'Yellow legged' Gull, 15/1/12. Digiscoped. A blurred Herring Gull stands behind it.
note the full chest in particular here
On the afternoon of Sunday 15th January , I came across this very interesting but distant adult ‘Yellow legged’ type gull at Loch of Skene just outside Aberdeen whilst twitching a female Lesser Scaup. It was standing on the ice in the middle of the Loch for 10-15 minutes, but the distance of the bird made it really hard to call an ID on it; with Yellow-legged, Caspian Gull, hybrid Herring x Lesser Black backed to and eastern baltic race Herring Gull all possible. Furthermore, the bird was not seen through the scope in flight so I was unable to study the primary pattern of the bird, which would have allowed for potential identification. As it is this bird has remained unidentified despite expert help, partly due to the photos not doing it enough justice; it is virtually impossible to tell what species it is from these photos. It’s interesting to note however that a local birder had a possible Yellow-legged Gull (ssp. michahellis) at the gull roost there a few weeks earlier, implying that this mystery bird has been in the area for some time. During my time watching it, and having looked at the photos, the following features were noted:
- long, conspicuous yellow legs
- virtually unstreaked, flattish, squarish shaped head
- full chested
- darker backed and mantled than surrounding Herrings
- upright posture, elongated appearance
- bill narrow and long
- in flight longer wings in comparison to Herrings; also slightly larger
- A seemingly all white P10 (Pic 1)
Out of the abovementioned features (and in the pics) the most immediately striking were the vivid yellow legs, the full chested appearance and the length of the bill, the latter two of which I think can be seen best in Pic 2. This immediate jizz veered me towards Caspian Gull, but with no prior experience of this species I couldn’t rule out Yellow-legged Gull, and gulls can of course be a nightmare to ID even as a larophile (which I am not) . I would comment that this bird certainly didn’t stand out as a hybrd in the field (the most likely possibility being hybrid Lesser Black Backed x Herring). The head was square and a virtually unstreaked clean white; I would expect a Herring x LBB Gull to show more streaking than this bird. Furthermore the mantle and back were too light for a hybrid, the elongated apperance was unlike either species, and it seemed larger than Herrings nearby. The bird was so distant it really was too difficult to get an ID or pick out any absolutely clear cut Yellow-legged/Caspian features, especially without any way of inspecting the primary pattern. The bird remained on the ice for some 10-15 minutes before it flew off with several Herrings. I was unable to scope it here which defeated my purpose of studying the primary pattern, but through the bins it seemed longer-winged and somewhat larger than the Herrings around it; pro either Caspo or Yellow-legged. With a local birder stating that they had a possible Yellow-legged Gull a few weeks earlier and from examining the photos after others’ comments, it seems that Yellow-legged could be more likely than Caspo. A ‘guller’ on Birdforum thought Yellow-legged was the best of the possible candidates, commenting that the breast was full but not high and that the legs were vivid rather than paler yellow as expected in Caspian. Indeed, I did notice these features in the field. Regardless though, there is nothing conclusive on this gull to eliminate any of the 4 possibilities.
I was unaware whilst watching the bird that there is a race of Herring Gull which shows yellow legs and Caspian/Yellow-legged gull features and have since been made aware of this. Herrings from the eastern Baltics, can show an all white P10 (or not for that matter) as well as outstanding yellow legs, and can look deceiving like Yellow leggeds and Caspos in head shape etc.
adult 'yellow-legged' Eastern Baltic Herring Gull taken in Latvia. Image courtesy of Chris Gibbins
A different Eastern Baltic Herring taken by Chris in Latvia; quite noticeable head and neck streaking on this bird and absence of white P10
Thanks to Chris Gibbins for sending me these two shots of Eastern Baltic Herring Gulls from Latvia. In the first pic, the outstanding long yellow legs, dark mantle and back, thick bill with pronounced gonys, largerly unstreaked squarer head all look good for adult Yellow-legged. However this individual has an all white p10, a pro Caspian feature, and it doesn’t seem overly full chested. Whilst the former can be seen on a small percentage of Yellow-legged Gulls it is rare, thus making this bird immensely tricky to ID. The second bird looks even better for Yellow-legged, with the absence of an all white P10 and the abovementioned features all on show plus what seems to be a black band on P5, another pointer towards Yellow-legged. However, the head streaking seems rather heavy and extensive for a typical adult Yellow-legged and once again the chest isn’t that full. I cannot comment on how either of these are Eastern Baltic Herrings but they are certainly anomalous birds. Certainly, this subspecies throws a spanner in the works for IDing less clear cut and most importantly distant Yellow-leggeds or Caspians.
If my bird was an Eastern Baltic Herrings, it would be a local rarity in itself . In fact, any ‘yellow-legged’ type gull in Aberdeenshire is a rarity so I am hoping this is re-found and an ID confirmed. However, it has not been seen since then and it’s likely it’ll never be seen again. I will have to continue speculating on what it was, but personally I’m inclined to rule out hybridity and keep michahellis Yellow-legged, Caspian Gull and Eastern Baltic Herring Gull as possibilities. The ‘gull that got away’ is a fitting description; a fascinating gull.
Thanks for reading,
Joseph
Lothian Young Birder 