Rarity finders: White-winged Scoter in Co Mayo


While birding over the 2022 Christmas period in the west of Ireland I decided to go to Achill Island on 29 December. Almost immediately after arriving at the northern end of Sruhill Lough, in the north-east corner of the island, at 2 pm, I picked up a female Velvet-type scoter on the sea 500 m to the north, in a small cove just below Valley Pier.

Velvet Scoter is scarce in the west of Ireland and one relatively close to shore even rarer. Furthermore, given the recent sightings of two Bufflehead near Belmullet, some 30 km to the north, and a Hooded Merganser near Newport, some 30 km to the south, I was acutely aware of the potential – albeit low – for White-winged Scoter. As a result, I immediately headed north along the shore to get a bit closer.

I have seen a few White-winged Scoter in the US on various winter visits and always thought female-types looked 'different' from Velvet, based on the well described differences in bill profile and feathering on the bill sides. However, it's easy to be confident looking at a scoter flock in Massachusetts; when faced with a lone potential vagrant at home, it's a different story! 

One of the initial photos of the bird, taken in strong light on one of the few occasions the sun broke through. Here, the bill shape and extent of feathering on the bill sides appeared to match White-winged Scoter (Pat Lonergan).

Nonetheless, I got the impression of a distinctive head and bill profile from the Achill bird; it was very different, to my eyes at least, from the typical 'ski-slope' profile of Velvet Scoter, where the contour of the head and bill curves beautifully right from the peak of the crown to the nail of the bill.

Although the light conditions and distance from the bird were not ideal, I took some poor-quality photos using my phone through the 'scope and these confirmed my impressions of the head shape, as well as the bill structure and profile. I now strongly suspected the bird was a deglandi. I was keen to get a second opinion and sent some photos to my friend Killian Mullarney for his views.

Killian was abroad at the time but when he responded later that evening he was convinced, as I was by then, that it was a strong candidate for a deglandi. I returned to Achill at first light the next morning and was joined by Brian McCloskey and John Cusack, who had travelled across from Co Fermanagh. The scoter gave excellent views and on one occasion, in bright sunlight, I managed to obtain a photo that seemed to show the diagnostic extent of feathering on the side of the bill, which differs from that of Velvet Scoter.

Several carloads of birders travelled to see the bird the next day and a lot of photos and some videos were circulated that evening. Due to the distance and somewhat challenging light conditions it was difficult to determine more subtle details, but worryingly, one or two of the images seemed to contradict my earlier impressions of the extent of feathering on the bill sides, leading me and others to question the identification. 

This photo shows the long rather deep-based bill with a distinct angle in the contour where the bill meets the head and, importantly, the extent of the feathering on the bill-sides (Micheál O'Briain).

Given the significance of the record – a first for Ireland – and the nuanced nature of the identification criteria, it was important not to take anything for granted. Luckily, on the following day – 1 January 2023 – the bird came much closer to shore, when Micheál O'Briain and others managed to get some excellent photos. The much more detailed images established that the extent of feathering on the bill side was exactly as it should be, forming a distinct angle at the furthest point along the bill, confirming that the bird was indeed a White-winged Scoter.

The bird spent most of its time alone, although was joined by a few Common Scoter on one occasion. The combination of rather large, deep-based bill, pale face spots and square-headed appearance at times recalled Surf Scoter. The bird was aged as a first winter based on the pale belly (revealed when it sat up while wing-flapping). Sexing is more difficult but it appears to be a female based on the lack of any colour coming through on the bill. Some newer blackish feathering was apparent on the throat.

This was a very instructive bird and highlighted, to me at least, the challenges in confidently identifying lone vagrants, especially in subtle plumages such as this one. A combination of small differences, the difficulty in accurately assessing the exact bill shape and the extent of bill feathering, coupled with my relatively poor experience of close Velvet Scoter, all added to the challenge. The experience also highlights the importance of obtaining good images where critical analysis of the finer points of identification, out of the wind and rain, can be more rigorously tested.

Thanks to Killian for his help and informed discussion about the identification and for commenting on an earlier version of this account.

Written by: Pat Lonergan

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