Yellow-legged Gulls in Cork city July-November 2020

 Since late July this year, encouraged in part because of limited opportunities, I have been paying close attention to gulls in Cork city, originally near the sewage outflow and mud at Tivoli and, from mid September on, at the city quays. As ever during the midsummer lull, and more so this year once passerine song had started to die off, my main targets were Mediterranean and Yellow-legged Gulls. While I did succeed in seeing some of the former, of various ages, numbers weren't impressive by any means, especially when compared to the large counts routinely made in the Whitegate/Aghada area of Cork Harbour. However, as the season went on, impressive numbers of Yellow-legged Gulls were noted, at least by local standards here in Ireland. 

I made a valiant attempt to count the number of individuals earlier today, aided by my written notes from the time and the fact that I managed at least record shots of most of the birds, but I failed to arrive at a confident tally. Nevertheless, there were at least 14 individuals seen, as the most conservative estimate. Prior to September, I had only seen perhaps 4 birds, a 3CY, 2 4CY and an adult type that may have been a more advanced 4CY, but, from 3rd September onwards, at least 10 new birds were noted, 1 2CY and 9+ 1CY birds. 

The dominance of 1CY birds is perhaps not too surprising, as this age class can often predominate elsewhere in NW Europe, but, in Ireland, whether through being overlooked or a genuine scarcity, such birds seemed to be unduly rare. Most years, one would hear about one or two somewhere like Tacumshin, but, as per an older blog post of mine (https://notjustgulls.blogspot.com/2018/03/juvenile-and-1st-winter-yellow-legged.html), 1st cycle birds eluded me personally in Ireland for many years. A few of my earlier birds were included in that earlier blog post, up to and including a lovely 1CY at Blackrock Castle in Cork city in August 2017, but events of autumn 2018 provided more of a hint at what was to come in 2020, when Brian Power and myself had a few birds between us on the city quays, at least 2-3 of which were 1CY birds. 

1CY Yellow-legged Gull Cork city 26th October 2018. An absolutely typical bird, with a whitish head with dark concentrated around the eye, already very worn juvenile tertials, long dark primaries, whitish ground colour to the underparts, pale grey 2nd generation scapulars with internal anchor markings (overlapping with Herring Gull and even some LBBG) and 2nd generation innermost greater coverts. Structure is also typical, with a thick almost 'hooked' bill, flat crown and long pale pink legs. They're not all this easy!

Because of the peak from September on in 2020, I wonder if it's the case that 1CY birds slowly filter west to us after initially turning up in England, northern France or the Low Countries in July/August, or, perhaps just as likely, if they just become easier to pick out as they advance from full juvenile plumage during the partial autumn moult? Note that birds were often a bit more distant at Tivoli, and I only discovered decent numbers of large gulls in the docks from mid September on: I plan on paying a few visits there earlier in the season next year to see if I can pick up fresher, more juvenile birds at close range. 

The future is another day, however, so here are a selection of birds noted at Tivoli or the city docks this season, with captions. Given that two individuals were noted as recently as this week, this may not be the end of it, but numbers do appear to have fallen off since the autumn.

4CY Yellow-legged Gull Tivoli 27th July 2020. Basically, very adult-like in most respects, but note darker markings on retained 3rd generation tertials and greater coverts. Mostly white-headed at this date.

Adult type Yellow-legged Gull Tivoli 27th July 2020. Note more advanced primary moult, with some fresh primaries visible beyond the tertials contrasting with retained P9-10. The head and bill structure on this individual in this pose are almost stereotyped, with a very flat crown and thick blunt bill.

1CY Yellow-legged Gull Tivoli 10th September 2020. This individual, first seen on 3rd September, was the first 1CY of the season. Note the typical structure, whitish head, very worn tertials already by early September, plus most of the scapulars have been moulted to 2nd generation.

1CY Yellow-legged Gull Cork city 17th September 2020. This bird, green '660:C', is, as far as I can tell, the first Darvic-ringed YLGU to be seen in Ireland. I have yet to hear back from the project organisers, but it seems that this originates from a scheme in the Camargue in southern France. A distinctive bird even without the green plastic, presenting a very advanced appearance compared to 1CY Herring or Lesser Black-backed Gulls at that time of year. Note the very white ground colour to the head and underparts, typical structure, paler and purer pink legs than on most Herring or (especially) LBBG of this age class, scattered 2nd generation coverts (in particular, 1-2 greater coverts on the left wing), and, in flight, note the nice neat black tail band to a very whitish tail (next to no dark barring on the outermost two tail feathers apart from the black subterminal band) and typical inner primary pattern, being darker than on Herring Gull but with a more obvious dark outer web/pale inner web than on most LBBG.

