A camera trap appraisal of mammal species richness and spatio-temporal characteristics in a private nature reserve in KwaZulu-Natal, South Africa

Abstract

Globally biodiversity declined by an average of 73% between 1970 and 2022. Given the irreplaceable ecosystem services supplied by biodiversity to human populations, it is imperative that the remaining biodiversity on Earth is protected. Protected areas (PAs) have been found to be the most effective method to conserve biodiversity, with larger PAs being more impactful than smaller PAs. As the human population on Earth continues to grow, space for the proclamation of new PAs is limited, and private as well as governmental resources to adequately manage already existing PAs is insufficient. In order to best conserve remaining biodiversity it would be most effective to focus conservation efforts on Earths 35 biodiversity hotspots. Three of these hotspots occur in South Africa and vary in their threats and conservation status. Of these three hotspots, the Maputaland Pondoland-Albany hotspot (MPAh) has the greatest number of people living in it, with large portions of the area having been transformed and habitat degraded. Roughly only 25% of this hotspot still remaining in a wild, unaltered state. To ensure adequate conservation practices and management plans for PAs it is helpful to have a good understanding as to what biodiversity still remains on the PA and how the present biodiversity responds to the many anthropogenic and environmental pressures that pose a risk to the longevity and health of the PA. One PA, within the MPAh, that is potentially to be included in a larger PA is the 11 000 ha Mawana Game Reserve (MGR). This private reserve, found in South Africa's KZN province, is made up of 85% savannah biome and around 15% grassland, one of South Africa’s most threatened biomes. Since the 1980s, after many small subsistence farms were consolidated into one larger farm, MGR has seen multiple species of medium and large herbivorous mammal (> 0.5 kg) reintroductions take place, including a herd of elephants (Loxodonta africana) reintroduced in 2003. To assess the current state of the medium to large mammal population on MGR a survey was conducted that used camera traps, a technology that has proven to be very useful in the assessment of mammal populations. A four-month camera trap study was conducted on MGR over the wet season from November 2021 until March 2022. A total of 51 survey locations, spaced evenly across the landscape, using a 1.3 x 1.3 km grid, were sampled for 40 days each, with 19 and 18 camera traps moved from north to south across three separate survey blocks. A total of 29 species of medium to large mammals were observed during the survey period, while Bayesian and non-parametric estimates suggested that between 3 and 6 more species are present but went undetected. It is suggested, therefore, that a maximum of 35 medium to large mammal species occur on MGR, a number supported by the fact that 6 species detected on MGR before and since this research were not detected during the camera trap survey. The 29 species detected represents 56% of the 51 species thought to be historically present on MGR. A Bayesian analysis was performed using a hierarchical detection-based multi-species occupancy model to assess the space use of mammal species and species richness. Ten potential predictors (covariates), - seven environmental (altitude, fire, grass biomass, heterogeneity, slope, vegetation type, visibility) - three anthropogenic (proximity to human settlement, roads and reserve boundary), were analysed to see which covariates significantly predicted mammal space use and species richness. All environmental covariates other than slope and fire were found to impact species richness. Blesbok (Damaliscus pygargus phillipsi) and impala (Aepyceros melampus) were impacted by altitude, giraffe (Giraffa giraffa) were impacted by fires, vervet monkeys (Chlorocebus pygertythrus) and bushpigs (Potamochoerus larvatus) were impacted by grass biomass. Giraffe, impala, plains zebra (Equus quagga burchellii) and black-backed jackal (Lupulella mesomelas) were impacted by heterogeneity, plains zebra and blesbok were both influenced by visibility. Plains zebra, blesbok, black-backed jackal, giraffe, baboons (Papio ursinus) and vervet monkeys all showed preferences for specific vegetation types across MGR. Impala, nyala (Tragelaphus angasii) and vervet monkeys were impacted by proximity to human settlements, warthogs and baboons were affected by proximity to roads and nyala and blesbok were affected by proximity to reserve boundaries. After spatial analyses were conducted, the medium to large mammals of MGR were assessed for temporal behavioural responses to: each other, human settlements and perceived anthropogenic and predatory risks. Both warthogs and common duiker were found to be active at significantly different times of the day to each other as well as impala and nyala for duikers and impala, nyala, wildebeest (Connochaetes taurinus) and zebra for warthogs. Common duiker were found to change their behavioural patterns as they got closer to human settlements, while no species were detected changing their behavioural patterns in response to varying visibility facilitated by open or closed (dense) vegetation. This repeatable study has assisted MGR by establishing baseline data that may be used to assess the area-specific conservation and management practices and actions that may occur on the reserve in the future. This study has allowed MGR and similar small PAs in southern Africa to gain more knowledge on the anthropogenic and environmental pressures that pose a risk to the medium and large mammals present.