Wildlife Biologist
Well-Known Member
Home Pest Squirrel Control
I am a retired wildlife biologist and these are some of my thoughts and observations/experiences of investigating pest gray squirrels in houses and other damage issues on the properties. Although most cases I have investigated involved predators, agricultural crop and other property damage caused by deer and feral hogs, pesky gray squirrels certainly cause their share of damage.
A little background:
The number of grey squirrels around a residence is greatly influenced by the availability of resources such as ample food, water, trees, nests, den trees, etc. The more resources in the yard the higher the carrying capacity will be. The number of squirrels on adjacent properties and their available resources will greatly influence the number of squirrels on your property. Trees and other avenues in which squirrels can travel from neighboring properties also influence the numbers of squirrels in the yard and subsequently the time required to reduce the squirrel population. Grey squirrels also like to travel on phone/cable utility lines, fences, and will even travel short distances on the ground and in hedge rows. Throw in fruit /berry trees, nut trees, oak trees, pine trees, bird feeders, etc. and they have a smorgasbord in which to attract them. Fruit & nut trees are squirrel magnets! Squirrels frequently travel 150 yards or so during their daily activities. Thus, with the availability of the aforementioned attractive resources, not only will you have squirrels living in your yard but also you will have squirrels traveling from adjacent properties to take advantage of the resources. Squirrels typically live several years in a residential environment. By exploring in previous years, squirrels have learned the resources available at different times of the year and will travel short distances daily from adjacent properties for them. They usually travel the same path in reverse back to the adjacent properties in the late evening to den. I have observed this behavior for years. This pattern becomes predictive and will aid in ambushing the squirrels. The fact that there are fewer predators in a residential environment results in less predation and coupled with the fact that there is usually no hunting will lead to longer lives and increased numbers of squirrels in municipal areas. Squirrels typically breed and have two litters of 3-4 young per year. With that many squirrels in a yard, there is a good probability some will seek to den in your attic or wall, especially if there is access to the roof.
In addition they often cause many other issues at a residence. I have investigated bark stripping damage by grey squirrels, eating of and damage to cultivated fruit /nuts, killing/eating of young birds in nests, disruption of birds at bird feeders, and nesting/chewing of wiring in automobile and other equipment. At this point usually removal becomes necessary.
Grey squirrels have become a serious conservation threat to native red squirrel populations in the United Kingdom and Ireland. Invasive grey squirrels have been introduced from North America to other parts of the world where they are causing pest and conservation issues.
Management of these grey menacing squirrels will be similar no matter where they are found. The following information is primarily meant to be for control of squirrels around the home but the management techniques can be extrapolated for control of invasive or pest squirrels in wooded forests.
Concerning squirrels in the attic or wall:
Most complaints of grey squirrels I have investigated are from homeowners with squirrels in their attic. Squirrels will readily take up residence in a building if access to sheltered areas such as eaves, attic spaces, or walls is available. Signs of squirrels in the house include gnawing, scratching, and scurrying around sounds in the attic or wall spaces in early morning or daylight hours and usually signal their presence.
I've been to many houses in which various scent deterrents and ultrasonic sound deterrent devices have been used, and none of them help at all, because a squirrel's survival/nesting instinct is so strong that it won't leave the attic just because of scent and ultrasonic devices. Let’s face it, by the time you even think about scent or sound deterrents the squirrels are already homesteaded in your house. Scent and ultrasonic sound devices simply don't work effectively as a deterrent. I have seen literally a dozen or more scent deterrents used by home owners or suggested because they read about it on the internet. I have observed that squirrels usually stay in the vicinity of the attic’s edge (eaves/soffits), which is well-ventilated with soffit vents, and the scent odors just don't help because the soffit ventilation disperses a lot of the scent. In addition the entire attic is too well ventilated using ridge vents, attic fans, gable vents/fans, and other ventilation. I have even seen the very cotton balls soaked with the deterrent scent incorporated into the nest in the attic. Research has confirmed the ineffectiveness of scent deterrents and ultrasonic devices. My observations concur with these studies.
Some have tried light/strobe light deterrents. The problem is that these aren’t enough to make the squirrels leave the attic. The practice of leaving a light on, or using a high-intensity light often isn’t annoying enough and the squirrels get used to it. If there’s a strobe light, they may move to another spot in the attic or just end up somewhere else in your home such as the walls. That is even a much harder problem to deal with, especially chewed wiring. It can cost many dollars for an electrician to rewire the effected parts of the house. Either way, squirrels are not going to leave an attic because of lights, most especially if they have already nested and young squirrels are present. Besides, the lights will have to be connected into existing wiring and/or batteries/bulbs changed etc. I can testify that crawling around in the attic is NOT fun (any time of the year) and doing so repeatedly is even less so.
