Snow White (and friends)
Saturday, 22. December 2007, 17:37:02
Just as I was despairing of even seeing that reclusive albino squirrel...
Truthfully, on the occasions when it is in sight, it is difficult to miss (for now, at least; that may change if we have a thick snowfall!) It is a stunning sight scurrying amongst the dark grass and leaves. It's a pretty large squirrel, too
It is a full albino; you can see the lack of pigment in its eyes. This condition is caused by a recessive gene that must be carried by both parents for the chance of a "white" offspring. This one probably had grey siblings. Albinism can apparently cause varying degrees of vision problems but this squirrel seems to be surviving well enough. At any rate, there have been albino squirrels appearing, and evidentally breeding, here for decades. Sometimes I wonder what proportion of the local squirrel population carries the gene can potentially produce an albino kit.
This is one of the better known wildlife colour morphs in the UK, even though (according to the BBC) the odds of a squirrel being albino are nationally 1 in 100,000! But they're not the rarest colour morph we've had locally
Years ago, the territory now patrolled by birdfeeder-stealing foxes was, of course, occupied by different individuals. One of these caught my attention in particular as he was a rare example of a part-melanistic British fox. In plain English: he was black and red, rather than white and red.
And I've searched through the archives
and found the footage!
In North America, foxes just a bit darker than this are known as "cross foxes" (because they often have a cross-shaped mark over their shoulders) and are common in some areas like the Beartooth Mountains. But European foxes are overwhelmingly "normal" colours. A study in Finland found that just 0.3% of 3000 foxes examined showed "cross" markings, and that's in a northern environment where the colour phase is relatively common! The figure is much lower in Britain, and completely black foxes are almost unknown; one did appear in West Sussex in 1993, and it's possible, although rather unlikely, it was related to the black-chested one in the film.
All of which is weird enough; but I've also seen melanistic fallow deer (here on the far left):
...and an erythristic (red) badger here! I don't know what the odds are on four rare colour phases appearing in my local area by simple chance, but they must be pretty astronomical. Either a) I see more strange colours because I'm looking for them more, or b) there's some external factor which is making them more common.
Reduced genetic diversity caused by habitat fragmention could be a possible suspect. The local motorway is so lethal that no terrestrial animal could survive an attempt to cross it, and that might be cutting off all "new blood" from dispersing young foxes and badgers from elsewhere. Because albinism and melanism are caused by recessive genes, they will show up when inbreeding is a problem. Those cute white tigers and black panthers displayed by zoos are produced by mating close relations, which is something the staff rarely tell the public, and is certainly not much to do with genuine conservation!
I'm curious to know if anything wild at all uses the motorway underpasses built for people, and will take the trail camera down to the nearest tunnel in the new year. Even if the occasional fox does use it, it hardly makes up for the damage that road is doing - but more on that later. Anyway, this is very complicated subject and scientists are forever arguing about the impact and relevance of genetic diversity
Finally today then, two creatures in their usual, but attractive colours. A roe deer who didn't want to slow down for anyone:
And a jay foraging for cached peanuts.
























