Ursidae is a family of mammals in the order Carnivora, which includes the giant panda, brown bear, and polar bear, and many other extant or extinct mammals. A member of this family is called a bear or an ursid. They are widespread across the Americas and Eurasia. Bear habitats are generally forests, though some species can be found in grassland and savana regions, and the polar bear lives in arctic and aquatic habitats. Most bears are 1.2– long, plus a 3– tail, though the polar bear is 2.2– long, and some subspecies of brown bear can be up to 2.80NaN0. Weights range greatly from the sun bear, which can be as low as 350NaN0, to the polar bear, which can be as high as 726-1NaN-1. Population sizes vary, with six species classified as vulnerable with populations as low as 500, while the brown bear has a population of over 100,000 and the American black bear around 800,000. Many bear species primarily eat specific foods, such as seals for the polar bear or termites and fruit for the sloth bear, but with the exception of the giant panda, which exclusively eats bamboo, ursids are omnivorous when necessary. No ursid species have been domesticated, though some bears have been trained for entertainment.
The eight species of Ursidae are split into five genera in three subfamilies: the monotypic Ailuropodinae, the panda bears; Tremarctinae, the short-faced bears; and Ursinae, containing all other extant bears. Extinct species have also been placed into all three extant subfamilies, as well as three extinct ones: Agriotheriinae, Hemicyoninae, and Ursavinae. Over 100 extinct Ursidae species have been found, though due to ongoing research and discoveries the exact number and categorization is not fixed.
Conservation status codes listed follow the International Union for Conservation of Nature (IUCN) Red List of Threatened Species. Ranges are based on the IUCN Red List for that species unless otherwise noted. All extinct species or subspecies listed alongside extant species went extinct after 1500 CE, and are indicated by a dagger symbol "". Population figures are rounded to the nearest hundred.
The family Ursidae consists of eight extant species belonging to five genera in three subfamilies and divided into dozens of extant subspecies. This does not include ursid hybrid species such as grizzly–polar bear hybrids or extinct prehistoric species.
The following classification is based on the taxonomy described by Mammal Species of the World (2005), with augmentation by generally accepted proposals made since using molecular phylogenetic analysis; this includes the division of the giant panda into two subspecies. There are several additional proposals which are disputed, such as reclassifying the subspecies of the brown bear into a smaller set of clades, which are not included here.
See main article: article and Ailuropodinae.
See main article: article and Tremarctinae.
See main article: article and Ursinae.
In addition to extant bears, a number of prehistoric species have been discovered and classified as a part of Ursidae. In addition to being placed within the three extant subfamilies, they have been categorized within the extinct subfamilies Agriotheriinae, Hemicyoninae, and Ursavinae, some of which are subdivided into named tribes. There is no generally accepted classification of extinct ursid species. The species listed here are based on data from the Paleobiology Database, unless otherwise cited. Where available, the approximate time period the species was extant is given in millions of years before the present (Mya), also based on data from the Paleobiology Database. All listed species are extinct; where a genus or subfamily within Ursidae comprises only extinct species, it is indicated with a dagger symbol .