Red-breasted Mergansers wintered regularly in small numbers on the Cleddau Estuary and other sites around Pembrokeshire. The maximum counts for each year are shown on the Wetland Bird Survey page. That page also shows the maximum numbers recorded in Carmarthen Bay from the Amroth/Wiseman’s Bridge area – these counts are ad hoc, and not part of WeBS.
The Wetland Bird survey shows a decline in the UK’s wintering population of Red-breasted Mergansers evident since the mid-1990s. Numbers wintering to the east of the UK increased steadily in the same period, suggesting a shift in wintering range, as has been shown for other waterbirds. However, there is now evidence of a decline there too.
Given the decline in numbers, this page shows all records as presented in the Pembrokeshire Bird Reports since 2010.
Max. 25 at Amroth on 27th Jan and 20 there on 11th Dec. All other records were of one or two birds from the Gann, Teifi, West Angle, Wisemans Bridge, Newport and Fishguard Harbour. Single birds passed Strumble Head on 3rd Sept & 23rd Oct.
Max. Amroth/Wisemans Bridge 21 on 18th Dec, three at Carew Millpond 20th Nov, two redheads were Broad haven (N) 6th Jan & Pwllgwaelod 19th Feb. All other records were of single birds at Fishguard Harbour on 3rd & 22nd Jan, Teifi Estuary 11th Oct and at Pembroke on 29th & 30th Dec.
Max 48 Wisemans Bridge 5th Jan with nine there on 3rd March, six Amroth on 8th Jan with 20 there on 18th Dec. The Gann had two on 1st Oct with all the other records being of single birds at the Teifi 21st March, Bluckspool 30th Oct & finally at Pencarnan on 12th Dec.
Max count was 12 at Wisemans Bridge on 21st Nov, a male at the Gann on 2nd June was quite late, possibly indicating an interest in breeding at the site again ?
Another species surely under recorded with only eight records received from five different sites, all counts received were of four at Wiseman’s Bridge on 8th Jan, a pair at Fishguard Harbour on 4th Jan (the only record from the North of the county), a pair at Amroth on 28th Dec, then singles at Bosherston 1st to 4th Jan and another on 4th Mar, at Carew Mill on 5th Jan and at Amroth on 10th Nov.
Recorded at The Gann, Newport & the Teifi in the North of the county and Saundersfoot, Amroth, Wisemans Bridge area in the South. Maximum count was of seven at Amroth on 28th Dec and four at Newport on 20th Oct. A bird seen from Lydstep Headland on 7th May was an interesting record and could possibly indicate a breeding attempt in the area.
A single fly past bird at Strumble Head on 21st Aug & two seen between Pwll Deri & Strumble Head on 21st Oct. Elsewhere: only recorded from the Teifi which had a max of four on 4th April and Amroth/Wiseman’s Bridge/Coppet Hall area which had the only double figure count of 12 at Amroth on 6th March.
Another species recorded at just a few sites, a maximum count of nine birds at Wiseman’s Bridge on 15th Dec.
Seven Amroth 31st Mar, four off Wiseman’s Bridge 3rd & 4th Jan, three off Monkstone Point 26th Dec, two Teifi Estuary 13th Nov. Otherwise singles at the Gann and Nevern.
see below. Elsewhere: single Solva 15 Dec and five Wiseman’s Bridge 23 Dec.
St Bride’s Bay
Singles: off Aber Fforest 6 Jan, in Fishguard Harbour 8, 9 & 19 Jan, Solva 12 Jan, off Broad Haven (N) on 23 Oct, at Gann 4 – 22 Nov. Two on the Teifi Est 20 -21 Mar and 26 Oct. Largest numbers were off Wiseman’s Bridge with up to 11 in Jan (peak 26th), three in Feb (peak 3rd) and nine in December (peak 11th). Three off Skokholm 18 Sept.
