Aren't Grey Squirrels Amazing!
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GREY SQUIRRELS ARE AMAZING! A recent social media post, showing our squirrel Sonia gently holding her human carer’s finger between her teeth, elicited the following comment: 7000 psi. 7000 pounds per square inch, that’s how strong a squirrel’s bite can be. Compared to a human’s 160, a dog’s 250, and a great white shark’s 4000, as the author of the comment elaborated. Aren’t squirrels amazing! This social media exchange prompted me to list several more sound bites of information on our grey clients.
SOUND BITE ONE – the origin. Squirrels (the genus Sciurus, comprising nearly 30 species) originated in Eurasia. They migrated to America about 9 million years ago, where they diverged into several local species. This colonization proved very successful, and several species emerged from that process: eastern fox squirrels, western grey squirrels, and, of course, our friends eastern grey squirrels, who were brought back to Eurasia, to Great Britain, in the 19th century. The squirrels that stayed behind in Eurasia, the red squirrels, are very common over an extremely large territory, from Scandinavia to Siberia to Turkey. Wherever the habitat is suitable for them, they thrive. Unfortunately, this is no longer the case in Britain, where the habitat is now unsuitable for them, due to deforestation. (My “propaganda point” here is that all tree squirrels are native to Eurasia, because this is where they originated as a species.)
SOUND BITE TWO – housing. When it comes to housing, grey squirrels do not leave much to chance. They regularly use three or four dreys or dens. If one is destroyed, or, where there are babies in residence, when it becomes too dirty, the squirrels move to their second, third or fourth home. This is one of the reasons why they are so successful.
SOUND BITE THREE – caching nuts. Squirrels bury nuts. Everyone knows that. People used to think that they do it in a haphazard fashion and forget where most of them are. Nothing could be further from the truth. First of all, they remember, but also, before burying a nut, here are some of the things a grey squirrel has to consider: (a) the calorific value of the food: is the energy, in calories, of eating the nut in future going to be worth spending the calories in going to the place where it is buried, digging it out and opening it, (b) how long would it last in the ground without rotting (with acorns, a bit called the embryo has to be bitten off in order for the acorns not to germinate too early), (c) pilfering: how likely is it that someone else will dig out the nut and steal it; in this case, it is worth burying the larger nuts further apart - you will spend more energy getting them, but at least if you lose them to a thief, you do not lose everything valuable at once (the equivalent of investing money in a diverse portfolio), (d) predation: how dangerous is the place where you are burying the nut; you do not want to be eaten by predators yourself while you are too worried about your food; on the other hand, a more dangerous place, perhaps a more open place, the is going to be safer from potential thieves.And so the grey squirrel makes the decision, guided by her instinct and her intelligence. And a team of scientists, guided by reference books, computer models and supervisors confirm that her choice is indeed the optimum, given all of the above factors.
SOUND BITE FOUR - X-ray vision! Some acorns that grey squirrels gather are infested with larvae of weevils. Such acorns can by eaten (by squirrels, anyway), but not stored. With no visual clues to infestation, squirrels are able to tell which acorns have the larvae in them and which do not. Their ability to detect the infestation exceeds the researchers’ ability of determine infestation with x-rays. The mechanism for this amazing perception is unknown. It is more likely to be smell, rather than actual vision, since the squirrels were observed to shake their heads at the infested acorns. In any case, it works.
SOUND BITE FIVE – breeding in accordance with predicted food availability. Many trees display a pattern of producing seeds called masting, where an abundant crop one year if followed by up to 10 years of poor crops. This is nature’s way of keeping down the numbers of seed-eater, squirrels among them. Do I have a hidden agenda in saying this? Yes, I do. People sometimes say that if we do not cull grey squirrels, there will be too many of them, we will be knee-deep in squirrels. Nature, however, has its own way of keeping down their numbers, even in the absence of predators, through food availability. But that does not mean that squirrel babies starve to death. Squirrels seem to know when food is going to be abundant, and have more babies in those years. More importantly still, they know when food is going to be scarce, and have fewer babies, if any, in those years. The mechanism for this prediction is unknown, though flower buds and the size of cones may be the cues.
SOUND BITE SIX – shouting over the urban noise. Squirrels communicate both vocally, e.g., by clicks, moans and screeches, and non-vocally, e.g. by tail-flicking and flagging. In urban areas, where there is a lot of noise, grey squirrels get around that problem by relying more on non-verbal methods, so that they can still communicate over the noise.
SOUND BITE SEVEN - the cognitive skills of grey squirrels. These are truly remarkable, as anyone who watched them for any length of time would now. These skills have also attracted researchers’ interest, and, in cognitive experiments, squirrels demonstrate that they can problem-solve, solve counter-intuitive puzzles, tell colours, change their strategy when necessary, quickly learn from their mistakes, and remember solutions to puzzles for up to two years.
AND THE CONCLUSION IS – it is a privilege to help such remarkable creatures and a crime against morality to persecute them, cull them, and adopt legislation effectively outlawing their rescue.