Pest advice for controlling Grey Squirrels

by | Sep 29, 2020 | General, Squirrels | 0 comments

Have you heard something rustling in your attic or loft and suspect squirrels? As cute as squirrels might appear to be, they can be an incredibly destructive and distressing pest to have in your home or work. Learn all about grey squirrels in our ultimate pest control guide.

Pest controllers get thousands of call-outs for squirrels every year, and this is in part due to the damage they cause to your home and the noises squirrels make at night – which can be very distressing.

Whether you’re thinking about doing some DIY squirrel pest control, or you’re looking to get a professional pest controller to come out to you, this guide is for you.


Grey squirrels Sciurus carolinensis are invasive pests, not native to the UK.

They were first introduced to the UK from North America in the 1870’s, as ornamental additions to high-class estates and country homes.

Introductions continued until the 1930’s, when the damage they can cause was finally acknowledged and it became illegal to release grey squirrels into the wild.

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The dangers: why we control grey squirrels

Even though the grey squirrel is widely appreciated for its grace and ‘cuteness’ by much of the UK – the pest management industry knows that there are times when the lethal control of grey squirrels is necessary.

The grey squirrel is recognised as being in the top worst 100 invasive pest species in the world by the International Union for Conservation of Nature (IUCN).

Here in Britain and Europe, is classed as an Invasive Alien Species (IAS) which is any animal that is not native to the UK.

Because grey squirrels are an invasive pest species, it is against the law to re-release a grey squirrel if it’s been caught alive, per the Wildlife and Countryside Act 1981 and Invasive Alien Species (Enforcement and Permitting) Order 2019.

That means that any person who catches a grey squirrel alive is legally obliged to humanely dispatch it.

As their numbers have increased in the UK, so has the damage they cause. This is where professional pest control comes in.

There are three reasons we control grey squirrels:

  • Their potential to damage to your home, business and health
  • The destruction of UK forests
  • The impact on our native wildlife, in particular the red squirrel.

Male and female squirrels

Squirrel damage in your home, business and to your health 

Grey squirrels can cause damage when they enter roof spaces of houses and buildings. For example, they can:

  • Gnaw on woodwork and ceilings
  • Strip insulation from electrical wires
  • Tear up fibreglass insulation
  • Contaminate cold water tanks and attic space with urine and droppings.

People also report sleep issues due to the loud noises they make at night while they’re scuttling around your attic.

Squirrels are most active before sunrise, especially in winter. Their peak activity is activity is four-five hours before daybreak.

Grey squirrels often associate humans with food, meaning they sometime approach people. Some people fear being attacked, however it’s very rare for a squirrel to actually attack!

In gardens and allotments, they can take fruit, raid nests of small birds and dig holes in lawns to bury food.

Grey squirrels and UK forests

Grey squirrels cause damage to trees such as beech, oak and chestnut. They strip bark at the base of trees which causes them to weaken and eventually to die.

Grey squirrels also:

  • Raid birds’ nests to prey on eggs and fledglings (figures from the Game and Wildlife Conservation Trust suggest fledgling rates reduced by 15% due to predation by grey squirrels)
  • Damage orchards and gardens, destroying bulbs and corms, eating tree nuts and recently sown seeds
  • Wreak havoc on historic and ancient woodlands.

Squirrels cause 40 million damage to British forestry every year

The European Squirrel Initiative (ESI) point out that around 12% of England is covered by trees and this is set to rise.

Woods and forests provide for carbon sequestration and help fight global warming. Timber also has an economic value and commercial forestry plays an important part in our rural economy.

According to the ESI grey squirrels cause £40 million damage to British forestry industry per year.

ESI are concerned unless something is done, there will be no oak, beech, or sweet chestnut mature trees left in the years to come.

The native red squirrel vs invasive grey squirrels

Squirrels can be right or left handed

The grey squirrel was deliberately introduced to England, Wales, Scotland and Northern Ireland from North America in the Victorian era. Since then, it’s colonised 90% of England and Wales and is becoming a problem in Scotland.

Grey squirrels are responsible for the decline in native red squirrel (Sciurus vulgaris) numbers.

The Wildlife Trusts estimates there are only around 140,000 native red squirrels left in the UK, compared to 2.5 million grey squirrels.

