Nontoxic Rodent Control

Rodenticides are expensive, counterproductive and incredibly destructive to wildlife and our shared environment. A recent study showed nearly 80% of raptors and other rodent consuming wildlife tested by WildCare were found positive for secondary rodenticide poisoning. 

(You may download and share the images on this page social media. Please link to hungryowls.org.)

(You may download and share the images on this page social media. Please link to hungryowls.org.)

Rodenticides provide a very slow and horrific death for rodents, usually taking several days after ingestion to actually kill. During those several days the rodent will still go out to find food and water. They will be sluggish and debilitated, and as a result, will be the first to be caught. This is often called the toxic food web.

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Whether or not you choose to use an owl box, we recommend using humane exclusion and an integrated pest management approach to control rodent populations humanely and without the use of toxic chemicals that harm wildlife.

Nontoxic Rodent Control without Owls

The below recommendations are based on hundreds of home consultations in the Bay Area, and years of experience with nontoxic and humane animal exclusion, including excluding rodents and animals that hunt rodents, such as skunks. These recommendations address the most common problems homes and businesses face in our region. These techniques work to humanely resolve conflicts with a variety of local species, both inside and outside of your building. If implemented diligently, these techniques will work on all but the most persistent of animals to get them to leave on their own so you can do the work needed to keep them out of your structure without harming any animals.

Deterrents

To encourage wildlife to leave an area you will need to add deterrents to the place where any animals are. Without effective deterrents the animals will most likely stay.

The most effective deterrents for all animals are based on the senses of the animal. We recommend deterrents that irritate the sight, sound, and smell of the animals to pressure them to spend less time on your property. We have to be careful not to use deterrents that are so strong that they could cause an animal to abandon their litter, but strong enough that they will successfully pressure the animal to find a more suitable home for themselves and any potential babies.

Visual Deterrents

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Light is one of the most effective deterrents. Many species choose spaces that are dark and quiet, so an effective deterrent would be to make the area bright and loud. Install lights where the animals are seen most often and it will help deter them. We recommend buying heavy duty string lights and hanging them where the animals are most active.

Bulbs should be 100-watt equivalent LED and daylight temperature.

Sound Deterrents

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Sound is another important deterrent. Putting a radio where the animals are on a talk radio station is an effective and safe deterrent. This is often underestimated, but is very effective if the humans can tolerate the sound. We recommend putting the radio out in a way that protects it from the weather and aiming the speakers toward the location where the animals are.

If neighbors are close by, do a sound test and ask them how loud they can tolerate it. We recommend getting on a phone with someone who can walk away from the radio and listen to how loud it is from a distance or inside a building. Turn it down one notch at a time until it’s tolerable for your closest neighbor. Once you have established an acceptable volume, leave it on 24/7 until the animals are gone. Even on three or four, having a radio on all day and night is a deterrent to most animals.

For burrowing animals we've found that underground audio deterrents work very well.

Scent Deterrents

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Scent deterrents are very useful, especially when combined with other deterrents. You can safely spray this homemade peppermint essential oil solution wherever animals are without worrying about harming them.

We recommend mixing it with water and isopropyl alcohol and using a spray bottle to apply it liberally anywhere that the animals are active.

In a standard 32 ounce spray bottle:

Humane Exclusion

One of the most important parts of living well with wildlife is making sure they can’t get into your home. This is called humane exclusion. Below are some of the most common ways animals find their way in, and how to deter the animals, confirm that they have left, and fix the structural issue.

Crawlspace Vent Covers

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If your house was built more than ten years ago you will most likely need new vent covers. Rats, mice, raccoons, skunks, and many other animals will find their way into your crawlspace through rusted or broken vent covers. We recommend that all homeowners test their vent covers yearly. Walk the perimeter of your building and give a light kick to vent covers. If they give way or have any cracked paint, rust spots, small holes or loose screws it is time to replace all of the vent covers on your house. They are typically under five dollars each.

We recommend solid metal vent covers with a mesh screen on back to keep insects out. Be sure to measure your crawlspace vents before buying.

Crawlspace Doors and Access Panels

People entering the crawlspace through a door or access panel often forget to close them securely when they leave. Rodents often use this as a way to get into the crawlspace. We recommend installing a standard self closing door handle, standard door hinges, solid wood or metal door, and a deadbolt with key or combination lock. This reduces user error greatly as most people are able to close a door without being reminded. Many crawlspace doors don’t have a standard handle and the bolts are often rusted, causing them to be left open. Where a standard door install isn't possible, two heavy duty barrel bolts on the top and bottom of the door are recommended.

Concrete Foundations

Rodents can dig under your foundation, and so can skunks chasing after rodents. We have responded to hundreds of calls where a rodent or skunk has dug a hole under the foundation of a house and accessed the crawlspace. Foundations are especially vulnerable on a slope. The more steep the hill, the more vulnerable the foundation. As a preventative measure, we recommend closely monitoring your foundation for erosion and digging, and using the trenching technique described below if a problem occurs.

