Snake Exclusion — How to “Snake-Proof” Your Yard & Home 3

—  This article by Jerry Cates, first published on 23 March 2010, was last revised on 24 April 2016. © Bugsinthenews Vol. 11:03(20).

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If you are being troubled by snakes, don’t despair. It is possible for anyone willing to study the issues involved, learn what is required, then take matters into their own hands and fix things so that they may never see a snake in those places again. Below are a number of important steps you can take to reduce the chances of having a future  snake encounter. If these steps are followed carefully, you should be able to live in a reasonably snake-free environment.

Let’s start by taking stock of two important caveats related to snakes and snake exclusion:

FIRST: Many home or business owners are equipped to properly perform a serpent removal and exclusion project at their homes or businesses, but some are not. If you don’t have the time or interest needed to (1) study the technical issues involved, (2) tackle the necessary mechanical habitat modifications, (3) obtain and properly use the protective gear needed to avoid injury from the snake and its associated disease-causing organisms, (4) inspect for, find, and then seal all the ingress/egress ports in your home’s or business’s exterior, (5) clean up, disinfect, and remove the contaminants left behind by the snake, and (6) do all this within a reasonable time, you should consider hiring a wildlife specialist with expertise in reptile biology, removal, disinfecting and control. To find a qualified wildlife specialist in your local area (anywhere in North America), call Jerry RIGHT NOW at 512-331-1111.

SECOND: The information provided here applies specifically to areas in North America. Species of snakes in other regions around the globe behave differently enough that additional measures may be required, and some of the measures advocated here may not be suitable. Even in North America, your particular situation may be so unusual as to require special measures not described in this article. Readers are encouraged to contact me directly, and to post comments below, that can be used to help me cover as many situations as possible. And, of course, your suggestions, criticisms, and ideas are always welcome.

1. Before doing anything else, survey your home, yard, and neighborhood for potential snake, mouse, or rat feeding or harborage areas. Any place that is hospitable to mice, rats, toads, frogs, and geckos, is also highly attractive to snakes, because rodents and anurans are the favorite prey of most snakes. This includes our common rat snakes, hog-nosed snakes, and garter snakes, but also our venomous pit vipers such as copperheads, cottonmouths, and rattlesnakes. Venomous coral snakes, too, favor places where they can find abundant prey (mostly small snakes), and ready-made shelter. The most likely places where snakes and their prey congregate involve

a. The vicinity of, and sometimes within, bird feeders* (except hummingbird feeders),

b. Within and around woodpiles,

c. Within and around rock piles,

d. Within and around piles of leaves, tree limbs, or weeds,

d. Within and around stacks of debris, masonry**, or un-racked firewood*** lying on the ground,

e. Within expanses of uncut weeds or grasses, both in the yard, and bordering the yard within 10 feet of the yard perimeter,

f. Within the confines of thick and impenetrable shrubbery, and

g. Occupying harborage space in, around, and beneath structures such as fence and foundation voids, mobile homes, homes and/or garages on pier & beam foundations, sheds, dog houses, playhouses, and the like.

2. For all but the last item in the above list, the obvious fix is to correct and/or remove these feeding and harborage areas from your yard. However, except for bird feeders*, it is generally unwise to undertake such removal operations without first observing certain precautions, and then planning the removal carefully. These considerations are covered in more detail under paragraph 5, below.

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*Regarding bird feeders: Watching the birds that visit feeders that are well-supplied with birdseed, grains, and other forms of food favored by our avian friends evokes a primal joy in the human breast that, once enjoyed, begs to be repeated. Unfortunately, the ground under most bird feeders quickly becomes littered with the same food materials that rodents love. Hummingbird feeders are exceptions, as the liquids in such feeders are unlikely to attract rodents. Certain kinds of “Rodent-proof, Snake-Proof, and Squirrel-Proof” bird feeders are provisionally exceptions to this rule, too, but most that claim to be rodent-proof, snake-proof, and/or squirrel-proof fail to work as advertised, especially when they are not maintained properly. Properly maintaining such feeders often entails a lot more work than most people are willing to expend. Some require the use of special attachments that, if omitted, render the feeder as susceptible to rodents, snakes, and squirrels as any other feeder. For example, some so-called “rodent-proof” feeders instruct the user to rake up the spilled birdseed under them once a week, as if rodents only visit such places every seven days or so; even if that were true (it isn’t) can you see yourself or anyone else spending an hour every week — without fail — wielding a rake and a garbage bag, carefully raking up, bagging, and disposing of all the spilled seeds under every bird feeder in your yard?

