Hunter's hartebeest, Hunter's antelope
Hirola are critically endangered antelopes that are found in eastern Africa. They are tan to rufous-tawny in color with slightly lighter underparts, predominantly white inner ears, and a white tail. These antelopes have very sharp horns which are ridged along three-quarters of their length. As hirola age, their coat darkens becoming slate grey and the number of ridges along their horns increases. Hirola have large, dark sub-orbital glands used for marking their territories and give them the name "four-eyed antelope". They have white spectacles around their eyes and an inverted white chevron running between the eyes. The horns, hooves, udders, nostrils, lips and ear tips are black. Males and females look similar although males are slightly larger with thicker horns and darker coats.
Hirola are found on the border between Kenya and Somalia. They inhabit seasonally flooded open grassland with light bush, wooded savannahs with low shrubs and scattered trees, most often on sandy soils.
Hirola are crepuscular creatures and feed mostly around sunrise and then again right after sunset. They are social and most of the time live in small groups of 15-40 individuals; these groups consist of females and their offspring, and a dominant male. Depending on the time of year these small groups may form herds of several hundred individuals. Males that do not have a harem often form bachelor groups of up to 5 individuals and when juveniles reach 1 year of age they form their own separate groups. Adult males are territorial; their territories are marked with dung, secretions from the sub-orbital glands and by stamping grounds where males scrape the soil with their hooves and slash the vegetation with their horns. When males defend their harem or their territory they drop to their knees in a serious fight with the opponent and sometimes such fights become very fierce. Hirola are often found in association with other species such as oryx, Grant's gazelles, Burchell's zebras, and topi; they avoid Coke's hartebeests, buffalo, and elephants.
Hirola have a polygynous mating system where males compete between each other for females and have small harems. These antelopes are seasonal breeders and usually breed in March-April. The gestation period lasts around 7.5 months after which a single calf is born in September-November. Females give birth alone and may remain separate from the herd for up to two months, which makes both the female and the calf vulnerable to predation. Females nurse and care for their calves, Newborn calves are born fully developed and can stand and run soon after birth. When calves are 1 year old they separate from the main nursery herd and form another herd with other juveniles. Females become reproductively mature when they are 2-3 years old; males do not mate until they are able to successfully compete with other males, which is usually between 3 and 4 years of age.
Disease (particularly rinderpest), poaching, severe drought, predation, competition for food and water from domestic livestock and habitat loss are main threats to these antelopes. Hirola prefer areas that are used by livestock which puts them at increased risk from diseases like tuberculosis. Due to the lack of protection, they are also still very vulnerable to poaching. Hirola are also threatened by predation and competition with other wild herbivores such as topi and Coke's hartebeest.
According to the IUCN Red List, the total population size of hirola is fewer than 250 mature individuals. There is also an introduced population of this species in Tsavo East National Park (Kenya) which contains around 76 individuals. Currently, hirola are classified as Critically Endangered (CR) on the IUCN Red List and its numbers today are decreasing.