Let's reiterate this, squirrel repellents such as light/sound/scent deterrents don’t work effectively. They certainly don't work to evict an animal that has already moved in.
To solve the problem, the squirrels have to be removed from your attic and around the property.
Trust me, it is probably best to not spread the word around about pest squirrel control activity or let neighbors see any of the aforementioned squirrel control measures. High privacy fences make good neighbors. I have investigated squirrels in an attic at a residence and the adjacent property owner would be feeding squirrels and enjoying watching them. If pellet guns are utilized for squirrel pest removal, it is advisable to use a moderator to lessen the sound. So…keep this in mind when conducting pest control of any kind.
There are actually a number of methods that you could turn to when it comes to removing squirrels from your attic, but not all of them are going to be effective, cost-effective, or worth your while. Your goal should be to remove the pest squirrels ASAP! The best thing to do once the squirrels are confirmed or suspected of being in the attic is first locate the entrance hole(s).
Once the entrance hole is discovered an exclusion device (door) can be used temporarily to seal the hole. This exclusion door can be bought commercially or made. The exclusion device is simply a one way door that will allow the squirrels to come out of the attic but not go back in. Therefore don’t permanently seal the opening at this time. If the attic is permanently sealed at this time any squirrels in the house will starve and possibly cause severe damage if trapped in the attic where they can’t get out. Once excluded the adult female can cause additional damage by chewing to regain entrance to reach their young. For this reason, after the exclusion door is installed, special attention should be given to the area and any squirrels observed should quickly be killed. I have found an exclusion door to be both an ethical and cost effective method of ridding an attic of pest squirrels. Because squirrels in the attic are known for gnawing electrical wiring and thus creating an imminent fire hazard, you or a qualified person should then gain entrance into your attic and survey for damage especially gnawed electrical wiring. Any damage to wiring should be repaired per international electrical codes ASAP! Look closely for structural damage in the attic and repair as necessary. While in the attic, look for signs of nesting like torn insulation, cardboard, paper, cloth, dried leaves and twigs to help pinpoint a nest. Many nests and young are within the eaves or totally concealed deep within the wall spaces. Because of this an inspection camera can be used to better look in these hard to reach or concealed spaces. The attic survey should include nest removal (if present) and if baby squirrels are found they should be disposed of in a humane way…more on that in the next paragraph. In addition squirrels can gnaw roof attic vents, gutters and do other damage resulting in roof leaks and severe rain damage to the home. Thus it is a good idea to include a roof damage survey. Immediately repair any roof structural damage.
It is a very good possibility that a single squirrel found in the attic (especially during breeding season) will be a female looking for a nesting area. During non-breeding months there may be multiple squirrels in the attic. Breeding seasons are not a given thing and vary in different parts of the country. If a breeding female has been in the attic any length of time, it may have already nested and given birth. Weaned squirrels will remain with the mother for some length of time thus stay in the attic and potentially do damage. Note some people don't consider exclusion door devices suitable for female squirrels with a nest of young, unless the young are old enough to leave the nest. Otherwise, you’ll just have a nest full of baby squirrels in the attic which will die of starvation if the mother squirrel on the outside can’t get back in because of the exclusion door. I stated previously I advocate the removal of young un-weaned squirrels and their humane disposal to prevent starvation after the female is excluded from the house. In my opinion you can't do otherwise and allow the female squirrel to have attic access to nurse/wean the babies because you risk the gnawing of wiring and the real possibility of a subsequent house fire or at a minimum an expensive repair to the wiring! I therefore advocate the immediate use of an exclusion door for any known squirrel activity in the house. Also any baby squirrels allowed to wean will ultimately have to be dealt with (eliminated) when they come out of the attic. Squirrels raised in the attic are very likely as adults to again regain access to your loft/attic in the future. So…
Once you have gotten the squirrel(s) out of your attic/building, you must do everything that you can to keep them out. You will need to make certain your home or building is properly sealed. Without the proper sealing of the house, you are letting not only squirrels into the attic, but possibly other wild animals too. This will involve removing the temporary exclusion door and properly/permanently sealing up the entrance hole and protecting your home to ensure other squirrels or wild critters can’t get back in, alongside making modifications to your actual property. At a minimum, removal of limbs, cutting trees back, trimming bushes giving access to the roof or house and adding flashing etc. where and if needed is essential. Stopping access to the house is imperative to prevent future incursions of squirrels into your attic! If access to the house is not controlled the problem may reoccur. Even with these measures I have observed instances where squirrels gained entrance into the house by climbing the outside walls, utilizing electrical service/cable/phone utility lines, utilizing ornamental English ivy growing on the walls, etc. These entrance points must be mitigated if possible. It is not uncommon for squirrels to get electrocuted at the power pole transformer while in route to or from a house.
