Greater/Lesser White-fronted Goose (California, USA)

[wimvdam]

[Apologies to those who have seen this question already before at other venues. Some have said that this is an "obvious Greater", but I'm still interested in opinions on such a clear eye-ring for a White-fronted Goose.]

Last week a birder friend of mine photographed two White-fronted Geese at Castaic Lagoon near Los Angeles, California, and one of them had an obvious yellow eye-ring. In most parts of Europe this would make it a contender to be a Lesser White-fronted Goose (as opposed to a Greater) but here in California that would be unheard-of (my National Geographic guide mentions only one US sighting in Alaska in 1994). For those not familiar with the English American names of geese: I'm talking about Anser albifrons versus A. erythropus here.

You can look at her photos of the two White-fronted Geese here: http://tinyurl.com/yht3py7

The bird does appear a bit smaller than the other WfG but its beak seems too big and not pink enough for a Lesser. This week I learned from Collins that Greater WfG sometimes have a narrow eye-ring, something my American guides do not mention. So, all in all, this is most likely a Greater White-fronted Geese with a yellow eye-ring, but before putting this ID to a rest I would like to have some confirmation from those of you who have more experience with the Lesser versus Greater Wf Goose question.

Specifically, is this indeed the kind of narrow eye-ring that some Greater WfG have?

Thanks,

Wim

[Steve Moon]

I have never seen a Greater Wfg with any sort of yellow eye-ring. That is a clincher for Lesser.

[MichaelF]

Greater, definite. The bill (and the bird as a whole) is much too heavy for LW-fG, and the forehead blaze doesn't extend up the middle of the crown the way it would in LW-fG.

LW-fG is a dainty little thing. Think Ross's Goose, except even smaller.

[Kev Hewitt]

I agree with MichaelF here - the general jizz of the bird is definitely more Greater White-front than Lesser White-front. The geometry of the head is all wrong, Lesser White-front has a more pointed crown and the bill is also very short giving it a "cute" almost innocent look (e.g. in a way similar to the Mew Gull as opposed to the Ring-billed Gull). The plumage of the upper-parts is also relatively uniformly dark in Lesser white-front which is not the case here.

I have also seen the odd Greater White-front show a hint of a yellow eye-ring, but not as pronounced as the bird in the photograph, so can see why there is some confusion.

[Alcedo atthis]

I also agree - the jizz of the bird is Greater White-front, the only thing that is unusual is the eyering. Greater very rarely can show this, but normaly much less pronounced than Lesser White-front.

Individuals with that pronounced eyering I have only seen on a few photos , I think from the Netherlands

[AndyB]

Hi Wim, I also saw this bird last weekend. I chanced upon them as I walked around the lake trying to get a better view of the Yellow-billed Loon. The eye-ringed bird instantly caught my attention and I tried to turn it in to a Lesser but the size, structure of both the bird and bill all pointed to Greater. They really are a small-billed goose
http://www.unep-aewa.org/images/news_images/2008/lwfg_jostein_oien.jpg
Best, Andy

[Sherpa]

The Collins Guide (inc. the first edition) illustrates this potential pitfall quite nicely.

[Johnny X]

Agree with Greater. I saw a very similar 'eye-ringed' Greater in the UK many years ago which caused me a lot of trouble at the time...

[phil baber]

Agree absolutely.

LWFG is a different prospect entirely.

Watched this with great interest on Bird Forum. And couldn't see why people kept returning to it?

When you have seen a LWFG, it can never be confused again with a GWFG IMO.

They are small, delicate, well-marked, and ultimately, themselves!

[John Bell]

Hi all,

Sorry for late response to this thread but some of you might be interested to know that a while ago (c2000) some research was done on the relationships between the grey geese. In a paper called 'Close relatedness between mitochondrial DNA from seven Anser goose species' Roukonen et al presented evidence that Lesser White-front appeared to be more closely related the Bean Geese than to Greater White-front.

I wonder how others feel about the similarity of LWf to GWf? Although both show a white blaze it is different in the extent. This combined with the fact that all populations of grey geese can show some white around the bill maybe suggests that the superficial similarity between these two is just that. Also some grey geese can show reduced black belly blotches (eg some Greylags). Maybe these similarities are just traits of all grey geese that are more extensive in the two white-fronted geese.

It is interesting to ponder this and we can take the topic further. I think most of us (well me anyway) would always have thought that GWf and LWf were a species pair within a closely related group. But looking at the structural differences as well as the plumage features maybe not being as intrinsic as we thought then is it maybe not so surprising that LWf is closer to Bean Goose?

The flip side of this is that papers on systematics are always publishing new data and it is conceivable that in two months time a new paper could come out suggesting that the two white-fronted geese are much closely related than the previous paper implied. What then happens to those of us that were authoritatively pointing fingers at the 'subtle' clues to their supposed relative separation. We might look a little silly! So what do the rest of you think that have looked at white-fronted geese? Do you reckon they really are quite different and it wouldn't surprise you if they weren't 'too close'?

Also although the DNA put LWf closer to Bean Goose some studies of proteins implied it might be closer to GWf. My limited understanding is that DNA is much more reliable than proteins. If you were a scientist looking at the protein data and wondering if this was a subtle clue that the DNA was misleading so you decided to look at the plumages of the birds what would you conclude? I guess that it would be easy to look at them and go 'hey they look very much alike' or would you?

Lastly if I recall rightly there was hardly any genetic separation of Greenland and European (Greater) White-fronts. No research was done on extralimital (well extralimital if you are in the UK!) forms of White-fronts. Also I think there was little between the bean geese forms if I remember rightly.

cheers,
John Bell

[MichaelF]

Found this the other day: Pedall, I., Gonzalez, J., Sauer-Gürth, H., Wink, M. (2009). Genetic analysis of captive Lesser White-fronted Geese Anser erythropus in Germany. Vogelwelt 129: 304-309. http://www.uni-heidelberg.de/institute/fak14/ipmb/phazb/pubwink/2009/28-Pedall_et_al%5B1%5D.pdf (pdf file). It includes (Fig. 1) a goose phylogeny which puts LWf and GWf as a pair next to Bean. No comment on different Bean subspecies though (nor Pinkfoot either, unfortunately).

[wimvdam]

Thanks everybody for your thoughts on this. "Greater" it is then. Once again structure trumps individual field marks.

- Wim