American black bear

American black bear
Temporal range: 2.6–0  Ma
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Late PlioceneHolocene
01 Schwarzbär.jpg
Found near Riding Mountain National Park, Manitoba, Canada
Scientific classification e
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Carnivora
Suborder: Caniformia
Family: Ursidae
Genus: Ursus
Species: U. americanus
Binomial name
Ursus americanus
( Pallas, 1780)
Subspecies

16, see text

American Black bear map.png
Synonyms

Euarctos americanus

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.

It is listed by the International Union for Conservation of Nature (IUCN) as a least-concern species, due to its widespread distribution and a large 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. [1]

Taxonomy and evolution

Detail of head – taken at the Cincinnati Zoo
Cinnamon-colored black bear eating dandelions in Waterton Lakes National Park

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). [2] American and Asian black bears are considered sister taxa, and are more closely related to each other than to other species of bear. [2] [3] According to recent studies, the sun bear is also a relatively recent split from this lineage. [4]

A small primitive bear called Ursus abstrusus is the oldest known North American fossil member of the genus Ursus, dated to 4.95 mya. [5] This suggests that U. abstrusus may be the direct ancestor of the American black bear, which evolved in North America. [2] [6] Although Wolverton and Lyman still consider U. vitabilis an "apparent precursor to modern black bears", [7] it has also been placed within U. americanus. [6]

The ancestors of American black bears and Asiatic black bears diverged from sun bears 4.58 mya. The American black bear then split from the Asian black bear 4.08 mya. [2] [8] The earliest American black bear fossils, which were located in Port Kennedy, Pennsylvania, greatly resemble the Asiatic species, [9] though later specimens grew to sizes comparable to grizzlies. [10] From the Holocene to present, American black bears seem to have shrunk in size, [2] but this has been disputed because of problems with dating these fossil specimens. [7]

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 7–8 ma. [11] The short-faced bears are thought to have been heavily carnivorous and the Florida spectacled bear more herbivorous, [12] 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 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 ice ages. After these prehistoric ursids became 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 migration of brown bears to the rest of the continent. [10]

Hybrids

American black bears are reproductively compatible with several other bear species, and have occasionally produced hybrid offspring. According to Jack Hanna's Monkeys on the Interstate, a bear captured in Sanford, Florida, was thought to have been the offspring of an escaped female Asian black bear and a male American black bear. [13] In 1859, a black bear and a Eurasian brown bear were bred together in the London Zoological Gardens, but the three cubs died before they reached maturity. In The Variation of Animals and Plants under Domestication, Charles Darwin noted:

In the nine-year Report it is stated that the bears had been seen in the zoological gardens to couple freely, but previously to 1848 most had rarely conceived. In the reports published since this date three species have produced young (hybrids in one case), ... [14]

A black bear shot in autumn 1986 in Michigan was thought by some to be a black bear/ grizzly bear hybrid, due to its unusually large size and its proportionately larger braincase and skull. DNA testing was unable to determine whether it was a large black bear or grizzly. [15]

Subspecies

Listed alphabetically. [16] [17]

American black bear sub-species
Sub-species name Common name Distribution Description
Ursus americanus altifrontalis Olympic black bear Pacific Northwest coast from central British Columbia through northern California and inland to the tip of northern Idaho and British Columbia
Ursus americanus amblyceps New Mexico black bear Native to Colorado, New Mexico, west Texas, the eastern half of Arizona into northern Mexico, and southeastern Utah
Ursus americanus americanus Eastern black bear Eastern Montana to the Atlantic coast, from Alaska south and east through Canada to Maine and south to Texas. Thought to be increasing in some regions. Common to Eastern Canada and U.S. wherever suitable habitat is found. A large-bodied subspecies, almost all specimens have black fur. May very rarely sport a white blaze on chest.
Ursus americanus californiensis California black bear Mountain ranges of southern California, north through the Central Valley to southern Oregon Able to live in varied climates: found in temperate rainforest in the north and chaparral shrubland in the south. Small numbers may feature a cinnamon brown fur.
Ursus americanus carlottae Haida Gwaii black bear, Queen Charlotte black bear Haida Gwaii/ Queen Charlotte Islands and Alaska Generally larger than its mainland counterparts with a huge skull and molars, and is found only as a black color phase [18]
Ursus americanus cinnamomum Cinnamon bear Colorado, Idaho, western Montana, and Wyoming, eastern Washington and Oregon, northeastern Utah Has brown or red-brown fur, reminiscent of cinnamon
Ursus americanus emmonsii Glacier bear Southeast Alaska. Stable. Distinguished by the fur of its flanks being silvery gray with a blue luster [19]
Ursus americanus eremicus Mexican black bear Northeastern Mexico and US borderlands with Texas. Very endangered. Most often found in Big Bend National Park and the desert border with Mexico. Numbers unknown in Mexico, but presumed very low.
Ursus americanus floridanus Florida black bear Florida, southern Georgia, and Alabama Has a light brown nose and shiny black fur. A white chest patch is also common. An average male weighs 136 kg (300 lb).
Ursus americanus hamiltoni Newfoundland black bear Newfoundland Generally bigger than its mainland relatives, ranging in size from 90 to 270 kg (200 to 600 lb) and averaging 135 kg (298 lb). It has one of the longest hibernation periods of any bear in North America. [20] Known to favor foraging in fields of Vaccinium species.
Ursus americanus kermodei Kermode bear, spirit bear Central coast of British Columbia Approximately 10% of the population of this subspecies have white or cream-colored coats due to a recessive gene and are called "kermodes" or "spirit bears". The other 90% appear as normal-colored black bears. [21]
Ursus americanus luteolus Louisiana black bear Eastern Texas, Louisiana, southern Mississippi. Threatened (federal list). Has relatively long, narrow, and flat skull, and proportionately large molars [22] Prefers hardwood bottom forests and bayous as habitat
Ursus americanus machetes West Mexico black bear North-central Mexico
Ursus americanus perniger Kenai black bear Kenai Peninsula, Alaska
Ursus americanus pugnax Dall black bear Alexander Archipelago, Alaska
Ursus americanus vancouveri Vancouver Island black bear Vancouver Island, British Columbia Found in the northern section of the island, but occasionally will appear in the suburbs of Victoria metropolitan area
Other Languages
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