Squirrel Eradication:
Now begin your squirrel eradication in the yard. This too is an essential step in pest squirrel control. Shoot and/or trap all you can! If you desire to use a squirrel feeder to concentrate the squirrels in an area to safely shoot them, ensure a safe backstop. Be certain to locate it as far as possible from the house and to remove the feeder ASAP when the squirrels are under control. Don't continue its use for the aforementioned reason. This part of the process to eradicate the squirrels usually takes months to accomplish. The squirrel population will never be completely eradicated. This is a frustrating experience. Squirrel control will be ongoing.
Removal of these pest squirrels should ideally include multiple methods. Shooting squirrels is probably the most recognized and effective method. Pellet guns are often used and sometimes they are the only appropriate or legal gun that can safely be used, especially in a populated area. Pellet guns are thus my weapon of choice for shooting pest squirrels. Although not an issue in the U.S. some countries have restrictions on airgun power. Where appropriate and if legal…firearms can be used to shoot squirrels. Always strive for a humane kill with a chest or brain shot. Any wounded squirrel should be quickly dispatched with a follow-up shot. Check and adhere to local and state laws concerning squirrel pest control, bag limits, seasons, and permissible weapons/methods. Many states in the U.S. have provisions allowing year round shooting/trapping of pest/nuisance squirrels causing damage to your property. In some countries gray squirrels are an invasive species and there are no bag limits or seasons. However, shooting pest squirrels is not the only means of their elimination.
Trapping, if permissible, is a very effective tool for squirrel pest control. Live cage traps can be used to capture squirrels alive. They should be placed strategically around the yard where squirrels are known to frequent. The best bait is whole or shelled peanuts. Another effective live trap is known as a “teeter totter” which is easily made from PVC and parts available at local hardware and home improvement stores. A word of caution, if you don't shoot the squirrels in the live traps but instead desire to relocate them, take them at least two miles and preferably several miles away for release or they may come back! Research has proven this. Releasing squirrels may be unlawful in places. Squirrels released in severe freezing winter conditions far from their home area may freeze if unable to find refuge in a den tree or drey. This certainly is a very likely scenario and would negate the humane practice of live trapping squirrels and releasing them. Because of this issue it is advisable not to live trap for release during severe freezing weather conditions.
I have used #110 conibear/body grip weasel box traps for trapping squirrels with very good results. The 110 body grip trap (commonly called a 110 conibear) is a small, single spring body gripping trap that typically measures about 4.5″ square. 110’s are used for trapping (killing) small animals like the muskrat, mink, weasel and squirrel. Check the internet for purchase and use. They are very affordable. I would again use whole or shelled peanuts for bait in the back of the trap box and just behind the trap. Strategically place sufficient numbers of these box sets around the yard where squirrels are known to frequent and far enough above the ground to keep out of reach of children and pets. If limbs are not accessible in which to place the box traps, the traps can strategically be placed on small platforms temporally constructed on the tree or placed on fences by the tree etc. By all means locate the trap boxes where the squirrels are frequenting. Instead of conibear traps, rat traps may be used inside the box. I prefer the double trap with one on each end. The rat traps are certainly less expensive and more available at local hardware/home improvement stores than conibear traps. The rat trap box may be the more viable or the only trap option appropriate if pets and children are present. I have used both conibear and rat trap boxes but prefer conibear trap boxes and believe them to be slightly more effective. Follow directions, using caution when setting the traps and determining the trap location(s)!
There are many examples of squirrel trap box construction on the internet. The box design is similar for rat trap and conibear trap sets. A basic box design is very similar to a classic mail box. If fact some people use mail boxes for the conibear traps. The biggest difference in the conibear box trap is that the end is left open to accommodate the trap. The rat trap design closes the opening leaving only a 1-1/2 inch diameter hole for the squirrel to gain access. There are many variations of the rat trap box design that will work. These traps can even be placed on the ground. Do not place squirrel conibear traps on the ground if pets or children may be present. Other squirrel trapping devices (of which there are many) such as the Goodnature A18 Squirrel Destroyer and the Squirrel Tube trap can be just as effective and should also be considered. Thus trapping of squirrels can be a valuable tool in controlling pest squirrels.
Also snares can be used for pest squirrel control if set properly. A series of snares can be attached about 18 inches apart to a 2x4 or bare limb and be leaned against a tree that squirrels frequent. Also the 2x4/bare limb containing the snares can be placed between two adjacent trees either horizontally or at an angle. The snare opening of each snare should be set to ~2 inches diameter. Any larger opening may allow the squirrel to pass through without getting captured. Place the bottom of each snare loop opening ~1 inch above the board/limb in which it is attached. This is the height that the squirrel will traverse and hopefully step into the loop.