——Wherever ordinary bird feeders containing birdseed, grains, or other solid forms of bird food are found, rats and mice will also be abundant and well-fed. Those rats and mice have to live somewhere, too, and if they can find a way into your home, nursing facility, hospital, or commercial building, they will take up housekeeping there. The rodent feces and urine that quickly accumulates in such areas, and under the bird feeders that attracted them in the first place, are efficient attractors of snakes. Therefore, if you don’t want snakes in your yard or inside your structure, don’t place bird feeders anywhere in your yard. Sadly, the presence of bird feeders inevitably leads to the presence of rodents, and the latter inevitably leads to the presence of snakes.

**Regarding stacks of masonry: it is common for homes and businesses to have, somewhere in their yards, one or more stacks of bricks, cinder blocks, building rock, etc. Often these represent left-over masonry products from initial or add-on construction at the site. Because such materials have a high economic value, the temptation to retain them — in expectation that they will be useful in a future construction project — is great. Too, such materials weigh so much it isn’t easy to move them out of the weather to a covered spot, on concrete or on an elevated platform, where they are less likely to provide habitat to rodents and snakes. All those excellent “becauses” aside, stacks of masonry on the ground provide outstanding cryptic harborage for rodents and snakes, emphasis on cryptic , a word with Greek roots (κρυπος) that means “hidden, concealed, secret.” The rodents and snakes hidden in such grottoes are concealed so well from view you won’t even suspect their presence. Their travels, however, from those places of concealment to other parts of your yard and home will soon become problematic, and you’ll wonder why. 

——One important precaution is to treat the voids of such stacks with rodenticides, to exterminate the rodents that loiter and feed there before they set up housekeeping But what does “regularly” mean? Mice tend to move within a relatively small area, while rats migrate over large ranges, so the pressures they pose vary by the season, the prevailing weather, and the availability of nearby food sources. This means, from a practical perspective, that the stacks need to be inspected and treated on a case-by-case basis, sometimes daily, other times weekly or monthly, which is not practical for most home and business owners  However, new EPA Regulations, which went into effect in June 2011, prohibited the use of rodenticides in outside settings that are more than fifty feet from a structure (defined by EPA as a building with walls and a roof); thus, if masonry stacks are more than fifty feet from your home or any other structure, you (even if you are a licensed, professional pest exterminator) could no longer legally bait such locations with rodenticides. Pause for a second and reflect on how “far” fifty feet is… My back yard fence is over 75 feet from the back of my home, so — for me — fifty feet isn’t very “far” at all… The lesson? Bite the bullet and get those stacks of masonry out of there. Otherwise, you will suffer considerably from rodent and snake problems, no matter what else you do…

***Regarding un-racked firewood lying on the ground: a disorganized pile of firewood invites all kinds of animal and insect life, and — once established — such piles pose hazards to all who later attempt to reorganize them (due to the likely presence of potentially venomous serpents hidden in the pile). If the pile is, at its lower reaches, in direct contact with the ground, termites are also attracted to it, and subterranean termite colonies often get a start in such places from whence they later become able to launch an attack on homes and other structures. Thus, it is never wise to permit the existence of piles of un-racked firewood lying on the ground. Instead, raise all firewood off the ground, with at least 4-6 inches (preferably 12-18 inches) of space between the wood and the soil. The firewood should be arranged in racks that are never more than one length of firewood thick, because double or triple racks provide abundant interior space in which vermin may live and hide.

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3. For harborage space in, around, and under structures that serve important functions, the fix is to seal such spaces wherever possible using

a. sand, decayed granite, or fine gravel to fill voids in dry stack rock fences, gaps between patios and home foundations,

b. hardware cloth with a mesh of 1/4th inch or less for gaps that require ventilation, burying the bottom 6-12 inches of hardware cloth in the soil,

c. caulk, metal sheathing or wood planking for gaps that do not require ventilation

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Caution: note first that if you are not sure if ventilation of the sealed void will be compromised by the contemplated sealant, it is wise to consult someone in the building trades for advice, as tightly sealing a space that is subject to constant or intermittent high-moisture conditions will lead to wood rot; second: never place wood in contact with the soil, to avoid the risk of a termite infestation; third, if the void you are sealing presently houses mice or rats, it is wise to treat such voids with rodent baits first, before sealing the void (see the comments on this under para. 5, below); and fourth, if the void you are sealing presently houses larger animals, such as feral cats or dogs, or sylvan animals such as foxes, armadillos, opossums, raccoons, squirrels, or skunks–the void should be sealed with a one-way door that allows the animal to exit without letting it re-enter; however, sealing the void at the wrong time of year may lead to the presence of a litter of young in the void, and that can lead to nasty results; in such cases it is wise to consult a wildlife biologist or animal control specialist for advice before proceeding.

