The bird was first seen by AGG, flying west or north-west over Middle Hare Head, a mile to the south of the watchpoint. The other two observers present quickly got onto the bird while it was still in that area. The bird moved on over Halton Edge, once or twice dropping just yards beyond the skyline, and then crossed over the Eastby road to Barden Moor near the cattle grid, now on ‘our’ side of the skyline. The bird next dived at a gull passing beneath (see later note), before returning to its course and continuing on over the moor in a north or north-westerly direction, disappearing behind a rise in the ground at 1.54 pm north of Lower Barden Reservoir.

Even at first glance with the binoculars, the bird was obviously a medium-sized skua. It was a very dark-looking bird, gull-like but with a more rakish built, long, narrow, pointed wings, a long-ish tail with a tapered projection, and a buoyant, athletic flight more reminiscent of a falcon. I only ever saw the tail in profile and, while I know that some of the overall length was due to the effect of projecting, pointed, central feathers, I could not tell if these feathers were truly pointed at the tips. The projection, however, tapered off rather than ending bluntly or broadening at the feather tips, and it extended beyond the rest of the tail for a distance of half/two-thirds again. The bird’s size was difficult to judge without a comparison species alongside, but it appeared to be somewhat larger than a Black-headed Gull and near Common Gull in size.

I soon got the ‘scope onto the bird and immediately saw that its plumage was not wholly dark as it first seemed. The upperparts were indeed very dark coloured (dark brown, even blackish looking), but the underbody was basically white, except for a greyish breast band. I was not able to see if the breast band was complete, but it certainly went well down the right side of the breast and probably was complete. A noticeable feature of the underbody plumage was that the white belly ended squarely against, and was sharply demarcated from, the blackish-looking ventral area/undertail coverts.

I never got good enough views to accurately judge the shape of the head and bill or the precise extent of dark and light plumage on the head, because the bird was slightly angled away from us most of the time. Neither did I get a decent look at the underwings. On my views, the bird never wavered from a more-or-less horizontal course, cruising with easy wing beats that gave the impression of plenty of power in reserve, but yet not lifting the wings high enough to reveal much of the undersides. The only other feature noted was on the upperside of the right wing (then seen to be dark brown in colour) and it consisted of four or five (six?) white shaft streaks at the bases of the primaries with a touch more white at the bases of the streaks. These marks contrasted quite strongly against the rest of the dark upperwing and appeared as a small fan of white lines or streaks in the middle of the hand when the bird was watched against the background.

Of all things, I temporarily lost sight of the bird behind the raised boot lid of one of our cars and it chose just those few frantic (on my part) moments to attack at a gull over Barden Moor. Obviously, I missed this action, but MKT saw it and he was most struck by white areas on the underwings. These can only have been the prominent, white flashes on the underside of the primaries, which all likely candidates have, except Long-tailed Skua. MKT thought the gull was a Common Gull, but he was not sure, and I think Black-headed Gull was more likely, especially at this time of the year here. He also thought the gull seemed a bit smaller than the skua. Unfortunately, I never saw the gull at all! (As it happens, a Common Gull was seen later that same day, but this species is only just beginning to reappear after the breeding season.).

The clean white underbody indicated that the bird was a pale-morph adult. I think that sub-adults, which might sometimes resemble adults, either remain in winter quarters or at least much further south than adults returning to breeding grounds. The tail shape and length, and the manner in which the white belly ended ventrally point to just one species - Arctic Skua which is, in any event, the most likely species to occur. In fact, the white underbody alone seems to rule out all juvenile skuas, although it seems too early in the year anyway for a juvenile of any skua species to turn up here.

Of the other skua possibilities, Great Skua of any age was immediately ruled out as it does not have a pale morph. Other grounds for excluding this species were the absence of prominent, white, upperwing flashes, the lack of body bulk (Great Skua being quite portly by comparison), the longer and much more obvious tail projection, and the very pointed hands to the narrower wings.
The bird was also too rakish-looking and lightly-built for an Pomarine Skua, lacking the relatively broad arms to the wings of that species. It also looked smaller and with a lighter and more Curlew or falcon-like flight than the normal (as on passage) fairly heavy, plodding flight of Pomarine. In any event, the tail projection was tapered, unlike the twisted, blunt ‘spoons’ of adult Pomarine.
The last possibility, Long-tailed Skua, was easily discounted as the bird lacked that species very long, whippy-looking central tail feathers in adult plumage which also shows greyer upperparts and no white wing flashes. The bird also looked bigger and more strongly-built than Long-tailed.