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Nature Notes
by Bob Thomas

I’ve been plagued for several years with gnawing rats with bushy tails (i.e., eastern gray squirrels, Sciurus carolinensis). I love their antics, and don’t mind seeing them on my birdfeeders. In fact, I call my feeders wildlife feeders so the squirrels’ presence doesn’t make me angry.

Thankfully, the squirrels are not gnawing holes into my walls, and thus far have not gained entry into my attic. They are attacking the lead-clad roof jacks, or roof vent stack covers, on my roof, the pipes that we all have that vent our bathrooms and other plumbing.

The purpose of the lead covering is to prevent rainwater from leaking into the attic and resulting in roof rot. You can go years without having any animal damage to these roof jacks. It appears that once it occurs, the little gnawers (squirrels and rats) just can’t seem to quit.

Nobody really knows why squirrels gnaw on the lead. We do know that their incisors grow continuously, as do those of all rodents and some other groups, and that if they don’t wear them down by gnawing, the teeth will grow in a circular pattern until the tips don’t touch and the animals cannot gnaw to wear down the teeth. This malocclusion of the teeth results in death, normally due to starvation but sometimes due to the spiraling incisors actually penetrating the roof of the mouth and brain as they continue to grow. What a gruesome way to go.

I do wonder, though, if gnawing such soft metal wears on the teeth. I have to wonder if there is a craving that develops over time. We know that it has been well documented that children eat chips of paint and soil, each of which may have high doses of lead (although it still has some legal uses, lead was phased out of residential home paint between the 1950s and 1978, and in gasoline, as tetraethyl lead, between 1975 and 1986). Dr. Raoult Ratard, Louisiana State Epidemiologist, verified that lead doesn’t seem to create cravings in children. Instead, they passively ingest lead as they eat non-nutritive substances (we call this pica). One of my sisters couldn’t eat enough red clay when we lived in Alabama, but she was okay when we moved away – she didn’t seem to like the blackland prairie clays of central Texas.

A fellow at Lowe’s assured me that squirrels chew on the lead because it is “sweet.” He said people come in all the time looking for solutions to the chewed lead problem, and that thousands of leaks occur due to the rodents’ love for lead. Another customer told me they like copper and aluminum as well.

At first this was just a pain. Then I found a leak that damaged the ceiling in a bathroom. When I replaced the chewed lead covers, it cost about $100. A year later, I have about the same damage again. Enough is enough.

I assumed that poetic justice would prevail in the demise of the perpetrators from eating lead. Dr. Howard Mielke, expert lead researcher at Tulane’s Center for Bioenvironmental Research, told me that lead is normally absorbed into the bloodstream when it exists in very fine particles (nano-sized), resulting from sanding leaded paints or accumulating from exhaust in the days of leaded gasoline. He suspects that the larger chunks removed by the squirrels simply pass through their intestines and are deposited around my yard.

Others believe the lead does kill at least some of the squirrels, but not before they teach their hoards of littles to enjoy the metal.

So what is one to do when local squirrels take a liking to one’s roof jacks? Here is a list of options:
1. Have an animal control professional trap and remove your squirrels. Be aware that this will probably be a never-ending process and you will lose.
2. Replace, replace, and replace the roof jack covers.
3. Replace and paint them with coal tar, paint laced with cayenne pepper or Tabasco (doesn’t work as well on Cajun squirrels), or alum (aluminum sulfate) mixed in with a powdered paste.
4. Wrap them with layers of hardware cloth.
5. Place a neoprene stack boot flashing (Google for sources) over them.
6. Make your own plastic covers: 3 or 4 inch diameter PVC sewer pipe, topped by an appropriately sized ABS general purpose drain (with a heavy gauge stainless steel strainer to keep critters out); the whole unit is then slipped over the PVC pipe that extends above the roof line.
7. The best commercial product I found that appears to be squirrel-proof is the Critter Quitter vent shield (Avalon Manufacturing, LLC, This pipe is effective, attractive, and highly functional. They cost about $35 each, plus installation cost. If you are installing a new roof, that cost is negligible; if you are not, the avoided cost of roof damage from leakage is worth the price.

One fellow responding to a question in a blog gave his two-step answer to squirrel damage: one was an advertisement for a pellet gun and the other was a recipe for Brunswick stew made of squirrel! Obviously not from a Louisianan, since it was not a gumbo.

The best advice I have is to relax, go with the flow, and develop and implement a plan that works for you. The one thing I’ve learned is that the squirrels could care less that I’m concerned, and I don’t need to have a stroke over the anxiety.

I’m convinced that if I work at it, I can ultimately outwit a squirrel – maybe.


Eastern gray squirrels, Sciurus carolinensis,                                Roof jack with the lead covering eaten away
are very cute, incredibly interesting, and                                    by gray squirrels, or possibly rats as well.
sometimes quite a bother.                                                         Note that the lead covering was coated with
Photo by Rene Guas.                                                             coal tar, and it obviously had no effect
                                                                                              on the gnawer.
                                                                                                 Photo by Bob Thomas.


Another roof jack with the same issue. On                                  My first attempt to beat the squirrels. This
this one, the lead flashing has also been eaten.                           homemade roof jack cover is effective, but
Rainwater now easily runs into the attic                                      there is still leakage of rainwater.
between the lead jack and the PVC vent pipe.                             Photo by Bob Thomas.
Photo by Bob Thomas.

A Critter QuitterTM showing a typical installation.
I plan to replace by roof jacks with these.
Photo by Avalon Manufacturing, LLC.