Browsing by Author "Bronner, Gary"

Now showing 1 - 4 of 4
  • Thumbnail Image
    Item
    Open Access
    Mammalian and avian diversity in a coastal nature reserve and an adjacent eco-estate
    (2022) Ross, Michael; O'riain, Mannus Justine; Bronner, Gary
    The burgeoning human population is placing increasing pressure on natural resources, including undeveloped land, for a variety of human activities including residential housing. Despite making up only a small percentage (5.4 %) of transformed land, urban areas have had a disproportionate impact on biodiversity with many cities having been founded in biodiversity hotspots at the confluence of marine, freshwater and terrestrial ecosystems. A growing trend worldwide and particularly in countries with a large wealth gap is the development of low density private residential estates. Although primarily conceived to improve home security, private estates are nevertheless regarded as a form of geographical escapism, and they are increasingly being marketed as eco- and lifestyle estates. While no formal definition of an eco-estate exists nor what ecological criteria must be satisfied to qualify for the status of an “ecological estate,” increasingly such estates make bold claims concerning their contributions to the conservation of native flora and fauna. Currently, little is known about the impacts of eco-estates on the ecology and wildlife of an area, particularly when compared to natural land. To date, most research on estates has focused on comparing their impact with transformed, agricultural or even urban land uses. In this study I compare select elements of the fauna within a golfing eco-estate (Atlantic Beach Estate), located 25 km north of Cape Town to the neighbouring Blaauwberg Nature Reserve, from which the estate was originally cleaved. I used live trapping, camera trapping and point counts for small mammals, medium/large mammals and birds respectively to compare the fauna in both the estate and reserve. For birds I was able to include a before and after comparison with a similar study in the early phases of the estate's development. All fieldwork was conducted between September and November 2019. Small mammal diversity was similar within the estate and the reserve, but the former included an exotic invasive (the house rat (Rattus rattus)) while the latter supported the vulnerable white-tailed rat (Mystromys albicaudatus). Medium sized mammal species composition varied significantly between the estate and reserve with the latter having more native species and the estate having three domestic species in addition to an introduced, extralimital wild species, the springbok (Antidorcas marsupialis). Bird communities were similar, with marked overlap in species between the two land uses. The addition of permanent water and private gardens with both native and non-native flora has increased both the niche breadth and food availability within the estate which was reflected in a higher avian diversity than in the neighbouring, more homogenous, reserve. In addition to supporting almost all the species found in the reserve, the estate was able to support multiple fynbos-endemic species not found in the nature reserve, as well as species closely associated with water. The presence of the eco-estate does not appear to have negatively impacted the bird community as the additional resources provided by the estate allow both urban exploiters and urban tolerators/avoiders to persist. In summary the estate has adversely impacted medium sized mammals more than both small mammals and birds with the latter taxon arguably benefiting from the increased habitat heterogeneity. Improving medium sized mammal richness would require increasing the permeability of the estate boundary but this will compromise both the safety of residents from external human threats and mammals within the reserve from domestic animals originating from the estate. Restricting domestic animals to private property, eliminating exotic species, improving connectivity between patches of natural habitat and naturalizing the edges of the golf course are all attainable goals that may improve small mammal and bird communities within the estate. However medium and large mammals are seldom compatible with human habitation and are thus likely to be the faunal component most adversely impacted by eco-estates with their limited size and impermeable edges. Ultimately while eco-estates may offer habitat for some species, they are not uniformly suitable for all species, and particular attention must be given to characteristics of prevailing species which might preclude them from an estate before estate construction. Given the increasing popularity of eco-estates and increased pressure on wildlife these are important findings which can help improve conditions for wildlife on current eco-estates and help facilitate site selection for any future eco-estate construction.
