Hirola are found in the area between the Tana River in Kenya and the Juba River in Somalia. In 1963 a small population of about 20 individuals were introduced into the Tsavo East National Park from the South Garissa District. (Kingdon, 1997; Nowak, 1999)
inhabits short-grass, seasonally arid, grasslands in dry acacia bush/scrub and forest-savannah mosaic habitats.
Suitable grazing lands change over time as they become unsuitable by the invasion of predators or large herds, drought, or over-growth of grasses. The largest known area grazed by a herd is over 100 square km. (Andanje, 2001; Kingdon, 1997)
Hirola have long legs, a long body, long face with a slightly convex forehead, and a relatively short neck. Total body length ranges from 1200 to 2050 mm, tail length from 300 to 450 mm, and height at the shoulder from 1000 to 1250 mm.
Generally a mixture of soft and coarser hairs that vary in color from sandy brown to slate grey cover the body. The ears are white with black tips and the tail is white. A white line passes across the forehead from one eye to the other creating a white emphasis around the eyes in the likeness of a mask.
The horns of both males and females are angular, curved, and slightly flared. They are ringed most of the length of the horn, and reach about 700mm in length when fully developed. (Kingdon, 1997)
- Sexual Dimorphism
- male larger
- Range mass
- 65 to 155 kg
- 143.17 to 341.41 lb
- Range length
- 1200 to 2050 mm
- 47.24 to 80.71 in
Males compete among themselves for access to females and generally defend territories in which they maintain a harem of about 7 or 8 females. Male posturing includes head-flagging, marking of grass stems with preorbital glands, ground scraping with their hooves, and dung accumulations. Aggressive fighting between males is different from play-fighting by their stance. Earnest fights take place on their knees, whereas play-fighting takes place in an upright position. (Andanje, 2001; Kingdon, 1997; Nowak, 1999)
- Mating System
Hirolas mate at the beginning of the long rainy season in March or April and gives birth at the beginning of the short rainy season in October and November. Gestation typically lasts 7 to 8 months and a single calf is born, though twins are possible. Females become sexually mature at 2 to 3 years of age, while males do not mate until they are large enough and dominant enough to successfully compete with other males, usually between 3 to 4 year old. (Nowak, 1999)
- Key Reproductive Features
- seasonal breeding
- gonochoric/gonochoristic/dioecious (sexes separate)
- Breeding interval
- Hirolas breed once yearly.
- Breeding season
- Breeding occurs in March and April.
- Range number of offspring
- 1 (low)
- Average number of offspring
- Range gestation period
- 7 to 8 months
- Range age at sexual or reproductive maturity (female)
- 2 to 3 years
- Range age at sexual or reproductive maturity (male)
- 3 to 4 years
Females nurse and care for their young, who are capable of standing and running soon after birth. Calving females will separate from the group for the two weeks following birth. During this time the female and the calf are vulnerable to predation. When the calf has reached yearling status, it separates from the herd to join a sub group of yearlings. (Andanje, 2001; Kingdon, 1997; Nowak, 1999)
- Parental Investment
- post-independence association with parents
In captivity, the average lifespan of hirola is 10.2 years. Lifespan in the wild is unknown (Huffman, 2001; Solomon Kyalo, pers.comm.).
- Average lifespan
- 10.2 years
- Average lifespan
Hirola cluster in harems, consisting of a territorial male, several females, and their young. Small groups of bachelor males and yearlings also occur. Hirola form larger herds ranging in size from 15 to 40 individuals to many hundreds, depending on the time of year. During this time, smaller herds often exchange individuals before breaking apart from the larger group. This exchange of individuals helps decrease the likelihood of genetic drift and inbreeding within smaller herds.
- Key Behaviors
- dominance hierarchies
During occupancy of a region, hirola will graze an area of about 4 square km.
Communication and Perception
Preorbital gland secretions and posturing are used in male-male competition for access to females. Females are also likely to communicate their reproductive state via chemical cues.
Hirola are selective grazers, depending on short grasses. Occasionaly they have been oberserved to consume forbs. Their selectivity creates a need to follow the progress of newly sprouting grasses on the savannah and grasslands. If grasses grow too long, or if the grasses are disturbed by other grazers, they will move to another area. Early evening and morning are the times of highest intensity feeding.
Hirola are able to survive lengthy periods without drinking by avoiding energetic activities and storing fats.
Grasses eaten include Panicum infestum, Digitaria rivae, and Latipes senegalensis. Forbes eaten include Portulaca oleraceae, Commelina erecta, and Tephrosia subtriglora. (Andanje, 2001; Kingdon, 1997; Nowak, 1999)
- Plant Foods
- wood, bark, or stems
In the Garissa area, hirola are preyed on by lions and hunting dogs, while in the Tsavo region, they are preyed on by cheetahs and lions. Hyenas and eagles prey on young soon after birth and before the mother and calf rejoin the herd. Poaching plays a role in the 'predation' of Hirola. The poachers are composed of military personal, civilians, herdsmen, and local gangs.
