A study on the effects of prescribed burning on rodent community ecology was conducted in Serengeti National Park, Tanzania. The study aimed at generating ecological knowledge about the changes in rodent communities when areas of the park are intentionally burned to regulate grasslands or reduce undergrowth that can lead to uncontrolled forest fires. A completely randomized design (CRD) factorial layout with two treatments (burned and unburned) and two replications was applied. A total of 148 animals comprising six species of rodent and one insectivore were captured over 2,940 trap nights. Among the trapped individuals, 41.9% were adults, 16.1% juveniles and 41.9% sub-adults. Males and females were at parity between treatments. Species abundance was estimated using the minimum number alive (MNA) method for different rodent species and was found to vary with treatment where Mastomys natalensis declined in burned plots whilst Arvicanthis niloticus increased. However, species diversity did not differ across treatments (F1, 10 = 0.15, p = 0.70). Differences in the reproductive condition of female M. natalensis (z = 4.408, df = 15, p < 0.001) and A. niloticus (z = 2.381, df = 15, p = 0.017) were observed between treatments showing that higher numbers of reproductively active females were observed in burned plots in March, whilst in unburned plots more were observed from November to February. Conservation strategies involving periodic habitat burning should, therefore, consider small mammal reproductive periods to ensure that species potentially at risk are not adversely affected and able to rapidly recover from the effects of burning in temporarily lowering food resources and longer term impacts of increased predation caused by reduced cover.
The Uluguru Mountains, which are part of the Eastern Arc Mountains, is a hotspot for diversity and an important area for the conservation of biodiversity in Tanzania, but faces increasing disturbance due to anthropogenic activities leading to a high rate of forest degradation and fragmentation. Changes in habitat structure have caused significant changes in the faunal assemblage of the region. However, information on these effects in the Uluguru Mountains is currently lacking. We conducted a survey of the small rodent assemblage on the Uluguru Mountains in three different habitats: forest, fallow, and cultivated land along two elevation gradients: 900-1,400 and 1,500-2,000 m a.s.l. Additionally, we recorded the habitat structure for each transect by looking at grass cover, tree density and shrub density. Generalised linear mixed models were used to examine the effects of habitat structure on both species richness as well as abundance. Our results revealed that, even while species richness remained similar over the whole study area, the species composition significantly changed depending on habitat structure. This finding arose particularly from changes in the numbers of Praomys delectorum and Mastomys natalensis, with the latter more abundant in cultivated and fallow land but not in forest, where P. delectorum is more abundant. This outcome may indicate that an increase in forest degradation and expansion of agriculture could have an impact on rodent assemblage and potentially on their population dynamics.
Small rodents are increasingly gaining importance as agricultural pests, with their distribution and abundance known to vary across landscapes. This study aimed at identifying ecological factors in the landscape that may influence small rodent distribution and abundance across agricultural landscapes in Uganda. This information may be used to inform the development of adaptive control measures for small rodent pests. Small rodent trapping surveys were conducted in three agro-ecosystem landscapes: Butaleja, Mayuge and Bulambuli districts in Eastern Uganda between November 2017 to June 2018 covering both dry and wet seasons. Data on small rodent abundance and richness, vegetation characteristics, land use/cover characteristics, farm management practices and soil characteristics were collected from quadrats. Additionally, Geographic Information System and remote sensing were used to determine vegetation characteristics (Normalized Difference Vegetation Index – NDVI) and land use/cover from satellite images. and Our results showed that crop field state (including hygiene, crop type and growth stage) is the most important variable with an overall relative importance of 34.4% prediction value for the abundance of Mastomys natalensis across the landscape studied. In terms of number of species encountered (species richness), results showed field crop status scoring highest with an overall relative importance of 39.8% at predicting small rodent species richness. Second in importance for overall rodent abundance was percentage composition soil silt particles with 15.6% and 18.1% for species richness and abundance respectively. Our findings have important implications for small rodent management, where land use characteristics, especially field crop state, is a critical factor as different conditions tend to affect rodent abundances differently. The study thus recommends that control efforts should be planned to consider field crop state; i.e. field hygiene where fields should be kept free of weeds to eliminate potential rodent breeding/habitation sites thus lowering rates of reproduction and population increase.
A study was conducted in Mabira Central Forest Reserve in Uganda to determine rodent species composition, relative abundance, and habitat association. A total of 1,030 rodents belonging to 14 species were captured on 10,584 trap nights. Rodent species recorded include: Lophuromys stanleyi, Hylomyscus stella, Praomys jacksoni, Mastomys natalensis, Lophuromys ansorgei, Lemniscomys striatus, Aethomys hindei, Mus triton, Mus minutoides, Deomys ferrugineus, Gerbilliscus kempi, Rattus rattus, Grammomys kuru, and Hybomys univittatus. Overall, L. stanleyi (23.7%) was the most dominant species followed by H. stella, P. jacksoni, and M. natalensis. Species richness and evenness was highest in the regenerating forest habitat and least in the intact forest habitat. Rodent abundance was significantly affected by habitat type. The regenerating forest habitat had the highest number of animals, while the lowest numbers were observed in the depleted forest habitat. Species diversity was higher in regenerating forest habitat and lowest in the intact forest. The three habitats appeared distinct in terms of rodent species composition and there was a strong association between the two trapping grids in the same habitat type. All ordination plots showed that different rodent species consistently associated with distinct habitats. Habitat type and seasonal changes influenced rodent composition, relative abundance and habitat association. Composition of rodent community reflected the level of habitat degradation and can be used as a proxy for evaluating the biodiversity of lowland tropical forests.