Regarding sealing your home to prevent rodents and snakes from entering from outside:

Many authorities recommend (foolishly, in my opinion) the use of caulk and other liquid/gel/silicone and similar sealants (as opposed to the use of hardware cloth and other screening materials) that fully obstruct any and all ingress/egress ports that your home or business has in its outer walls, and in its roof.

In my experience, which spans more than fifty years of working with residential and business structures in Missouri, Florida, Georgia, New York, and Texas, it is generally unwise to undertake vigorous sealing projects of that nature to fully seal all potential ingress/egress ports in a building. In the process, one inevitably obstructs and closes off the routes by which moisture in interior walls and voids is wicked and ventilated to the outside.

Normal wicking and ventilation of moisture accumulations in wall voids reduces the risk of wood rot and fungal growth. On the other hand, anything that restricts the flow of air between the home interior and the outside environment can lead to the creation of a wide variety of health issues. Health professionals recommend that the entire air-content of a home be fully exchanged with outside air at least twice and preferably three times a day, so that collections of toxic fumes from furnishings, cooking appliances, etc., will remain within healthy limits. Homes that are carefully sealed with caulk/gels/silicone or similar sealants to prevent entry of rodents, insects, and snakes, inevitably trap moisture and toxic gases inside the home. That is not only unhealthy for the structure itself, it is downright dangerous for the humans and pets that occupy that structure.

Instead of relying on practices that restrict airflow, use screening and hardware cloth wherever possible, and consider taking as many steps as appropriate on the outside of your home or business to create an environment that neither nurtures nor attracts pests of any kind.

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4. For harborage areas that are not under your control, find out who is responsible for them and courteously (remember, courtesy is contagious, so it’s a good bug to catch) request, preferably in writing, that they be corrected or removed. If such harborage areas are on property belonging to a business or governmental entity, consider taking photographs to support your complaint, and submit them along with your written request that corrective action be taken. Do not be dismayed if the business or governmental entity you deal with is less than cooperative. It seems more typical today than in any time in the recent past that some businesses and governments tend to think that they are not responsible for the health hazards that exist on the properties under their control. If you experience a lack of cooperation, document the conditions well, with photographs and text, and take your case to the next level. You may have to become something of an irritating gadfly, willing to — as the I-Ching of all wisdom, the Godfather puts it — “go to the mattresses” to get things done. Eventually you will prevail, even when the law is on their side (e.g., in some locales, home-rule cities cannot be forced, legally, to correct the health hazards they create, but I have yet to find a corporate body or city council that won’t undertake reasonable corrections, after having the unsavory consequences of their actions repeatedly pointed out under a veiled threat of public exposure; I speak from experience on this).

5. For all snake, mouse, or rat harborage areas under your direct control, it is wise to begin dealing with them by taking precautionary steps to prepare them for correction or removal: these include

a. treating the harborage areas with a commercial mouse & rat bait, carefully following the directions on the label for the bait that you use, and waiting a suitable period of time to ensure no mice or rats remain in those areas (there are no baits for toads and anurans, but removal of harborage will suffice to cause them to move elsewhere, the moment their food supply disappears);

b. treating intractable harborage areas with a snake repellent, carefully following the directions supplied by the manufacturer for the snake repellent of your choice, then waiting a suitable period of time to reduce the risk that snakes remain in those areas.

After the above precautionary steps have been carried out:

6. Remove the harborage areas completely, or pay someone else to have the harborage areas removed for you. BUT REMEMBER THIS FIRST: Snake harborage areas may continue to harbor snakes, even after you have removed their prey and treated the area with snake repellent, as they remain attractive as places of congregation. Before contracting with someone to remove harborage areas for you, first make sure they have the competence to know what they are doing and are willing and able to accept the risks involved. When attempting to remove woodpiles, rock piles, piles of debris, etc., yourself, first take appropriate precautions, including but not limited to, (a) wearing heavy, leather, and, if possible, specially constructed snake-proof boots on your feet, ankles, and shins as far up the legs to the knees as possible, overlain loosely with denim trousers that droop over the ankles, (b) following safe practices such as never disturbing a portion of harborage with a hand or foot; use a long-handled pry-tool instead, and (c) taking the time to carefully scrutinize the materials and surfaces underneath all the harborage you are removing, using a bright flashlight or other bright light source capable of illuminating all the snakes that may be hiding there.

Suggestion: If possible, conduct harborage removal during the winter months, when outside temperatures are low and cold-blooded reptiles are more likely to be hibernating underground (but remember: snakes may still be found in such areas, and though they will be sluggish from the cold, they can still bite). Also, conduct harborage removal during daylight hours, on a sunny day, when you will have good visibility and will be more likely to observe a snake that is being sheltered beneath a portion of the harborage that you are in the process of moving.

