Unusual duck

[Jonathan]

Pretty sure I know what this is but does anyone else want to hazard a guess? More than one species involved. Seen last month in Cheshire, not far from the coast if that gives you a clue!

Cheers
Jonathan

[RKB]

It's a hybrid between the shelduck species. I think it's a female Shelduck x Paradise Shelduck.

[PeteIsntAPuffin]

*sigh*

Private collectors ruining Shelducks

[RKB]

Don't think it was deliberate! It will be an escaped paradise, pairing up with a wild shelduck.

[Jonathan]

Originally Posted by RKB

It's a hybrid between the shelduck species. I think it's a female Shelduck x Paradise Shelduck.

This bird has been knocking about around the Dee Estuary for several years, though it's the first time I've seen it since 2009. One parent is almost certainly a common shelduck but popular opinion suggests the other is not a shelduck, more a sea duck . . .

It hasn't necessarily flown over a fence either!

Cheers
Jonathan

[RKB]

Originally Posted by Jonathan

This bird has been knocking about around the Dee Estuary for several years, though it's the first time I've seen it since 2009. One parent is almost certainly a common shelduck but popular opinion suggests the other is not a shelduck, more a sea duck . . .

It hasn't necessarily flown over a fence either!

Cheers
Jonathan

I can see why - it's got a superficial resemblance to an eider. But I think Paradise Shelduck female is an excellent match. Have a google at the females, and note the pure white head, thin dark collar on the neck, dusky flanks and dark bill (mixed with the red bill on your bird). It fits very well, and is a more likely proposition for a lonely Shelduck than an Eider, which would require much thicker beer-goggles. I suspect the Paradise Shelduck escaped or was feral, and met up with a Shelduck in the wild (although Shelducks are fairly common in captivity too, so it could be an escaped hybrid). Hybrids among the Shelduck are not unheard of, and there's several species at large (Cape, Ruddy, Paradise).

[RoyW]

A putative Shelduck x Eider hybrid eh?

I can see the potential for a combination like that, but the parentage of birds like this are rarely proven (and hybrids sometimes resemble a species that wasn't actually involved).

[RKB]

Paradise and Common Shelduck are both in the same genus, Tadorna. Wildfowl in the same genus are notorious for hybridisation, such as Tufted Duck x Pochard or either of those x Ferruginous Duck, American x Eurasian Wigeon etc etc etc.

[Jonathan]

Originally Posted by RKB

Paradise and Common Shelduck are both in the same genus, Tadorna. Wildfowl in the same genus are notorious for hybridisation, such as Tufted Duck x Pochard or either of those x Ferruginous Duck, American x Eurasian Wigeon etc etc etc.

I agree, but eider have hybridised with birds of a different genus before. There was a brood of captive eider x goosander at Martin Mere a few years ago:

Hybrid - Gooder | Flickr - Photo Sharing!

Here's the video that the original pic was taken from, shows the bird's shape when compared to shelduck.

YouTube - ‪shelduck-x-eider.mp4‬‏

Cheers
Jonathan

[RKB]

Yeah, there's lots of hybridisation between groups too, but we have to ask what's more likely. Species prefer their own genus.

I just can't square this bird with an eider. Mixed features can generate patterns that resemble another bird, but those features have to come from somewhere in the first place.

How can one explain the neck collar? Neither bird has one (if it's male).

Where does the black on the bill come from? Males of neither species have black on the bill.

Where does the white crown and forehead come from? Both species have dark crowns (in all ages/sexes)

Where does the black back come from? Both species have white mantles.

Where does the chestnut on the upper breast come from? Both species are white there.

Male Eider has none of the features listed above, but female Paradise Shelduck has all of them. Plus the dark legs and tail, plus the dusky flanks, plus the chestnut on the upper breast. Everything fits, whereas close examination shows that little fits for Eider. For these features to be produced, the genes have to be there in the first place.

The shape you mention is actually very like Paradise Shelduck - more barrel-chested than Common Shelduck.

Having just googled around I found this thread on BirdForum HYBRID Wildfowl ID please, Burton, Merseyside, UK - BirdForum in which Joern Lehmus thinks what is probably this bird is a Shelduck x Eider too. Normally I'd take his word for it, but for the reasons above I just can't agree. His basis seems to be "it has white on the rear flank, like an Eider" [note: only a male], and mentions some "similar" birds from known parents at Basel Zoo. Until I see convincing documentation of those, I'm afraid I'm not buying it. The mixed features of Paradise Shelduck appear much more obvious.

As you say, though, pretty difficult to prove, and basically everyone (including Joern) are going on appearances. Yer pays yer money....