Bark Stripping by Fox and Gray Squirrels

Damage to Tree Bark

stripped 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)
  • Hackberry (NE)
  • Honey Locust (NE)
  • Maple (FL, MN)
  • Maple, Red (NE)
  • Maple, Sugar (MN)
  • Poplar (GA)
  • Poplar (Tulip Variety)
  • Sycamore (NE)

Why Squirrels Strip Bark

There are essentially three theories.
  1. Pregnant females often don't eat just prior to giving birth. Bark stripping may be their way of responding to the pain.
  2. Searching for water (although this theory has been weakened by observing that squirrels strip bark even when during a wet spring).
  3. 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).

Solutions to 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 to be squirrel resistant.

Repellents

Repellants are of 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 trapping!

A wide variety of traps can be used to control squirrels, including, cage traps, box traps, bodygripping traps, and specialty traps such as Kania and Tunnel Traps.

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

None available.
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