Tuesday, 10 March 2020

Confusing Bean Geese

With it being a Tuesday I was out with Anders. With rain in the air we were unsure where to go but ended up going on a wild goose chase. Our first stop was close to Gardemoen Airport to look for Woodlarks but we found none. It is still very early and the weather was not great but Skylarks were numerous in the same area so I expected Woodlarks to be back.


We noted the odd Lapwing and Skylark from the car as we drove around but there was no sign of any new arrival of migrants. We headed for the Taiga Bean Geese as another GPS tagged bird had joined them sometime yesterday so I was keen to see how large the flock was now. As we entered Bean territory we saw a flock of Whooper Swans on a field that the Taiga Beans have used in previous years. Amongst the swans were 9 geese with orange legs that unsurprisingly turned out to be Beans. We saw them really well and I was sure they were Taiga’s (which is what I had expected) as their bills seemed long and thin, heads small and many of them had lots of orange on their bills. I did comment how some of the birds looked Tundra like and how difficult it can be when you only see a photograph or a single bird but explained that there was always variation in a flock of Taigas. I also commented how unusual it was for us to see Taiga Beans so close without them seeming to be scared…. (I think Anders was too polite to express his reservations with my ID).

We continued to where the Taigas were yesterday and initially only found a pair on a field. Looking at these at long range it immediately became clear that the birds we had seen just before were not the same (sub)species. The large size and long thin necks of these new birds (which were in all respects classic Taigas) were so different. In the end we only found 6 Taigas after checking the usual fields and the river but returned to the first group to scrutinise them again. Seeing them again the jizz was clearly wrong for Taiga but studying the plumage, head and bill individually it was difficult to point to specific features that nailed Tundra instead of Taiga although the lower mandible of the bill was clearly thick at the base and the neck when extended was not long or slender enough. I have previously had similar birds that have been a real headache for me and have always identified them as Tundra and wonder if they come from a specific population because they differ from expectation of what a classic Tundra should look like.

We finished the day in Maridalen where we went through a massive flock of around 500 Mealy Redpolls without managing to find a single Arctic or Lesser.

Three of the nine Tundra (rossicus) Bean Geese. Here they do look large headed, thick billed and short & thick necked (clear Tundra featres) but the bird on the right with is orange bill and small head makes me think Taiga

here I think that they look quite Taiga like although the thick base of the lower mandible is evident and the extended necks are not very long

but I would stuggle with this picture especially with the bird on the left having so much orange in the bill

Today's birds at the top compared with Taigas from yesterday. Here the much longer, thinner necks of the Taigas are clear to see plus the thicker base to the lower mandible of the Tundra but it is not always easy! The body of Taiga also looks slender compared to Tundra. 
there is a noticeable difference in head shape (in addition to bill shape) and also size of the eye


Two birds from today compared with a Taiga from yesterday. Apart from the length of the neck and body size there are not too many differences to point to in this comparison which again highlights the perils of making conclusions from single photos...Alternatively all three birds are Taiga...

Whooper Swans



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