General+Information

American Black Bear (//Ursus americanus//) is **Polygynous** (//animal mating in which a male mates with more than one female during any single breeding season//), although the American Black Bear is a solitary animal the males home ranges often over the area where several females may live. During there breeding season which generally occurs from June to mid July the two sexes are able to coexist with each other. During the previously mentioned time span females remain in estrus (a regular period of sexual excitement in many female mammals, during which the animal seeks to mate) until mating occurs.

On average female American Black Bears give birth once every two years, however there is sometimes a three to four year period where child birth will not take place. The female’s pregnancy usually lasts approximately 220 days, however this does include implantation (the process by which, or stage at which an embryo becomes embedded in the lining of the womb). The eggs that have been fertilized are not planted until autumn. Embryonic development only occurs in the last ten weeks of pregnancy. The majority of births take place in the time span of January and February while the female is in the hibernation stage. There rang of young per-litter is anywhere from one to five but on average is two or three. During this phase the black bear cub stay within the safety of the den mostly due to the fact that the cubs are born hairless, blind and relatively small in comparison to the size of an adult mammal. The family emerges in spring and is weaned off of the mother’s milk around six to eight month old. At the age of seventeen months old the mother goes back into estrus in which she forces the cubs of her territory.

At the time span of two through nine years old the females reach sexual maturity. Males however reach sexual maturity at a more precise age ranging only form three years to four years and continue growth until the age of ten or twelve. A few important features the American Black bear exhibit are that they are iteroparous (reproducing more than once in a lifetime) they are seasonal breeders and viviparous (bearing live young, not eggs). They also delay implantation for a more efficient birth cycle. American black bears are also one of the eight species of bear that reproduces with relative ease in captivity. (Boone et al., 2003).

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 * Habitat Distribution:

The American black bear, //Ursus americanus,// is the smallest of all the North American bear species. With the males being slightly bigger than the females. As we can see form the illustration above, the black bear is distributed throughout much of North America, with the majority of the population residing within the Canadian borders.

//Citations//
 * Boone, W., Richardson, M. & Greer, J.,** 2003. Breeding behavior of the American black bear //Ursus americanus//. //Theriogenology// **60**, 289–297.

//( Nelson Ralph A., G. Edgar Folk, Jr., Egbert W. Pfeiffer, John J. Craighead, Charles J. Jonkel and Dianne L. Steiger © 1983,Behavior, Biochemistry, and Hibernation in Black, Grizzly, and Polar Bears, by International Association of Bear Research and Management)//

Habitat Distribution: http://3.bp.blogspot.com/_6ldbdWnLMmA/SlIUeRVJ_CI/AAAAAAAAAjo/ysm14f2ZA5I/s400/Black_Bear_Map_rev.gif
 * Image credits:**

American Black bear: http://www.arktofile.net/images/bear_am.jpg

//Submitted by Hro//

Just interesting facts: The black bear head is smaller and narrower and is held up higher as the animal ambles along. Black bears also lack the shoulder hump of the grizzlies and have shorter, more curved claws that are razor-sharp to make tree-climbing swift and efficient. This is from the website: [] Also: black bears are great swimmers, and have been seen to swim across large lakes or fast pace rivers. And, can run in powerful bursts that can reach a speed of 30mph. ([])