Search

Threats to ecosystems are ever increasing from different drivers mostly being linked to anthropogenic activities. This has brought about various measures to restore/protect the wildlife in these areas. Considering the background of most protected areas in East Africa, small mammals have been given least attention, compared with large mammals, although they play a fundamental role in maintaining ecosystem health. It is therefore necessary to understand how small mammals are distributed in any given ecosystem as a baseline information to enable holistic and informed management. We investigated the diversity and distribution of small mammals in the Selous ecosystem, Tanzania. Two methods were used; Capture Mark Recapture (CMR) using grids of 70 m x 70 m and random placement of havahart traps in the selected habitats. Between July 2018 and June 2020, a total of 887 individuals belonging to 20 species were captured in 28 224 trap nights with 3% trap success. The small mammal species captured consisted of rodents (91.8%), Macroscelidea (3.9%), Carnivores (2.4%) Eulipotyphla (1.6%), and Primates (0.3%). Acomys ngurni(36%) and Aethomys chrysophilus(17%) were the most captured species, whereas Atilax paludinosus(0.23%), Helogale pervula(0.23%), Rattus rattus(0.23%) and Galerella sanguinea(0.11%) were the least contributing species. Acomys nguruiand Lemniscomys rosaliawere the most distributed species occurring in all four habitats, whereas Cricetomys ansorgei, Rattus rattus, Mungos mungoand Genetta genettahad low occurrence. Grammomys selousiis reported for the first time in the northern part of the Rufiji River. Acomys ngurniabundance differed significantly (χ2= 12, df = 3, p= 0.007) between the four habitats being higher in the seasonal riverine forest and across seasons (χ2= 6, df = 2, p= 0.049), with more individuals occurring in the wet season. The Sable Forest habitat had the highest species diversity (H' = 2.065) and the lowest diversity (H' = 1.506) was recorded in perennial riverine forest/thickets. The highest species diversity (H' = 1.65) was recorded in the dry season and the lowest diversity in the wet season (H' = 1.445). Most small mammals were associated with seasonal riverine forest than other habitats. Overall, the results from this study show that, the park is rich in small mammal fauna. Therefore, considerations in updating the General Management Plan (GMP) and other plans to include the small mammals in the park management actions is recommended.

Multimammate mice (Mastomys natalensis) are a key rodent pest species to cereal crop production in Sub-Saharan Africa. This study aimed at generating information on the population fluctuation and breeding patterns of M. natalensisin a maize dominated agro-ecosystem in the Mayuge district, Eastern Uganda. The area is characterised by a bimodal rainfall pattern with rains in the periods March to May and August to November. A Capture–Mark–Recapture study was established in cultivated and fallow field habitats with, in each habitat, two plots of 60 m by 60 m with 49 evenly spaced trapping points. Trapping was conducted monthly for three consecutive nights, and the study extended from January 2016 to June 2018. A Generalised Linear Mixed Model analysis showed significantly higher population density estimates (β = 0.69, p< 0.0001) in fallow land compared to cultivated fields, and also significantly higher density estimates( β = 0.75, p= 0.006) in the first wet season and lowest in the first dry season. The percentage breeding females differed significantly across months (χ2= 27.05, df = 11, p= 0.003) and seasons (χ2= 17.64, p= 0.0003). Breeding females occurred throughout all the months of trapping, but with significantly higher percentages in the months of March to July (i.e. first wet season extending to second dry season) and generally lowest in the first dry months (i.e. January and February in 2017, and February 2018). The results of this study have important consequences for the timing of control efforts, and recommends that control should be initiated during the dry seasons prior to wet seasons to counteract potential damaging population build up in later wet seasons when crop planting is expected.

Differences in the ecological niche requirements among rodent species competing in the same habitat may result from differences in the use of one to three resources: space, time and food or some combination of these. Alternatively, differences in resource use utilization among animal species may simply reflect availability of food, and when food is limited, different animal species compete. In this study, the diet of two rodent pest species, Mastomys natalensisand Gerbilliscus vicinus, coexisting in fallow land in central Tanzania were studied to assess the degree of diet differentiation among them. Dietary niche breadth of G. vicinuswas greater than that of M. natalensisin all stages of the maize cropping seasons. The rodent species studied overlapped considerably in the food items consumed ranging from niche overlap (Ojk) of 0.77–0.89. Grains/seeds featured high in the diet of M. natalensiswhile plant material occurrence was high in G. vicinus.These two food categories may have contributed to differences in diet partitioning, which may, in turn, facilitate their coexistence in fallow land.

As part of a three-year study to develop ecologically-based rodent management (EBRM) in southern Africa, a capture–mark–recapture study was carried out in Tanzania, Namibia and Swaziland to establish the demographic patterns and population dynamics of rodents. Two study grids were established in each country. In Tanzania, ten species of rodents and one shrew (Crocidurasp.) were identified in the study area. The rodent species consisted of Mastomys natalensis, Aethomys chrysophilus, Arvicanthis neumanni, Gerbilliscus vicina, Acomys spinosissimus, Lemniscomys griselda, Lemniscomys zebra, Rattus rattus, Graphiurussp. and Mus minutoides. Mastomys natalensiswas dominant and contributed more than 70% of the captures. In Namibia, five species were captured, namely Mastomys natalensis, Gerbilliscus leucogaster, Saccostomus campestris, Mus minutoidesand Steatomys pratensis. Mastomys natalensiscontributed about 50% of the captures. In Swaziland, only M. natalensiswas captured in the study grids. There was a clear pattern in the population dynamics, with breeding confined to the wet seasons in the three countries. Mastomys natalensiswas the dominant pest species, for which EBRM should focus on. The highest population density of M. natalensisoccurred during and after the rains, which coincided with the most susceptible phenological stage of crops. The breeding seasonality and density fluctuations observed in the three countries conform with observations made elsewhere in Africa, which support the hypothesis that rainfall events promote primary productivity on which murid rodents depend. Development of EBRM in these countries will be determined by the local conditions and how they influence the demographic processes of the rodent populations. EBRM should make use of the available ecological knowledge of the local rodent pest species and the focus should be on (ecological) management practices applicable at the community level including community based intensive trapping, field hygiene, removing cover and sources of food for rodents.