Waller’s gazelle, Giraffe gazelle
The Giraffe gazelle (otherwise known as gerenuk), is the only species of Litocranius genus. The animal exhibits conspicuously long and slender neck. The Giraffe gazelle can often be seen standing on its hind legs while stretching its neck to reach to high branches of trees, abundant with soft leaves. Victor Brooke, an Anglo-Irish naturalist, was first to describe this species in 1878. Gerenuks are endemic to the Horn of Africa as well as the Great Lakes region of Africa. Females of this species are identified by a dark colored area on their crown. Males, on the other hand, display short and robust horns, covered with a lot of rings. The magnificent horns of these animals curve backwards, having the characteristic "S" shape.
The natural range of Giraffe gazelles covers the Horn of Africa, stretching from southern Djibouti, Somalia and Ethiopia to as far south as Kenya and north-eastern portions of Tanzania. Within this territory, Giraffe gazelles generally occur in woody vegetation, deserts and open scrublands.
Habits and lifestyle
Gerenuks are highly social creatures, forming small, single-sex herds of 2 - 6 individuals, although all-female herds may sometimes contain juveniles. Meanwhile, males occasionally prefer living solitarily. Gerenuks are generally peaceful animals and rarely fight. They are sedentary and don't tend to travel, apparently in order to conserve enough energy for foraging. They become even less mobile as they age. Each herd has its own territory, typically 3 – 6 square km (1.2 – 2.3 square miles) in size. Home ranges of various herds often overlap. Males defend their territories by scent marking with special secretions, produced by their preorbital glands. Giraffe gazelles lead diurnal lifestyle, which means that they are active by day. However, these animals spend the midday hours standing or resting in shelters. The greater part of their active time is spent looking for food and eating. Meanwhile, female gerenuks appear to spend more time these activities than males. In order to cool off, they often expose themselves to rain.
Diet and nutrition
Gerenuks have a polygynous mating system, where each male mates with a number of females. They may breed at any time of year, although each female breeds once every 1 - 2 years. Intervals between breeding are related to the gender of the previous year's young. Gestation period lasts for 165 days, yielding 1 - 2 babies, which are born fully developed. During the first few minutes after birth, they are able to walk. The babies are cared for and fed by their mother until weaning, which occurs at 1 year old in females and at least 1.5 years old in males. The latter don't leave their mother until 2 years old. The age of reproductive maturity is 1 - 2 years old in females and 1.5 years old in males. Males in the wild typically start mating only at 3.5 years old, when they are dominant enough to occupy a maintain of their own.
Gerenuks are primarily threatened by loss and fragmentation of their natural habitat, associated with growth of local human populations, leading to developement of settlements, roads and agriculture. As a result, some isolated populations cannot find suitable food and shelter. Some are unable to find mates as well as escape predators. Further, this species has served as a game animal in Africa during a long period of more than 200 years. In spite of having limited supply and very small natural range, gerenuks heavily suffer from hunting as trophies and for consumption.
According to the IUCN Red List, the total population of gerenuks is around 95,000 individuals. Currently, this species is classified as Near Threatened (NT) and its numbers are decreasing.
Despite the small overall population, these animals play an important role in the local ecosystems. Thus, due to foraging, gerenuks enhance nutrient cycling. Then, they are key prey species for numerous predators of their range (leopards, lions, hyenas and others).
Fun facts for kids
- The word "gerenuk" derives from the Somali language and is translated as “giraffe-necked”.
- These animals are capable of walking on their hind legs, though only short distances.
- Along with many other gazelle species, these mammals scent mark their home ranges with special tar-like substance, produced by pre-orbital glands, found in front of their eyes. Additionally, gerenuks have similar scent glands on their knees, between their split hooves, hidden under tufts of hair.
- When feeding, they use their bodies to reach the best food items. They usually stand straight on their hind legs, stretching their neck to feed upon higher branches and twigs, situated about 2 metres (6.6 ft) off the ground.
- Gerenuks are able to live without directly drinking water and instead get all required moisture from the plants they consume, due to which they can sustain life in extremely dry habitats such as deserts and scrublands.
- Females of this species are very attentive and protective to their young. After feeding, mothers always clean their calves as well as eat up the rest of the food, since any remaining food may be perceived by predators of the area. They communicate with their calves through gentle sounds, typically using soft bleating calls.