Red or grey?

Is this the red squirrel some people believe they have seen in the park?

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In fact, it’s a grey squirrel; all the park’s squirrels are greys.

Grey squirrels come in a range of colours from very dark to positively blond. Each animal’s genes dictate the colour of its coat; differences between individuals are the result of varying amounts of two types of melanin, one producing dark brown or black and one producing red through to yellow.

There are genetic switches, not well understood yet, which turn the melanin-producing cells on or off, and can turn the density of the resulting colour up or down. Each hair, as it grows, is suffused with melanin in bands, ranging from almost black, through browns, reds and yellows to white.

This makes for a wide variety of possible coat-colours. Here is a selection, from Google Images, that run from chocolate brown to strawberry blond with the ordinary, everyday, tweedy grey with reddish highlights in the middle.

If genetic error fails to turn off the melanin-producing cells, the result will be a rare black squirrel. There are even rarer white squirrels, in which a different genetic error fails to produce any melanin at all.

The park’s squirrels are not a restricted population. An auburn outsider has joined it, travelling along a hedgerow or through a garden, bringing with it new genetic possibilities; this is how diversity works.

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More squirrels:

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