American Black Bear

American Black Bear

The American black bear (Ursus americanus) is a medium-sized bear native to North America. It is the continent's smallest and most widely distributed bear species. Black bears are omnivores with their diets varying greatly depending on season and location. They typically live in largely forested areas, but do leave forests in search of food. Sometimes they become attracted to human communities because of the immediate availability of food. The American black bear is the world's most common bear species.

The American black bear is listed by the IUCN as Least Concern, due to the species' widespread distribution and a large global population estimated to be twice that of all other bear species combined. Along with the brown bear, it is one of only two of the eight modern bear species not considered globally threatened with extinction by the IUCN. American black bears often mark trees using their teeth and claws as a form of communication with other bears, a behavior common to many species of bears.

Although they live 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. Both American and Asian black bears are considered sister taxa, and are more closely related to each other than to other species of bear. Reportedly, the Sun Bear is also a relatively recent split from this lineage.



The American black bear lived during the same period as short-faced bears (Arctodus simus and A. pristinus) and the Florida spectacled bear (Tremarctos floridanus). These Tremarctine bears evolved from bears that had emigrated from Asia to North America 78 ma. The 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 black bear's generalist behavior allowed it to exploit a wider variety of foods and has been given as a reason why of these 3 genera, it alone survived climate and vegetative changes through and last ice age while the other more specialized North American predators went extinct. However, both Arctodus and Tremarctos had survived several other ice ages. After these prehistoric Ursids went extinct during the last glacial period 10,000 years ago, black bears were probably the only bear present in much of North America until the arrival of brown bears to the rest of the continent.



Historically, black bears occupied the majority of North America's forested regions. Today, they are primarily limited to sparsely settled, forested areas. Black bears currently inhabit much of their original Canadian range, though they do not occur in the southern farmlands of Alberta, Saskatchewan, and Manitoba. They have been extinct in 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 black bear populations in New Brunswick, Northwest Territories, Nova Scotia, and Saskatchewan. All provinces indicated stable populations of black bears over the last decade.

The current range of black bears in the United States is constant throughout most of the northeast (down in the Appalachian Mountains almost continuously to Virginia and West Virginia), the northern midwest, the Rocky mountain region, the west coast and Alaska. However it becomes increasingly fragmented or absent in other regions. Despite this, black bears in those areas seems to have expanded their range during the last decade, such as with recent sightings in Ohio, though these probably do not represent stable breeding populations yet. Surveys taken from 35 states in the early 1990s indicate that black bears are either stable or increasing, except in Idaho and New Mexico. The overall population of black bears in the United States has been estimated to range between 339,000 and 465,000, though this excludes populations from Alaska, Idaho, South Dakota, Texas, and Wyoming, whose population sizes are unknown.


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 black bear having evolved alongside larger, more aggressive bear species, such as the extinct 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 black bears. Although found in the largest numbers in wild, undisturbed areas and rural regions, 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, black bears today are usually found in heavily vegetated mountainous areas, from 400 to 3,000 m (1,300 to 9,800 ft). For bears living 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 Southeast United States. 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 or Louisiana), bears inhabit a mixture of flatwoods, bays, and swampy hardwood sites.

In the northeast part of the range (United States and Canada), prime habitat consists of a forest canopy of hardwoods such as beech, maple, and birch, and coniferous species. Corn crops and oak-hickory mast are also common sources of food in some sections of the northeast; small, thick swampy areas provide excellent refuge cover largely in stands of white cedar. Along the Pacific coast, redwood, sitka spruce, and hemlocks predominate as overstory cover. Within these northern forest types are early successional areas important for black bears, such as fields of brush, wet and dry meadows, high tidelands, riparian areas and a variety of mast-producing hardwood species. The spruce-fir forest dominates much of the range of the black bear in the Rockies. Important nonforested areas here are wet meadows, riparian areas, avalanche chutes, roadsides, burns, sidehill parks, and subalpine ridgetops. In areas where human development is relatively low, such as stretches of Canada and Alaska, American black bears tend to be found more regularly in lowland regions. In parts of northeastern Canada, especially Labrador, black bears have adapted exclusively to semi-open areas which are more typical habitat in North America for brown bears (likely due to the absence here of brown and polar bears as well as other large carnivore species)




Tags:
amerikaanse zwarte beer, american black bear, ursus americanus, baribal, amerikanische schwarzbar, oso negro, ours noir, orso nero americano, beren, beer, bears, ursidae, mammals_, zoogdieren, predator, omnivoor, canada, khutzeymateen, british columbia, great bear rainforest, animal, roofdier, nature, wildlife, wildlifepics, dabinda, dennis binda
 

  

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American Black Bear
Amerikaanse Zeearend
Arctic Fox
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Barn Owl
Black Kite
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Black-tailed Godwit
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Blakiston's Fish Owl
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Brown Dipper
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Dunlin
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European Golden Plover
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Green Hermit
Grizzly Bear
IJsland 2008
Japanese Macaque
Kermode Bear
King Eider
Little Auk
Long-billed Starthroat
Northern Cardinal
Northern Gannet
Northern Pintail
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Pink-footed Goose
Red Fox
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Archief:
Whooper Swan
White-tailed Eagle
Vagrant Darter
Ural Owl
Steller's sea eagle
Snow Leopard
Snow Bunting
Scaly-breasted Hummingbird
Sapphire-throated Hummingbird
Red-rumped agouti
Red-crowned Crane
Red Fox
Pink-footed Goose
Parasitic Jaeger
Northern Pintail
Northern Gannet
Northern Cardinal
Long-billed Starthroat
Little Auk
King Eider
Kermode Bear
Japanese Macaque
IJsland 2008
Grizzly Bear
Green Hermit
Great Skua
European Golden Plover
Dusky Thrush
Dunlin
Coppery-headed Emerald
Common Kingfisher
Common Kestrel
Common Eider
Common Blue
Brown-eared Bulbul
Brown Dipper
Botswana 2011-10
Botswana 2011-09
Botswana 2011-08
Botswana 2011-07
Botswana 2011-06
Botswana 2011-05
Botswana 2011-04
Botswana 2011-03
Botswana 2011-02
Botswana 2011-01
Bluethroat
Blakiston's Fish Owl
Black-tailed Skimmer
Black-tailed Godwit
Black Skimmer
Black Kite
Barn Owl
Bank Vole
Bald Eagle
Arctic Fox
Amerikaanse Zeearend
American Black Bear