Squirrel distribution maps 1945-2000-2010

There have been many scientific studies which have shown that the major contributing factor for the decline of the red squirrel is the introduction of its grey cousin.

As well as outcompeting the red squirrel for shelter and food, grey squirrels can transmit the squirrelpox virus to red squirrels, to which they themselves are immune but red squirrels are not.

Once a red squirrel has squirrelpox, it’ll usually die of dehydration within 2 weeks. The grey squirrel can carry the disease, but their health is unaffected.

Red squirrels are extremely susceptible to Squirrelpox virus, which is lethal

Red squirrels are not only protected, but are much sought out because catching sight of them is so rare. Unless you’re around Scotland, Northern Ireland, the Forest of Dean or the Isle of Wight, there’s a good chance you’ve never seen a red squirrel.

In an interesting study titled ‘The enemy of my enemy is my friend: native pine marten recovery reverses the decline of the red squirrel by suppressing grey squirrel populations’, scientists have concluded that the rare pine marten could be a key player in curbing grey squirrel numbers.

Signs of squirrels in your home or business

Our figures suggest people have more problems with squirrels during the spring and autumn when they’re looking for food.

These are the seven signs easiest signs to spot when looking for evidence of squirrels in your home or loft.

  1. Scratching and rustling sound from your loft or a wall cavity
  2. Spotting droppings in the loft – although you might need a pest controller to identify these droppings (check out our droppings identification guide)
  3. Smell of urine in the loft area might indicate the infestation has been going on some time
  4. Spotting lots of other squirrels around your property, particularly near your roof or on high fences
  5. Fruit and nuts being stolen from bird feeders, or the feeders being disturbed/knocked over
  6. Bark being stripped from trees in your garden
  7. Holes in vents or damage to your insulation foam.

Grey squirrel biology, behaviour and habitat

Grey squirrel lifespan weight body length tail length


Grey squirrels have a silver-grey (sometimes slightly brown) coat with a white underside and a brownish face.

Squirrels moult their coat twice a year – once after winter and then in the late summer before the weather gets colder again.

They average between 24-26cm in length, with a very bushy tail almost the same length of the body.

They have a pointed nose with long whiskers, big eyes and small ears.

Their hind legs are longer and more powerful than the front, and all paws have very sharp claws which the squirrel uses for climbing.


The drey is a very messy looking, spherical nest which may be found in a hole in a tree or set against the trunk and branches.

grey squirrel a to z

These are easier to see in winter, when there are fewer leaves on the trees.

Alternatively they can make themselves quite at home in an attic or roof space.

The grey squirrel can be found in a wide range of outdoor habitats, including mixed woodland, deciduous woodland, suburban parks and domestic gardens.


They usually have two litters a year, in early spring and summer.

Grey squirrels typically have three to seven kittens.

Pregnancy (gestation) lasts roughly 44 days, with the young weaned at seven weeks and ready to leave the frey at 10 weeks old.

Kittens are born with closed eyes, no teeth and no hair. After about seven weeks they look like small versions of their parents and are ready to leave the drey.

Female squirrels can live up to five years, with male squirrels averaging around two-three years.


Active during the day, squirrels spend most of their time in the trees, coming down to the ground to search for food.

They are superb climbers, moving rapidly through the trees and leaping between them with ease.

It is one of the few mammals which can climb head first down a tree.

Grey squirrels do not hibernate, so may be seen at all times of the year.

However, in winter they are far less active, sleeping for long periods, sometimes several days at a time, and they are less frequently spotted during this season.

Squirrels are not territorial, often sharing food sources and home ranges.

Squirrels can hang upside down and are good swimmers

What do grey squirrels eat?

Grey squirrels are almost exclusively herbivorous.

They eat acorns, hazel nuts, sweet chestnuts, pine nuts, walnuts, berries, fungi, grains, vegetables, buds and shoots, bark and peanuts from bird feeders.

However, if plant food is scarce they will eat insects like caterpillars or crickets, smaller rodents, bird eggs and nestlings.

Squirrels will hoard nuts and seeds in preparation for winter, gathering them and burying them in caches all over.

Grey squirrel

In spite of their amazing memory, a large number of caches remain uneaten. This helps the seeds and nuts to spread, and allows them to grow.

Treating a squirrel bite

Grey squirrels often associate humans with food, meaning they sometimes approach people. Some people fear being attacked, however it’s very rare for a squirrel to actually attack!

