Alien invaders: the grey squirrel

Few British animals are as divisive as the grey squirrel. While its red cousin is universally popular, the grey squirrel seems to be loved and loathed in equal proportion.

History and spread

While red squirrels are native to the UK, grey squirrels are a north American species. They were first brought into the UK in the late 19th century , and have since become firmly established in Wales and England. They are very common, with several million in living in the UK, mostly in England. They are at home in urban areas and gardens as well as rural woodland. They now outnumber red squirrels 67 to 1 in England, and 32 to 1 in Wales, while in Scotland red squirrels still outnumber greys.

The case for grey squirrels

Say what you like about the down side of grey squirrels, they are attractive with their bushy tails and dextrous front paws. They’re also great fun to watch. They’re agile climbers and watching squirrels chase each other up trees is a delight. They spend a lot of time on the ground, hunting for food, or burying nuts, so they’re easy to see. For many people, the grey squirrel is the only British mammal that they regularly encounter. In some urban areas they can become very bold. I used to live in a suburb of London, and the squirrels in the park would happily take food from your hand. That kind of encounter with a wild animal is a rare pleasure, and the charisma of the grey squirrel may hook people (especially children) to be more interested in wildlife.

(In fact the grey squirrels in that particular park were so bold that I sometimes worried about being mugged by them, when walking through with shopping bags. It was surely only a matter of time before they carried a toddler to the treetops.)

Grey squirrels have adapted well to life in the UK. They thrive because they’re suited to the environment we’ve got.

The case against

The case against grey squirrels can be split into two main types: vandalism and their impact on red squirrels.

Grey squirrels are capable of inflicting quite a lot of damage. They have very strong teeth, and can easily wreck a standard bird feeder (hence the number of complex, expensive squirrel-proof feeders on the market). Unfortunately for us dormousers, they seem to like the glue used in the plywood that dormice boxes are often made of, gnawing great big holes that makes the box unusable. Over the course of a season the costs of this can add up to significant amounts. They also damage trees by eating bark, causing between £6 and £10million worth of damage to UK woodlands every year, according to the Forestry Commission. And you really don’t want grey squirrels moving into your attic.

The most serious charge against grey squirrels is their impact on red squirrels. Greys are bigger and less specialist than red squirrels, and soon out compete them (they may also outcompete dormice when there are limited supplies of hazelnuts). Greys can also carry a virus (that they’re immune to) that has wiped out large numbers of red squirrels. Grey squirrels are probably not the only factor that has contributed to the demise of the red squirrel in much of England and Wales. Habitat loss of woodland is also likely to have played a part. Grey squirrels are much better adapted to an urban lifestyle, and can get by in a more fragmented landscape than red squirrels need.

What’s to be done?

Every few years plans to do a huge cull of grey squirrels surface. The number of grey squirrels makes getting rid of them from the UK pretty much impossible, even if it was desirable. And culling in one area is unlikely to do any good, unless there are geographical boundaries that mean grey squirrels from neighbouring areas can’t just move in to fill the gap.

In places where red squirrels maintain a foothold, with good squirrel boundaries, keeping grey squirrels out is important. But we’ve missed the boat for the rest of the country. I’m following the progress of a red squirrel reintroduction programme on the Lizard peninsula in Cornwall with great interest. At the moment they are trying to get rid of the grey squirrels before releasing captive bred red squirrels. The Lizard isn’t an island, although it pretty cut off from the rest of the mainland by a river. Whether that’s enough to keep the greys at bay remains to be seen. Other reintroductions have tended to be on islands which have a more squirrel-proof border (like Tresco). It’s unlikely we will see red squirrels returning to most of England.

So there’s not much else that can be done, except for try to make the most of the grey squirrel as a charismatic ambassador for wildlife in our towns and cities. And enjoy watching their exploits.