Although shooting by itself is effective, ideally snares and trapping should at least be considered initially in conjunction with shooting to severely and more quickly reduce the pest squirrel population. Both snares and trapping have the advantage of working while you are not present to shoot the squirrels. After the initial successful population reduction, shooting may be the only method needed to keep the squirrel pest population under control. For various reasons snares and trapping are sometimes the only squirrel pest control methods available to a property owner or pest controller. If that is the case, the task of removing the pest squirrels is going to be prolonged and made more difficult.
Because of the dangers of toxic poisons I prefer to shoot the pest squirrels with an airgun and/or use snares/traps instead of utilizing poisons. In my opinion the use of poison is just too dangerous because of inherent issues which I won’t address here. However, where legal, some may choose to use poisons and some but not all of the inherent issues can be mitigated. The possibility of poisoning or collateral poisoning of non-target species (including pets) is just too great. Also some poisons may by law only be available for use by licensed pest controllers. In addition the poisoning of an animal results in a prolonged death.
Ensure that you aren't attracting the animals by mistake. Food is usually the biggest attractant; therefore bird feeders should not be used near the house or preferably not at all. They only serve to attract the squirrels thus exacerbating the problem. Even so called squirrel proof bird feeders are NOT exactly squirrel proof. Squirrels are very persistent in their attempts to gain access to a bird feeder and quite an acrobat. They usually find a way. They shake the feeders, etc. in their attempts. Even if the squirrels fail to get to the feeder, they can cause disruption to birds at the feeder. Besides the birds will knock out seeds from the feeder onto the ground and the squirrels will feed on them. The bottom line is bird feeders remain a food attractant. You might be surprised to learn that feeders are not the only attractant. Many natural foods and planted fruits and vegetables are attractive to a squirrel but it is infeasible or undesirable to go about their removal. Therefore you are left with removing the squirrels from your property.
If squirrel nests/dreys around the yard are accessible they should the destroyed. This however is usually not practical because they are too high in the trees. Squirrels also nest/den in hollow trees. Pay close attention to and target these trees when shooting/trapping squirrels.
As previously alluded to, squirrels often gain access to outlining buildings, automobile engine compartments and other equipment. There they build nest, stockpile nuts, and also chew the wiring. I have seen instances where greater than $1000 worth of damage was done to automobile wiring. I have even investigated squirrels in the chimney or inside the house. Elimination of squirrels around the home will hopefully prevent these issues.
Conclusion:
The ultimate goal should be ZERO squirrels on the property. That will never happen because squirrels will continue to move in from adjacent properties as you remove them from the property where the pest control is being conducted. That is why squirrel pest squirrel removal takes so many months. Over a period of about 10-11 months, I have supervised the removal of or personally killed/trapped 70 to 100 squirrels around individual residences having various property damage issues resulting from pesky gray squirrels. This is not an unusual amount of squirrels being removed from a residual property. Squirrels will become increasingly wary when the removal starts. You will have to be very stealthy when shooting them. I have found that a good quality high resolution thermal monocular aids in spotting the squirrels. I also use a 6x MTC Rapier Rangefinder to glass the trees and range the squirrels. Some residential dwellings have large properties that afford longer shots. A good rangefinder will serve both to range and spot squirrels. After the reduction, you will need to go into maintenance mode and keep the gray squirrels away from the house. The frequency of spotting the squirrels will become less. Weeks may go by without a sighting, but they will filter in from adjacent properties. Kill them when spotted. If not…you may have a “groundhog day”.
If you don't already have a squirrel issue in your house or yard, consider the appropriate preventative measures previously discussed to lessen the chances of pest squirrels homesteading your attic and causing other problems on your property. It is best to prevent this headache from happening.
I hope this information helps those who are dealing with pesky grey squirrels. Good luck!
Wildlife Biologist
In conducting residential grey squirrel pest control, I seldom advocate the use of a feeder unless needed to attract them to a safe area for shooting or to better hide from neighbors that frown on squirrel control. There is plenty of that. Squirrel feeders are not used in the States for hunting and to my knowledge are illegal for such as it would be considered baiting. In fact, from my experiences and interactions with hunters through the years I have seen squirrel and other small game hunting fall by the wayside in favor of deer and other big game. Squirrel populations for the most part in the wild are almost exclusively determined/controlled by predation and to a lessor extent disease/parasites. I am not aware of ANY pest control in the wild per se in my State other than pecan farms, fruit farms, etc. In the States grey squirrels are a game species with State regulations such as hunting seasons and bag limits. However most States have generous provisions for grey squirrel pest control. In the States grey squirrels are generally not problematic in the wild. The issues arise in municipalities for reasons given in the original post.
