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

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. 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: (1)
changes in tree cover across the hirola's historical range in eastern
Kenya over the past 27 years; (2) how tree cover has influenced resource
selection by hirola; and (3) interactions between tree cover and
predation. 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. Although hirola avoided tree cover, we found
no evidence that predation on hirola increased with increasing tree cover.
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.