Thursday, 25 October 2018

Tristis chiffchaffs

Siberian / tristis Chiffchaff used to be a national rarity in Norway with few accepted records. The lack of official records was due to there being a lack of agreement as to how to identify the (sub)species rather than any real rarity and the national rarities committee (NSKF) decided to remove it as a description species a few years ago. Genetic work in other countries in NW Europe has shown the species to be a regular migrant in late autumn and a regular over wintering bird in the UK. I am firmly in the camp that a brown chiffchaff that gives the classic piip call is a tristis and don’t think it needs to be anymore complicated than this. At the end of October and in November it is my experience that tristis are the commonest type of Chiffchaff around Oslo (not that any type is common at this time of year).

There are still those in Norway though who view tristis as a very complicated subject with the spectre of eastern abientinus clouding the waters and this has led to many people not subspecifically reporting birds as they can’t be bothered with having to explain their identification. From what I can make out from all recent research though if it looks like a tristis and most importantly sounds like one then it is one.

The reason for discussing this is that today there was not just one, but a flock of three tristis at Fornebu! All the birds looked like tristis and the only sound that came from them was the classic piip sound but whether all three called is another thing. I played the song and calls of tristis to them and they responded to this with one bird wing shivering. I also played the song of normal Chiffchaff (which is very similar to tristis) and they definitely showed an interest but there was no wing shivering. I managed quite a few pictures although the birds were always quite high up and I am not certain how many different birds I have taken pictures of. The pictures show the classic brown ear coverts and lack of any green or yellow in the plumage with the exception of a yellowy tinge at the base of the wing which is allowed.

Siberian / tristis Chiffchaff (gransanger). It was difficult to get pictures showing the upperparts of these birds. Here though the brown plumage can be seen and the suggestion of a wing bar which one often sees with Tristis

the rusty/tobacco brown ear coverts and lack of yellow in the superciliu can be seen

That these birds have turned up now may be because we have had our first heavy frosts of the winter over the last two nights; heavy enough that there was ice on the edges of Maridalsvannet. The frost has also caused some movement of ducks with 7 species on Maridalsvannet yesterday with a single flock comprising 6 Goldeneye, 1 Common Scoter, 1 Tufted Duck and 1 Teal. The other species present were Mallard, Goosander and the long staying Long-tailed Duck. 3 Guillemots were also still present along with 3 Whooper Swans and 2 Mute Swans represented a real wildfowl bonanza by local standards!

A Cormorant today. This is of the subspecies sinensis which is expanding in southern Norwway and has now become fra more numerous than carbo which breeds along the coats in northern Norway 
this Smew (lappfiskand) has been around a few days near Sandvika

Two Snipe (enkeltbekkasin) yesterday on the icy edge of Maridalsvannet

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