Afroalpine Rodents
The most detailed studies of rodents have been undertaken by the EWCP in the Afroalpine where rodents are known for sustaining the high densities of Ethiopian wolves and raptors. Some of the original studies undertaken by the EWCP provided data on the species composition, morphology and abundance of rodents in the Afroalpine belt and montane grasslands in the Bale Mountains. Work undertaken by Claudio Sillero and Dada Gottelli of the EWCP showed that three species - Lophuromys flavopunctatus, Stenocephalemys griseicauda and Otomys typus - characterise the montane grasslands. Stenocephalemys albocaudata, Arvicanthis blicki and Lophuromys melanonyx characterise the Afroalpine belt. All three species for which data were available bred during the wet season. Minimum density estimates ranged between 32-89/ha for L. melanonyx, 3.2-127/ha for A. blicki and 16-60/ha for S. albocaudata. Ethiopian wolf prey biomass was estimated between 27 kg/ha and 28.8 kg/ha in the Afroalpine. Research supported by the EWCP also assessed abundance of giant molerats (Tachyoryctes macrocephalus) in BMNP. Mean densities of giant molerats ranged from 17/ha to 40/ha, and they were most prevalent in Afroalpine grasslands, particularly along swamp shores in the Web Valley. This was later supporter by further studies conducted by Lucy Tallents and is now being followed up by Flavie Vial as part of her study on livestock impacts on rodents and vegetation in the Afroalpine .
Analysis of Ethiopian wolf faecal samples also revealed that 89% by volume of the wolves’ diet consist of just three species of rodent endemic to the southern highlands of Ethiopia: the two murine rats Arvicanthis blicki (Blick's grass rat) and Lophuromys melanonyx (the black-clawed mouse) and the Rhizomyid giant molerat Tachyoryctes macrocephalus. Ethiopian wolf abundance also correlated positively with an index of diurnal rodent biomass and total biomass, but not with nocturnal rodent biomass. Seasonal variation and annual variation in rodent density turned out to be very low revealing the overall stability of the Afroalpine rodent guild on which Ethiopian wolves depend and perhaps partly accounting for their small home ranges, high densities, and overall persistence in these relatively small patches of remnant habitat. Subsequently, rodent species habitat associations were mapped by Lucy Tallents using detailed vegetation maps created with GIS software and density estimates from rodent live-trapping, direct observations and sign surveys.
EWCP’s research on giant molerat activity patterns has shown that individuals spend just under an hour in total above ground, and their activity correlates positively with Ethiopian wolf hunting effort, since wolves appear to concentrate their foraging activity on giant molerats – they favoured prey. Giant molerat distribution may be restricted by thermoregulatory and burrowing requirements: field signs were most abundant where soil depth was greater than 50 cm, and there was a bias towards damp habitats. The restricted distribution of the giant molerat may, in turn, limit the distribution of the Ethiopian wolf. Research was also recently undertaken on the feeding habits of the giant mole rat by Mohammed Yaba towards his MSc at the University of Addis Ababa, under the auspices of the EWCP. The study site was on the Central Sanetti Plateau which supports a high density of molerats. Giant molerats emerge from their burrows to gather plant material which is taken back and stored. Molerats appear to gather all the plant material they can reach, but they show some food selection after the plant material has been collected. The two dominant plants, Alchemilla a dicot and Festuca a monocot are harvested in proportion to their abundance around mole rat burrows, although mole rats appear to favour dicots over monocots in the plants actually eaten. Alchemilla, which grows in dense stands on many molerat mounds, therefore forms the bulk of the diet. The reason why Alchemilla flourishes on mole rat mounds has not been determined. Other plants, such as Haplocarpha rueppelli, are positively selected around the burrows. Haypiles represent material that has been collected from the surface but not eaten. There were more species of plant identified from haypiles than from direct observation suggesting that the burrows sampled did not sample the full range of the molerat.