Oaks ‘n’ Folks – Volume 4, Issue 1 – August 1989
Introduction
The black bear is a large and rarely seen omnivore that has long fascinated Californians. For early California dwellers the black bear was hunted for meat and fur, and occasionally worshipped. Today, the black bear is one of California’s most popular big-game animals, providing many hours of recreation for both hunting and nonconsumptive values. Black bear habitat, however, is being degraded by increasing demands on the resources and lands of the state. This article presents basic information on the status, life history, and habitat requirements of black bears in California. It also reviews why proper management of our oak-dominated habitats is important for the well-being of this fascinating animal.
Status
The California Department of Fish and Game (CDFG) estimates that 10 to 15,000 black bears occupy about 40,000 square miles of California. They occur in California’s North, South, and Central Coast Ranges, and in the Sierra Nevada Mountains. Within these areas there may be as many as two bears per square mile, but generally densities are much less. Their distribution overlaps most of the 20 million acres that comprise California’s hardwood communities. The bears do best in areas which are a mix of habitat types. Areas with mast-producing and riparian elements are especially beneficial to bears.
Life History and Habitat Requirements
If you have been lucky enough to see a bear in California there is a good chance the black bear was not black. Several color phases occur: blond to chocolate to black. In some parts of California up to half or more of the black bears are the light color phase. Second in size only to the Roosevelt elk, the black bear is not nearly as large as its extinct cousin, the California grizzly. In a study conducted in Tulare County, the average weight of adult male black bears was about 250 pounds. Exceptional individuals can weigh much more. The California fish and Game Commission record for a black bear killed by a California hunter is 574 pounds.
In northern latitudes, black bears are long-winter snoozers. In California, however, winter dormancy may be full-time or intermittent, depending on climate and food availability. Cavities in living trees are used as dens, and dense are dug under the upturned root masses and trunks of fallen or leaning trees, or even excavated directly into a hillside. Pregnant females are most likely to either use cavities or excavate their dense. Dens of other bears, especially in areas of the state with mild and snowless winters, may consist of grasses and leaves shaped into nest-like structures on the surface of the ground, perhaps in dense habitat against the trunk of a tree or under a brush pile. Females give birth to one-to-three (usually two) cubs in the den in early February. Cubs of a 300-pound female weight only about 12 ounces at birth.
The peak of mating season is mid-June to late July. But the development of the embryo is delayed after only a few cell divisions. It is resumed when the mother enters the den in November or December. This unusual phenomenon, known as delayed implantation apparently makes it possible for adult male and female bears to fatten in fall for dennings, unfettered by any reproductive demands. Hence, although gestation lasts seven months, newborn cubs are unusually small and helpless for a mammal. They nurse and grow rapidly in the den and weigh four to six pounds when they leave in April. In temperament and appearance, the cubs resemble raucous, furry, domestic piglets. For the next six months, the cubs travel with their mother. They den with her the following winter and are weaned in June as sixteen-month-old yearlings.
Upon leaving their dens and until early summer, black bears in California eat mostly green plants such as grasses, legumes, and young browse. Mast and berries form the major food items from late summer to denning. Manzanita berries are important in the conifer lands of north California, but studies have shown that throughout the state’s range, acorns are a vital dietary item. For example, when insects rendered acorns inedible on a Placer County study area in 1980, three of four radio-monitored adult female black bears moved to areas where undamaged acorns were available. Adequate autumn weight gain may be necessary for adult And subadult bears to survive winter in their dens and for adult females to produce cubs. It was found in a study in Minnesota that adult females that weighed less than 148 pounds at denning time did not have cubs. Berries and mast, rich in fats, allow rapid pre-denning weight gain. This points out the importance of the availability of good acorn-producing oaks in oak-woodland and oak/conifer habitats.
The area a bear ranges over depends on its sex and age and food availability. Adult males have much larger ranges than females. Males may travel over at least 46 square miles during years of scarce food. Most black bear mortality is human-caused. CDFG declared the black bear a game animal in 1945. California hunters take about 1,000 bears a year. The harvest is about 50/50 male-female. Harvested bears are generally about four years old. Fewer than 3 percent of the animals are over 10. The CDFG feels that poaching may account for as many bears as the legal harvest. Other mortality factors are disease, parasites, bear-bear conflicts, starvation, and accidents. Interestingly, a large male black bear that weighed an estimated 400 pounds was killed recently by a vehicle just north of the city of San Luis Obispo.
Black bears do best in a mix of vegetation types that provides seasonal foods in close proximity to each other. Throughout California’s black bear range, oak trees are an important constituent of this mix. Unfortunately, the oak component is increasingly being removed or degraded by road building, intensive agriculture, subdivisions, or intensive forest management. As part of the Integrated Hardwood Range Management Program (IHRMP), the California State Board of Forestry called upon the CDFG to join with the University of California (UC) and the California Department of Forestry and Fire Protection (CDF) to implement actions to determine the quantity and quality of oak-woodland habitats necessary to maintain the state’s game populations. Recently the CDFG has included the black bear on a list of eight indicator wildlife species for oak woodlands.
Management
The black bear management goals of CDFG are to maintain a self-sustaining population in balance with its habitat and integrate the needs of black bears into resource planning at all levels of government. To accomplish these goals, the CDFG is: (1) working cooperatively with other governmental agencies such as county planning departments, (2) promoting protection of mast- and berry-producing and riparian habitats within woodlands occupied by black bears, and (3) developing a public-information system.
The CDFG is working close with UC and CDF in the IHRMP. The IHRMP provides a vehicle to develop information on the food and cover requirements of black bears in oak-dominated habitats. It also seeks to develop management strategies that will allow landowners to manage their land for profit and wildlife needs, to extend this information, and, importantly, to assess the impact of these educational efforts on changing attitudes, management practices, and on the maintenance of oak-woodland habitats. Hopefully, these efforts will ensure a healthy, productive black bear population for future generations of Californians to enjoy.
prepared and edited by John M. Harper, Richard B. Standiford, and John W. LeBlanc