Excluding Decks and Foundations

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Buy half inch hardware cloth. The roll should be at least 36 inches wide and long enough to go around the deck or foundation you are excluding. Dig a trench around your deck 12 to 18 inches below ground level and 18 to 24 inches out away from the deck. Attach one quarter inch wire mesh (hardware cloth) to the bottom of your deck so that it goes into the trench. Use screws and washers to hold the hardware cloth in place. Then bend the mesh at a 90-degree angle away from the deck into an ‘L’ shape at the bottom of the trench. Make sure you have 18 to 24 inches of mesh as the bottom of the “L” making a footer that animals can’t dig through. Then fill the trench back in with soil.

Be sure to use this technique only when a space is cleared of animals and you are positive none remain inside. If you know animals are inside, you need to leave a wildlife exit. See the wildlife exit section for more detail on this technique.

Leave a Wildlife Exit

Identifying and monitoring the single point of entry and exit that an animal is using is a key part of getting animals out of your building unharmed. Walk the perimeter of your building and scan from ground level to waist high as you go. The most common entry points are a hole under the foundation and a broken vent cover. If you find two holes and you are sure that they both lead to the same interior space, close one hole and leave the other one open. Once you have done the exclusion work needed to ensure that only one wildlife exit remains, you can begin to use wildlife tracking.

You will be tracking any holes on the exterior of the building for 72 hours. After 72 hours of inactivity, you can safely close the hole without worry of a trapped animal.

Animal Tracking

Animal tracking is the process you will need to use once all of the holes are closed up on your house, except for the wildlife exit you will be watching. Leave a single point of exit/entry into the animal’s living space and monitor the coming and going of the animal. Keep a wildlife journal of all activity. After you have monitored the animal you will begin to notice patterns.

Wax Paper

After you have isolated a single entry/exit, place a single sheet of wax paper over it and tape the edges in place. Don’t put tape in the middle, you want the animal to be able to easily break through the paper. Write the date and time on the wax paper so that you remember when it was placed. Check the paper daily, and replace it every time it breaks. Make a note of each time it is broken in your wildlife journal.

Flour

As a secondary measure you can sprinkle flour on the ground daily to track footprints. Make sure to sprinkle a fine dust across a large area, especially focusing on the ground immediately in front of the opening. Check daily and photograph footprints. Make note of all activity in your wildlife journal. Cover with new flour after documenting the activity.

Close the Exit

Be sure to double check the date in your wildlife journal. To be safe, ask all human residents in the building if they have heard any animal sounds in the 72 hours before closing. If they have, make note of the time and date in your wildlife journal, and start a new 72 hour count from that point. Once you have isolated a single point of entry/exit and there has been no animal activity, animal sightings, or animal sounds for 72 hours you can close up the entry point safely without harming wildlife.

Other Issues and Solutions

Attractants

There are a number of attractants that will cause wildlife to occupy your property. Food, water, finding a mate, giving birth, and finding shelter are the primary motivations of wild animals. If you have attractants on your property, many of the other things you can do to discourage animals may be counteracted by the presence of the attractants. Removing the attractants completely is always the best course of action, but there are some mitigating factors you can try as well.

Fruits, Vegetables, Nuts

Growing food attracts animals. Fruit trees, nut trees, vegetable gardens, compost and any other food plants will bring an entire food chain with it. From the animals that eat the plants directly, to the predators that follow, if you are growing food you are growing animals with it. The simplest thing to do is to completely remove any plants that are being eaten or completely exclude animals from accessing the plants. When you remove access to all food plants, animals will redistribute themselves over time to different locations where food is accessible.

Picking up fallen and ripe fruit daily can also help, but is a distant second to removing the access since many animals will eat even small unripe fruit and other food plants.

Excess Watering

Properties with a lot of green lawn end up attracting raccoons and skunks. Raccoons and skunks will tend to roll up and dig into the grass and other landscaping to get the grubs underneath. Reducing your watering as much as possible will cause the grubs to go deeper underground, making it more difficult for raccoons to forage. Once you have reduced watering enough, the raccoons will be forced to find other food sources, as the energy expended digging deep underground for grubs can’t be recovered by the nutrition they provide as a food source. Check with your landscaper about how much or how little watering is needed. If you’ve already cut back, another solution is to alter your watering schedule. Watering early in the morning can help. Fountains, bird feeders, fish ponds, and other water features provide hydration to wildlife. Remove these items if you have animals that you don’t want on your property.

Skunk and Other Odors

For ambient smells use the following solution. This works great for feces, urine, and skunks smells that linger, even after the area has been cleaned. if there are washable surfaces (like decking or concrete), the following mixture removes the smell pretty effectively:

  • 1 quart of 3% hydrogen peroxide

  • 1/4 cup baking soda

  • 1 teaspoon liquid soap

Mix into a large bucket of water and use a push broom or something similar to scrub any areas where there is a smell.

Ventilation

If you have undesirable smells that remain after the animals are humanely excluded, ventilation is key. Open windows to increase airflow. Place open boxes of baking soda (the more the better) in areas where the scent is strongest. Replace them weekly.

An industrial blower can clear a space of a smell quickly, but you have to keep in mind where the air is being pushed to and where it is being pulled from. Buildings with crawlspaces are designed to breathe, and the air naturally flows into the vents, into the crawlspace and then into your building interior. If there is a smell in your crawlspace, you want to place the industrial blower outside and orient the fans so that it is pulling air out of the crawlspace and pushing it into the exterior environment. Conversely, if you are pulling air from the interior living space and pushing it out the window, the smell from the crawlspace will be pulled into the interior living space.

Further Reading