grauwe x kolgans?

Gestart door Leon Olsthoorn, september 10, 2007, 22:44:05 PM

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Leon Olsthoorn

Bij onjuiste determinaties is een kleine discussie geweest over deze gans, die ik gisteren in Leidschendam fotografeerde. Ik determineerde hem in eerste instantie als grauwe gans, maar iemand merkte terecht op dat het dier ook veel van een kolgans heeft. Uiteindelijk kwam de suggestie dat het wellicht een hybride van beide soorten is. Wat denken julie?

Jag gillar blommor, jag gillar träd, jag gillar naturen som den är!

Alcedo atthis

Wel, it´s not a Grauwe Gans(Anser anser). I would suggest either Kolgans (A. albifrons ) or as a second option a hybrid of these 2 species, but do you have more photos?

Regards, Jörn
greetings,
Jörn Lehmhus

RWester

#2
Why is it not a 1st year Grauwe Gans? Books report that it's allowed to have some white around the bill, and the colour of the legs is in my opinion not really visible.

There are no other Kolgans-influences visible, which is something I would espect in a hybrid.
Met vriendelijke groet,

Remco Wester


Leon Olsthoorn

This is the only other picture of this goose I took last sunday:
Jag gillar blommor, jag gillar träd, jag gillar naturen som den är!

Leon Olsthoorn

I took this picture 3 weeks ago and I think this might be the same goose I photographed last sunday:
Jag gillar blommor, jag gillar träd, jag gillar naturen som den är!

Alcedo atthis

I thought bill shape and coloration is much like Kolgans, not like Grauwe...

these photos confirm it...

However i find this hybrid combination extremely difficult-especially some are difficult to distinguish from Kolgans... I have to check with some other pictures....
greetings,
Jörn Lehmhus

Jan Harteman

I believe it is a 100% Anser albifrons albifrons, maybe somewhat deviated as it does not show the blackish stripes on its chest. Bill shape and colour are also typical for White-fronted goose.

Alcedo atthis

#7
I think we can age it as a bird that was born in the previous year?

so black on the belly needn´t bee strongly expressed at that age...

and it is not that unusual to see oversummering whitefronts becoming quite tame ...especially if they associate with feral greylag in city parks.

So after comparing the new photos , I think , Jan , you are quite likely  right.

first generation hybrids greylag x whitefront have a higher bill than whitefroint, especially at the base, less white on head than whitefronts, and often less black on belly . coloration on bil often orange at the base more pinkish towards the tip. often they show a more pronounced eyering than whitefront...

If the picture labels on soem french websites are correct 2nd generation hybrids can look like F1 or like  one of the species....
greetings,
Jörn Lehmhus