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Ross's Goose or Snow/Ross's Hybrid - Lancs, England (1 Viewer)

Stuart Darbyshire

45th generation Northern
There has been quite a bit said about this bird currently at Marshside RSPB, one side saying pure Ross's (including a few American birders), the other Ross's/Snow Hybrid.

It is slightly larger than a mallard, so size is ok, but to me the bill looks on the large side and the head appears too flat and not the usual rounded shape (although 1st winter birds do seem flatter headed in the images I've seen online)

Origin aside, from a personal education point of view, I'd be interested to see what others think - especially anyone who has sees these birds on a regular basis.
 

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chris butterworth

aka The Person Named Above
Hybrid IMO. The bill looks too large / long, the junction of the bill side and the feathers appears curved and it's got a distinct 'grinning patch'.

Chris
 

Robin Edwards

Well-known member
I would say that this is not a pure Ross's - the bill and head shape seems wrong to me? Compare...
 

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DarkFireFalcon

Well-known member
I'm guessing there are other pictures, can you link to some? head and bill shape can be tricky to judge from just one picture. Ross's do sometimes show a slight grin patch, but the bill does look on the heavier side for Ross's.
 

chris butterworth

aka The Person Named Above
The Ross' that I've seen have all had the junction between the bill and feathering really straight, as though it has been drawn with a ruler, it seems to cut back at the gape and towards the top in the photo, even allowing for the head being slightly angled.

Chris
 

Stuart Darbyshire

45th generation Northern
a few more of mine here

Thanks Chris - I see what you mean - shown more in image 3 (if you ignore the grass and the fact its out of focus!)
 

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RJP

Well-known member
To me this is clearly a Ross'/Snow hybrid. The bill looks too large for a pure Ross', and the grin patch too prominent.
 

DarkFireFalcon

Well-known member
Playing devils advocate and perusing some pictures on the web, the bill length seems within variation to me for Ross (about half as long as the head, seen in profile) and the slight grin patch is also within variation for Ross (many pictures of obvious Ross's Goose show a slight grin patch).

I'm curious, why is it that out of range Ross's are often assumed to be hybrids, but (at least here in the states) no one ever questions out of range Cackling as hybrids.
Genetic evidence suggests that there are a good number of Cackling x Canada hybrids in the narrow overlap zone, with some birds phenotypically Cackling having Canada genes (suggesting they might not even be F1 hybrids). I can only guess that the same is possible for Ross's/Snow, especially given Snow's huge population increases in some areas. Are there any studies on how common Ross's x Snow hybridization actually is?
 

fugl

Well-known member
Playing devils advocate and perusing some pictures on the web, the bill length seems within variation to me for Ross (about half as long as the head, seen in profile) and the slight grin patch is also within variation for Ross (many pictures of obvious Ross's Goose show a slight grin patch).

I'm curious, why is it that out of range Ross's are often assumed to be hybrids, but (at least here in the states) no one ever questions out of range Cackling as hybrids.
Genetic evidence suggests that there are a good number of Cackling x Canada hybrids in the narrow overlap zone, with some birds phenotypically Cackling having Canada genes (suggesting they might not even be F1 hybrids). I can only guess that the same is possible for Ross's/Snow, especially given Snow's huge population increases in some areas. Are there any studies on how common Ross's x Snow hybridization actually is?

Agreed, some (maybe many) otherwise "normal" Ross's have slight grinning patches, but none that I've ever encountered has had a grinning patch as pronounced as the one under discussion here.

Re the incidence of hybridization, here is all that BNA-on-line has to say on the subject (last revised 2013)

"Opportunities for hybridization between the white geese have increased as a result of changes in distribution since the mid-1950s. . . .This interbreeding has altered the genetics, plumage, and size and structure of C. rossii (Trauger et al. 1971, McLandress and McLandress 1979, Weckstein et al. 2002). In one study, from 1962 to 1968 an estimated 4.7% (1400 of 29,880) of white geese were hybrids (Trauger et al. 1971), although hybridization rates dropped to 1.9% (52 of 2943) from 1989 to 1992 (Kerbes 1994)."

Doesn't leave us too much the wiser, I'm afraid.
 

Reuven_M

Well-known member
Playing devils advocate and perusing some pictures on the web, the bill length seems within variation to me for Ross (about half as long as the head, seen in profile) and the slight grin patch is also within variation for Ross (many pictures of obvious Ross's Goose show a slight grin patch).

I'm curious, why is it that out of range Ross's are often assumed to be hybrids, but (at least here in the states) no one ever questions out of range Cackling as hybrids.
Genetic evidence suggests that there are a good number of Cackling x Canada hybrids in the narrow overlap zone, with some birds phenotypically Cackling having Canada genes (suggesting they might not even be F1 hybrids). I can only guess that the same is possible for Ross's/Snow, especially given Snow's huge population increases in some areas. Are there any studies on how common Ross's x Snow hybridization actually is?

My feeling for the Canada/Cackling case is that because Canada Geese are so variable, only the most obvious Cackling Geese are generally called as such, and anything "off" is passed off as a Canada. A flock of Snow Geese is much more uniform, and thus any odd birds are easy to pick out as something different.
 

DarkFireFalcon

Well-known member
I see what you mean, it does have that slightly decurved lower culmen, where a Ross's with a slight grin patch usually still has a straight culmen.
 

Adam W

Well-known member
I agree with hybrid but can we read anything into that regarding it's origin?

Where would a hybrid escape come from? But at the same time the chances of a genuine wild hybrid would seem slim if both are quite rare as genuine migrants though I do think they are at times too easily written off.
 
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Robin Edwards

Well-known member
I think it' fair to say that we have plenty of Cat C/D/E geese at large either in UK or across into northern Europe and some of these will interbreed.

For instance, i have a local 500+ flock of Cat C Barnacle Geese and in amongst them is a single hybrid, most likely Ross's. A couple of years ago I was at York University and was surprised to see about a dozen Snow Geese fly in - similar thing.

On the other hand, true or hybrids may arrive from the North!
 

Reuven_M

Well-known member
Given the westerly distribution of Ross's Goose, I'd say wild hybrids are more likely if anything than pure Ross's to show up in Europe.
 

njlarsen

Gallery Moderator
Opus Editor
Supporter
Barbados
Given the westerly distribution of Ross's Goose, I'd say wild hybrids are more likely if anything than pure Ross's to show up in Europe.

For the same reason, collection birds are much, much more likely than wild ones. And birds in collections are more likely to hybridize than wild ones I believe

Niels
 

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