Hirola Antelope (Beatragus hunteri)

Mohamed bin Zayed Species project number 0925391

   

 

The hirola (Beatragus hunteri) is a poorly-known antelope endemic to the Horn of Africa, from southeastern Kenya northward to southern Somalia. For decades, its taxonomic classification has vexed scientists: the hirola was initially classified as a subspecies of hartebeest, and then as a subspecies as topi, before being recognized as distinct enough to merit its own genus. 

In 1965, Louis Leakey discovered fossil remains of a congener—Beatragus antiquus—in Tanzania’s Olduvai Gorge, and work by Leakey, Gentry, and others concluded that hirola were probably common ancestors of both hartebeest and topi. Subsequently, Kingdon proposed that the evolution and expansion of hartebeest throughout East Africa over a million years ago might have led to the hirola being restricted to its current range, north and east of the Tana River to a transitional region along the Kenya-Somali border, where grasslands give way to thick bushland.

 

In addition to its unique taxonomy, the hirola also has the unfortunate distinction of being one of the most—if not the most—endangered antelope in sub-Saharan Africa. Indeed, the hirola has been identified as one of the highest-ranking mammals on the Zoological Society of London’s EDGE (Evolutionarily Distinct and Globally Endangered) of Existence Programme, which seeks to promote understanding and conservation of globally-endangered species that have few living relatives.

Although they have never been common, hirola have dwindled in numbers from roughly 10,000 in 1970 to fewer than 500 today. Hirola have been legally protected in Kenya and Somalia since the 1970s, but their numbers have declined by more than 80% since 1976. Remaining populations occur almost solely on pastoral lands with no formal protection, while the few conservation areas that do exist within the hirola’s native range (e.g., the Arawale National Reserve and the eastern part of the Tana Primate National Reserve) lack adequate protection and attention from the international conservation community. Thus, ironically, the hirola ranks high as one of Africa's greatest conservation concerns, but public knowledge regarding its plight is almost entirely lacking outside of eastern Kenya.

 

Because of historic, political instability in this area, it has been difficult to pinpoint the reasons underlying hirola declines, although it is likely that many factors underlie this population crash. From the 1960s to the 1980s, Butynski, Kock, and others documented a series of disturbances—overgrazing, fire suppression, and local extinctions of elephants and black rhino—that occurred in Ijara, Fafi, and Garissa Districts. All three of these factors tend to favor the growth of trees and shrubs at the expense of understory plants, particularly grasses. Indeed, a recent analysis of satellite imagery demonstrates a slow but steady conversion of savanna grassland to Acacia refeciens-dominated bush over the past 30 years.  The geographic range of hirola has contracted with this shift in vegetation types, such that hirola now persist only in the small fraction of their historic range that is relatively open, and not dominated by trees. Because hirola are pure grazers that rely on grasses like Chloris, Cenchrus, and Digitaria throughout the year, these results imply that the chances of hirola recovery are low, so long as their preferred forage remains rare because of high levels of tree cover in Ijara. In addition, the increased cover afforded by trees and shrubs might result in more efficient killing of hirola by predators, relative to historic levels of predation in open, grassy expanses.  

 

In 2010, and along with a team representing the Hirola Management Committee, the Kenya Wildlife Service, and the Northern Rangelands Trust, we initiated work to answer the following questions that are critical to understanding and (hopefully) curbing declining numbers of hirola. These questions were identified by Butynski over 10 years ago as knowledge gaps that were necessary to fill to successfully conserve hirola.

First, what is the relative importance of range degradation, competition with livestock, and predation in driving the continued decline of hirola in Ijara? Answering this question requires conducting a series of repeated surveys, over many years, to document the birth and death rates for male, female, juvenile, and adult hirola in herds inhabiting areas with different levels of grass cover, livestock, and predators. From this data, we can build population viability analyses (PVAs), tools that can project the future status of populations under various environmental scenarios. Currently, we are conducting such work in Arawale National Reserve, Gababa Community, and Ishaqbini Conservancy to construct the building blocks necessary for PVAs. Armed with this knowledge, we will be able to 1) assess how important predation, for example, is, versus range quality in driving declines of hirola; 2) estimate which herds of hirola have the best chance of persisting 10, or 20, or 50 years into the future; and 3) inform which management solutions will provide the best “bang for our buck” to maximize chances for hirola recovery. 

 

 Second, what range management practices can be taken to offset the negative effects of tree encroachment on hirola, while simultaneously permitting livestock production through traditional pastoral practices? Because both hirola and cattle are pure grazers that depend on high-quality, open range, hirola declines can be regarded as the proverbial “canary in the coal mine”: they indicate chronic range degradation under which both hirola conservation and cattle grazing will be difficult over the long-term. Potential solutions that might enhance the long-term compatibility of hirola and livestock include, but are not limited to, ripping and reseeding large areas of range, prescribed burning, and holistic livestock management.  

 

 Finally, and most importantly, the success of our work hinges on close collaboration with Somali pastoralists, whose involvement is absolutely key to the long-term conservation of this species in its native range. In 2010, we administered a structured questionnaire to homesteads in Arawale, Gababa, and Ishaqbini. We made inquiries as to historical hirola distribution in the region, attitudes toward hirola, threats to livestock of humans from hirola, threats to hirola from people, and the future of wildlife in the areas. We were pleasantly surprised by the enthusiasm and support for our work by local communities. We appointed and trained three community scouts in each area as part of our team to assist in hirola research as a part of community capacity building.