TECHNICAL | PPC113 November 2023

Grey squirrels went from an imported ornament for stately homes to an invasive species that threatens our own ecosystem. Dave Archer talks about the problem with grey squirrels, modern attitudes to invasive species and how to approach grey squirrel control.

Initially, I recommend taking a look at the legislation pertaining to these animals, even if you think you are familiar with the legalities. It’s always useful to refresh your knowledge on the laws that affect your role.

Grey squirrels are classified as non-native pests, which means that they are subject to severe restrictive clauses in law; all of which are too involved to repeat here, but details are available on the GOV.UK page on invasive (non-native) animals.

Rule number one, that all good pest controllers should know: once in an (approved only!) trap, a grey squirrel must not be re-released into the wild.

How did grey squirrels find their way into the British countryside, and when?

In the past, the consensus of opinion was that different species of non-native fauna and flora, whether released by design or accident, would add to the diversity and attraction of our wildlife.

And so this was done with grey squirrels in 1876, with little or no historical experience of the detrimental impact such action would take.

Think of Reeve’s muntjac, sika deer, edible dormice, signal crayfish, Spanish bluebells, rhododendron and so on.

Once the genie was out of the bottle, the odds of sealing the stopper again were always in favour of the escapee!

Can’t we live and let live?

Why is there so much of a problem with greys? Well, they have driven red squirrels to the brink of extinction in the UK, either by being a more aggressive species or by infecting them with the fatal parapoxvirus.

Grey squirrels are vectors of this disease, but not affected by it themselves. Instead, they spread it to native red squirrels and cause devastation among populations.

They are incredibly destructive, damaging trees such as beech, oak and chestnut. They strip bark from trees, which weakens them and they may eventually die, wreaking havoc on historic and ancient woodlands.

Additionally, they cause damage to property; window frames, woodwork, doors, soffits are all gnawed to keep their teeth razor sharp and gain access to feed stores or homes.

However, while we as pest controllers may see the downside of grey squirrels, there are an increasing number of members of the public who do not agree with this.

Greys are actively encouraged and fed by a sympathetic population, and one must bear this in mind if any form of control is undertaken.

Unpalatable it may be to hear, but these days a TV personality’s point of view on wildlife issues will generally be more influential to the general public than that of a qualified pest controller.

However, managing their populations is our responsibility, so what tools do we have to help with that?

Live trapping

In our favour, grey squirrels will trap easily, having little fear or suspicion of man. Of course, this is tempered by the skill and experience of the trapper.

The advantage of a live trap is that if any non-target species are captured, releasing them is a fairly simple operation.

As part of an ongoing risk assessment, one should always question why and how non-targets entered the trap and if improvements in the treatment plan can be made.

Always secure the traps! A trapped squirrel can easily roll a cage trap away, even if it is trapped inside.

Secure it with metal (not plastic as it can be chewed through) or even better, wire the trap to a secured point. Dog lead clips, bird crimps and netting wire are ideal for these situations.

But never underestimate a squirrel’s intelligence, cunning, or physical abilities! Grey squirrels are extremely tough characters in all senses of the word.

The Elgeeco cage trap is a simple but very effective method of cage trapping squirrels. Personally, I cannot recommend it highly enough.

Even if the door closes before the squirrel enters the cage it will not alarm the squirrel; moreover the squirrel thinks the door has closed to prevent its entry to the food source! 

Should you choose to trap using traditional ground cages, ensure the cage is large enough for your chosen target species. Too small and you could be breaking the law – again due to welfare issues and confinement.

And, remembering those animal welfare opinions, ensure live catch traps are hidden from the sight of neighbours and the general public. Also consider the trapped animal's food and shelter needs, and bear in mind that a grey squirrel in a cage trap can be a very noisy animal indeed.

Consider how you will remove and dispose of any live trapped squirrels, which will sometimes spray a line of urine at the trapper in a last attempt to thwart them!

Ensure that your customer signs a declaration to say they are the authorised landowner and will not interfere with any traps.

They may sign to state they will only visually inspect live traps daily (as is a legal requirement) and contact you immediately if any squirrels are caught, only if you feel this is workable in the given situation.

Spring traps

These must be covered to prevent non-target entrance by law and you cannot use spring traps wherever stoats may be present. It may seem obvious, but if your traps kill non-target species there is no chance to amend the situation for the victim. And it will be your fault! 

Make part of your risk assessment about ensuring zero risk to non-target species. Your RA is a working document, so if something changes, change the assessment. Badly-set traps or poorly-designed (even artificial) tunnels can kill unintended victims.

Set traps will weaken the springs over time, so test their efficiency on a regular basis. If you have never set lethal traps, don’t attempt to do this without adequate training, otherwise broken fingers may result.

There are many and varied spring traps available these days but, for me, original Fenns were and are the best. Ensure your traps have Fenn stamped on the treadle (either Mk4 or 6) with two letter Ns and ‘Made in England’ on the pressure plate, or they are inferior imports!

For a better success rate, chum an area with a variety of fresh baits to see what the preference is, and leave spring traps baited in secure areas with the safety catch on until you are sure the squirrels have gained confidence in your traps.

But never underestimate a squirrel’s intelligence, cunning, or physical abilities!

Grey squirrels are extremely tough characters in all senses of the word – you must not equate them (as is often heard) as rats with bushy tails.

Any spring traps must be checked for efficiency.

Shooting

Possibly the most controversial method of control. Whether by air-rifle, rimfire rifle or shotgun, not only must you fully consider and compile a written risk assessment of your actions, but you should be discreet. 

In some situations, you may feel it appropriate to inform the local police force that you will be carrying out pest control with firearms, to prevent misunderstandings and head off any backlash.

Should any person who is in favour of grey squirrels be aware of your action, then expect the full gamut of emotions and possibly worse to be directed personally at you!

Again, your customer should sign a declaration that they are the authorised landowner.  In rural areas where boundaries may not be clear this is imperative.

Freshly shot squirrels may bleed onto inappropriate areas. To this end, always cover any carcasses before removal to prevent distress in other people. This must all be part of your experience and risk management.

We’ve already mentioned how tough grey squirrels are, so make sure weapons are of suitable design and power to allow for this.  

If you are using a gas-powered air rifle, have you ensured it is calibration tested to below the legal limit of 16.3Nm (12ft-lbs). Above this and it falls into the firearms category and you may have just unwittingly caused a serious firearms offence!

Another salient point to bear in mind is the fact that a customer reporting a few squirrels in a garden may actually have a very large infestation. The few they think they are seeing all the time may easily be in actual excess of twenty or thirty.

Your efforts may well serve to produce a temporary vacuum for others to very quickly fill. Think of urban feral pigeon control as opposed to proofing and you start to see the picture.

Your customer will be loath to pay for a control service, only to find more squirrels appearing in a matter of (sometimes) only days!

WANT TO LEARN MORE? 

Grey squirrel control for pest professionals is a training course led by Dave Archer and facilitated by BPCA. 

Find out more