Netherlands, strongly suggesting that birds migrating from the northeast, and possibly northwest, are stopping on the Wadden Sea.  This may be a consequence of the milder weather of recent winter. Previously, in October, after moulting on the Wash & Waddensee, many birds moved westwards to areas of milder winter climate.  Between February and April, many birds move east again before migrating to breeding grounds.

Annie Haycock, WeBS Review 2020

Spotted Redshank - winter

Tringa erythropus

There were two winter records in the 1960’s and just one winter record during the 1970’s.  It was in January 1983 that over wintering was first detected, ten birds feeding around the upper Cleddau Estuary between Landshipping / Sprinkle Pill and Hook, including Millin Pill, staying until the 17th April. These birds habitually kept together feeding communally, usually in deeper water than used by Redshanks and Greenshanks, sometimes upending like dabbling ducks. Variously five to 16 over wintered in that area each year up to 1991, departing in March. During this 10 year period there were winter records of one or two birds in four years from other parts of the Cleddau Estuary, most of them at Carew / Cresswell.

Post March 1992 fewer wintered on the upper Cleddau Estuary than previously but one to five did so elsewhere in the estuary system, principally at Carew / Cresswell and Sandy Haven Pill but they were also noted at Cosheston Pill, Castle Pill, Pembroke River and the Gann.

WINTER DISTRIBUTION IN CLEDDAU ESTUARY, blue = lower estuary, red = upper estuary.

During the period 1983 – 1992 just 11 % of winter records were away from the upper Cleddau Estuary but between 1993 and 2006 this had risen to 46 % and the total over wintering in the estuary as whole had decreased by 40 %. Reasons for the decline in winter numbers and local dispersal are speculative, the front runners being the cessation of raw sewage discharge into the Cleddau Estuary and a build up of wintering birds at Penclacwydd, Carmarthenshire, resulting in fewer travelling further west to Pembrokeshire. The latter is credible, for if the numbers wintering at Penclacwydd (provided by Wendell Thomas pers com) post 1992 are combined with those on the Cleddau Estuary for the same years, an average of nine birds per annum overwintered. The average overwintering on the Cleddau prior to the creation of the Penclacwydd wetland was 10.6.

All winter records were confined to the Cleddau Estuary and constituted 55.6 % of the county total.

 Graham Rees

(Covers records up to and including 2006).