Expert: Stephen Vantassel - 10/29/2009

Question
Hello Mr Vantassel.  THis is a query about mice damaging wires etc under the bonnet of my husband's Jeep. We live in Scotland (not known for EXTREME wildlife ! ) The house is old, situated in countryside on a shooting estate. There is no possibility of housing our vehicles inside, and the garden is surrounded by working farms, so reducing the mouse population is unlikely!  We have lived here for 7 years, and this problem is not constant - occurring only once before, when actual mousetraps became necessary INSIDE the vehicle.  However, this time the Jeep was immobilised and  had to be taken away for repair, so completely thorough was the destruction! The wires connected to spark plugs etc were chewed through.
Can you offer any help?
many thanks, Jean Henderson

Answer
Protecting vehicles from Wildlife damage


Protecting vehicles from wildlife damage requires a three pronged approach. Although employing all three prongs is ideal, it isn’t always practical. However, implementation of as many of the concepts as possible will increase the protection.

Normally, rodents such as mice and rats are responsible for damaging vehicles, although packrats can also be a culprit if you live in the S.W.. They can get up into the engine area, chew things and build nests. Rabbits, squirrels and even turkeys can also damage vehicles. Rabbits and squirrel damage will be similar to rodent damage but turkeys damage cars by pecking at the paint.

There are no long-term repellents that will resolve this problem. Odor repellents will fail as there will be too much air around and it will dilute the efficacy of the odor (assuming it works to begin with) Don’t bother with ultrasound. There is no evidence that it actually works in the real world. See http://www.icwdm.org/Prevention/repellents.asp  it has a link on ultrasound and why it fails too.

Since most damage is caused by rodents we will discuss solutions for those.

Prong 1. Habitat modification.   

If rodents can live in the area, they can’t be around to damage your car.  Remove or modify bird feeders http://www.icwdm.org/Prevention/birdfeeders.asp (contrary to popular mythology squirrels can be kept off of feeders), cut grass low, remove debris and anything where mice/rats can hide.   Make sure water sources are also eliminated as much as possible. Don’t feed pets outdoors.
Nature believes in supply-side economics, which teaches, where there is a supply there will be a demand to meet it. So if you have food around, the population of critters will rise until the food is consumed.

Prong 2. Prevent Access.   

Place your vehicle inside a secure facility, like a garage. Make sure you have tightened it up so that mice and rats can’t enter. This requires that gaps ¼” or larger be filled. Doors should seal securely, and attic vents should be screened with  ¼” hardware cloth.  Since mice are harder to keep out than rats, information on mouse control can be found at http://icwdm.org/wildlife/housemouse.asp
We have not heard of chipmunks nesting in vehicles but we can’t rule it out without more information. So for chipmunk control visit http://www.icwdm.org/ControlMethods/default.asp

Prong 3. Population reduction.

Rodent populations can be managed with traps and toxicants. Understand that the war on rodents will NEVER end. Don’t be misled that if you trap for a while you will never have to trap again.  Just as grass grows back after you mow, so rodent populations bounce back after control. Placing traps inside rodent stations should protect pets. Regarding toxicants, risks to pets can be reduced by using bait stations, block baits, and anticoagulant bait. Details on these techniques can be found in literature on the links already mentioned. Just a note. You DON’T have to eliminate all the mice (which is close to impossible anyway), just the mice that approach the vehicle. Like burglars, you don’t have to stop burglary, just the ones trying to enter your home.

Caveat.  It is easy to mis-identify the cause of the vehicle damage. People tend to blame the animal species they see, so they bias their accusation against squirrels and rabbits. While those animals can gnaw, one should never forget that mice and rats are far more prevalent then they think.   We would love high quality images of damage. Sometimes, the gnaw marks can help us narrow down likely suspects.  

This is especially true if you don’t employ habitat modification.   Be sure to follow all laws and regulations when trapping and using toxicants. For non-state specific information on control you can visit http://icwdm.org/wildlife/housemouse.asp for house mice   or http://icwdm.org/handbook/rodents/Woodrats.asp for woodrats/packrats.  This can be a starting link for you to the rest of the site.  http://www.icwdm.org/handbook/rodents/TreeSquirrels.asp Tree squirrels.

We would love to get pictures of the damage you are suffering if you can do so safely. Visit http://www.icwdm.org/Photos/shootingphotos.asp for tips on taking better photos.  High resolution images are highly appreciated (3 mg or higher). Help us educate others by sending them to svantassel2@unl.edu  we also scan prints and return them with digital versions as our thanks.

Disclaimer: As with any activity, remember that animal damage control comes with its own risks and problems which can include but are not limited to legalities, health threats, and personal liabilities. Be sure to follow all state laws governing wildlife and make sure you have a thorough understanding on how to resolve the animal damage complaint. My advice is only as good as your understanding of me and my understanding of your situation. If you have any questions be sure to write back.