Date of Award:
Master of Science (MS)
Frederick G. Lindzey
Patterns of vegetation use by black bears (Ursus americanus) on Long Island, Washington were documented using radio-telemetry in 1973-74 and 1980-81. Secondary succession altered the vegetative compostion of clearcut areas through this time, reducing the areas dominated by productive brush species by nearly 50%. Seasonal food habits, consisted primarily of grasses and forbs in spring (den emergence-May) and flowers and fruits of shrub species in summer (June-September) and fall (October-den entrance).
Bears selected for clearcuts (5-21 years of age) over all other vegetation types for feeding but preferred areas dominated by large trees when inactive during both the day and night. Inactivity in clearcut areas occurred most frequently in clearcuts offering the greatest amount of horizontal cover. Although preferred in all seasons, clearcuts received the greatest use during the summer months when flowers and fruits of shrubs species were most abundant. Tidelands and meadows were used more in the spring than during other seasons and conifer stands received the greatest proportionate use in spring and fall. Old growth timber (200 +years of age) was used similarly to mature second growth.
Adult males were less influenced than other classes of bears by availability of horizontal cover and proximity of cover provided by adjacent vegetation types when feeding in clearcut areas. Adult females with cubs fed in timber stands and clearcuts with abundant horizontal cover more than other bears and generally remained in close proximity to bordering timber stands when feeding in clearcuts. Subadults, as well as adult females with cubs, appeared to use available habitats in a manner that allowed them to avoid other bears.
Areas in large timber stands that were long distances from clearcuts were used by bears more during the 1980-81 phase of the study, apparently because of the increased competition for declining resources in clearcut areas. Home ranges of the adult females present during both phases of the study were similar in both size and location.
Barber, Kim R., "Use of Clearcut Habitats by Black Bears in the Pacific Northwest" (1983). All Graduate Theses and Dissertations. 3590.
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