In the rare event you are bitten by a squirrel, you should immediately wash the wound as thoroughly as possible; squirrel bites can be deep, but it’s important to do this even if the skin hasn’t been broken.

Once the area is cleaned, treat it with antiseptic cream and seek medical advice.

Preventing squirrels getting into your property or damaging your trees

Prevention is always better than cure.

Habitat management like as cutting back trees or branches that are overhanging a building, or trimming dense ivy can help prevent squirrels gaining access to a roof in the first place.

Next consider proofing entry points to your roof. For example, block the gaps and entrances holes with tightly wedged mesh or metal plates, wherever possible. A pest control professional should be able to help you with this.

Squirrels are fairly strong for their size and also persistent. If the proofing is not secure then the squirrels may be able to pull it out!

For tree protection, close fitting metal sleeves can protect them from the strong rodent incisors. This should be at least 0.75m deep, and the bottom edge should be at least 1.5m from the ground.

The metal should be a smooth surface to assist in preventing the squirrel from gaining a toehold.

DIY grey squirrel control

Although you can potentially do a lot of the proofing work to stop squirrels entering your property, DIY squirrel control is unlikely to be affective – and could potentially be very dangerous and illegal, as you must know the legislation around the control of squirrels.

Traps are available online, however not every rodent trap is authorised to control squirrels. Any squirrel you caught alive would have to be killed, as per the Wildlife and Countryside Act 1981 (Spring trap approval order).

Traps should never be used without adequate training.

Any squirrel that you kill would have to be done humanely and this can be very distressing. Some amateur attempts at squirrel control have resulted in people drowning the rodent which is against the law and can result in prosecution.

There are no amateur use products for poisoning squirrels available to the public. Pest professionals do have access to legally authorised grey squirrel poisons (Warfarin only) that are only for use inside buildings.

Things you can do:

  • Trim tree branches that overhang your roof
  • Rove anything stacked up against the side of your building
  • Seal all entry points (proofing).

Professional grey squirrel control

It’s important with squirrels (as with all pest species) that a pest professional assesses whether lethal control is necessary.

In the first instance, proofing such as the guidance in the previous section should be put into place. If this is unsuccessful calling a professional should be your next action.

Squirrels in the UK are invasive species

To control squirrels, professionals might use:

  • Spring traps
  • Live capture traps
  • Use of poison (Warfarin only)
  • Drey poking
  • Other shooting methods.

It’s important to know the law surrounding control of any pest species, which is where a pest management professional comes in.

For example, it is an offence to use or permit the use of a spring trap, other than an approved spring trap, for the purpose of killing or taking animals, as per the Spring Traps Approval Order.

Live capture trapping is what it sounds like – capturing an animal live. This may be used where it would be impractical or against best practice to use another control method, for example where placing rodenticide would put non-target species at risk.

There are several reasons why this should only be done by a qualified pest technician.

  • Live capture trapping needs to be humane, legal and carried out with sensitivity. It is an offence to cause unnecessary suffering to any animal as stated in the Wild Mammals (Protection) Act 1996
  • Traps need to be inspected regularly and must contain a food source, water source and be suitably sheltered from extremes of weather as per the Animal Welfare Act 2006
  • Non-target species should be released unharmed, which means you must be able to correctly identify the animal that has been caught
  • Target species need to be dispatched humanely by a competent person.

You also cannot use live capture traps to remove a grey squirrel from your property in order to release it elsewhere. As an invasive species, it is against the law to release a grey squirrel once caught.

Use of poisons (Warfarin only) – these are only to be used by pest professionals and can only be used inside buildings.

The poison is laid in strategic locations, usually in multiple feeding trays and then checked at regular intervals to assess if it has been successful.

It is important to be aware that these poisons can take a few days to work and, in this time, the squirrel may die out of reach. This can cause a bad smell!

Drey poking is especially effective in winter, when all the leaves are gone from the trees and the nests can be seen more clearly.

It involves a team of people clearing the squirrels from an area by disturbing the dreys and dispatching the emerging squirrels using an air rifle.

Other shooting methods may be employed, for example to clear a population residing in your attic before proofing works commence.

Anyone using air rifles and firearms must have the appropriate skills, experience and training to safely carry out control using these devices.


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