Tuesday, 21 April 2009

Freak of Nature

A couple of mysteries today. 1) What is going on with all these Buzzards over the farm (at least 19 yesterday and 9 today and also 4 Red Kites- a species only recorded 20 times before 2006 and now 17 records in late two years) and 2) What the hell is that thing (above).
The answer to both questions is I don't know. But dealing with the gull first. To my eye the concolourous dark underparts and head, large build and all dark bill give some sort of impression (with some imagination) of a Glaucous-winged Gull (GWG). However amongst many things, this species is generally more structurally robust with a thick bulbous-tipped bill and by a miracle this species has already turned up at Beddington before, so the probability of another turning up would render the theories of probability obsolete. Plumage wise the amount of dark in the primaries is more extensive in GWG and the plain dark grey mantle feathers are simply off the radar for anything that I am aware of in the way a good species.
As this bird shows little in the way of coherent features with any particular species and appears outside the range of variation within, we are probably talking about a hybrid. There are some features on this bird which are more associated with taxa from the nearctic- the dark concolourous underparts, all dark rectrices and heavily barred uppertail coverts. It is possible that we could be dealing with a nearctic hybrid but it is also perhaps possible that some of these features are basal to other gulls and this bird represents some kind of 'throw back'- ancient features being expressed. The most likely hybrid would be a Herring Gull x Glaucous Gull (structurally it is fairly okay for Herring Gull as a parent) but other theoretical possibilities include American Herring Gull x Glaucous Gull, Glaucous-winged Gull x Glaucous Gull or in fact a large number of possibilities of F2, F3.....etc etc hybrids between any of these taxa- don't even get me on the possibility of some other Pacific taxa parent species and come to think of it: is it possible to get a hybrid x hybrid:- something like (Western GullxGlaucous-winged Gull hybrid) x (Glaucous GullxHerring Gull). The mind boggles- if it is not a classic- it is in the wilderness of the 'unknown'.
Links to discussions on this bird:
Also possibly/probably the same bird seen at various locations previously (could be more than one about- check out Michael McKee's shots- is that the same bird? Got to consider ware and moult but is it? :

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