  • Thumbnail Image
    Item
    Open Access
    A phylogenetic estimate for golden moles (Mammalia, Afrotheria, Chrysochloridae)
    (BioMed Central Ltd, 2010) Asher, Robert; Maree, Sarita; Bronner, Gary; Bennett, Nigel C; Bloomer, Paulette; Czechowski, Paul; Meyer, Matthias; Hofreiter, Michael
    BACKGROUND: Golden moles (Chrysochloridae) are small, subterranean, afrotherian mammals from South Africa and neighboring regions. Of the 21 species now recognized, some (e.g., Chrysochloris asiatica, Amblysomus hottentotus) are relatively common, whereas others (e.g., species of Chrysospalax, Cryptochloris, Neamblysomus) are rare and endangered. Here, we use a combined analysis of partial sequences of the nuclear GHR gene and morphological characters to derive a phylogeny of species in the family Chrysochloridae. RESULTS: Although not all nodes of the combined analysis have high support values, the overall pattern of relationships obtained from different methods of phylogeny reconstruction allow us to make several recommendations regarding the current taxonomy of golden moles. We elevate Huetia to generic status to include the species leucorhinus and confirm the use of the Linnean binomial Carpitalpa arendsi, which belongs within Amblysominae along with Amblysomus and Neamblysomus. A second group, Chrysochlorinae, includes Chrysochloris, Cryptochloris, Huetia, Eremitalpa, Chrysospalax, and Calcochloris. Bayesian methods make chrysochlorines paraphyletic by placing the root within them, coinciding with root positions favored by a majority of randomly-generated outgroup taxa. Maximum Parsimony (MP) places the root either between chrysochlorines and amblysomines (with Chlorotalpa as sister taxon to amblysomines), or at Chlorotalpa, with the former two groups reconstructed as monophyletic in all optimal MP trees. CONCLUSIONS: The inclusion of additional genetic loci for this clade is important to confirm our taxonomic results and resolve the chrysochlorid root. Nevertheless, our optimal topologies support a division of chrysochlorids into amblysomines and chrysochlorines, with Chlorotalpa intermediate between the two. Furthermore, evolution of the chrysochlorid malleus exhibits homoplasy. The elongate malleus has evolved just once in the Cryptochloris-Chrysochloris group; other changes in shape have occurred at multiple nodes, regardless of how the root is resolved.
  • Thumbnail Image
    Item
    Open Access
    Spatial variation in small mammal communities across the Karoo Shale Gas Development Area of South Africa
    (2020) Nadine, Aboul-Hassan; Bronner, Gary; O'riain, Justin
    This study details results of small mammal surveys at 24 sites in four biomes (Nama- and Succulent Karoo, Albany Thicket, Grassland) as part of the Karoo BioGaps project to augment baseline biodiversity information needed to guide proposed fracking activities in the Shale Gas Development Area (SGDA) (Holness et al. 2016). A strategic Environmental Assessment (SEA), commissioned by the South African Government, evaluated the potential to exploit the supposedly substantial reserves of shale gas using hydraulic fracturing (“fracking”) in the Great Karoo Basin of South Africa. Terrestrial micromammals (<500g) were captured using Sherman livetraps (September 2016 to March 2017). Sampling over 6580 trap-nights produced 339 captures of 271 individuals representing 14 taxa. Trapping success was low 5.14% (mean per site 0.37± 0.61%). Most captures (87%) and individuals (83%) were recorded in the Nama-Karoo (294 captures, 226 individuals, 15 sites), whereas only 5 captures were recorded in Albany Thicket (3 sites). Four xerophilous/generalist species (Micaelamys spp. (Rock rats), Gerbilluscus paeba (Hairyfooted Gerbil), Macroscelides proboscideus (Round-eared Sengi), and Elephantulus spp. were numerically dominant at most sites, and within most biomes/bioregions; while five rare species were only ever recorded once. Mean α diversity (observed species richness Sobs) per site (2.88 ±1.99) and Shannon-Wiener diversity (1.70 overall, 1.04 ±0.33 per site) were low, with only 5.47 effective species (mean = 3.04 ±1.08 per site) and low equitability (0.64 overall). Sobs was highest in Nama-Karoo (13 species), and lowest in the Grassland and Albany Thicket biomes (2-5 species). Species accumulation/rarefaction curves did not reach asymptotes, and Sobs values for most sites/biomes/bioregions were significantly lower than Chao1 predicted species richness, suggesting that sampling effort did not accurately estimate species richness. However, trapping efficiency was generally high (56-100%; mean 86.7%) which compares favourably with that of two recent published studies in South Africa. Multiplicative beta diversity (βMt) across the SGDA was 4.56 indicating high species turnover between sites/biomes/bioregions. Species turnover was high across biome boundaries, notably Albany Thicket-Grassland (15), Nama-Karoo-Albany Thicket (14), and Succulent Karoo-Grassland (12). Biomes and bioregions tended to plot apart in ordination analyses with relatively low (40-60%) Sorenson similarity, indicating that most regional small mammal communities were well-differentiated. Despite data limitations, 66 new distribution records for 21 sites are reported for the SGDA. Total species richness (including historical records) was highest in the Nama-Karoo (19), particularly the Upper Karoo bioregion (19, mean 6.45 ±2.16, 11 sites), followed by the Grassland (16), and Albany Thicket (5) biomes. Total species richness records for most sites/regions fell within the iChao2 CI bounds, thus integrating trapping and historical records provided a relatively robust data set for subsequent spatial diversity analyses. However, even the total species richness dataset is likely to underestimate true diversity owing to not sampling arboreal species or detecting some cryptic species. Generalized linear analyses indicated that small mammal diversity indices were significantly associated with certain environmental/climatic parameters (livestock, drought). Despite the west to east increase in precipitation, highest diversity was concentrated in the arid north-west Nama-Karoo where dwarf shrubs and succulents predominate. This suggests that environmental and niche filtering are significant proximate factors shaping small mammal assemblages. No significant effects of biotic interactions (particularly competition following Diamond's (1975) first two rules) or resource-mediated niche limitations were evident for SGDA species assemblages. However, results for the Nama-Karoo (i.e. for a natural phytogeographical rather than geoeconomically-defined area) were significant suggesting that biotic interactions may also be proximate factors shaping local assemblages. Site assemblages were significantly nested, indicating that species at species-poor sites were subsets of those at richer sites; and thus, that site communities may have been structured by either long-term (ultimate) regional biogeographic processes (e.g. immigration and extinction related to distances between sites) or habitat filtering operating at local scales. Data deficiencies notwithstanding, my results present the most comprehensive landscape-level analysis for small mammals, and the only baseline dataset (based on randomized sampling) for the Greater Karoo and SGDA. While my results must be treated with caution, I am confident that the recommendations I make on species, sites and regions potentially vulnerable will be a useful guide to possible impacts of fracking in the study area.
