Each male may only breed a few cows during the breeding season. In about 243 days the female gives birth to one or two calves with most being born around the first part of June. At birth the calves are light colored and weigh from 25 to 35 pounds. They gain one pound a day for about a month and 2 to 3 pounds per day during the second month. At one year of age the yearlings weigh from 400 to 600 pounds.
Twin births are common in good habitat range.
Within a week of birth calves are able to follow their mother on land and water. At two weeks of age they are able to swim. At six months of age they are weaned and just before the birth of a new calf they are driven away. The moose, Alces alces, is the world's largest member of the deer family. A full grown bull moose can weigh from 900 to 1,500 pounds with an adult female weighing form 700 to 1,100 pounds.