Hybrid argentatus x marinus?

[Paul French]

This was seen in Lerwick, Shetland in 15/02/2002. I've only just got around to digitising the slides. Thoughts at the time were that it was either a hybrid argentatus x marinus or perhaps just a very dark argentatus. Apologies for the poor quality of the pictures, but I'd be very interested in your thoughts on this.

Thanks,

Paul

[pim wolf]

Hello Paul,

a reply to "bump" your question. I think that the lack of response does not mean that it's not an interesting bird but rather reflects the level of experience of the forum members (including myself) with this type of presumed hybrid. I think it could well be a hybrid, size and build are very marinus like (closer to L. m. than to northern argentatus even if p10 is still growing) and it does look like it is much more grey and less black than any "normal" marinus. I know that there have been some presumed hybrids between Herring s.l. and marinus in North America but I have not seen anything like this at the sites where i watch gulls in the SW Netherlands. Maybe JanJ has some relevant literature at hand?

regards, pim wolf

[JanJ]

Paul, Pim!

Alongside the GBBG, the shade seems to be somewhere around graellsii, from the pic. to dark for argentatus with a somehow in between structure between the two mentioned, although judging from the pic. - closer to GBBG. As Pim mentioned, the lack of responses surely reflects the true dificulties to handle gulls like this. If now to be considered as a hybrid, the suggested marinus X argentatus (argenteus) might be a good suggestion. The visible primary looks close to GBBG - a better view would be prefered - with an all white tipped p10 and mirror on p9 smaller than usual and obvious white tongue tips to p6 and p7 (?). Broad white trailing edge to secondaries could be considered as in between marinus and argentatus. One would expect more black in wingtip with a fuscus x argentatus. Pale iris and yellowish orbital ring in the middle of an angry face expression is notable.

Not so easy to come by good images of presumed marinus x argentatus (smithsonianus) but here are some possibilities, relevant or not:

http://www.tarsiger.com/gallery/index.p ... 0&lang=eng

http://www.netfugl.dk/pictures.php?id=s ... re_id=8545

While you schroll down to the end - where there is a (presumed) marinus x smtihsonianus hybrid - notice all the very good images on this site!

http://www.capebretonbirds.ca/rarebird.html

http://www.elisanet.fi/hj.koskinen/Dark ... 71114.html

http://www.elisanet.fi/hj.koskinen/Dark ... 71113.html

http://www.flickr.com/photos/bonxie88/3231238527/

http://www.flickr.com/photos/bonxie88/3231238523/

Maybe Peter has something (usually wiser) to add?

JanJ

[adriaens]

Not much to add other than that this looks most like a hybrid GBBG x HG to me also.
The white-headed appearance also seems to point to influence of GBBG, though the colour contrasts in the photos look a bit unnatural.

It is remarkable how rare this hybrid combination is in Europe. I had expected a few in Iceland, where GBBG and HG are among the most numerous gulls (and indeed birds), but saw none.
The combination GBBG x American HG seems a bit more regular. I saw one or two on my visit to Newfoundland, and I think they may be annual over there (?)
Here is another link to photos:
http://www.amazilia.net/images/Birds/Gu ... edGull.htm

[Rui_Caratão]

It is remarkable how rare this hybrid combination is in Europe. I had expected a few in Iceland, where GBBG and HG are among the most numerous gulls (and indeed birds), but saw none.

Hybrids tend to be more numerous, when at least one of 2 species are not well established as a breeding population. The lack of a breeding partner could lead more easily for mixed couples……

Another candidate for the usual GBBG x HG, or GBBG x American HR.....
http://www.flickriver.com/photos/antoni ... 530/#large

For a few years, a GBBG as tried to breed with a YLG, at Sintra coast, Portugal, apparently untill now, without any visible success. Next year who knows!!!!!

regards,
Rui

[Paul French]

Thanks for the postings guys, really appreciate your input. It certainly feels like argentatus x marinus is the correct solution, but i guess that smiths x marinus can't be ruled out either, especially considering there was a small influx (3-4 birds) of kumlieni a few weeks later.

Thanks for all the links, very interesting stuff. Just one question though. Is this more likely to be a argentatus x heuglini hybrid rather than marinus? - http://www.elisanet.fi/hj.koskinen/Dark ... 71114.html Just looks to be a bit on the small side when compared to the other birds, and would marinus breed so far inland in Finland?

[lou bertalan]

paul, as mentioned in the text, structurally it looks a lot like an argentatus but almost nothing reminds of heuglini - leg colour, primary pattern with 2 very large mirrors (this would be totally off for heuglini but good for marinus involvement). some female GBBG are as small as herring gulls. hard to be sure if the parents at the ringing site haven't been noted and i guess hannu would have searched for that before putting this gull on his site. kuusamo is about half way between white see and botnic gulf and i guess there is some exchange in GBBGs between these two breeding regions.
personally i don't see anything apart the dark mantle suggesting another sp. than argentatus.

[Rui_Caratão]

Another candidate for the usual GBBG x HG, or GBBG x American HR.....
http://www.flickriver.com/photos/antoni ... 530/#large

Obviously not for the gull on this topic......it was just aditional info.

Rui

[Paul French]

paul, as mentioned in the text, structurally it looks a lot like an argentatus but almost nothing reminds of heuglini - leg colour, primary pattern with 2 very large mirrors (this would be totally off for heuglini but good for marinus involvement). some female GBBG are as small as herring gulls. hard to be sure if the parents at the ringing site haven't been noted and i guess hannu would have searched for that before putting this gull on his site. kuusamo is about half way between white see and botnic gulf and i guess there is some exchange in GBBGs between these two breeding regions.
personally i don't see anything apart the dark mantle suggesting another sp. than argentatus.

I agree that there is very little to suggest hybrid other than the dark mantle. Since hybrid graellsii x argenteus don't always have yellow legs (eg: http://www.freewebs.com/merseybirders/g ... onpage.htm (scroll down to hybrids) and pers obs), and the other features could easily be from argentatus, I'm struggling to see any marinus influence in the Kuusamo bird, hence my question about argentatus x heuglini. If the parents were not noted (implied from the labeling as possible hybrid...), then i guess we'll never know for sure.