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
Types of Trees Stripped
- Ash (Boise, ID)
- Atlas Cedar (ID)
- Autumn Olives (NE)
- Corkscrew Willow (OR) December, 2008
- Elm (San Mateo, CA) May, 2009 Damaged branched up to 2-inches in diameter
- Ginkos (TX)
- Globe Willow (ID)
- Hackberry (NE)
- Honeysuckle (NH) (Gray Squirrel) Winter 2008/9
- Honey Locust (NE)
- Japenese Maple (OR) December, 2008
- Linden--Small Leaf (Ontario, Canada) stripped in Mid-November, 2008.
- Maple (FL, MN, NE July, 09; )
- Maple, Japanese (TX)
- Maple, Red (NE)
- Maple, Sugar (MN)
- Oaks--various varieties (TX)
- Pin Oak
- Live Oak (DFW Airport, TX, June, 2009)
- Pecan (GA June, 2009)
- Poplar (GA)
- Poplar (Tulip Variety)
- Russian Olive (Milton, Ontario)
- 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).