above a certain threshold, an increase in sweating and panting is also observed. Common elands use their sparse fur coats to dissipate excess heat via reradiation. The dewlap is also believed to play a role in thermoregulation. Due to its high surface area to volume ratio, it may allow for efficient thermoregulation in larger common elands with larger dewlaps. Sociability and reproduction Females are sexually mature at 15 to 36 months and males at 4 to 5 years. Mating may occur anytime after reaching sexual maturity, but is mostly seen in the rainy season. In Zambia, young are born in July and August, while elsewhere this is the mating season. Mating begins when elands gather to feed on lush, green plains with plentiful grass, and some males and females start mating with each other in separate pairs. Males chase the females to find out if they are in estrus. They also test the female's urine. Usually, a female chooses the most dominant and fit male to mate with. Sometimes, she runs away from males trying to mate, causing more attraction. This results in fights between males, in which their hard horns are used. A female allows a male to mount after two to four hours. Males usually keep close contact with females in the mating period. The dominant male can mate with more than one female. Females have a gestation period of nine months, and give birth to only one calf each time. Males, females, and juveniles each form separate social groups. The male groups are the smallest; the members stay together and search for food or water sources. The female group is much larger and covers greater areas. They travel the grassy plains in wet periods and prefer bushy areas in dry periods. Females have a complex linear hierarchy. The nursery and juvenile group is naturally formed when females give birth to calves. After about 24 hours of the delivery, the mother and calf join this group. The calves start befriending each other and stay back in the nursery group, while the mother returns to the female group. The calves leave the nursery group when they are at least two years old and join a male or female group. Diseases and parasites Common elands are resistant to trypanosomiasis, a protozoan infection that has the tsetse fly as a vector, but not to the Rhipicephalus-transmitted disease theileriosis. The disease-causing bacterium