Species Composition, Distribution, Abundance and Economic Importance of Rodents in Choke Mountains, East Gojjam, Ethiopia
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Date
2016-11
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Addis Ababa University
Abstract
Studies on population ecology and economic significance of rodents were conducted in Choke Mountains between October 2013 and January 2016. Rodents were surveyed in eight habitats comprised of natural and human modified landscapes. It was conducted in live and snap trap grids established on each habitat. Eight rodent species were recorded in the Choke Mountains region: Arvicanthis abyssinicus, Otomys typus, Stenocephalemys griseicauda, Mastomys natalensis, Rattus rattus, Lophuromys flavopunctatus, Tachyoryctes splendens and Hystrix cristata. Arvicanthis abyssinicus and Stenocephalemys griseicauda are endemic to Ethiopia. There was significant variation in the spatial distribution of rodents (p<0.05). Species richness and diversity was highest in Euryops-Lobelia shrub (n=4, H=1.257) and Festuca-Alchemilla grassland (n=4, H=0.979) habitats. A. abyssinicus was the most widely distributed species captured from six habitats (75%). In eight trapping sessions, about 1,473 rodents were captured from the live and snap trap grids. Abundance of rodents varied among habitats of different management level (p<0.001). The highest proportion of trapped rodents was recorded in protected habitats: Festuca grassland (22.51%) and Erica forest (15.89%). Rodent abundance was significantly lower in livestock dominated habitats: open grazing fields (p=0.0006), afroalpine shrubs (p<0.05) and moorlands (p<0.05). A. abyssinicus was the highest in relative abundance (36.99%). Rodent abundance varied on seasonal basis (p<0.05). It was higher during the wet (57.09%) than the dry season (42.91%). However, the seasonal variation in the protected habitats was not significant (p>0.05). Species exhibit seasonal reproduction following rain. Plant materials occupied the dominant portion (62.08%) in the diet of the rodent species. Among the rodents, A. abyssinicus, O. typus, M. natalensis, and R. rattus were found to be crop pests. Croplands were seasonal refugee sites for the pest species. The dry season rodent abundance in barley fields was highly significant (p<0.001). Rodent abundance in barley fields reached peak (36%) at maturity stage of the crop, and declined after harvest (9.6%). Rodent abundance in fragmented barley fields interspersed with fallow lands was higher (62.13%) than those fields cultured in continuous system (37.87%). Rodent pest population density and crop damage was higher during the 2015/16 crop year (227/ha, 29.95%) than the 2014/15 (102/ha, 17.04%). Rodents may favour the extended rain period that occurred during the crop year. Rodenticides (60.8%), field sanitation (51.2%) and trapping (38%) were rodent control techniques practiced by farmers. Even with rodent control practices, farmers (82%) perceived crop damage by rodents was uncontrollable. Farmers lack technical support from selection to application of rodenticides. Annually, 23.5% pre-harvest yield loss was estimated from barley fields. This much yield loss is unbearable for small landholding people of the region that only depend on crop production. Livestock grazing pressure and disturbance are major threats to rodents and the whole biodiversity in Choke Mountains. Protection of this ecosystem has great importance to maintain rodent species, benefit from their ecological roles and minimize crop damage caused by pest rodents.
Key words/phrases: Choke Mountains, crop damage, rodent, species composition
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Keywords
Choke Mountains, Crop Damage, Rodent, Species Composition