We had a mystery that I think has now been solved. A swan had been seen walking along the road near Widdrington. When it was brought in to us it weighed in at only 3.5kg. Normal adults usually weigh from about 6.5kg to 13kg so this bird was very much underweight.
In appearance it looked only about half the size of a normal adult bird. We then started looking at the evidence more closely. It’s plumage was white, so obviously an adult. Its beak was blackish grey so presumably one of last year’s birds although mature birds start getting the yellowish orange beak colouration at the same time as they lose the brownish grey feathers when about a year old.
It was when the bird started getting some mild bullying from a couple of this year’s cygnets that we really appreciated how small it was in comparison. It came out of the water and that was when I spotted that its legs were not the normal dark grey or black of standard mute swans. They had a definite pink tinge and I wondered if it was perhaps some sort of a cross between a swan and a goose.
That was when I started hunting on the internet. Sweese, if that’s what you call swan/goose crosses, are extremely rare and the only photos I could find looked nothing like this bird. Talking to Kay about my detective work, she was able to tell me our bird cheeped like a young cygnet even though it had white feathers. Was our bird perhaps an albino cygnet and not an adult bird after all?
Then I googled dwarf swan and stumbled across Polish Swan. This looked more promising; many years ago, on 13 February 1838, Mr William Yarrell presented a paper to the Zoological Society in which he stated that a distinct new species of swan which he called a Polish Swan had been imported into London from the Baltic.
In several instances these swans had produced young in this country which were pure white like the adults and at no stage did they have the brown feathers borne by other species of white swans.
I have since spoken to Graham Bell who agrees that my identification appears to be correct but that current thinking is that the white cygnet feathers are a morph caused by a pigment deficiency in one of the sex chromosomes and that it should properly be called a Polish Mute Swan as it is not recognised as a distinct species.
My picture shows the wee fellow in front of an adult and a young ordinary mute swan. Being in the foreground one would expect it to appear larger than the others if it was a fully grown swan. I think what we have is a late born cygnet of the Polish variation.
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