Date of this Version
The Prairie Naturalist· 42(1/2): June 2010, pp 71-72
Fox squirrels (Sciurus niger) feed on >30 different types of food across their extensive range ~Korschgen 1981) including tree buds, flowers, fruits, seeds, and, on occasion, bark. For a large portion of the year, fox squirrels rely heavily on tree seeds (Koprowski 1991). For three consecutive years (2007-2009), we observed fox squirrels feeding on bark of elm trees ( Ulmus sp.) on the campus of West Texas A&M University, Canyon, Texas. Squirrels began feeding on bark in late November shortly after leaves had fallen off the trees and continued almost daily throughout the winter. In late February, when the buds appeared on the elm trees, squirrels began feeding on buds and were no longer observed feeding on bark. We were unable to distinguish which sex fed on bark but based on the amount of activity we assumed it was both sexes. When feeding, bark was peeled and ripped off of the smaller branches near the top of the trees. Most branches from which bark was removed were approximately 2-8 cm in diameter and bark was completely removed from the entire circumference of the sections of branch. We never noticed bark removal from trunks or larger branches. To our knowledge, only one other researcher has documented fox squirrels feeding on the bark of elms, but the period of use differed from ours. In Kansas, Packard (1956) observed squirrels feeding on elm bark in January and attributed this to depletion of cached food. Researchers have documented feeding on bark by fox squirrels in other tree species. In Colorado, fox squirrels used cottonwood (Populus sp.) bark as a predominant food source (Yeager 1959) and buckeye (Aesculus glabra) pith was fed upon during late fall and winter in Illinois (Havera et al. 1976). Kenward and Parish (1986) documented bark stripping by eastern gray squirrels (S. carolinensis) in England but detected no evidence linking bark stripping with food shortages. Various mammals feed on bark seasonally and in some species composed an important part of their diet. Lagomorphs and small rodents feed on bark from the base of trees and bushes during snow cover, most likely in response to food shortages (Kenward and Parish 1986) and North American porcupines (Erethizon dorsatum) fed almost exclusively on bark of trees during winter (Dodge 1967, Griesemer et al. 1998). Further, many species of primates feed on bark seasonally in relation to absence of preferred foods (Nishida 1976).