The recent planting of the new wood out on the Oakington road set me thinking about the Histon wood (the one on the Girton footpath next to the guided busway) that we helped to plant way back in 1993.
It was a bitter December day, one of those cold, grey days when the horizontal sleet cuts right through you. The field was ploughed bare and muddy, and the trees were short bare-rooted sticks that, quite frankly, looked decidedly unpromising. As we stuck them into the mud it required something of a leap of faith to imagine that one day the field would be a ‘real’ wood!
As spring came round we watched excitedly as our sticks grew leaves. The following summer was dry, and we worried that the saplings would succumb to drought, but they survived and grew (in retrospect we decided that the lack of water actually made the tiny trees stronger, as they put down deep roots in search of water).
Over the years we’ve watched ‘our’ wood grow and flourish. The trees are a mixture of species: oak, ash, alder, field maple, wild cherry, birch and hawthorn, with wild roses and guelder rose mixed in. The wood is particularly beautiful in spring and early summer, resplendent with blossom and fresh green leaves, but it’s worth a visit any time of year.
In the winter the wood is visited by roving flocks of tits and finches, and jays searching for acorns to eat, while the oak trees and rose bushes bear the signs of insect life in the shape of marble and spangle galls, and Robin’s Pincushion galls (all formed as a result of the activities of various species of gall wasp). Spring brings migrant warblers to the wood: chiffchaffs, willow warblers, blackcaps, and whitethroats, filling the wood with song, while the froth of hawthorn blossom attracts insects galore. Summer is a lush and lazy time, sleepy and green, when the trees cast welcome shade, and early visitors may spot a fox or muntjac deer. In the autumn the wood displays bright colours – maple leaves in all shades of yellows, oranges and reds, oaks in browns, coppers and russets, and hawthorn and guelder rose berries and rose hips in a variety of startling bright reds. At any time of year you may spot a black squirrel, a kestrel or a sparrowhawk.
Walking through the wood today, the trees meet over my head. It feels like a ‘real’ wood now that I can walk through it rather than being able to look over it, and it seems all the more special and beautiful to me because I can remember how it started.
Some day very soon I’m going to take a walk out to the new wood on the Impington road, stand in the middle of it, and let my imagination wander forwards to the day that it, too, will be tall and green and full of wildlife.
Red, grey – and now black. Just exactly what is going on with our squirrels?
I’m sure that many people are aware that here in Cambridgeshire our native red squirrel was replaced long ago by the grey squirrel, an American species (grey squirrels were introduced from America in 1892 and quickly spread; by 1958 there were no longer any red squirrels in Cambridgeshire). However, in the woods and gardens around Histon and Impington there is another shade of squirrel to be seen: black. And they may be taking over.
You may be forgiven for thinking that the black squirrel is a new species – it certainly looks strikingly different from our ‘normal’ squirrels. However, that is not the case: the black squirrels are actually a colour variant of the grey. The normal grey colour is a result of a balance between two versions of the pigment melanin, a darker one and a lighter one. In the black squirrels, a genetic mutation causes overproduction of the darker pigment, resulting in the black coat colour. This mutation is dominant, which means that any squirrel that inherits a copy of the mutated gene from either parent will be black, with squirrels inheriting a copy from both parents being a particularly deep, glossy black.
There has been some speculation about the origin of the black squirrels here in the UK. The first black squirrels were spotted on the outskirts of Letchworth as long ago as 1912, and since then they have spread northwards and eastwards, reaching Cambridge in the 1990s. Initially scientists thought that the black mutation had occurred here in the UK; however, more recently, examination of the gene involved has shown that the mutation matches that found in black squirrels in the United States. This suggests that the black mutation was introduced into the UK population by American black squirrels that escaped from zoos.
Whatever the origin of the colouring, the black squirrel is here to stay, and it’s spreading. Again, it’s somewhat unclear why this is so. It’s hard to see how the black colour gives any survival advantage over being grey, unless perhaps their dark colour allows them to absorb more sunlight in winter and therefore stay warmer and thus need less food. There are also many reports of black squirrels being more aggressive than grey ones, perhaps because their genetic mutation also means that they produce more testosterone than greys, and are therefore able to out-compete them for resources such as food.
Perhaps one day all our squirrels will be black, but until then, keep an eye out for them (Girton is a hotspot, and I’ve seen them many times in Histon wood and the Coppice) – they are, after all, an interesting local speciality!
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