Grebe controversy - Sweden (1 Viewer)

[pinussen]

Hi,

We have a strange Grebe currently just outside Stockholm. It hangs around with two Slavonian Grebes.

Some ppl are sure it's a deviant Slavonian, some it's a strange Black-necked. I don't know what to think :king: A BN here in winter plymage is very rare so we don't have so much experince with that..

http://artportalen.se/birds/gallery_imageinfo.asp?imageID=353662
http://artportalen.se/birds/gallery_imageinfo.asp?imageID=353569

Any input?

//Björn

 

[wintibird]

Head shape strongly suggests Black-necked.

André

 

[nickderry]

I know, I know, it seems to be the convenient answer to everything, but have there been hybrids of these species. To me it's right between slav and black-necked

 

[aikidoka]

According to this database, there have been hybrids between Slav and Black-necked. I see traits of both species too.

 

[pinussen]

Yep, sure is a difficult bird And differnt pictures of it shows it in different ways... The face pattern is quite different from a normal BH, more like a slav. Same with the beak colour, white tip.

 

[stevo]

The slightly upturned bill,more delicate looking also suggests B n grebe to me coupled with the steep forehead.However the sooty black cap usually extends down onto the cheek.So I wouldn`t rule out a hybrid either.

Steve.

 

[Dave Appleton]

Wow! Fascinating bird!

With that bill I can see why people would identify this as a Black-necked Grebe, however I don't think it can be a pure Black-necked Grebe.

There is one pertinent feature that no-one's mentioned yet, although I'm not sure how good a feature it is as I've never seen it noted in the field guides. But Slavonian Grebe usually, if not always, shows a pink gape/loral line (also often pink on the base of the bill) whereas this is usually, if not always, black on Black-necked Grebe. Perhaps it's more variable than it seems to me, but I've checked it on enough birds, either in life or in photos, to think it's a pretty good pointer at the very least. I've just had another look at a load of images and can't see any exceptions.

A pink loral line is clearly visible in this photo. This feature, together with the straight and clear-cut border between the black crown and white cheeks without any downward extension of black into the cheeks , makes me think that this bird cannot be a pure Black-necked Grebe.

Structurally however I agree it looks much more like Black-necked Grebe. Actually the bill looks right for Black-necked Grebe and totally wrong for Slavonian but the head and neck IMO looks somewhat intermediate between typical structures of each species. I am not sure the extend of light/dark on the breast is clearly out of range for etiher species.

I can just about conceive that a defect could result in an aberrant bill structure on a Slavonian Grebe which, by chance, happened to resemble Black-necked Grebe. It seems a bit far fetched though, especially in the light of the rather un-Slavonian-like head shape.

So for me it's either a really, really weird Slavonian Grebe or, much more likely in my opinion, a hybrid Slavonian x Black-necked Grebe.

Very cool!

 

[lou salomon]

could it be a slav grebe with a 'deformed' bill and hanging black line? its headshape is auritus like!

 

[steve west]

IMHO a Black-necked x Slavonian hybrid sounds right.

Steve

 

[fugl]

It's aberrant Slavonian or Black-necked/Slavonian hybrid for me. Black-necked Grebes are almost year-round in Reno & I see lots and lots of them annually in all plumages but I've never encountered one like the bird under discussion here.

Fascinating bird & thread.

 

[Jhanlon]

I wonder if such hybrids are fertile... could be a hybrid back-crossed with a slav, as seems to closer to latter, just with that weird bill

 

[pinussen]

In Sweden we haven't really dared to venture to the hybrid theory, mostly because it seems to belong to the two other Grebes like a family. And there are not much evidence of BH/Slav hybrids earlier, saw one possible hybrid mentioned in Scotland 1973, as well as some lists mentioning that they do hybridize(?).

Could some kind of deformation of the skull/bill produce a Slav looking like this? That would be the closest explanation.

 

[Jane Turner]

Its a relatively well documented hybrid

http://www.bird-hybrids.com/references.php?id=4959&nomenclature=cinfosci

 

[pinussen]

Too bad there are no pictures of the older hybrids, would be interesting to see.

The Grebe is gone now, but not the two Slav. Maybe they weren't a family after all.