Feature technical | PPC90 March 2018
We’ve changed our regular PestWatch feature and asked our technical team to focus on just one pest to look out for over the coming months. To kick off, Dee and Natalie have chosen the grey squirrel.
A bit of biology
Habitat
The drey (nest) may be in a hole in a tree or set against the trunk and branches. Alternatively they can make themselves quite at home in an attic or roof space.
Reproduction
Pregnancy (gestation) lasts 44 days, and their young are called kittens. They usually have two litters a year, each with three to seven kittens.
Young
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.
Coats
Squirrels moult their coat twice a year – once after Winter and then in the late Summer before the weather gets colder again.
Why control grey squirrels?
We can all appreciate the joy that both red and grey squirrels bring the UK fauna enthusiasts. 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 or the Isle of Wight, there’s a good chance you’ve never seen a red squirrel. This has been at least in part attributed to the rise in invasive grey squirrel numbers.
Even though the grey squirrel is still appreciated for its grace and ‘cuteness’ by much of the UK – pest technicians know that there are times when lethal control is necessary.
Grey squirrels can cause damage when they enter roof spaces of houses and buildings. For example, they can:
- Chew on woodwork and ceilings
- Strip insulation from electrical wires
- Tear up fibreglass insulation
- Contaminate cold water tanks with urine and droppings.
Clients also report sleep pattern issues due to noise and even fear of being attacked (although being attacked by a squirrel is very rare).
In gardens and allotments, they can take fruit, raid nests of small birds and dig holes in lawns to bury food.
One of the major financial implications of grey squirrel activity relates to damage to forestry, woodlands and parks. Grey squirrels damage trees, particularly sycamore and beech, by stripping bark at the base of trees which causes them to weaken or die.
Lethal control of squirrels
It’s important with squirrels (as with all pest species) that we assess whether lethal control is necessary. While some see them as vermin others may see them as a welcome natural occurrence, and pest controllers could see themselves in the middle of this conflict.
Always ensure management of grey squirrels is undertaken sympathetically and, as far as possible, without drawing undue attention to control activities.
Did you know?
- The male squirrel is called a buck and the female a doe.
- Squirrels can be right or left-handed!
- Squirrels were deliberately introduced from the USA and Canada to approximately 30 sites in England, Scotland and Wales from 1876 to 1930.
- Squirrels can hang upside down like bats and are pretty good swimmers.
Options for squirrel control
Proofing and habitat
Proofing measures need to be tailored to each site and where reasonably practicable to do so (regarding effort and expense). Proofing entry points to roofs should be considered first. For example, block gaps and entrance holes with tightly wedged mesh or metal plates, where possible.
Habitat management such as cutting back trees or branches that are overhanging a building, or trimming dense ivy can also help prevent squirrels gaining access to a roof in the first place.
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.
Spring traps
The law states that only approved spring traps must be used and that they are set in natural or artificial tunnels to reduce the risk of killing non-target species.
The most current and up-to-date information about spring traps can be found on the Spring Traps Approval Order 1995 (check for amendments).
At present, one of the most popular and well-used spring traps is the Kania 2000, which has been around a few years but remains one of the best lethal traps for controlling squirrels off the ground, away from non-target species, pets and humans.
Additionally, three versions of Fenn-type traps are legal in the UK today. There are also cheap Chinese imports/copies that are not legal to use. Make sure you only ever buy approved traps for squirrel control.
Live capture traps
The intrusive and inquisitive nature of squirrels means that they can be caught in baited cage traps, albeit some can be trickier to catch than others –
as many of us know too well!
Most single catch traps operate on treadle system that is triggered when the squirrel enters the cage and steps on
the treadle at the end of the cage to get to the bait. Multicatch traps are not particularly popular as they rarely catch more than a couple of squirrels at a time. The traps work on
a series of baffle doors allowing the squirrels to enter a
central chamber.
Live capture traps, as with most trapping techniques, have laws associated with them to ensure humane and safe use. The most important legislation will be the Animal Welfare Act which requires the captured animal to be treated humanely and to not suffer unduly.
Traps must be visited at least once (but preferably twice) a day to check for catches. Non-target catches can be released unharmed. Captured grey squirrels can be dispatched with a sharp blow to the back of the head with an appropriate instrument.
IMPORTANT: Grey squirrels cannot be re-released under the Wildlife and Countryside Act 1981.
Poison baiting
Poison bait (Warfarin) is no longer available for the control of grey squirrels.
Drey poking and shooting
Drey poking can be useful, especially on cold winter days. A team effort is needed to work the poles and to cover the tree. With this method, you can clear a lot of dreys in a single day. When all the dreys are removed in Winter, it becomes easy to spot new drey nests made in the Summer.
There are a few rules you must adhere to when carrying out this activity. Safety is paramount – gunners should stand well back from the tree.
When using the poles, tap the bottom of the drey gently. This will allow the squirrel to run out slowly. It will probably stop just outside, which will give the gunners time to shoot.
Never shoot at a squirrel running down a tree. It is better to either let it run down and run away from you or stop it and turn it back up the tree.
Remember you are aiming to cull squirrels, so be efficient and effective.
Free shooting of grey squirrels can be a useful method of control, especially in early spring when young shoots are showing in trees. On a sunny day, grey squirrels will work in the outmost branches of a tree chewing the new shoots and can present an easy target.
IMPORTANT: Users of air rifles and firearms must have the appropriate skills, experience and training to safely carry out control using these devices.
FURTHER READING
Legislation:
- Wildlife and Countryside Act 1981
- Spring Trap Approval Order 1995
- Wild Mammals Protection Act 1996
- Animal Welfare Act 2006
BPCA Codes of Best Practice:
Want to know more about a particular pest?
Email us with your PestWatch suggestions:
hello@bpca.org.uk
Dee Ward-Thompson and Natalie Bungay
BPCA Technical Team
1 March 2017 | PPC90
Source: PPC90