Published: 11:33 Monday 25
February 2019
The first thing to say this week
is that the bird reported to me was not the one in this picture. However, this
was the closest image to what I wanted to show.
A local resident in the Totley area,
Joyce Sandford, spotted an unusual bird in her garden and she described it as
coloured like a ‘great grey shrike’ or a ‘northern shrike’ that she saw in her
identification book. Well, the great grey shrike does visit it us, and it does
so in winter too. Furthermore, they do show up on the moors above Dore and
Totley to the west of Sheffield. There is a big ‘but’ however, and that is
because the great grey shrike is exceedingly rare and most unlikely to come
into a garden.
The most likely explanation is
not a rare bird but an unusual form of a common one, namely a crow. I have seen
albino (i.e. pure white) carrion crows on the peak District moors and they do
look most odd. Also, when you get partial or full albinos the effect can
totally mask their real identity and even confuse their apparent size. So I
wondered if anyone else had seen a white or piebald crow in the area west of
Sheffield. The picture I have used is from a visit to Poland a few years ago,
where the common crow is the hooded crow or ‘hoodie’ and just shows the
potential for variation. The hoodie is really the same species as the carrion
crow (or maybe part of a ‘super-species complex’!) but has a more northerly
distribution.
They used to occur in England
when times were colder in the 1700s and 1800s for example, but have been
squeezed northwards and today just occur occasionally in winter. The crow
family clearly has the genetic potential to produce predominantly both black
plumage and white plumage, and can mix the two.
When these oddball birds turn up
then they do grab the attention because they look so strange. Do let me know if
you have seen one and better still, send me a picture.
Professor Ian D. Rotherham, of
Sheffield Hallam University, researcher, writer and broadcaster on wildlife and
environmental issues.
