BHGull ?

[Fred Wright]

Found on Paddy's pool today. Poss just a slightly abherent Juv BH Gull. Any idea's anyone

[SteveClifton]

It is a Black-headed Gull Fred (1st summer), definitely with something odd going on with the bare-part colouration.

I presume it's caused by a lack of the pigment which causes the darkness (melanin?) in normal individuals, but I'm no expert on such colour-related aberrations.

[Fred Wright]

Thanks Steve. I've trawled the web and my Helm guide and it appears that it is a BH- Med Gull hybrid. "Slimmer billed, slender built with longer legs and showing many traits of BH gull". Also, not uncommon so they say. I suppose with the number of Meds about it was probably inevitable. Ta mate.

[SteveClifton]

Fred, I'm not seeing any hybrid traits in this bird to indicate any Med Gull influence.

Med Gull is a more heavy-billed bird than BHG, so if hybrid genes were present than you'd surely expect to see some structural differences. The head shape is more angular too. If anything this bird has a smaller, more dainty bill than the accompanying adult BHG, and a similar neat, rounded head profile. Therefore I'm still firmly of the opinion that this is probably a pigment (or lack of) issue.

In addition to any structural differences, you would expect a hybrid to differ in one or more of the following ways:

Shape of hood-in Med extends further down the nape
Primary pattern-obvious white outer primaries on upper side of BHG wing. Med is dark here.

There are other differences, but I'm really not sure we need look any further.

[Fred Wright]

Hi Steve. I think that's one of the problems with Hybrids. It fits all the criteria in that the bill is slimmer but the head colour is not BH brown and definitely darker, the bird itself is of lighter build.All points clearly outlined in Helms guide "note particularly the hybrids slimmer bill and slighter build, as well as traces of BH plumage( such as a hint of a white primary wedge and black tips to the trailing edge of the primaries)". Wikepedia and other sites provide similar descriptions. I've perused several websites and the Hybrid variations are practically endless, They should rename hybrids as hemorrhoids, they're a pain in the &%se. Certainly get you looking tho.

[IanF]

It was still around this morning. Repeatedly chased by the other BH Gulls and even the juveniles.