By Dani López-Velasco
One of the main aims of the ID paper Dick Newell, Steve Howell and myself published in British Birds in 2013 (Newell et al, 2013) was to help build a clearer picture of the identification of South Polar and Great Skuas by using a new approach. That is, using the timing of primary moult as an aid to identification. Furthermore, we found some new features, which we discussed in detail, and also refuted some common assumptions. As a summary, the breeding seasons of Great and South Polar Skuas differ by six months but the moulting periods of adults of each species overlap broadly with the moulting period of first-cycle birds of the other species. Consequently, if a bird can be aged, its wing moult is often diagnostic for identification. The other main purpose of the paper was to reassure field birders that, given good views and photos, the identification of a South Polar Skua in the Western Palearctic was feasible. A handful of recent records of “good” South Polars in European waters have come to light, and we hope that, by increasing birders awareness, more will follow.
In Spain, there have already been at least 4 presumed South Polars seen well from land, all in Estaca de Bares, Galicia, NW Spain, arguably the best seawatching spot in Europe. Furthermore, a further 3 birds have been photographed at sea off Galicia.
The following record, of a presumed second cycle (or older) South Polar is worth publishing. In early September this year, 2016, and during a good seawatching day, the intrepid birder Victor Paris ventured out on his kayak just in front of Estaca, about 1 mile offshore. In good weather, but rough seas, He had a very enjoyable time photographing the skuas that flew overhead. Amongst all the Great Skuas that flew past was the bird depicted in this post, that he tentatively identified as a South Polar after reviewing the pics.
The moult score (45) of this individual, with a growing p10, in early September, is strongly suggestive of a second cycle (or older) South Polar. However, a late moulting second calendar year Great Skua, completing its first primary moult, could show a similar moult score in early September. Based on our research, and after analysing a lot of photos, we couldn´t find any evidence of any 2cy Bonxie in early autumn showing a plain back (relatively plain, dark, back feathers and scapulars) and smooth and uniformly colored underparts showing no spotting/streaking in the flanks. All of the 2cy Bonxies we analysed showed at least some obvious pale, coarsely marked scaps as well as some pale spots in the flanks.
Although the entire back of this bird can´t be seen properly due to the angle, at least part of it is visible in some pics. It shows the expected plain looking, uniformly dark colours of a South Polar, lacking any coarsely marked scapulars, typical of 2cy Bonxie, that should be even visible from that angle –compare with some of the bonxies below-. Furthermore, the entire underparts are really smooth looking, showing the same uniformly cold-toned tones, without any pale spots or marks in the flanks. The very dark, almost black axillaries are also supportive of SP, (although note that some Bonxies can show similarly toned axillaries), as is the hint of a golden nape collar and the compact structure, better judged in the more distant pics of the bird approaching. The white peppering around the eye is interesting. Although more commonly found in Great Skua, it´s also shown by some South Polars, like an almost identical bird depicted below.
All classic SPS features are visible on these high-quality images, including very smooth-looking and uniformly cold-toned underparts without any markings on the flanks, hint of a golden nape collar, very dark axillaries and relatively compact structure. Part of the back is visible in two of the pics, showing no hints of the pale markings that are expected on any 2cy Bonxie at this time of the year. Note also growing p10, typical of a second cycle or older SPS in September.
This is a relatively late-moulting 2cy Bonxie , with P10 still growing in late August. Classic bird, with dark upperwing but typically showing scattered pale scapulars and back feathers, as well as pale markings on the warm-toned underparts.
Three more examples of 2cy Great Skuas from late summer-early autumn, finishing primary moult and showing typical coarse markings on the back:
South Polar Skua – a very similar looking to the Galician bird, even showing some white peppering around the eye:
A typical South Polar showing a very similar head pattern to the Galician bird:
So, all in all, although the ideas in the paper could be regarded as a working hypothesis, where we invite people to provide more evidence to support or refute our conclusions, it seems clear that this certain individual ticks all the boxes for a second cycle South Polar. So everyone, especially avid seabirders in Ireland and Portugal, watch out, pay attention to all suspicious looking bonxies, and, above all, take photos!
Congratulations to Victor Paris for this exciting sighting in unbelievable conditions. I mean, who would have ventured out in a kayak, in rough seas, to photograph migrating skuas….? Such efforts are usually eventually rewarded.
Newell, D., Howell, S., and López-Velasco, D. (2013). South Polar and Great Skuas: the timing of primary moult as an aid to identification. British Birds, 106: 325-346.