Hirola avoid predation by remaining in the herd, thereby relying on the vigilance of many individuals. (Kingdon, 1997)
It is likely that hirola play an important role in their habitats by influencing the growth and composition of plant communities. They also act as important prey species for large predators.
Economic Importance for Humans: Positive
Hirola are sometimes hunted for meat, they have suffered drastic declines as a result of overhunting in the past.
- Positive Impacts
Economic Importance for Humans: Negative
There are no known negative effects of hirola on humans.
Hirola populations suffered two drastic declines during 1976-1978 and then in 1995. In 1976-1978 the population declined from 14,000 individuals to about 2,000 for unknown reasons. The second decline saw the population decrease from ~2,000 to 300, this decline was attributed to hunting by poachers, competition with cattle, and loss of habitat due to human encroachment. The natural habitat of hirola occurs in southwestern Somalia and southeastern Kenya, though the Somalian population is thought to be extinct or only occuring in small patchy groups. Hirola are considered one of the world's rarest species.
Conservation efforts have been underway for this species since 1963 when they were reported to be threatened. A small population was relocated in Tsavo East National Park and placed under protection by the park. By 1996 the population had reached 56 individuals. That same year, 35 more individuals were relocated to the park from Kenya in the operation "Hirola Now or Never" to increase the genetic diversity of the park population.
Efforts are being made to study the wild populations and to immplement community programs to educate local people about this species and how to help conserve it.
(Solomon Kyalo, pers. comm.)
Taxonomy of hirola has been a point of debate for many years. Hirola were considered a subspecies of topi in 1977, giving it the name Damaliscus lunatus hunteri, later they were given specific status as Damaliscus hunteri. Recently they were placed in their own genus, Beatragus, as . Hirola are in the subfamily Alcelaphinae based on DNA evidence and morphology.
(Solomon Kyalo, personal communication) (Nowak, 1999)
Hannah Olney (author), University of Northern Iowa, Jim Demastes (editor), University of Northern Iowa.
living in sub-Saharan Africa (south of 30 degrees north) and Madagascar.
uses sound to communicate
young are born in a relatively underdeveloped state; they are unable to feed or care for themselves or locomote independently for a period of time after birth/hatching. In birds, naked and helpless after hatching.
- bilateral symmetry
having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.
uses smells or other chemicals to communicate
active at dawn and dusk
- dominance hierarchies
ranking system or pecking order among members of a long-term social group, where dominance status affects access to resources or mates
animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.
an animal that mainly eats leaves.
A substance that provides both nutrients and energy to a living thing.
An animal that eats mainly plants or parts of plants.
referring to animal species that have been transported to and established populations in regions outside of their natural range, usually through human action.
offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).
having the capacity to move from one place to another.
- native range
the area in which the animal is naturally found, the region in which it is endemic.
generally wanders from place to place, usually within a well-defined range.
having more than one female as a mate at one time
- scrub forest
scrub forests develop in areas that experience dry seasons.
- seasonal breeding
breeding is confined to a particular season
reproduction that includes combining the genetic contribution of two individuals, a male and a female
- sexual ornamentation
one of the sexes (usually males) has special physical structures used in courting the other sex or fighting the same sex. For example: antlers, elongated tails, special spurs.
associates with others of its species; forms social groups.
uses touch to communicate
Living on the ground.
defends an area within the home range, occupied by a single animals or group of animals of the same species and held through overt defense, display, or advertisement
the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.
- tropical savanna and grassland
A terrestrial biome. Savannas are grasslands with scattered individual trees that do not form a closed canopy. Extensive savannas are found in parts of subtropical and tropical Africa and South America, and in Australia.
A grassland with scattered trees or scattered clumps of trees, a type of community intermediate between grassland and forest. See also Tropical savanna and grassland biome.
- temperate grassland
A terrestrial biome found in temperate latitudes (>23.5° N or S latitude). Vegetation is made up mostly of grasses, the height and species diversity of which depend largely on the amount of moisture available. Fire and grazing are important in the long-term maintenance of grasslands.
uses sight to communicate
reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.
Andanje, S. 2001. "Hirola Conservation PhD Study by Andanje" (On-line). Accessed October 8, 2001 at http://www.kenya-wildlift-service.org/andanje.htm.
Huffman, B. "Hunter's Hartebeest, Hirola" (On-line). Accessed September 13, 2001 at http://www.ultimateungulate.com/hirola.html.
Kingdon, J. 1997. The Kingon Field Guide to African Mammals. London and California: Academic Press.
Massicot, P. August 15, 2001. "Animal Info - Hirola" (On-line). Accessed September 13, 2001 at http://www.animalinfo.org/species/artiperi/damahunt.html.
Meester, J., H. Setzer. 1971. The Mammals of Africa An Identfication Manual. New York, NY: Smithsonain Institution; Distributed by George Braziller, Inc..
Nowak, R. 1999. Walker's Mammals of the World Sixth Edition Volume II. Baltimore and London: The Johns Hopkins University Press.