The abundance and microhabitat use of rodents were investigated in four different habitats: two rain-fed crop fields with differing stone bund density, an irrigated field and bushland. A total of 444 individual small mammals belonging to six rodent and one shrew species were recorded in trapping grids and line transects. Of these, 230 individuals (52%) belonged to three pest rodent species of crop fields in northern Ethiopia: Stenocephalemys albipes (65%), Mastomys awashensis (25%) and Arvicanthis niloticus (10%). Population abundance of the three species was higher in the early dry season compared to the rainy season. While the bushland was significantly (p < 0.05) favoured by S. albipes and M. awashensis in both seasons, the irrigated field was preferred by Arvicanthis niloticus in the early dry season. In the early dry season, the microhabitat use of A. niloticus was strongly associated with the type of ground cover (herb) (R2adj = 0.152, P < 0.01). While M. awashensis was associated with vegetation density (R2adj = 0.13, P < 0.01), S. albipes was associated with vegetation cover (R2adj = 0.102, P < 0.001). The findings indicate that co-occurring pest rodent species prefer different microhabitats. Understanding their co-occurrence particularly in crop fields is vital for crop protection as they are known serious agricultural pests in northern Ethiopia.
The contribution of woodiniee (Apodemus sylvaticus), yellow-necked mice (Apodemus flavicollis) and bank voles (Clethrionomys glareolus) was compared in a focus of Lyme borreliosis in Switzerland during a 7 months’ study. All three species of mice and one species of shrews (Sorex araneus) were shown parasitized by infected Ixodes ricinus immatures. About 14% of larvae and 50% of nymphs collected on small mammals were infected with B. burgdorferi. Spirochetes were isolated from blood of 3 woodmice and one yellow-necked mouse. The infectious status of rodents was estimated by tick xenodiagnosis. Prevalence of infected rodents ranged from 20% to 44%. Mice presented a higher potential infectivity than voles. The prevalence of infected rodents showed a seasonal variation.
To investigate the relationship between food habits and digestive tract morphology, the lengths of gastrointestinal tracts of six species of rodents with different food habits were compared. The results showed that the strict herbivores, Microtus brandti, had the largest large intestine and ceacum, and the tracts of the other five granivorous/omnivorous species (Spermophilus daurica, Phodopus robovskii, Cricetulus barabensis, Cricetulus triton, Meriones unguiculatus) varied to different extents depending on the proportions of seed, vegetative and animal foods in their diets. Small intestine lengths did not reflect diet fiber content for these six rodent species and stomach lengths in granivorous/omnivorous rodents were not larger than herbivores. Our results suggest that the hind gut is more important for herbivorous than for granivorous/omnivorous rodents and could be a relative reliable indicator for food habits, however, small intestine is not a good indicator for food habits. This study also showed that there is no direct relationship between life history traits and gut morphology in these six rodent species, although more life history traits should be considered.
In this study we analysed whether the diet composition of a wintering population (40–70 individuals) of long-eared owls (Asio otus) in northern Italy showed within-season variation, and whether it was influenced by ambient temperature and rainfall. Diet composition was determined by pellet content, and over 5500 prey items were analysed; pellets were collected at 2-wk intervals over two consecutive winters (October to April), 1996–1998. Three out of five main prey categories showed a marked within-season variability in relative frequency in diet, both considering the number of prey items and prey biomass, whereas between-year variability was shown only by a single prey category (Savi’s pine vole). Although rainfall had no influence on diet composition, temperature affected negatively the prevalence of harvest mouse, a relatively unimportant prey category. Thus, the considered weather variables seem to have little influence on the winter diet composition (at the level of individual prey categories) of these owls. However, diet breadth (estimated by the Levins’ index of niche breadth) increased with increasing rainfall and decreasing temperature, when calculated on the proportion of prey items: hence it seems that the owls become more generalists under unfavourable weather conditions.
Faunal studies of rodent assemblages from the areas on and around Choke Mountain (north-western Ethiopia) were conducted during two field seasons in 2012 and 2018. Here we present results of a genetic study of nine rodent species, and evaluate their genetic diversity and evolutionary relationships between conspecific populations from neighbouring montane massifs. Results of comparative analysis of phylogeographic patterns in Lophuromys, Desmomys, Stenocephalemys and Tachyoryctes have emphasized the role of the Blue Nile gorge as a strong biogeographic barrier, separating “northern” and “southern” independently evolved populations. Results of genetic analysis also revealed the presence of a new taxon of Dendromus, presumably belonging to a new species. Our study allows re-evaluation this area as an important “hotspot” of Ethiopian small mammal biodiversity.
Parasitism among individuals in a population often varies more than expected by chance only, leading to parasite aggregation, which is a parameter of paramount importance in parasite population dynamics and particularly in vector-borne epidemiology. However, the origin of this phenomenon is yet not fully elucidated. An increasing body of literature has demonstrated that individuals vary consistently in their behaviour, which is referred to as animal personality. Such behavioural variation could potentially lead to different encounter rates with parasites. To test this hypothesis, the relationship between personality and burden with ticks (Ixodes spp.) in the bank vole, Myodes glareolus (Schreber), was assessed. Wild rodents (eight females and 18 males) were live-trapped, identified, sexed, weighted, and inspected for ticks. Behavioural profiling was then performed using standardised tests measuring activity/exploration and boldness with a combination of automatically and manually recorded behavioural variables summarised using multivariate analyses. The resulting personality descriptors and questing tick variables were used as explanatory variables in negative binomial generalised linear models of tick burden and Bayesian simulations were performed to better estimate coefficients. Tick burden was associated to body mass and sex, but not to personality descriptors, which was mainly associated to activity/exploration. These results are discussed regarding the complex relationships among individual personality, physiological status, space use and health status.