In the greater Yellowstone
ecosystem, where the hunting of grizzlies is banned, the number of people injured by grizzlies fell from an average of two per year in 1970, to fewer than 1.3 per year in 1995.
In Alaska, where bear hunting is legal, 76 people - an
average of 3.6 per year - were killed or injured badly enough to need hospitalization between 1976 and 1997. Around a third of those were hunters.
In late summer and early fall, grizzlies enter a stage called hyperphagia, in which they consume vast amounts of food -
80 to 90 pounds
a day - to prepare for hibernation. They put on 40 pounds of fat a week, gorging on roots, insects, berries, vegetation and the occasional animal carcass. The grizzly's ability to consume vast amounts of rich food and not suffer heart disease or cholesterol problems intrigues medical scientists.
If a mother grizzly does not have enough fat reserves to
gestate cubs during hibernation, her body absorbs the embryos before they implant in the uterus wall.
Grizzlies lose from 15 to 40 percent of their body weight during hibernation.
Newborn grizzly cubs are hairless, toothless and the size of chipmunks. They stay with their mother for two and a half years and don't reach sexual maturity until their fifth year.
The grizzly needs a huge territory - from 50 to 300 square miles for females and 200 to 500 square miles for males.
Adult male grizzlies commonly kill young cubs. Three reasons have been postulated: food, sex (females with nursing cubs do not enter heat) and turf (to reduce competition for limited territory).
In the 175 years before grizzlies received federal protection under the Endangered Species Act in 1975, grizzly bear populations in the lower 48 states fell from more than 50,000 to less than 1,000 animals.