Black bears occupy a variety of habitat; however, bear populations are densest in forested areas with a wide variety of seral stages. habitats with both vegetative and structural diversity provide alternate food resources when other foods are in short supply. Food availability for black bears has been strongly correlated to reproductive success in female black bears (Rogers 1987, Piekielek and burton 1975, Jonkel and Cowan 1971). Vegetation and structure diversity not only allow for greater survival of existing bears, they also provide for increased reproduction.
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As with all wildlife, black bears have specific preferences for reproduction, cover, and feeding. With respect to reproduction, secure, dry den sites are needed for female bears giving birth or raising cubs. Many studies have indicated that female black bears selected the most secure den locations (Mack 1989, Alt and Gruttadauria 1984, LeCount 1983, Johnson and Pelton 1981, Lindzey and Meslow 1976). While black bears have been found to den in slash piles, under large rocks, and even on open ground, the most secure and thermally protective den sites are associated with large trees.
On a regional basis, black bears "thrive" in some habitats while other habitat types are marginal. For instance, black bears are known to use annual grasslands sporadically during the year. However, self sustaining bear populations are not found in this habitat type. In contrast, montane hardwood, montane chaparral, and mixed conifer forests sustain high bear populations because they supply sufficient food, cover and water. Other habitat types, such as valley foothill hardwood, provide seasonally important habitat. Similarly, some habitat types vary in importance depending on the composition of surrounding areas.
Habitat loss is the leading threat to wildlife populations in California. Over half of the suitable black bear habitat in California is in public ownership of which an estimated 10 percent is managed as either wilderness or park. Current ownership patterns allow large blocks of habitat to remain undeveloped and core areas within these blocks where bears encounter few humans. Furthermore, black bears typically inhabit rugged lands and conversion projections indicate that only 1 percent of existing black bear habitat is expected to be lost each decade (FFRAP 1989).
Land management activities can effect the capability of an area to support bear populations. For instance, many of the important food plants (manzanita, oaks) only grow in forest openings. Therefore, controlled burns or other management strategies aimed at creating a mosaic of forest openings can be especially beneficial for black bears by providing abundant food resources in close proximity to cover. Additionally, retention and recruitment of snags and large woody debris provide den sites and potential food sources (colonial insects). Conversely, management practices (i.e.-fire suppression) which result in even aged stands without structural and vegetational diversity decrease habitat value for black bears. Often attendant activities such as road construction, which do not directly reduce habitat, adversely effect bear populations by increasing hunting vulnerability.