Common Porcupine (Erethizon dorsatum)

County List:

Rule:

Forested or Mixed Forested/Nonforested Landscapes

1st alternative:
      (Assorted Hardwoods (Pole or Sm Saw or Lg Saw or Uneven))
      or (Northern Hardwoods (Pole or Sm Saw or Lg Saw or Uneven))
   containing:
      (Conifer Inclusions and Dead Down Woody Debris and Snags and Living Cavity Trees)

2nd alternative: 
      (Any Upland Conifer (Pole or Sm Saw or Lg Saw or Uneven))
      or (Northern White Cedar (Pole or Sm Saw or Lg Saw or Uneven))
   containing:
      (Deciduous Inclusions and Dead Down Woody Debris and Snags and Living Cavity Trees)

3rd alternative:
      (Any Upland Mixed (Pole or Sm Saw or Lg Saw or Uneven))
      or (Northern White Cedar (Pole or Sm Saw or Lg Saw or Uneven))
   containing:
      (Dead Down Woody Debris and Snags and Living Cavity Trees)

Habitat List:

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Literature:

Although once found throughout the Great Lakes drainage, the porcupine has been exterminated from southern areas now dominated by farmland. In the north, this large rodent lives in deciduous and coniferous woodlands and has a particular liking for stands containing pine and hemlock.

In the winter, a porcupine seeks refuge in a cave, decaying log, or hollow tree but does not build a nest.

The winter diet consists of conifer needles, buds, and the soft inner bark of trees, such as white pine, hemlock, sugar maple, and birch. In the summer, it relies heavily on leaves plucked from basswood, aspen, elm, and birch. In addition to this leafy diet, a porcupine consumes roots, flowers, fruits, seeds, and nuts as they become available.

Habitat: Mixed or coniferous forests especially northern hardwood-hemlock, with adequate denning sites. Not restricted to any plant or edaphic community.

Special Habitat Requirements: Den sites in rock ledges, trees, or other protected places.

Habitat Preferences: Most observers in northeastern North America describe the porcupine as a woodland species. It frequents both deciduous and coniferous forested areas and prefers hemlock and pine habitats. Its food preferences tend to dictate local habitat use. In winter, the animal remains in the heavy cover of tree boughs to feed generally on the phloem layer of trees; in summer it searches for leaves of herbaceous plants in forest openings, conifer and aspen swamps, and adjacent croplands. In Gogebic, Ontonagon, and Iron counties, Golley found second-growth maple-hemlock forest was a favored winter range. White-tailed deer hunters in the Upper Peninsula in mid-November most commonly see porcupines in hardwood forest, less in swamp forests, and rarely in pine forests. In Gogebic and Ontonagon counties, Dice and Sherman most often observed porcupines in hardwood forests in summer and autumn; in Wexford County, Wenzel reported the animals in hardwood and hemlock forests.

Density and Movement: In hardwood-hemlock forest in Iron County, Brander estimated porcupine numbers (based on winter counts) at 25 per sq. mile in an area logged in 1961 shortly before his study the same year; at 32 animals per sq. mile in areas heavily logged in 1957; and at 43 animals per sq. mile in areas lightly logged many years prior to his studies. Brander's study points to the porcupine's preference for older hardwoods-hemlock stands as winter habitat.

Behavior: There is some evidence that porcupines are most adept at climbing trees with a diameter between 6 and 10 inches dbh; trees of massive girth are too large to be readily ascended.

The porcupine rarely digs in the ground for shelter. Instead it uses hollow trees, rock ledges, logs, windfalls, and even garbage dumps as cover. According to Shapiro, dens may be selected more for protection from winds and snow than for insulation against cold. An individual may also have several temporary shelters as far as ½ mile away from the main den. Dens are used more in winter than in summer. Den locations are often discovered because of great accumulations of fecal pellets. Porcupines also use summer "station trees" as roosts, with no protected dens nearby. These roosts are in large trees, usually hemlocks, with large branches often gnawed and pruned. These tree roosts are possibly used in late spring and early summer to avoid mosquitoes.

Associates: There is a significant relationship between the porcupine, and the snowshoe hare and the white-tailed deer. It is primarily a one-sided association because the latter two species profit from the porcupine's "wasteful" eating habits. When feeding on white cedar, poplar, and white spruce, porcupines are prone to drop numerous unbrowsed and partly-browsed branches. These unretrieved parts can be a winter food bonus for snowshoe hare and white-tailed deer when snow is deep and when the understory in a mature forest is sparse.

Food Habits: The porcupine is a more complete vegetarian than any other Michigan rodent except the beaver. Its choice of food is directed correlated with the availability of green stuff in summer and inner bark of favored trees in winter.

In forest situations they seem to prefer the leaves of basswood, elm, and yellow birch, but will also eat the leaves and buds of sugar maple, hemlock, white cedar, aspen, pin cherry, red maple, and red oak. Porcupines often move away from woodlands to feed on plant foliage at the meadow-forest edge, in riparian growth along waterways, and in cultivated fields, orchards, and gardens. Eating the leaves of water lilies and other emergent aquatic plant life has also been documented.

The winter diet consists almost entirely of the succulent (sugar and starch-filled) inner bark (cambium and phloem layers) of favored food trees. Brander found Upper Peninsula porcupines feeding on the inner bark of hemlock, sugar maple, basswood, elm, and yellow birch. Golley added tamarack; jack pine and beech are also used. These authors agree with observers in other areas that second-growth stands are preferred over older trees in mature forests.