Two small Canada Geese on Islay

[Tom McKinney]

Attached are piccies of two of three small Canada Goose we saw on Islay 4th-7th January. I'd be keen to know what these birds would be based on Hanson's white-cheeked geese book (I should probably just buy a copy of it and find out for myself, but hey, this is cheaper!)

This first bird was on The Oa on 7th January. It didn't have a throat stripe.

[Tom McKinney]

And this second bird was at Mulindry on 6th January. Again no throat stripe. Also two hybrid birds there as well. Oh yeah, sorry about the quality of photos!

[AndyB]

Hi Tom, in terms of body mass compared to those Barnacles, you have a small one. Don't believe the lack of neck collar would preclude it from "showing features of Richardson's." Not so sure about the head,bill shape but integrades are apparently widespread.

Think I had read that on Islay the small cacklers mix in amongst the Barnacles and that the larger birds parvipes types hang with the Greenland White-fronts.

The following weblinks seem to be the most comprehensive:

Sibley Guides (http://www.sibleyguides.com/canada_cackling.htm)
Angus Wilson (http://www.oceanwanderers.com/CAGO.Subspecies.html)
Harry Krueger (http://www.idahobirds.net/identification/cackling.html)

Also, if you had actually shot the bird, the following somewhat comedic yet helpful video tutorial (http://www.youtube.com/watch?v=3-ccPNfHQf0) would have been useful.

[Alex Lees]

mmmm the minefield of Canada Goose identification and taxonomy, I'm tempted to enter into the fray with some overarching ill-informed comment that they are impossible to identify given their apparent phenotypic plasticity and genetic admixture. However, despite the intractable nature of their field identification (I guess BBRC are now getting their teeth stuck in...) I think that pondering the origins and identification of these vagrant individuals is a worthwhile thought-exercise...

So, although I'm not going to venture a contribution on the identification of Tom's birds per se, I want to pose a question/statement...?

Surely the only likely* vagrant canada goose taxa to Europe are:

Canada Goose Branta canadensis

B. c. canadensis - although anyone claiming this would be laughed off, maybe people should keep reading ring-numbers...

B. c. interior - expanding its range in Greenland and considering this source-region and syntopic carrier species wintering in Europe, ought to be most prone to vagrancy...

Cackling Goose Branta hutchinsii
B. h. hutchinsii breeds widely across eastern Canadian Arctic and is thought to be expanding its range

*Although individuals resembling B.h. taverneri, minima and B.c. parvipes have been extensively photo-documented, what is a more parsimonious explanation - extra-limital occurrence of relatively short-distance migrant North American west coast taxa or vagrancy by non-textbook hutchinsii - a long-distance, central and eastern migrant (for which identification criteria are far from resolved, probably largely owing to apparent repeated genetic exchanges with other taxa)?

Alex

[AndyB]

Hi Alex, nice to see you on here. I'd agree it's probably more likely to be non-textbook hutchinsii turning up on the other side of the Atlantic.

What's the current status of Ross's Goose in Europe? Are they all laughed at?

[Tom McKinney]

Cheers guys. Hadn't seen the Krueger link before, plenty of good photos on there.

I reckon that up until quite recently my birds would have been labelled as hutchinsii and parvipes without too many sleepless nights, but with recent developments and Hanson, most people over here now seem very confused! Me especially, though that's not unusual.

Whilst the first very small bird is certainly a neat little looking thing, the second larger bird wouldn't be at all out of place on some of the dreadful inland gravel pits I unfortunately watch. How much size variation is there in canadensis in their true homeland?

[Alex Lees]

Hi Andy, Tom

I think most waterfowl experts would now* consider Ross's to be an excellent candidate for vagrancy; the only problem masking its pattern of occurence is the background 'noise' created by various escaped individuals that tour the country.

*for current population trends see REPORT OF THE ROSS’S GOOSE SUBCOMMITTEE (http://www.fws.gov/migratorybirds/reports/rossgeese/rossgeese.pdf)

There's an informative article on Cackling Geese in Ontario publised in OFO News 23(1):2-6. February 2005 (http://www.ofo.ca/reportsandarticles/cacklinggoose.php)

Alex

[Alex Lees]

Some unaffiliated researchers have also attempted a taxonomic overhaul (http://maskedstrike.blogspot.com/)of the Branta complex...

[Josh Jones]

I think most waterfowl experts would now* consider Ross's to be an excellent candidate for vagrancy; the only problem masking its pattern of occurence is the background 'noise' created by various escaped individuals that tour the country.


Exactly the problem - just how many different birds have been in Norfolk this winter? I'm trying to make sense of it, but struggling....

And then of course once you've sorted that out, its a case of sorting out which are the local escapees, and which ones are potentially 'wild'....

[AndyB]

Just to keep the thread comprehensive for future browsers of Canada Goose info, check out James Smith's recent blog entry with lots of photos of birds from AZ (http://pioneerbirding.blogspot.com/2008/02/cackling-and-canada-goose-selection.html).