Black Bear (Ursus americanus)
Main sources: Nowak, Ronald, 1991, Walker's Mammals of the world, Fifth Edition (two vols.), Baltimore: Johns Hopkins University Press; Hoffmeister, D. F., 1986, Mammals of Arizona, Tucson: University of Arizona Press; Burt, W. & R. Grossenheider, eds., 1976, A Field Guide to the Mammals, Peterson Field Guides: Houghton Mifflin; Eisenberg, John, 1980, The Mammalian Radiations, Chicago: University of Chicago Press; Cockrum, E.L., 1960, The Recent Mammals of Arizona: Their Taxonomy and Distribution, Tucson: University of Arizona Press;
Among the carnivores, the family Ursidae are large animals: head and body length run from nearly 4 feet (1000mm) to 9 feet (2,800mm), weight runs from 72 lbs (27 kg) to 2100 lbs (780 kg). Males are considerably larger than females. Bears have a big head, a large, heavily built body, short, powerful limbs, a short tail, and small eyes. Their teeth have evolved away from a more canid-like pattern to emphasize crushing and masticating processes, and bears have become more fully omnivorous and herbivorous. The coat is long and shaggy, usually of one color. Hearing and eyesight are mediocre, but sense of smell is excellent. They characteristically walk plantigrade (on all four soles, with heels touching the ground), but can walk upright (bipedally) for short distances, and while they are slower-moving than the canids, they are surprisingly agile. Bears become fat during autumn and sleep through the winter in dens (except for non-pregnant polar bears). Ursidae first appear in the Late Eocene of Europe, the late Miocene in North America.
Two kinds of bears are native to Arizona -- the Black and the Grizzly Bear (Ursus arctos) -- but Grizzlies have been extirpated from here for many years. Before their systematic slaughter began in the late 19th century, at least three species of Grizzlies roamed the State. Cockrum (pp. 224-6) shows a distribution of Grizzly sightings from the Mogollon Rim to the Chiricahua Mountains, ending mainly in the second decade of the 20th century, with one report from the Grand Canyon dated 1935, nothing later; Hoffmeister reports the "last killed in Arizona" was from Greenlee County in 1935. While they were here, individual Grizzlies were tremendous traversers of our lands -- one was tracked traveling more than 500 miles in a two months' span of time -- and they were fearless "even in the face of packs of trained dogs and men with rifles" (Hoffmeister p. 480).
In Arizona today, our more retiring Black Bear lives mainly in Encinal Woodland (usually composed of evergreen oaks, juniper, and pinyon pine, running from 4,000-7000' elevation) and Coniferous Forest, in a distribution running along the Mogollon Rim from south of the Grand Canyon through the White Mountains and eastward into New Mexico, and southward through the Sky Islands (Catalinas-Rincons complex, Galiuros, etc) into contiguous northern Mexico. Hoffmeister reported in 1986 that its range has not greatly diminished since the wholesale slaughterings of the 1910s, but it seems unlikely that a stable population will be sustained for long in the face of Arizona's current explosive growth.
Our Black Bears run in weight from about 200 to more than 475 lbs., with head and body length from 5-6 feet. Color varies from black to cinnamon. They are usually nocturnal, but occasionally seen at midday, and are solitary except for females with cubs. We very seldom see them at our San Pedro River Valley elevations (below 4,500'), but they do appear occasionally, sometimes traversing our lower-elevation wildlife corridors as they shift from one Sky Island to another. An example is seen in the track images above, made by a bear who was moving downstream along Sierra Blanca Canyon Wash through our lands, following shortly after a late summer flood (while pools of water remained along the wash all the way to the San Pedro River, providing convenient sources of drinking water). We suspect this might have been a young male, displaced from Galiuros habitat and seeking something new, probably in the Rincon Mountains across the Valley. (Click on the images above to enlarge them. The pen's length is 5 inches -- 13 cm.)