1CY Yellow-legged Gull Cork city 3rd October. Not as white-headed as some of the other 1CY birds featured here, but many michahellis of this age class look like this. This individual had moulted several median and lesser coverts and the innermost greater coverts, the 2nd generation feathers contrasting markedly. Such extensive moult of coverts would be unusual in Herring or Lesser Black-backed Gull of this age class. Tertial pattern typical, with a pale thin fringe reaching roughly halfway along the outer web of the feathers, but many LBBG have a similar pattern. Likewise, the greater covert pattern, with the inner juvenile feathers being more barred and the outer ones darker, is commonly seen in YLGU and LBBG but not as usual in Herring Gull.

1CY Yellow-legged Gull Cork city 3rd October. A second individual present on the same date as the above bird. In contrast to that bird, this one was whiter-headed, with fresher juvenile coverts (and no 2nd generation coverts moulted in), and more 'delicately' marked 2nd generation scapulars. Note that the mantle feathers on this bird are almost unmarked grey, but for small dark areas near the shafts. A beautiful individual!

2CY Yellow-legged Gull Cork city 3rd October. A relatively small bird, and surprisingly tricky, especially as the grey on the mantle and scapulars was perhaps a little paler than on adult-type feathers. Note the slight green-yellow tones to the legs and the bill base, also the solidly black areas on the tertials (compared to 2CY Herring).

1CY Yellow-legged Gull Cork city 4th October 2020. A longer-billed bird, almost suggesting Caspian influence, and, given the more barred, Herring Gull-like greater coverts than on many YLGU, a case could be made for this being a Caspian x Herring hybrid or backcross from Germany, say. However, some YLGU are longer-billed, and the features of this bird seem to fit that species best. Despite the more barred greater coverts, note on the spread wing that the outermost feathers tend towards being plainer and darker, as is typical for YLGU.

Adult type Yellow-legged Gull Cork city 4th October 2020. Despite being erroneously described in older literature as white-headed all year around, adult type YLGU often attain some finer streaking outside the breeding season, and the extent and nature of the streaking on this bird are typical enough. 

1CY Yellow-legged Gull Cork city 5th October 2020.A few scattered 2nd generation lesser coverts, a moderately whitish ground colour to the head and underparts, typical tertial pattern, relatively long pale pink legs and, in flight, typical neat blackish tail band/whitish tail and inner primary pattern. Note the presence of pale 'lozenges' within the dark outer webs of some inner primaries, this is commonly thought of as a Caspian Gull feature but, in my limited experience, isn't that unusual on 1st cycle Yellow-legged Gull.

1CY Yellow-legged Gull Cork city 5th October 2020. A slightly trickier bird than the above, as in, while the head is whitish enough and the tertial pattern typical, some 1st cycle LBBGs moult in surprisingly pale 2nd generation scapulars. This bird is relatively 'dainty', overlapping in structure with LBBG easily, but the general closer resemblance to a 1st-winter Herring Gull (1st cycle YLGU often resemble LBBG more as juveniles but HEGU more in 1st-w plumage) coupled with the tertial wear and the plain pale pink legs suggest YLGU more, and it 'felt' like one in the field, albeit a small bird.

1CY Yellow-legged Gull Cork city 14th October 2020. Note the typical spread wing pattern, whitish head, moulted 2nd generation median covert on the right wing, tertial pattern and general structure, also plain pale pink legs.

Adult type Yellow-legged Gull Cork city 2nd November 2020. Note the completely moulted wing feathers, with a large white mirror on P10 visible on the underside of the far wing, a short pale tongue on the inner web of P10, a complete black band on P5, head streaking typical of YLGU but seems to be being moulted out, bare parts more washed out than in breeding condition. Upperparts tone perhaps closest to reality in the image of the bird preening.

It remains to be seen how many, if any, of these birds (or some as yet undiscovered) will overwinter in the area. Perhaps none will, but, given that there were a few birds at Blackrock Castle in late winter/early spring 2020, it is possibly more likely that one or two will hang on. I certainly will keep an eye out to try to document how their appearance changes during the winter if any do, and, even if not, it's good to get such close views of the common taxa.