OSLO BIRDER: The right diet?

Temperatures down to -10C and a thick layer of frost make it feel almost wintery at the moment but by Friday temperatures will be up to +7C meaning the small amount of snow that is forecast to fall tomorrow night will not last long.

Today I had a nice stroll in Maridalen but soon regretted not having a hat as my ears started burning in the cold. The Shrike was not visible to me at first but four scolding Common Crossbills soon alerted me to it as they chased it in flight. It perched briefly on its once favoured wires before continuing away on its search for food. Amongst the crossbills was one giving the 2BC like trumpet call that I have heard a few times and which is a real trap for the unwary. Maridalen had little else to offer with no raptors making use of the nice conditions – a wondering Golden Eagle must be a distant possibility. The lake had a thin layer of ice in the bays and a couple of young Mute Swans were looking a little forlorn. It is interesting how Mute Swan parents push their offspring away much earlier than Whooper and Bewick’s although this is presumably explained by the latter two species being migratory and needing to teach their young the migration routes whereas the Mute Swans just make small local movements and reckon the young can work things out themselves.

I made a stop at Østensjøvannet which was well and truly frozen with just the usual two small areas of open water which the bread eating birds themselves keep ice free. The usual overwintering wildfowl population seems to be in place now although I was surprised to see the escaped Ruddy Shelduck still here as by this time last year it had moved off. Amongst 320 Mallard, were 28 Coots, 7 Canada Geese, 4 Barnacle Geese, 1 Greylag Goose and a female Pintail which is the only non-Mallard duck that is trying its luck this year. On the hybrid front the long staying Canada x Greylag and the newly arrived Wigeon x Mallard were present. The Wigeon hybrid is making good use of its Mallard genes and had no problem fighting for food when a women who the birds clearly recognised turned up with a plastic bag full of bread.

Amongst the Coots are two 1cy birds which are still in juvenile plumage. One of these must be the late juvenile I photographed on 21 October. The younger looking of the two juveniles has a misformed wing which apparently can be blamed on a poor diet which would not be surprising so late in the season when there must be much less choice of vegetable matter. This defect is often blamed on an artificial, for example bread rich, diet but I cannot remember ever having seen it on Mallards. The female Pintail which has been here a couple of months was in a very bad state today and I wonder whether this can be blamed on a bread rich diet. Mallards are presumably OK with bread rich diets which explains why they are able to adapt to so many habitats and climates whereas Pintails may not be so adaptable. Anyway the Pintail was standing on the bank when all the other ducks were in the water and was facing the sun and vigorously preening. Whilst preening it had its tail spread and both wings were shivering/vibrating coninually. Some of the feathers were clearly in a bad state although it was able to flap its wings normally. In one of the pictures I took it looks as though it may be injured under one of its wings although this may just be as a result of it being in bad condition. When the bread lady arrived it made no attempt to join in the scrum and I also never saw it on the water even when someone walked too close and scared it. Difficult to know the cause of the birds problems but it wouldn’t surprise me if it stopped being reported quite soon.

The juvenile Coot (sothøne) with a misformed wing. The ice on the feathers is a sign that it is not able to care for its feathers properly but it is amazingly still alive

from behind it doesn't look well

what I assume to be the same bird on 21 October

another bird still with some juvenile plumage on the chest but no deformities

a healthy looking adult Coot

this Coot was ringed just two days ago and aged as a 1cy and sexed as a male. That it is a 1cy can just about be seen from the small white frontal shield and the darker eye than the adult in the picture above. That it is a male was presumably determined from measurements with males and particularly their toes being significantly larger

surprisingly the Wigeon x Mallard hybrid remains bling free. Here it is joining in the bread melee

and it had no problem fighting its way to some

The unwell female Pintail (stjertand). From behind the spread tail and wings plus general poor state of the plumage can be seen

the wings were always hanging and shivering

here on the underwin it can be seen tat many feathers look to be in poor condition and there is flesh showing and possibly some blood on the feathers. Is this the result of an injury or just from being in bad form?