Physical Characteristics
The topi is a medium-sized antelope with a striking reddish-brown to purplish-red coat. Distinct black patches appear on the face, the upper forelegs and on the hips and thighs. To complete its singular appearance, the topi's yellowish-tan legs look like they are encased in stockings. Among the most socially advanced of the ungulates, the topi (also called the sassaby) occurs in the largest numbers in southern Sudan and in Tanzania's Serengeti National Park. Its distribution is scattered, and populations isolated, probably because of habitat loss and hunting.
Although not quite as large as its relative the hartebeest (kongoni), the topi has a similar body features. But it does not have such a long narrow head nor is it as high at the shoulder level. The female is usually lighter in color than the male. Both sexes have thick, heavily ringed, lyre-shaped horns about 21 inches long. Topis have good sight and hearing and can run quite fast with a bounding gait.

Habitat
Their favorite habitat are flood plains, but they are sometimes found in dry areas of open savanna and park woodland, taking to the shade during the heat of the day. They prefer flat lowlands, and can go without water for long periods of time only if they have access to green pastures.

Behavior and Habits
Topis are exceptionally gregarious and live in herds of 15 to 20, although in some places it is possible to see herds of hundreds. Their social structure is flexible; sedentary populations display the usual residence pattern—small herds led by a dominant male. During migratory periods, large numbers of animals congregate together indiscriminately. When the group stops, if only for a few hours, males establish small temporary territories in which they shepherd the females. Like the kob, the topi establishes specific breeding arenas in areas of high population density, which are fiercely fought for by males.
Topis are most active in the morning and evening. Like other ruminants, they feed for a while, then rest and chew their cud before they continue feeding. They have several rest breaks during the day and the rhythm of their daily activities is influenced by the food supply - the coarser and drier the feed, the longer rest time needed for digestion.
Females reach mature at about 1 1/2 years and males at about 3 years. Between 4 and 5 years of age, males begin to fight over territories, but only the strongest win. Mating takes place in the territories. Infant topis spend their first 3 to 12 days lying out and about 3 months start growing horns and acquiring adult coloring.
Calving normally occurs once a year and is timed for periods when grass supplies are plentiful. Nonetheless topis are almost as flexible in their reproduction as they are in their social organization. If food supplies are particularly good, topis will conceive at different times of the year, with shorter intervals between calves.
Diet
The topi eats only grass, its narrow muzzle being well adapted for selecting the most tender growth. Their favorite habitat is the flood plain, but they are sometimes found in dry areas of open savanna and park woodlands, taking to the shade during the heat of the day. If green grazing is not available, the topi must drink daily.
Predators and Threats
The topi’s ecological limitations make competition for resources its biggest threat. Hardier antelope like the wildebeest fair better when conditions are less than favorable (such as during drought). Also, cattle out-compete topis on dry season grazing ranges.
Thought You Should Know

• Both male and female topi like to rub their heads on the ground (to spread scent from facial glands), roll in earth and stir up mud with their horns. They smear mud on their bodies with their hooves.

• The gregarious topi spend much of their life with other antelopes such as wildebeest, and with zebra and ostrich. Female topi have developed the ability to stall the labor process in order to delay giving birth if they sense immediate danger. Topi are the swiftest of the ungulates, able to run at faster speeds than other similar antelope species.