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another one via inaturalist: 'just' hybrid Mallard x Eastern Spot-billed Duck | NW Tokyo | march 2023 (1 Viewer)


Well-known member
Dear those interested,
Note: this is not my record/photo, I am just passing on information as I deem it interesting for the greater BF community.

This duck has been id'd on inaturalist as a hybrid Mallard X Eastern Spot-billed Duck male.
It looks a bit domestic Mallard x Eastern Spot-billed Duck to me, but that may be just my biased view directing me there.
The strong reddish breast and bulky posture suggest Domestic to me...

What would you say?

Mallard × Eastern Spot-billed Duck (Hybrid Anas platyrhynchos × zonorhyncha)

(photo copied from source file without asking permission of user, this post is linked in the inaturalist comment)

Hope to hear from you
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I know nothing about zonorhyncha and less than that about its hybrids, but I see mallards all day long. The pattern of black on the bill is very unusual for a mallard, and I think a cross with eastern spot-billed would explain it well. The overall color pattern is roughly right for wild-type mallard in breeding plumage, though a few things are "off" : the head pattern, the "texture" of the grey on the flank, lack of curly tail coverts, an unusually visible bit of grey in the lower breast. Those are all the sorts of things that commonly happen with hybrids. I don't see anything that would lead me to believe the mallard parent was anything other than wild-type. I could be wrong. I don't know whether this appearance is normal for platy x zono. Hybrids are usually somewhat variable, and then there's usually back-crosses to worry about too. (Again, I don't know about eastern spot-billed, but mallard x american black duck, or x mottled duck, for example, are fertile and frequently back-cross.)

In particular, I don't know of a domestic breed with an unusually red breast. The redness of the breast on this photo looks within normal variation to me, except that the patches of grey within it are a little unusual. I also don't see anything unusual about the shape of this bird. It doesn't look bulky to me, it's just floating in a slightly odd posture with its head low and maybe its wings slightly raised.
This looks rather typical for a hybrid zonorhyncha x platyrhynchos with the combination of head pattern , yellowtipped black bill, pale edged mantle feathers and no fully curled mallard tail locks.

As these hybrids are fertile and can backcross with either parent species and can also cross among themselves, variation in phenotype is rather high.

some examples linked here:

There can be also totally yellowbilled birds, like this one from Birding Beijing misidentified as a Mallard x Gadwall:

or these two different ones from Japan:

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