2 research outputs found
Population Ecology of Rhabdomys dilectus dilectus in the Western Soutpansberg Mountains
No full textMENVSCDepartment of Geography and Environmental SciencesThis thesis explores the population ecology of the four-striped grass mouse (Rhabdomys dilectus dilectus) at the Lajuma Research Centre, within the Luvhondo Nature Reserve in the Western Soutpansberg Mountains, South Africa. Conducted from July 2020 to November 2021, the study examined the species' population dynamics, habitat preferences, and reproductive patterns across three distinct ecological sites: Wetland, Wilderness Camp, and Patches. Specifically, it aimed to assess how environmental variables, such as rainfall and habitat characteristics, influence the distribution, abundance, and reproductive success of R.d. dilectus in these diverse habitats.
R.d. dilectus is known to inhabit mesic environments, favoring continuous vegetation cover while avoiding bare soil. However, findings from this study suggest that its habitat range may be slightly broader than previously documented. Extensive bi-monthly trapping sessions using PVC live traps baited with peanut butter, oats, sunflower seeds, and salt were conducted to capture individuals, which were then identified, measured, marked, and released. Habitat characteristics, including vegetation cover and composition, were assessed alongside local weather conditions. Statistical analyses, including non-parametric and parametric tests, Jaccard Similarity Index for vegetation comparison, and rarefaction curves for species diversity, were used to evaluate trapping success, the influence of environmental factors, and the composition of the small mammal community.
Results indicate that R.d. dilectus was the most abundant species across all study sites, with the highest population density observed in the Wetland due to its mesic conditions. Rainfall significantly influenced trapping success, with a delayed response linked to increased vegetation growth and resource availability, particularly in the Wetland. The Wilderness Camp exhibited greater species diversity, while the Patches had higher diversity indices despite lower overall species richness. Microhabitat conditions, such as grass cover and predation risk, played a crucial role in shaping the spatial distribution of R.d. dilectus and other small mammal species. Reproductive activity varied across sites, with continuous breeding observed in the Wetland, whereas the Wilderness Camp and Patches exhibited more sporadic reproductive patterns.
This research provides valuable insights into the ecological flexibility and habitat preferences of R.d. dilectus, expanding current knowledge of its population dynamics in heterogeneous environments. The findings highlight the role of environmental factors in shaping small mammal communities and offer important implications for the conservation management of rodent populations in fluctuating ecosystems
Environmental effects on nocturnal encounters of two sympatric bushbabies, Galago moholi and Otolemur crassicaudatus, in a high-altitude South African northern mistbelt montane habitat
No full textTemperate living primates cope with a variety of environmental stressors, which may vary by body mass. We studied two sympatric galagos, the thick-tailed greater galago, Otolemur crassicaudatus (1.5 kg) and the southern lesser galago, Galago moholi (146 g), living in a South African northern mistbelt forest. We used 75 nightly encounter walks using thermal imaging from July 2017 to June 2018 to locate galagos (245 thick-tailed greater galago encounters, 207 southern lesser galago encounters). For each species’ encounters we documented survey location, growing season, insect and gum availability, ambient temperature, temperature season, rainfall, humidity, night length, hour, moon phase and fraction of moon illumination. We encountered the southern lesser galago at both cooler and warmer temperatures, later in the night, and more often during greater lunar illumination, e.g., they were lunarphilic. We had few encounters of the thick-tailed greater galago during very cold and very warm temperatures, more encounters earlier in the night, and more encounters during periods of low lunar illumination, e.g., they were lunarphobic. Our results can be understood in terms of body mass differences. A smaller body mass requires greater and more consistent energy, meaning the southern lesser galago needs to both maintain energy needs across different temperature regimes and to forage more extensively later in the night to attain enough food to support them throughout the following day. The thick-tailed greater galago’s larger body mass may buffer them during colder periods and allow them to forage earlier in the night. Being either lunarphobic or lunarphilic may relate to activity patterns of their predators. The southern lesser galago are visually oriented insect predators and being lunarphilic may facilitate both predator detection and enhance successful insect predation. Understanding how body mass may facilitate or hinder physiological and behavioral responses to environmental stressors is thus relevant to understanding species’ resilience to climate change.The National Science Foundation, USA and the University of Colorado, Boulder (USA).https://link.springer.com/journal/107642025-04-11hj2024Mammal Research InstituteParaclinical SciencesSDG-03:Good heatlh and well-beingSDG-15:Life on lan