No Red-breasted Mergansers were seen during the 2020-21 season. The above averages are for 2014-15 to 2019-20.
The area of Carmarthen Bay viewable from the Amroth/Wiseman’s Bridge area is not part of the Wetland Bird Survey. Nor is it watched on a regular basis. However, virtually all the double-figure counts of red-breasted mergansers are from this site. The counts below are taken from the Pembrokeshire Bird Reports since 1990.
Note from the BTO Waterbirds in the UK report for 2019-20
Species that migrate from the east, including Mergansers, were down compared with the previous winter, likely related to the exceptionally mild weather across Europe. Red-breasted Merganser 10-year trend was -23%, their lowest index value since 1980s, as shown below.
Note from the BTO Waterbirds in the UK report for 2013-14
The decline in the UK’s wintering population of Red-breasted Mergansers, evident since the mid 1990s, has slowed slightly. However, following a spike in numbers in 2010-11 (perhaps associated with the coldest winter across northwest Europe for 35 years), the annual index has resumed its downward trajectory.
Given that numbers wintering to the east of the UK have increased steadily in the last 30-40 years, for example in The Netherlands, the observed trends are suggestive of a range shift perhaps induced by climate change – as has been demonstrated for other waterbirds. However, this hypothesis has not yet been tested for this species, and perhaps pertinently, large decreases have been reported from further east in the Baltic Sea.
Scarce in Mathew’s (1894) time, who knew of no dated or recent records, but Lockley et al. (1949) reported that it had become a regular winter visitor to the upper Cleddau Estuary, with occasional occurrences elsewhere. It has continued to increase gradually since then, and is now regular in winter at the Teifi Estuary, Fishguard Harbour, Cleddau Estuary and off Amroth—Saundersfoot. Numbers involved are small, with probably only 40 birds present in most winters, including odd ones and twos scattered around the outer coast. The largest group recorded was 28 in Hook Reach on 31 January 1987.
Red-breasted Mergansers arrive in October and November and usually depart in March and April, but have lingered late into May on the Teifi and Cleddau and might well breed in Pembrokeshire in the future. They breed in neighbouring Ceredigion as close as the Afon Ystwyth.
Mathew knew of no dated or recent record, but Mathias and Dix included it in their lists. H.E.Evans obtained four in Solva Harbour over a period of fifty years. An immature male shot Teifi Estuary 20 Oct 1909 (B.Birds XVIII 234). One male, Dale, 8 Mar 1937; one 10 Feb 1938; two 13 Feb 1940. Seen regularly in upper reaches of Milford Haven in winter (H.A.G and R.M.L.).
Mergus serrator – HWYADEN FRONGOCH – Winter visitor 1995 – Female noted at the Gann 18 June. Reappeared on 6-7 July with 2 large flightless young (GHR et al), the first breeding recorded in Pembs. 2005 – Female with 4 ducklings Eastern Cleddau, 24 June Records from Pembrokeshire Bird Reports More about the Red-breasted Merganser […]
Mergus serrator – HWYADEN FRONGOCH – Winter visitor Scarce in Mathew’s (1894) time, who knew of no dated or recent records, but Lockley et al. (1949) reported that it had become a regular winter visitor to the upper Cleddau Estuary, with occasional occurrences elsewhere. It has continued to increase gradually since then, and is now regular in […]
Winter visitor Mergus serrator – HWYADEN FRONGOCH – Winter visitor The BTO winter atlas showed that Red-breasted Mergansers were present in some coastal and all estuarine 10km squares during the winters of 1981-82, 1982-82 and 1983-84. The darker the colour, the higher the relative total count for each 10km square. The darkest blue represents 6-18 birds. More […]
Mergus serrator – A winter visitor; rare. In Mr. Mathias’ list. Mr. Dix says “occasionally obtained.” We know of no recent occurrences. Mathew M.A. 1894, Birds of Pembrokeshire and its Islands More about the Red-breasted Merganser in Pembrokeshire