The American black bear (Ursus americanus), or simply black bear, is a medium-sized bear endemic to North America. It is the continent's smallest and most widely distributed bear species. American black bears are omnivores, with their diets varying greatly depending on season and location. They typically live in largely forested areas, but will leave forests in search of food, and are sometimes attracted to human communities due to the immediate availability of food. Despite the name, some subspecies can be brown or even blond in coloration.
Despite living in North America, American black bears are not closely related to brown bears and polar bears; genetic studies reveal that they split from a common ancestor 5.05 million years ago (mya). American and Asian black bears are considered sister taxa and are more closely related to each other than to the other modern species of bears.[page needed] According to recent studies, the sun bear is also a relatively recent split from this lineage.[page needed] A small primitive bear called Ursus abstrusus is the oldest known North American fossil member of the genus Ursus, dated to 4.95 mya. This suggests that U. abstrusus may be the direct ancestor of the American black bear, which evolved in North America. Although Wolverton and Lyman still consider U. vitabilis an "apparent precursor to modern black bears", it has also been placed within U. americanus. The ancestors of American black bears and Asian black bears diverged from sun bears 4.58 mya. The American black bear then split from the Asian black bear 4.08 mya. The earliest American black bear fossils, which were located in Port Kennedy, Pennsylvania, greatly resemble the Asian species, though later specimens grew to sizes comparable to grizzly bears. From the Holocene to the present, American black bears seem to have shrunk in size, but this has been disputed because of problems with dating these fossil specimens. The American black bear lived during the same period as the giant and lesser short-faced bears (Arctodus simus and A. pristinus, respectively) and the Florida spectacled bear (Tremarctos floridanus). These tremarctine bears evolved from bears that had emigrated from Asia to the Americas 7–8 mya. The giant and lesser short-faced bears are thought to have been heavily carnivorous and the Florida spectacled bear more herbivorous, while the American black bears remained arboreal omnivores, like their Asian ancestors. The American black bear's generalist behavior allowed it to exploit a wider variety of foods and has been given as a reason why, of these three genera, it alone survived climate and vegetative changes through the last Ice Age while the other, more specialized North American predators became extinct. However, both Arctodus and Tremarctos had survived several other, previous ice ages. After these prehistoric ursids became extinct during the last glacial period 10,000 years ago, American black bears were probably the only bear present in much of North America until the migration of brown bears to the rest of the continent.
Historically, American black bears occupied the majority of North America's forested regions. Today, they are primarily limited to sparsely settled, forested areas. American black bears currently inhabit much of their original Canadian range, though they seldom occur in the southern farmlands of Alberta, Saskatchewan and Manitoba; they have been extirpated on Prince Edward Island since 1937. The total Canadian black bear population is between 396,000 and 476,000, based on surveys taken in the mid-1990s in seven Canadian provinces, though this estimate excludes American black bear populations in New Brunswick, the Northwest Territories, Nova Scotia and Saskatchewan. All provinces indicated stable populations of American black bears over the last decade.
The current range of American black bears in the United States is constant throughout most of the Northeast and within the Appalachian Mountains almost continuously from Maine to northern Georgia, the northern Midwest, the Rocky Mountain region, the West Coast and Alaska. However, it becomes increasingly fragmented or absent in other regions. Despite this, American black bears in those areas seem to have expanded their range during the last decade, such as with recent sightings in Ohio, Illinois, and southern Indiana, though these probably do not yet represent stable breeding populations. Sightings of itinerant American black bears in the Driftless Area of southeastern Minnesota, northeastern Iowa, and southwestern Wisconsin are common. In the spring of 2019, biologists with the Iowa Department of Natural Resources confirmed documentation of an American black bear living year-round in woodlands near the town of Decorah in northeastern Iowa, believed to be the first instance of a resident black bear in Iowa since the 1880s.
Throughout their range, habitats preferred by American black bears have a few shared characteristics. They are often found in areas with relatively inaccessible terrain, thick understory vegetation and large quantities of edible material (especially masts). The adaptation to woodlands and thick vegetation in this species may have originally been due to the American black bear having evolved alongside larger, more aggressive bear species, such as the extinct giant short-faced bear and the still-living grizzly bear, that monopolized more open habitats and the historic presence of larger predators, such as Smilodon and the American lion, that could have preyed on American black bears. Although found in the largest numbers in wild, undisturbed areas and rural regions, American black bears can adapt to surviving in some numbers in peri-urban regions, as long as they contain easily accessible foods and some vegetative coverage.
In most of the contiguous United States, American black bears today are usually found in heavily vegetated mountainous areas, from 400 to 3,000 m (1,300 to 9,800 ft) in elevation. For American black bears living in the American Southwest and Mexico, habitat usually consists of stands of chaparral and pinyon juniper woods. In this region, bears occasionally move to more open areas to feed on prickly pear cactus. At least two distinct, prime habitat types are inhabited in the Southeastern United States. American black bears in the southern Appalachian Mountains survive in predominantly oak-hickory and mixed mesophytic forests. In the coastal areas of the Southeast (such as Florida, the Carolinas and Louisiana), bears inhabit a mixture of flatwoods, bays and swampy hardwood sites.
