[jurek]

Originally Posted by David Ball

a vagrant Ring-necked Duck, American Wigeon or Blue-winged Teal has to find another member of the same species to breed with

I think never a North American bird became a regular breeder in Europe by transatlantic vagrancy? There are some single broods or hybrid pairs, but they always quickly died out.

[Dimitris]

Originally Posted by jurek

I think never a North American bird became a regular breeder in Europe by transatlantic vagrancy? There are some single broods or hybrid pairs, but they always quickly died out.

Pectoral Sandpipers seem to be getting established in Europe, but they could have just as well come from Asia.

D.

[Reuven_M]

Originally Posted by jurek

I think never a North American bird became a regular breeder in Europe by transatlantic vagrancy? There are some single broods or hybrid pairs, but they always quickly died out.

How do we know that none of mallards, gadwalls, pintails, shovelers, greater scaup, common eiders, king eiders, black (common) scoters, white-winged (velvet) scoters, long-tailed ducks, harlequins, goldeneyes, common mergansers (goosander) or red-breasted mergansers were once restricted to North America?
Ducks have been around for a lot longer than we know where they were found.

[Xenospiza]

Originally Posted by Dimitris

Pectoral Sandpipers seem to be getting established in Europe, but they could have just as well come from Asia.

D.

I've also heard rumours about White-rumped...

[jurek]

Originally Posted by Reuven_M

How do we know that none of mallards, gadwalls, pintails, shovelers, greater scaup, common eiders, king eiders, black (common) scoters, white-winged (velvet) scoters, long-tailed ducks, harlequins, goldeneyes, common mergansers (goosander) or red-breasted mergansers were once restricted to North America?

I think almost all are different subspecies (Velvet Scoters are even split into two species), and usually Asian subspecies are more close. So they became distinct long ago and spread through N Asia and Bering Strait.

[ColinD]

Originally Posted by Reuven_M

How do we know that none of mallards, gadwalls, pintails, shovelers, greater scaup, common eiders, king eiders, black (common) scoters, white-winged (velvet) scoters, long-tailed ducks, harlequins, goldeneyes, common mergansers (goosander) or red-breasted mergansers were once restricted to North America?
Ducks have been around for a lot longer than we know where they were found.

True, in fact how do we know that vagrant Ruddy Ducks don't already breed here?

As far as I'm aware, European Mallard, Gadwall, Pintail, Shoveler, Greater Scaup, Eider, Long-tailed Ducks, Goldeneyes, Goosander and Red-breasted Merganser are inseperable from their North American counterparts.

[DEREK CHARLES]

Colin, American Eiders do look different check this http://www.birdsireland.com/pages/si...der/eider.html

derek

[Andrew Whitehouse]

I think Common Merganser is also separable in the field from Goosander, although it's tricky (seem to remember an ID paper on this from a few years ago).

[Xenospiza]

Originally Posted by ColinD

True, in fact how do we know that vagrant Ruddy Ducks don't already breed here?

DNA sampling of European birds + comparison with American Ruddies has shown the European birds are all derived from the same stock. Unless coincidentally a vagrant with the same DNA arrived here (I am sorry that I can't tell you what the chance would be...), that appears to prove that this has not happened.

[The Moore-hen]

2071 'hits' for 'Ruddy Duck'....thats more than DEFRA have managed!!

[ColinD]

Originally Posted by Xenospiza

DNA sampling of European birds + comparison with American Ruddies has shown the European birds are all derived from the same stock. Unless coincidentally a vagrant with the same DNA arrived here (I am sorry that I can't tell you what the chance would be...), that appears to prove that this has not happened.

Does it? It seems to me that it's only conclusive as long as the DNA of every Ruddy Duck in the UK has been checked. Surely it doesn't prove anything regards unchecked birds.

[Xenospiza]

The article can be read here: http://www.ebd.csic.es/andy/MolEcol06.pdf
It even includes birds from Iceland.

[Farnboro John]

Originally Posted by Xenospiza

If I'm not mistaken these were small forms, not the usual duck pond Greater Canada Geese.

They were (or at least one lot were - parvipes with Maryland neck ring - subsequently shot), but that doesn;t really address whether atlantis might make it - they would disappear in local Canadas in UK and might be dismissed even on Islay etc - though perhaps not the latter, goose watchers there seem pretty alert to what is likely.

John