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Q: Something stripped bark from a maple tree in my yard. What could have done that and why?
-- Danielle from Youngstown
A: In our area, it is most likely a squirrel. It probably was a gray squirrel, but it could be a fox squirrel or red squirrel as well.
If it were winter, it might be deer or rabbits, but that would be at the snow line and this stripping was higher up in the tree. In our area, the time frame for squirrels to do this is usually May through July.
Squirrels will also lop off twig tips. The twig pruning can occur any time from spring through fall and causes no real damage. The "natural pruning" may actually increase canopy density.
This damage is very different than that caused by woodpeckers. These birds make a line of holes and do not remove any bark.
Eastern gray squirrels were introduced to various areas in the United Kingdom from the late 1880s through the 1920s. They are now wreaking havoc throughout the U.K., producing widespread severe debarking of woodland and landscape trees and threatening biodiversity -- gray squirrels have caused regional extinctions of their native red squirrel.
Reasons have been suggested in both the U.K. and U.S. for the odd bark-stripping behavior. Some of the more reasonable ones are feeding on the sugar-rich phloem, searching for a water source, gnawing on trees to wear down ever-growing incisors.
A number of studies conducted in the U.K. on gray squirrels noted two important findings. First, the damage most often occurs in the spring to early summer. Although bark-stripping may be observed later in the season, the vast majority occurs from March through May.
Secondly, the greatest amount of damage seems to occur after a good mast year with the larger food supply that supports an elevated population of juvenile squirrels. A high population of young squirrels also means there is a high relative population of post-pregnant females.
A study published in 2016 coupled these findings with naturally occurring elevated levels of calcium in tree phloem in the spring to early summer as much as a 40 percent increase compared to other times of the year. It is well documented that gray squirrels will gnaw on calcium-rich sources such as bones, antlers and even limestone to get this much-needed mineral.
The problem with the study is that research doesn't support the hypothesis. The calcium in the tree phloem is not the type needed for bone strength.
Much of the damage in Ohio seems to occur on landscape trees, trees at the edge of wooded areas or in limited woodlots, including some parks, but there are no reports of trees being damaged in heavily forested areas. The indications are that this is an urban / suburban problem.
Some might confuse some of this damage with woodpecker or sapsucker damage. This type of damage always has lines of holes but can occasionally include the removal of larger areas of bark.
For further information on squirrel bark damage and photos, go to http://go.osu.edu/treebarkdamage.
To see what woodpecker and sapsucker damage looks like, go to http://go.osu.edu/birdbarkdamage.
Scudier is an Ohio State University Mahoning County Extension Master Gardener Volunteer. The Extension Office's Plant and Pest Clinic is open 9 a.m. to noon Mondays and Thursdays for help with plant issues, soil testing and insect identification. Find details at go.osu.edu/mahoningclinic.