7. Once all the harborage areas under your control have been removed,

a. regularly treat your home, garage, sheds, and storage areas thereafter with mouse and rat bait (always follow the label directions, to the letter) to ensure rodents will not take up residence in such areas in the future,

b. regularly treat the perimeters of your yard, home, sheds, and shrubbery with a snake repellent or non-repellent habitat modifier, replenishing those treatments in accordance with the manufacturer’s directions for the snake repellent or non-repellent habitat modifier of your choice,

c. keep the grass in your yard, and on the border of your yard within 10 feet of your yard’s perimeter, and maintain the grass throughout your yard at a height of no more than 2 inches at all times, and

d. frequently check for and correct all new rodent and snake harborage areas that pop up over time, keeping in mind that such areas tend to arise unbidden as the natural accompaniment of ordinary life, and should be found and remedied as quickly as possible in order to keep the risk of snake encounters as low as possible.

Related Links on BugsInTheNews:

• North American Snake Markings & Coloration Guide.
• Ophidian Dentition — Snake Teeth & Fangs — Morphology & Specialization
• Snake Anatomy, Physiology, and Taxonomy.
• Snake Repellents — How, and How Well, do They Work?
• Snakebite First Aid.
• Snakes, Rodents, & Droughts.
• What is Meant by “A Reasonably Snake-Free Environment”?
• Cottonmouths & Copperheads in Travis and Harris Counties, Texas — June to August, 2010
• Western Cottonmouth (Agkistrodon piscivorus leucostoma, Troost 1836); Tammy D., Santa Fe, TX — 28 Aug 2011
• Western Diamond-backed Rattlesnake (Crotalus atrox, Baird & Girard, 1853), Cedar Creek, TX — 22 Oct 2010

Related Links:

• Habitat Modification for a Nurturing and Attractive Environment.
• PestAvoidance

References to Scientific Articles, Books, and Papers:

• Arikan, Hüseyin et al. 2008. Electrophoretic characterisation of the venom samples obtained from various Anatolian snakes(Serpentes: Colubridae, Viperidae, Elapidae). N.W.  J. Zool. Vol. 4, No. 1, pp.16-28.
• Birchard, Geoffrey F., et al., 1984. Foetal-Maternal Blood Respiratory Properties of an Ovoviviparous Snake; the Cottonmouth, Agkistrodon piscivorus. J. exp. Biol. 108, 247-25
• Chao, Betty H., et al. 1989. Agkistrodon piscivorus piscivorus platelet aggregation inhibitor: A potent inhibitor of platelet activation. Proc. Natl. Acad. Sci. USA Vol. 86, pp. 8050-8054
• Chippaux, J. P., et al. 1991. Snake Venom Variability: Methods of study, results, and Interpretation. Toxicon Vol. 29, No. I I , pp. 1279-1303.
• Conant, Roger, and Joseph T. Collins, 1998. Reptiles and Amphibians — Eastern/Central North America, Third Ed. Peterson Field Guides. Houghton Mifflin Co.
• Cundall, David. 2009. Viper Fangs: Functional Limitations of Extreme Teeth. Physiological and Biochemical Zoology 82(1):63–79.
• Deufel, Alexandra, and David Cundall. 2004.Functional plasticity of the venom delivery system in snakes with a focus on the poststrike prey release behavior. Zoologischer Anzeiger 245 (2006) 249–267
• Grachevca, Elena, et al., 2010. Molecular Basis for Infrared Detection by Snakes. Nature, 15 April 2010.
• Greene, Harry W., 1997. Snakes: the Evolution of Mystery in Nature. University of California Press.
• Schulz, Klaus-Dieter, 1996. A Monograph of the Colubrid Snakes of the Genus Elaphe Fitzinger. Koeltz Scientific Books.
• Tennant, Alan,1998. A Field Guide to Texas Snakes, Second Ed. Gulf Publishing.
• Weinstein, Scott A., et al. 1994.Reptile Venom Glands — Form, Function, and Future. Handbook of Venoms and Toxins of Reptiles. CRC Press.
• Werler, John E., and James R. Dixon, 2000. Texas Snakes. University of Texas Press.
• World Health Organization. 2002. Management of Snakebite and Research. WHO SEA-RES-2.
• Zaidan, Frederick III, 2002. Variation in cottonmouth (Agkistrodon piscivorus leucostoma) resting metabolic rates. Comparative Biochemistry and Physiology Part A 134 (2003) 511–523
• Zamudio, Kelly R., et al., 2000. Fang tip spread, puncture distance, and suction for snake bite. Toxicon 38 (2000) 723 – 728