Camels are day and night creatures, which means they are active during the day. They depend on vegetation such as low valerian and other thorny and salty plants. In order to achieve such low-lying plants and grasses, the camels have formed a split upper lip structure, allowing each half of their upper lip to move independently, which helps them eat low-lying plants and grasses. Like cows, camels return food from their stomachs to their mouths so they can chew food again. Camels can replenish water faster than other mammals. They allegedly drank about 30 gallons of water in 10 minutes. Camels travel in a herd of dominant males and some females. Depending on the species, the peak fertility of male bulls (called ruts) occurs at different times of the year. Bactrian’s birth peak appears between November and May, while the dromedary camel can reach its peak throughout the year. Males usually mate with six or so females, although some males can mate with more than 50 females in a season. The female camel has a gestation period of 12 to 14 months. At the time of childbirth, expectant mothers are usually separated from the main herd. Newborn calves can walk shortly after birth, and in just a few weeks, the mother and calf will rejoin the larger herd. Singletons are the most common, but twins are reported to have been born.