Size:

Black bears are the smaller of Yellowstone's bear species, but not by as much as one might think. They stand xxx at the shoulder and weigh in typically between 275 and 175 pounds, with males being significantly larger. That being said, some black bears have been reported weighing in excess of 400 lbs.

Diet:

Bears are highly effective foragers and among the most adaptable species on earth, especially when it comes to diet. One significant factor shaping the diet of black bears in the Greater Yellowstone Ecosystem (GYE) is the presence of and competition with grizzly bears. In areas where grizzly bears are densely populated, black bears tend to consume more calories from pine nuts during the autumn and eat very little meat, likely due to competition pressures.

Conversely, black bears living in regions with low grizzly bear density depend more heavily on fruits, which is probably influenced by the habitat type available to them. A particularly notable aspect of their diet is their reliance on insects. In summer, insects make up about 50% of the diet for male bears and nearly 75% for female bears. This demonstrates how bears can efficiently survive on just the bear necessities

Mating:

Black bears typically breed from late May through early June. During the breeding season, females come into estrus 2-3 times, regardless of whether conception has occurred, with each estrus period lasting around 9 days and during which they are receptive to males. Black bears usually give birth to 2-3 cubs per litter and have litters once every other year. After fertilization, the embryos are not immediately implanted; instead, implantation occurs after the female enters hibernation, typically in late November. They call this delayed implantation, and it is common among a few clades of mammals. Gestation lasts only about 6 weeks following implantation.

Birth takes place in the den during February, with the official "birthday" for bears in the GYE designated as February 1st. At birth, cubs are altricial; they are blind, hairless, and entirely helpless, requiring extensive maternal care during their early life stages.

Population:

An accurate population count for black bears hasn’t been made for the GYE. Yellowstone National Parks data from 1975-1979 show between 300 and 500 bears in the park.