Signs of winter...
I've seen a few reports on Northants birding sites of sightings of white stoats - stoats in ermine. And a report of one in Norfolk from Twitter. I'm envious, I've never seen a white stoat (but they still have black tail tips). Except this Sunday, when out for my normal walk, a stoat ran across the path and it was half white - a half ermine! I wish I'd seen it for longer and closer and better. But I'm half way to seeing an ermine.
Presumably, in some complicated way, all that cold and/or all that snow before Christmas has 'persuaded' our stoats (some of them) to go white this year - or partly white.
If white fur gives you camouflage advantage then you don't want to be brown when the ground is covered in snow but neither do you want to be white when the snow and ice have gone. Can anyone tell me the mechanism behind the switch in coat colour - I am now fascinated and need to know? Here is some information from the Mammal Society.
Signs of spring...
If ermines are signs of winter then the good showing of hazel catkins around our way is a sign of spring. And the snowdrops and winter aconites are showing well too. I've heard it said that the snowdrops are all a bit smaller this year because of the cold weather. Is there anything in that, I wonder?
When will I hear my first chiffchaff and see my first sand martin? There were robins, great tits, and Cetti's warblers singing at the weekend.
A love of the natural world demonstrates that a person is a cultured inhabitant of planet Earth.
mirlo - thank you. That's very helpful and makes a lot of sense.
I can't believe it Mark. Signs of winter - flocks of starlings absolutely superb. Tonight on Points West an item about farmers in Somerset complaining about increasing starling numbers being a pest and health hazhard. The reporter even referring to Australia stating that they have been declared a pest there but that they are protected here. A farmer was interviewed and also what seemed to be a farmers' representative but they didn't name him.
At least the RSPB officer was able to talk about working with farmers to prevent the birds access to buildings.
Nothing to show these are pests down under because they are in an alien environment.
The Cotswold Water park sightings website
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Hi Mark
The mechanism behind the switch to white in stoats is I believe largely genetic although there is a strong correllation between the amount of northernness/ colder climate and the amount of stoats that turn white. Almost all stoats in northern britain turn white or are capable of turning white, few stoats in southern britain turn white.Natural selection has favoured a gene pool relevant to whether there is usually winter snow or not. A moult occurs in autumn and at this stage the stoat has the winter fur fully grown below the summer fur which is to be cast. The autumn moult is initiated by a withdrawal of sex hormones and probably by a change in daylength. The whiteness of the winter coat is decided by cold temperatures experienced before the moult takes place. Mark, your theory that the snow and cold weather before christmas may have caused the stoats to turn white doesn't stand up i am afraid, because the colour of the stoats winter coat has already been decided in the autumn. However the effect of the cold temperatures and snow in December could be that stoats next year turn white. There can be quite a time lag between the cold effect and how it changes the winter coat colour. In fact it is possibly the cold winter last year which has caused the large numbers of white stoats seen this year.
A stoat can change from a brown coat to a white one in only 3 days if the weather is cold, but if the weather is warmer the moult proceeds at a much slower pace and can take as long as 3 weeks.
This answer is based on some research I did on a study of mountain hares and from "British Mammals" and a "Handbook of British Mammals". There may be some newer research which I am not aware of.
Sorry I can't help on your ermine stoat query, Mark, you probably need a zoologist/micro biologist on that one. Maybe it is a similar biological mechanism to the mountain hare and the ptarmigan. It's encouraging you heard Cettis warblers singing in you patch this weekend, only we are concerned about our Cettis at Otmoor and the effect on them from very cold weather, not having heard them sing this year so far. But if they have survived your way maybe the cold winter has just given the Otmoor Cettis sore throats and hopefully they will strike up their song any time now.
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