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Damage to Tree Bark
Fox squirrel (Sciurus niger) and gray squirrels' (Sciurus carolinensis) damage to tree bark (called bark stripping) can be quite severe. See photo at
right by Dallas Virchow.
We have recently heard from a gentleman in Pennsylvania that red squirrels (Tamiasciurus hudsonicus) also strip bark. We would love to hear from anyone who has had similar experience.
Identification of Bark Stripping
- Fox squirrels exist in the middle portion of the continental U.S.
- Gray squirrels exist in the Eastern portion of the continental U.S.
- Typically, strippings are 1/2 inch wide and three to six inches long. Other small limbs branches of one- to two-feet in length and 1/4 to 1/2 inch diameter are clipped and dropped to the ground.
- Squirrels prefer to strip branches that are horizontal, but have been known to strip trunks too.
- Bark stripping usually occurs in late winter. But it can occur in the spring if trees don't produce mast.
Types of Trees Stripped
- Autumn Olives (NE)
- Ginkos (TX)
- Hackberry (NE)
- Honey Locust (NE)
- Maple (FL, MN)
- Maple, Japanese (TX)
- Maple, Red (NE)
- Maple, Sugar (MN)
- Oaks--various varieties (TX)
- Poplar (GA)
- Poplar (Tulip Variety)
- Sycamore (NE)
Why Squirrels Strip Bark
There are essentially three theories.
- Pregnant females often don't eat just prior to giving birth. Bark stripping may be their way of responding to the pain.
- Searching for water (although this theory has been weakened by observing that squirrels strip bark even when during a wet spring, stripping during a dry August reaffirms this theory).
- Searching for food by eating the inner bark layer.
Squirrels also damage trees by limb/twig cuttings
- Timing: Typically occurs in Spring (nest construction) and Fall as in (crop gathering). Pin oaks seem to be typically hard hit (Source: Jerry Pickel of PA).
- Tassel-eared squirrels use the twigs to feed on the nutrients found in the cambium and subcambium layers of pine and firs (Source: Richard Wadleigh).
Solutionsto Stop Bark Stripping
Habitat Modification
- Isolated trees or groups of trees
- Wrap tree trunks with 12" (or greater) aluminum flashing at least 6 feet off ground to prevent climbing. See picture at right. Note how flashing is used on trunk to reduce climbing access. Photo by Stephen Vantassel.
- Wrapping 3 rows of porcupine wire spaced with tines 2 inches apart may also prevent squirrel climbing. Be sure the porcupine wire is at least 8 feet off the ground to prevent people from accidental impalement.
- Remove or modify all bird feeders.
Repellents
- Limited value. Taste repellents can be effective to stop
squirrel gnawing on a particular spot. Read label to see if tree would be harmed.
Trapping
 Check state laws before instituting a trapping program.
A wide variety of traps can be used to control squirrels, including, cage traps, box traps, bodygripping traps, and sp ecialty traps such as Kania and Tunnel Traps. Learn how to use traps properly by consulting
Shooting
- .22 caliber guns, air rifles, and shotguns provide effective methods of
population control in areas where safe and legal. Consult local authorities before initiating any shooting activities. Note: many communities now treat air-rifles as firearms.
Toxicants
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