Summary:
A dark-phase juvenile Long-tailed Skua was photographed in Winterton Dunes, Oct 14 2020 by Jonathan Farooqi (JF). The record was submitted to Norfolk Records Committee (NRC) and was accepted by all five members (Tim Allwood, Mark Golley, Ashley Saunders, Mick Saunt and Kayn Forbes) on its first circulation.
Doubts were then raised about the identification and JF asked for the record to be withdrawn. NRC reviewed the identification on receipt of those concerns and the initial identification was considered correct. Wider expert opinion was sought (Killian Mullarney, Dani Lopez, Pete Morris, Alan Lewis, Steve Howell etc) and all supported the identification as a dark-phase Long-tailed Skua. The record was submission was opened again and it was officially accepted and included in the official county record for 2020.
Skua identification is extremely difficult and a lot of experience and care are required. Even then, there are doubtless individuals – particularly darker juveniles - that may be misidentified, even with excellent field views or from photographs showing plumage detail well, never mind of birds hurtling through in a gale. Hopefully the process of identifying this bird will be helpful to everyone in some way or other in their own challenges with skuas.
It’s probably best to begin with JF’s field description. He noted:
long, narrow wings immediately looked interesting in the field. The body also appeared quite narrow and the bird lacked much ‘bulk’. While it was harder to appreciate the structure than on a prolonged seawatch view, it very much resembled the LT Skuas I have on seawatches in my home county of Northumberland.
The overall colour was a cold, earthy-looking dark brown, lacking any gingery tones.
Undertail coverts barred black and white, although were quite wet and matted, causing some of the UTC feathers to stick together and reveal white underneath (see photo above).
Only the slightest hint of a white flash on underside of primaries.
Extensive pale mottling to underwing coverts.
Striking black and white barring on uppertail coverts.
Upperside of body and wings a cold, dark brown with faint whitish barring to upperparts.
White flash on upperside of primaries limited to two obvious white outer primary shafts and just a hint of white shafts on the inner primaries.
Two toned bill with a dark tip and pale greyish-blue base.
The above notes together with the photographs were sufficient to see the bird accepted by NRC. Shortly after, concerns were received from one source citing the bill structure (deep-based, heavy and long, with only 1/3 dark; short central tail feather projection; lack of pale fringes to upperwing coverts; broad wings. A couple of other well-respected sources thought the bird might be an Arctic Skua, citing bill structure, body shape and underwing pattern etc
So, now we had three species thrown into the mix. Discussions around the committee initially centred on ensuring we had a solid evaluation of the bill structure – Long-tailed skuas show a bill roughly 50:50 in terms of pale base : dark tip. Accurate perception of this will obviously be impacted by the quality of photographs/optics, the distance involved, the angle of observation and conditions. Fortunately, JF’s pics were pretty decent all things considered, showing the bird in reasonable detail at close range. Conditions were also fairly benign and showed the bill structure in two pics – one against a pale background and one against a darker background. Close and accurate assessment of the images was very important.
Although at first glance it appears that the bill is quite long and perhaps not a great fit for Long-tailed Skua, a careful assessment shows that the head feathering reaches further down the bill than is initially apparent, causing the pale area to look slightly larger than it actually is. Once this is taken into account, the bill isn’t particularly long and the structure of the bill is much better for a Long-tailed Skua being roughly 50:50 pale : dark with dark cutting edges not far off the feathering. This can be seen in both photographs. As such, the bill is also a poor feature for an Arctic Skua.
Other features mitigating against an identification of Arctic Skua are the lack of any warm tones in the plumage, noted in the photos and in the field, the clearly well-barred uppertail and undertail coverts, being more or less black and white with no buff qualities, the presence of no more than 1-2 white primary shafts, and the fact that such a heavily barred uppertail and undertail would point to much more white in the underwing primary flash and a paler neck and nape.
The major discrepancy with a Pomarine Skua is perhaps the lack of double underwing flash. A juvenile Pomarine Skua – even a dark bird – could be expected to show something of a double underwing flash; one at the base of the primaries and one at the base of the primary coverts. In rare cases the second flash can be absent. This bird doesn’t even show one. NRC tried to find an example of a known Pomarine Skua with such an underwing pattern and not a single bird could be found.
The structure of the bird is hard to assess with certainty from the photographs but they don’t show a broad-winged and heavy bird, and JF certainly didn’t get that impression in the field. The chest actually looks quite deep to me, having quite a steep downward angle from the chin. Other features pointing to Long-tailed Skua are the pale whitish fringing visible in the upperparts, the lack of pale primary tips, the suggestion of a pale “hotspot” on the breast, present in many paler Long-tails, and perhaps most interestingly and one I’ve only noticed recently, is the pattern of the small white flash under the primaries. It has recently been discovered that Long-tailed Skua consistently shows a small notch in the white underwing flash towards the outer edge of the wing. This small notch seems to be present in the rudimentary wing flash of the bird in question, almost as a gap such is the reduced amount of white.
JF’s field notes should, of course, be given another mention in all this talk of minutiae in photographs, as they clearly point to the bird being a Long-tailed Skua and along with the features visible in his photos back up the initial identification. In fact, for the bird to be considered either an Arctic Skua or a Pomarine Skua, several anomalous features have to be accommodated.
The photographs were sent to widely-known experts like Killian Mullarney, Steve Howell and Dani Lopez and a few others, and all agreed with the initial NRC identification. In fact, it was very pleasing to have the initial decision and reasoning supported by such luminaries. Killian was kind enough to send some annotated images with his reasoning, and they are included below:
Skuas are hard. Especially so in the conditions we often see them. I only log them if I am happy with the plumage details that I can see. I may overlook distant birds but as we can see, they’re hard enough when they’re close in. So, enjoy your skuas, don’t expect to be able to name all of them but with plenty of practice, some reading and some independent thought, you’ll be well placed to make more confident identifications. We all will.
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