Distribution:  Range from northern Tanzania to southern Sudan and Ethiopia, throughout Kenya from coast to Lake Victoria. 

Habitat:  Lowland thornbush, savannah woodland, open plains and montane grassland up to 8,000 feet as well as arid subdesert in northern Kenya and Ethiopia.  Occupies open plains during dry season when other water-dependent antelope are absent, avoiding competition by using its ability to subsist on vegetation available under waterless, subdesert conditions.  During wet season, lives on small woodland plains while main migratory herds are on open short-grass plains.  Tolerates drier and more closed habitat than Thompson’s gazelle.

Food and Feeding Methods:  A mixed feeder but more of a browser than a grazer.  Herbs and shrub foliage are preferred during later wet and dry seasons, while grass is grazed only when young and green.  Intense grazing by other species removes grass, making herbs available for gazelles.  Rarely, if ever, drinks water.

Social Behavior:  Gregarious, territorial, migratory.  Size and composition of herds vary with habitat and seasonal changes.  In the dry season, mixed herds are at their peak and territoriality at a low ebb; during rains female breeding herds are largest and most stable, and territoriality reaches its peak.  Mixed herds circulate within ranges up to 12 sq miles but defended male territories range from 1 to 6 sq miles.  Larger (up to 400 or more) mixed herds tend to form on open plains while smaller ‘harems’ composed of females and young with 1 territorial male are found on patches of grassland in woodland areas during the rains.  Sedentary breeding herds will sometimes remain on a woodland territory for up to a year or as long as it’s occupied by  a territorial male.  Optimal size for breeding herds is 10 to 25; below 10, females will leave to look for a larger herd that offers more protection.  Except for breeding or ‘harem’ herds, all other types of social groups are open with members free to come and go. Females develop little bond except with offspring and are passive in social relations.

Large herds only occur when males and females aggregate on open plains near landmarks, such as rock outcrops, mounds or trees, for orientation in a largely featureless landscape.  Social attraction increases with size of herd as individual animals will change course to approach members of their own species.  On plains, males establish territories around landmarks frequented by mixed herds, but have to tolerate presence of other males due to sheer numbers.  A territorial male may only enjoy domination of mixed herd for a few hours before it moves onto a neighbor’s property.  When this happens, territorial male often goes along, though he reverts to bachelor status as soon as he leaves his own territory. 

In woodlands, limited open space and natural obstructions limit size and formation of mixed groups.  Territorial males in woodland areas are more intolerant of males who are forced to stay in bachelor herds in less desirable areas. Territories in woodland areas are clearly defined, strictly defended and owners only vacate in emergencies.  Woodland territories tend to last longer than those on open plains, sometimes for up to 8 months if herds are sedentary. The difference in tolerance between territorial males on plains and in woodland areas is probably due the need for definite landmarks to define territories. 

Younger males seek company of older males in bachelor herds where strict dominance hierarchy based on age exists and is maintained through aggressive interactions.  Dominant males always walk behind subordinates.  When bachelor male matures at 3 years, he leaves herd to find territory or drives all other bachelors away and appropriates area.  Males don’t mark with preorbital glands but maintain dung middens to mark boundaries of territories.  Male dominance is usually settled through displays rather than fighting, with display duels lasting for 15 minutes or more.  Most distinctive form of territorial display is ‘head-flagging’, where male stands erectly and abruptly turns head from side to side, swelling muscular neck like a man flexing his biceps, and showing his horns to advantage. 

Reproduction:  Gestation is about 6 ½ months.  After birth, fawn remains hidden for 4 to 6 weeks.  When mother approaches to suckle, she calls it by head-bobbing and bleating.  During concealment period, mothers with young in same area will join together in ‘mother’ herds of 2 to 10 and sometimes cooperate in defending young.  As fawn leaves concealment, it associates in peer groups with other fawns and accompanies its mother. Weaning occurs at 6 months but mother-fawn bond continues until adolescence.  Females start breeding at 1 ½ years and males at 3 years when they become socially and physically mature. 

Status:  Although eliminated in some agricultural areas where poaching is uncontrolled, still widespread both within and outside parks and reserves.  Not endangered.

Adaptations:  Long limbs and necks have evolved to aid greater mobility and speed.  Flexible noses act as blood-cooling bellows to regulate temperature in hot, arid areas. 

Head/Body Length:    4 ½  - 5 ½ ft.                               Tail Length:    ½ - 1 ft.
Shoulder Height:        2 ½  - 3 ft.            
Weight:                          132 - 180 lbs. (male)   84 - 148 lbs. (female)