Grant’s Gazelle, Nanger granti
Grant’s gazelle (Nanger granti) is native to Africa. Its northern range of Tanzania extends south to Ethiopia and the Sudan, and from the coast of Kenya to Lake Victoria. It prefers habitats within shrub lands and grass plains, but can also be found in regions that are more arid. In Swahili, Grant’s gazelle is called Swala Granti. It was placed within the Nanger subgenus of the genus Gazella, before Nanger became a separate genus. Grant’s gazelle holds five recognized subspecies.
The closest relative of Grant’s gazelle is Soemmering’s gazelle, but it is also related to Thomson’s gazelle. Although there is no fragmentation between Grant’s gazelle populations, there is a great genetic variation among individuals. It is thought that this occurred as a result of many expansions and reductions of dry habitats during the late Pleistocene era, causing possible fragmentation to the populations of that time.
Grant’s gazelle can reach an average height of up to 37 inches at the shoulder, and can weigh as much as 180 pounds depending on sex. The short fur is typically buff orange in color, with white fur occurring on the underbelly. It is very similar in appearance to Thomson’s gazelle, with the exception of the stout, ringed horns that can reach a length of up to 32 inches. Its long legs can carry it at speeds of up to 56 miles per hour.
Grant’s gazelles are social by nature, and are territorial and migratory. Although they do migrate, they do not follow the same paths as other migratory species such as zebras and wildebeests, as they require less water, and so they will travel in the opposite direction of a popular watering site. Male gazelles hold territories that will sometimes overlap, and they are the only individuals to be territorial. If a doe enters a buck’s territory, he will herd the female into his group and keep her there while she is in estrous. Typically, females do not try to leave, but if they do, they are aggressively driven back.
Many times, male Grant’s gazelle will form bachelor groups comprised of territorial young males and non-territorial bucks. Typically, these groups will not force any male to stay and are relatively “laid back”. If a male attempts to join the group, he must show his neck strength in an intimidation display. In this process, males will circle around each other and throw their necks back and forth. Whichever male has the better neck strength will win. If two bucks have equal neck strength, a fight may follow the intimidation displays, although older bucks do not usually fight.
At 18 months of age, Grant’s gazelle is sexually mature. Males are able to mate with many females within their territory. In order to know if a doe is ready to mate, the buck will follow behind her after she urinates, and will perform the flehmen response. Once it has been established that she is ready to mate, the male will continue to follow her and wait for her tail to rise.
Grant’s gazelle does remain pregnant for up to 198 days, after which one fawn is born in January or February. Does will isolate themselves from the herd before giving birth, and will take care to remove any afterbirth or fluids that can leave the fawn dirty or open to the noses of predators. Females who have recently given birth will group together to provide better protection. Because the fawns are not able to move for the first few days of their lives, the mothers will stay nearby and nurse them up to four times a day. At six months of age, the fawn is weaned and it will leave to find a separate herd, although it will remain in association with its mother for some time.
The diet of Grant’s gazelle consists mainly of browse, like shrubs, but they will eat graze, like grass. It is thought that rainfall may affect the diet of these gazelle, as most of the water they consume comes from what they eat. During the months of July to September, Grant’s gazelle will migrate into areas with dense grass and consume small, brittle plants and red oats while they wait for the rainy season to return.
Grant’s gazelles are an important food source for cheetahs in Nairobi National Park, while in the Serengeti cheetahs prefer to eat Thomson’s gazelle. Other common predators include wild dogs, and jackals, which eat young gazelle. Humans also hunt Grant’s gazelle.
There are major threats to Grant’s gazelle including habitat destruction and fragmentation, and hunting. Some local populations have already become extinct. Although it is recorded on the IUCN Red List as of “Least Concern”, the overall populations are decreasing. Many national parks have created protected lands for Grant’s gazelle, which number from 140,000 to 350,000, including Lake Turkana National Parks in Kenya and Serengeti National Park in Tanzania.
Image Caption: Grant’s Gazelle (Gazella granti) in the Ngorongoro crater. Credit: Ikiwaner/Wikipedia