Walia Special Edition on the Bale Mountains (2011) - Zoologische ...

Table 3. Distance from road at which ungulate species were observed on the Gaysay grassland
during night and daytime transects.
Species
Mean (SE) distance from road (m)
Day Night
Mountain Nyala 156 (29) 66 (3)
Reedbuck 212 (30) 52 (2)
Warthog 179 (75) 18 (2)
All species combined 141 (4.2) 50 (1.4)
As these wild ungulates showed a clear aversion to the road during the daytime, the
assumptions of the distance sampling analytical technique were violated and it could not be used for
density estimation. However, as aversion to the road were less extreme at night, with none exhibited
by warthog, night sightings, from the 17 transects and 595 ungulate group sightings could be used
to estimate ungulate densities.
Mountain nyala were estimated to occur at a density of 8.9 km-2 (95% CI 4.3-18.3), grey
duiker at 3.35 km-2 (1.3-8.3), reedbuck at 4.5 km-2 (2.25-13.3) and warthogs at 2.9 km-2 (0.8 - 10.2),
but there were insufficient sightings to estimate bushbuck density. Average group size were 4.0 for
mountain nyala, 1.25 for grey duiker, 1.9 for Bohor reedbuck, 1.3 for warthogs and 2.4 bushbuck.
Using a figure of 51.4 km2 of available habitat, this estimates 458 mountain nyala for Gaysay/
Gassury, within a range of 222-940.
Discussion and Conclusion
This study examined some aspects of pathogen transmission between domestic animals and
livestock in the Bale Mountains of Ethiopia and demonstrated for the first time that mountain nyalasheep
helminths transmission can occur. Overall, it has shown that transmission of disease between
domestic and wild species is both possible and likely in the Bale Mountains in Ethiopia for a number
of reasons. First, both domestic sheep and cattle in the area can carry high parasite loads. All pastures
used by domestic animals will therefore have high parasite infestations from domestic stock and are
potential sources of helminth infection for wild species.
Second, the experimental transmission of nematodes (H. contortus, T. colubriformis and
Oesophagostomum spp.) to sheep from mountain nyala in this study demonstrates the potential for
cross transmission of helminths amongst wildlife and domestic species. Similar transmission has
been recorded between antelopes and sheep (e.g. Preston et al. 1979, from Thomson’s gazelles)
and strongylate species in Antilopinae are generally considered to be capable of infecting sheep
and goats. Fewer parasites species may be capable of maintaining infections in cattle, perhaps due
to differences in immune response development. Other research suggests that such shared parasites
generally impact more on wild species where communal grazing occurs, where antelopes have
acquired predominantly ovine helminth species from domestic ruminant reservoirs (Dunn 1968).
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