are black bears and brown bears different species
American black bear 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]
Polar bear There are 19 generally recognized, discrete subpopulations, though polar bears are thought to exist only in low densities in the area of the Arctic Basin.[36][38] The subpopulations display seasonal fidelity to particular areas, but DNA studies show that they are not reproductively isolated.[33] The thirteen North American subpopulations range from the Beaufort Sea south to Hudson Bay and east to Baffin Bay in western Greenland and account for about 54% of the global population.[39]