Population and habitat assessment of the Critically Endangered hirola <i>Beatragus hunteri</i> in Tsavo East National Park, Kenya

Journal of Applied Ecology

Ford

Mallon

et al. 2017

Self Cite

1. Understanding how bottom-up and top-down forces affect resource selection can inform restoration efforts. With a global population size of <500 individuals, the hirola Beatragus hunteri is the world's most endangered antelope, with a declining population since the 1970s. While the underlying mechanisms are unclear, some combination of habitat loss and predation are thought to be responsible for low abundances of contemporary populations. 2. Efforts to conserve hirola are hindered by a lack of understanding as to why population density remains low, despite eradication of the viral disease, rinderpest. To elucidate factors underlying chronically low numbers, we examined resource selection and landscape change within the hirola's native range. Because hirola are grazers, we hypothesized that the availability of open areas would be linked both to forage and safety from predators. We quantified: (i) changes in tree cover across the hirola's historical range in eastern Kenya over the past 27 years; (ii) how tree cover has influenced resource selection by hirola; and (iii) interactions between tree cover and predation. 3. Between 1985 and 2012, tree cover increased by 251% across the historical range of hirola. Tree encroachment was associated with a 98% decline of hirola and elephant Loxodonta africana populations, a 74% decline in cattle Bos indicus, an increase in browsing livestock by 327%, and a reduction in rainfall. 4. Although hirola avoided tree cover, we found no evidence that predation on hirola increased with increasing tree cover. 5. Synthesis and applications. Hirola may qualify as a refugee species, in which contemporary populations are restricted to suboptimal habitat and exhibit low survival, reproduction or both. The extinction of hirola would be the first of a mammalian genus on the African continent in modern history. We conclude that contemporary low numbers of hirola are due at least partly to habitat loss via tree encroachment, triggered by some combination of elephant extirpation, overgrazing, drought and perhaps fire suppression. We recommend a combination of rangeland restoration efforts (including conservation of elephants, manual clearing of trees, and grass seeding), increased enforcement of an existing protected area (Arawale National Reserve), and reintroductions to enhance recovery for this endangered species. These efforts will rely on enhanced support from the international conservation community and the cooperation of pastoralist communities with which the hirola coexist.

Section: Introductionmentioning

confidence: 99%

Resource selection and landscape change reveal mechanisms suppressing population recovery for the world's most endangered antelope

Journal of Applied Ecology

Ford

Mallon

et al. 2017

Self Cite

“…1). Additionally, some have speculated that a combination of heightened predation and reduced rangeland quality are responsible for its current status as the world's most endangered antelope (Probert et al 2015). Additionally, some have speculated that a combination of heightened predation and reduced rangeland quality are responsible for its current status as the world's most endangered antelope (Probert et al 2015).…”

Section: Introductionmentioning

confidence: 99%

“…Our recent work has demonstrated that range degradation, through tree encroachment, may underlie continued suppression of hirola populations (Ali et al 2017). Additionally, some have speculated that a combination of heightened predation and reduced rangeland quality are responsible for its current status as the world's most endangered antelope (Probert et al 2015). Such uncertainty characterizes the plight of many species of conservation concern, and can translate to variable outcomes in reintroduction efforts (Sarrazin and Barbault 1996, Sutherland et al 2004, Armstrong and Seddon 2008.…”

Section: Introductionmentioning

confidence: 99%

Demographic drivers of a refugee species: large‐scale experiments guide strategies for reintroductions of hirola

Ecological Applications

Kauffman

Amin

et al. 2018

Self Cite

Effective reintroduction strategies require accurate estimates of vital rates and the factors that influence them. The hirola (Beatragus hunteri) is the rarest antelope on Earth, with a global population size of <500 individuals restricted to the Kenya-Somali border. We estimated vital rates of hirola populations exposed to varying levels of predation and rangeland quality from 2012 to 2015, and then built population matrices to estimate the finite rate of population change (λ) and demographic sensitivities. Mean survival for all age classes and population growth was highest in the low-predation-high-rangeland-quality setting (λ = 1.08 ± 0.03 [mean ± SE]), and lowest in the high-predation-low-rangeland-quality setting (λ = 0.70 ± 0.22). Retrospective demographic analyses revealed that increased fecundity (the number of female calves born to adult females annually) and female calf survival were responsible for higher population growth where large carnivores were absent. In contrast, variation in adult female survival was the primary contributor to differences in population growth attributable to rangeland quality. Our analyses suggest that hirola demography is driven by a combination of top-down (predation) and bottom-up (rangeland quality) forces, with populations in the contemporary geographic range impacted both by declining rangeland quality and predation. To enhance the chances of successful reintroductions, conservationists can consider rangeland restoration to boost both the survival and fecundity of adult females within the hirola's historical range.

“…The hirola is the world's most endangered antelope (IUCN, 2008), restricted to 1200 km 2 on the Kenya-Somali border. 13 000 individuals in 1970 to <500 individuals currently (Probert et al, 2015). Although they have never been common, hirola have dwindled from ca.…”

Section: Introductionmentioning

confidence: 99%

“…Although they have never been common, hirola have dwindled from ca. 13 000 individuals in 1970 to <500 individuals currently (Probert et al, 2015). Remaining populations occur almost solely on pastoral lands with no formal protection, while the single protected area that exists within the hirola's native range (Arawale National Reserve) lacks adequate support from both the Kenyan government and the international conservation community.…”

Section: Introductionmentioning

confidence: 99%

Evaluating support for rangeland‐restoration practices by rural Somalis: an unlikely win‐win for local livelihoods and hirola antelope?

Amin

Fischer

et al. 2018

Animal Conservation

In developing countries, governments often lack the authority and resources to implement conservation outside of protected areas. In such situations, the integration of conservation with local livelihoods is crucial to species recovery and reintroduction efforts. The hirola Beatragus hunteri is the world's most endangered antelope, with a population of <500 individuals that is restricted to <5% of its historical geographic range on the Kenya-Somali border. Long-term hirola declines have been attributed to a combination of disease and rangeland degradation. Tree encroachment-driven by some combination of extirpation of elephants, overgrazing by livestock, and perhaps fire suppression-is at least partly responsible for habitat loss and the decline of contemporary populations. Through interviews in local communities across the hirola's current range, we identified socially acceptable strategies for habitat restoration and hirola recovery. We used classification and regression trees, conditional inference trees, and generalized linear models to identify sociodemographic predictors of support for range-restoration strategies. Locals supported efforts to conserve elephants (which kill trees and thus facilitate grass growth), seed and fertilize grass, and remove trees, but were opposed to livestock reduction. Locals were ambivalent toward controlled burns and soil ripping (a practice through which soil is broken up to prevent compaction). Livestock ownership and years of residency were key predictors of locals' perceptions toward rangeland-restoration practices. Locals owning few livestock were more supportive of elephant conservation, and seeding and fertilization of grass, while longer term residents were more supportive of livestock reduction but were less supportive of elephant conservation. Ultimately, wildlife conservation outside protected areas requires long-term, community-based efforts that are compatible with human livelihoods. We recommend elephant conservation, grass seeding and fertilization, manual tree removal and resting range from livestock both to enhance the potential for hirola recovery and to build positive rapport with local communities in the geographic range of this critically endangered species.