American black bears vary in size depending on sex, food availability and quality, and other factors. Male black bears may grow 20 to 60 percent larger than females. Weight of black bears vary with age, sex, season and health. Seasonal variation in weight is very pronounced: in autumn, their pre-den weight tends to be 30% higher than in spring, when black bears emerge from their dens. Black bears on the East coast tend to be heavier than the black beas from the West coast. Adult males usually weight between 125 and 550 lb, while females weigh 33% less at 90–275 lb. The largest subspecies on average is U. americanus carlottae of the Queen Charlotte Islands and Alaska. The biggest wild American Black Bear ever recorded was a male from North Carolina, shot in 1998, that weighed 400 kg (880 lb). Adults are 4–6 ft in length, and 2.5–3 ft in shoulder height. The North American Bear Center, located in Ely, Minnesota, is home to the world's largest captive male and female black bears. Ted, the male, weighed 950–1,000 lb (430–450 kg) in the fall of 2006. , the female, weighed 555.5 lb (252.0 kg) in the fall of 2007.