A family unit usually comprises of eight to 10 animals and is led by the matriarch, usually the oldest, largest, dominant cow. During times of danger, such as severe drought or intense poaching, many family units will come together to form a large herd comprised of 500-1,000 individuals. When young male elephants reach puberty at around 12-15 years of age, they become more independent and strike out on their own or are driven out by the family unit's females. Bulls temporarily rejoin female-centered units, especially when females are sexually receptive. During musth, a bull's testosterone blood level skyrockets, and he becomes dangerously aggressive, unpredictable and highly competitive with other bulls for females.
Females appear to prefer males in musth for mating.
Woodland Park Zoo's one female East African bush elephant and four female Asian elephants can be seen at the Elephant Forest exhibit located in the Tropical Asia bioclimatic zone. The elephants have use of a large area that includes a paddock, bathing pond and barn. On cold or wet days, visitors can expect to find the elephants in their comfortable barn. The African elephant is an endangered species. This is due to poaching for ivory and loss of habitat.