Males and female Bengal tigers in Panna Tiger Reserve reach a head-body length of 183–211 cm (72–83 in) and 164–193 cm (65–76 in) respectively, including a tail of 85–110 cm (33–43 in) long. Total length ranges from 283 to 311 cm (111 to 122 in) for male tigers and 255–285 cm (100–112 in) for female tigers. They typically range 90–110 cm (35–43 in) in height at the shoulders.
Subadult males weigh between 130 and 170 kg (290 and 370 lb) and reach 200 to 260 kg (440 to 570 lb) when adult; subadult females weigh 80 to 100 kg (180 to 220 lb) and reach between 110 and 180 kg (240 and 400 lb) when adult. In central India, 42 adult male Bengal tigers weighed on average 190 kg (420 lb) with a range of 167–234 kg (368–516 lb); their total length was 282 cm (111 in) with a range of 267–312 cm (105–123 in), and their average shoulder height was 99 cm (39 in); 39 adult female Bengal tigers weighed on average 132 kg (291 lb) with a maximum of 156 kg (344 lb) and an average total length of 254 cm (100 in) ranging 239–277 cm (94–109 in). Several scientists indicated that adult male Bengal tigers in the Terai consistently attain more than 227 kg (500 lb) of body weight. Seven adult males captured in Chitwan National Park in the early 1970s had an average weight of 235 kg (518 lb) ranging from 200 to 261 kg (441 to 575 lb), and that of the females was 140 kg (310 lb) ranging from 116 to 164 kg (256 to 362 lb). Two male tigers captured in Chitwan National Park in the 1980s exceeded weights of 270 kg (600 lb) and are the largest free ranging tigers reported to date.
The smallest recorded weights for Bengal tigers are from the Bangladesh Sundarbans, where adult females weigh 75 to 80 kg (165 to 176 lb). Three tigresses from the Bangladesh Sundarbans had a mean weight of 76.7 kg (169 lb). The oldest female weighed 75 kg (165 lb) and was in a relatively poor condition at the time of capture. Their skulls and body weights were distinct from those of tigers in other habitats, indicating that they may have adapted to the unique conditions of the mangrove habitat. Their small sizes are probably due to a combination of intense intraspecific competition and small size of prey available to tigers in the Sundarbans, compared to the larger deer and other prey available to tigers in other parts.
The Indian subcontinent has served as a stage for intense confrontations between tigers and people. At the beginning of the 19th century tigers were so numerous, that the killing of tigers was officially rewarded in many localities. The Terai region supported large numbers of tigers that were pushed into marginal habitat after the 1950s, when the conversion of natural habitat for paddy fields increased. Marauding tigers began to take a toll of human life in areas bordering cultivation. They are thought to have followed domestic livestock that wintered in the plains when they returned to the hills in the spring, and then being left without prey when the herds dispersed back to their respective villages. These tigers were the old, the young and the disabled. All suffered from some disability, mainly caused either by gunshot wounds or porcupine quills.
In the Sundarbans, 10 out of 13-man-eaters recorded in the 1970s were males, and they accounted for 86% of the victims. These man-eaters have been grouped into the confirmed or dedicated ones who go hunting especially for human prey; and the opportunistic ones, who do not search for humans but will, if they encounter a man, attack, kill and devour him. In areas where opportunistic man-eaters were found, the killing of humans was correlated with their availability, most victims being claimed during the honey gathering season. Tigers in the Sunderbans presumably attacked humans who entered their territories in search of wood, honey or fish, thus causing them to defend their territories. The number of tiger attacks on humans may be higher outside suitable areas for tigers, where numerous people are present, but with little wild prey for tigers.
In Nepal, the incidence of man-eating tigers has been only sporadic. In Chitwan National Park no cases were recorded before 1980. In the following few years, 13 people have been killed and eaten in the park and its environs. In the majority of cases, man-eating appeared to have been related to an intra-specific competition among male tigers. An interview survey with 499 local people in Chitwan revealed that lower caste Hindus and people with less than eight years of formal education had negative attitudes to the tiger; most of them owned livestock and had heard about tigers attacking people and livestock.
In December 2012, a tiger was shot by the Kerala Forest Department on a coffee plantation on the fringes of the Wayanad Wildlife Sanctuary. Chief Wildlife Warden of Kerala ordered the hunt for the animal after mass protests erupted as the tiger had been carrying away livestock. The Forest Department had constituted a special task force to capture the animal with the assistance of a 10-member Special Tiger Protection Force and two trained Indian elephants from the Bandipur Tiger Reserve in Karnataka.
