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“We do have a strange way of passing the buck for our errors, don’t we?”

26 July 2019, at 9:00am

What a sweet sight – sitting there munching a nut from last autumn before spotting me, then scampering off and heading up a tree trunk deftly to leap from one branch to another as it speeds away. And yet, apparently, I should see this animal as a pest – as vermin to be euthanised if it were presented to me in my clinic rather than to be cared for and released. And all because its name is Sciurus carolinensis rather than Sciurus vulgaris; it has a grey coat rather than a red one.

The grey squirrel didn’t ask to be introduced into the UK from North America back in 1876, did it? It’s not its fault that it is so well suited to living in the UK.

We might consider the grey squirrel responsible for the decimation of the red squirrel population. This happened because it is able to survive cold winters through its greater fat reserves and live with squirrel pox while its red counterpart dies of the disease. But neither the whole species nor any individual animal is “responsible” for the demise of its “vulgar” cousin in the same way that by driving our cars and flying across the world, we are responsible for climate change.

We do have a strange way of passing the buck for our errors, don’t we? We introduced the grey squirrel. We leave food litter around that it can easily scavenge. We persecuted the red squirrel as a pest for years – the Highland Squirrel Club killed 80,000 red squirrels more than 100 years ago and many such clubs existed across Scotland. We destroyed millions of acres of woodland that was the red squirrel’s natural habitat to make way for agriculture and housing.

I’m sure that much of this was done thinking it was exactly the right thing to do at the time. That being said, sometimes we did massacre species without thinking what we were doing. We killed off the beaver (Castor fiber, if Latin names give you a buzz!) by trapping them. We killed them for their meat and their pelts to some degree for sure, but mostly for castoreum: a sweet-smelling (apparently – I’m not speaking from experience) liquid that originates from glands (the castor sacs) between the beaver’s genitals. Beavers use the secretion to oil their fur and make it water-resistant. Very reasonable. But how anyone reasoned that a secretion from there would be appropriate to use in cosmetics and medicine, I don’t know. We wouldn’t say the same for what comes from a dog’s anal glands would we? (And there I do speak from experience!)

We exterminated beavers from the UK 400 years ago, yet still consider them indigenous in a way that grey squirrels which have been around for 100 years aren’t. “Indigenous” to the extent that we are spending £2 million or more to bring beavers back from Norway to repopulate Scotland. “Indigenous” to the extent that we don’t seem particularly bothered by the fact they may carry the zoonotic tapeworm Echinococcus multilocularis. “Indigenous” to the degree that we haven’t thought that their dams and lakes may alter environments irrevocably affecting species considered truly indigenous.

And what next? Wolves maybe? Computer modelling has suggested that wolves could significantly combat the problem of overabundant red deer in the Highlands (who caused that, I wonder?) but what about impacts on sheep farms and tourism? These potential issues need to be taken into consideration too. I’m worried: it seems that somehow whatever we do with the best intentions typically falls foul of one poor estimate or another.

Associate Lecturer, Veterinary Ophthalmology at St John's College, University of Cambridge

David Williams, MA, VetMB, PhD, CertVOphthal, CertWEL, FHEA, FRCVS, graduated from Cambridge in 1988 and has worked in veterinary ophthalmology at the Animal Health Trust. He gained his Certificate in Veterinary Ophthalmology before undertaking a PhD at the RVC. David now teaches at St John’s College, Cambridge.

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