Grey Squirrel (Sciurus carolinensis)

What are Squirrels?

The word 'squirrel' has it's origins in Greek history, where Aristostle used the word 'skiouros', 'skia' meaning shade, and 'oura' meaning tail. Thus the meaning "he who sits in the shadow of his tail" was recorded. The French much later created a noun "esquirel" to describe the mammal and from this the present word "squirrel" was derived.

Squirrels are tree dwelling rodents which can cause damage to a similar degree to mice and rats and for this reason have been given the nickname 'Tree Rat' by some.  There are over 365 species in the world which are divided into seven families, the grey squirrel belonging to the tree squirrel family as is the most common. They are about 40cm long (including tail) and weigh around 450g. In the countryside they live around six years whilst most urban squirrels live around a year (mainly due to car accidents).

The common grey squirrels we see in our gardens is not a native species to Britain unlike the Red Squirrel (Sciurus vulgaris).  The Grey Squirrel originates from North America and was introduced into Britain at various locations between 1876 and the 1920's.  It has gradually spread across most of Britain and has with few exceptions replaced the Red Squirrel.

Nesting in twig structures in trees called dreys, squirrels can produce a couple of litters a year. Typical litters are three or four in size. Squirrels are active most of the year with the exception of very cold days.

Do they harm plants?

Yes.

What damage do they cause?

Squirrels are especially destructive to trees as they strip off bark from the main stem and branches. This appears to be a behaviour associated with stress which is triggered by territorial disputes. If squirrels numbers are high, and there is an increased competition for territory, there is a higher likelihood of bark being stripped.  This is particularly a nuisance and expensive when populations live in deciduous tree plantations or forestry.  Squirrels are granivores, and grain and nuts are their primary diet therefore bird feeders in gardens are like a magnet to them.  They also damage lawns when they dig them up to bury food, eat fruit, vegetables, flower buds, bulbs, corms and they will also raid birds nests for their eggs.

Do they affect certain plants?

Beech, sycamore and maple are their most likely choice of tree for stripping bark.  Tulip bulbs, crocus corms, Sweet corn, strawberries, apples, pears, nuts, sunflower seed heads and flower buds of camellias and magnolias.

Is there any time of year particularly at risk from squirrels?

Bark stripping damage usually starts at the end of April and continues until the end of July (early September in high-risk years).  They can be exceptionally noisy during the mating season in late winter/early spring.  This can change however with the weather).  If you enjoy watching squirrels antics this is the best time to watch them.  It is also a time when you need to ensure squirrels cannot get into your loft space as they can cause a great deal of damage.

How do I get rid of them?

Quite simply the effective eradication of grey squirrels is impossible.  Studies have shown that once they are removed from a site, others will quickly take their place.  They are extremely mobile and can re-colonise isolated woodland within 3 months and a non-isolated area within 1 month.  It is a far better therefore to work with them and reduce the risks than to try to eradicate them.

Ensure that bird feeders are squirrel proof and other edibles like fruit are protected against squirrels by wire.

In terms of commercial forestry, in order to control tree damage prevention, the aim would be to have less than 5 squirrels per hectare just prior to and during the main damage period (April–July).

Non-chemical control

Shooting although within the law can be both inhumane and dangerous in a domestic garden.  Removing dreys can be difficult and dangerous as they tend to be high in trees.  Either way, both are generally seen as ineffective at reducing grey squirrel numbers to reduce the bark stripping and other problems.  Baited traps are a short term answer but under the Wildlife and Countryside Act it is illegal to release non-indigenous animals into the wild, so any grey squirrels caught have to be killed humanely.


Chemical control
 

No poisons are approved for the control of grey squirrels.

Red Squirrel (Sciurus vulgaris)

These are smaller than Greys. 20-25cm in length, with fur that ranges from red to black. Most will have a white belly and a long fluffy red tail.  Some have red or black ear tufts which are more pronounced in winter. Red squirrels live in coniferous forests feeding on pine, fir and spruce trees.  It is estimated that there are only 140,000 red squirrels left in Britain as opposed to 2.5 million greys.

They can be seen in numbers in the North West on the coast of the Irish sea between Crosby and Southport.

It is important to recognise that when thinking about eradicating grey squirrels, there are powerful laws protecting red squirrels which are indigenous to Britain and NOT considered pests.