  • Thumbnail Image
    Item
    Open Access
    The effects of land use change, from small livestock farming to protected area, on vegetation and mammal communities in the SKA region of the Karoo, South Africa
    (2021) Blanckenberg, Michelle Claire; O'riain, Mannus; Bronner, Gary
    Land-use change, particularly agriculture, has been identified as one of the major drivers of biodiversity loss worldwide. Meeting global biodiversity targets requires both the establishment of protected areas (PAs) and learning to coexist with wildlife in human-modified landscapes, particularly extensive rangelands. In the semi-arid regions of the Karoo, South Africa, small livestock production has been the primary land use for more than 350 years. This extensive agricultural activity has allowed much of the native flora and fauna to persist leading to a complex interplay between vegetation, livestock, humans and wildlife. Most farmers strive to optimise livestock production and thus actively seek to reduce or eradicate wild predators and competitors of livestock. It is against this background that the recent establishment of a large (131 000 ha) protected area within a well-established small livestock farming region in the Karoo represents a rather unprecedented event with clear benefits for biodiversity and both real and perceived costs to the farming community. This landscape level shift in land use from farming to protected area provided a unique opportunity to design a Before-After-ControlIntervention (BACI) study investigating how a cessation in farming activity impacts both natural vegetation and wildlife. I hypothesised that this change would positively impact vegetation, and small and medium/large mammals. To test this, I compared biota using standard surveys on farms before and after the cessation of farming (core, n = 3) and compared this to both neighbouring farms (edge, n = 3) that are likely to be impacted by the land use change and farms at least 50 km from the new PA (control, n = 3). I also explored the condition, maintenance levels and success of fences between the core and edge farms at preventing the movement of wildlife onto edge farms. Before the cessation of farming activities on the core, species richness and the abundance of vegetation, small mammals and medium/large mammals were similar across all farm types. After the cessation of farming activities forb cover and grass height increased slightly on core farms, while small and medium/large mammal richness and abundance remained constant. Daily activity patterns for several medium sized mammals shifted on the core farms from almost exclusively nocturnal to more diurnal. Both caracal and black-backed jackal naïve occupancy remained constant on all farm types over the study period. Despite this, edge farmers (as well as control farmers) complained of increased predator numbers and livestock losses and their attitudes to predators and the PA worsened over the study period. These perceived changes may well have been attributed to the extreme drought conditions that prevailed during the study. Most farmers resorted to food provisioning which concentrates livestock at feeding sites and around farm buildings both increasing the detection of livestock by predators and the detection of predators by farmers. Well maintained fences significantly reduced wildlife movement in general and predator movement from the core to edge farms. Poor quality and poorly maintained fences had a higher incidence of mammal movement along the fence line and a higher frequency of hole utilisation, particularly by small and medium sized herbivores. Overall, my results support expert predictions that the recovery of both flora and fauna in the Karoo following cessation of sustained livestock farming will be slow and dependent on rainfall. The drought conditions that prevailed during the study may well have dampened a resurgence in primary productivity on core farms and with that the recovery of small mammals and medium sized herbivores, followed by their predators. It will be important to continue monitoring these farms over the medium/long term to better understand the relative impacts of farmers and livestock on the flora and fauna of the Karoo and the recovery of biota within this newly proclaimed PA especially where abiotic factors such as variability of rainfall may confound these influences. In the interim improving relationships between farmers and managers of the PA is essential and will largely depend on the quality and maintenance of the fence line that separates these different land uses.