The nyala is a slender antelope of southeastern Africa. It is a member of the spiral-horned antelope tribe Tragelaphini (family Bovidae), which also includes the kudu and the eland. The scientific name of the nyala is Tragelaphus angasii.
Male nyalas weigh about 216–275 pounds (98–125 kilograms) and have a shoulder height of 42 inches (106 centimeters). Females are much smaller, weighing 128 pounds (58 kilograms) and standing 36 inches (92 centimeters) tall. Females and young have short, bright chestnut coats with 8–13 white stripes on the torso, spots and bands on the legs, chest, and cheeks, and a bushy tail with a white underside. Males gradually turn dark charcoal gray and shaggy as they mature and have a long fringe from throat to belly and a line of erect hair along the spine. The male’s stripes and spots mostly disappear under the long hair, but the tan lower legs, ears, and forehead persist. Only males have horns, which are about 24–33 inches (60–83 centimeters) long and have 1.5–2.5 twists.
Nyalas are herbivores and eat vegetation rather than meat. They spend daytimes in wooded areas and emerge at night to graze on green grass during the rainy season. Nyalas feed on foliage, seeds, and fruits during the dry season. Females and young form loose herds of five or six animals. Males are nonterritorial and share overlapping ranges. Mating peaks occur during the summer in the southernmost populations, but births occur year-round. The gestation period (the time between conception and birth) is about seven months. Calves hide for 10–18 days before accompanying and foraging with their mothers.
The related mountain nyala (Tragelaphus buxtoni) is native to the highlands of Ethiopia that lie east of the Great Rift Valley. The mountain nyala was discovered only in 1908 and resembles a greater kudu more than a nyala. Male mountain nyalas stand up to 51 inches (130 centimeters) and weigh up to 660 pounds (300 kilograms); females weigh 330–440 pounds (150–200 kilograms). Both males and females are gray-brown with faded stripes but have white on the throat, nose, cheeks, and underside of the bushy tail. The elongated hair along the spine is brown and white. The mountain nyala’s coat length varies according to the season. The male’s open spiral horns measure up to 47 inches (120 centimeters) along the curve.
Mountain nyalas are adapted for montane habitats between 10,000 and 15,000 feet (3,000 and 4,500 meters) high. Because they have a limited geographic range, they are a particularly vulnerable species. Over time, increasing human population and susceptibility to livestock diseases drastically reduced their numbers. Beginning in the 1970s, mountain nyalas increased to at least 1,700 within Ethiopia’s Bale Mountains National Park. However, after the Ethiopian revolution of 1991, the park was overrun, and the mountain nyala population was reduced to an estimated 150 animals. After protection was restored, the nyala population increased to more than 2,500 by the end of the 20th century. The mountain nyala is now classified as an endangered species.