Aspects of the ecology of three mongoose species along a rural–urban landscape gradient of KwaZulu- Natal, South Africa.

Abstract

Many small carnivore species are of particular concern for conservation because of their elusive behaviour, diminutive size and crepuscular habits. Management and research tend to be challenging and thus is often limited. Several members of the Herpestidae family fall into this research dead zone, including the large grey mongoose (Herpestes ichneumon), slender mongoose (Galerella sanguinea), white-tailed mongoose (Ichneumia albicauda) and marsh or water mongoose (Atilax paludinosus). The distribution range and other aspects of the ecology of these and other such species, has remained vague for much of the sub-tropical regions of southern Africa because of the scarcity of comprehensive data. There is little understanding of the basic ecology of these mongoose species, and limited progress has been made in understanding the tolerance of these species within a changing environment. These species of mongoose appear to persist across KwaZulu-Natal’s (KZN), South Africa, anthropogenically modified habitats (farmlands and urban). Small carnivore species, such as mongooses, can provide models of how medium-sized carnivores tolerate differing degrees of anthropogenic land-use change. A global review of the current knowledge and research effort for urban mammalian mesocarnivores was conducted. In the last decade, there has been a dramatic increase in the number of studies that focus on medium-sized mammalian carnivores. Disproportionate levels of urban studies exist for mesocarnivores. Several species have been comprehensively studied in the United States of America and the United Kingdom. These two developed countries held more than half of all studies on urban mammalian mesocarnivores. Areas of the world that are undergoing rapid urbanisation have the most significant deficiency of research. Across Africa, the spatial ecology of the Herpestidae family remains relatively poorly studied. We investigated how anthropogenic land-use change affects aspects of the ecology of three co-existing mongoose species (large grey, water and white-tailed) in the agricultural setting of the KZN Midlands. Individuals of these three species of mongooses were trapped, collared and tracked using GPS-UHF (ultra-high frequency). The results presented show that the three focal species have different spatial requirements and movements from previous stated in literature. The natural habitat and farmland mosaic of the KZN Midlands are segregating the preferred habitats into small fragments. These niche fragments are intensely used by each species and allow them to co-exist in these anthropogenically modified environments. Besides these species’ generalist nature, their behavioural plasticity may assist them in persisting in anthropogenically modified landscapes. In the absence of apex predatory control, an expansion in the range and population number of Herpestidae species is expected. This study provides crucial information on the spatio-temporal ecology of large grey, water and white-tailed mongoose in the KZN Midlands. The spatial movements of the three co-existing species in this study highlighted the variability that is present at a species and individual level. Further research is required to address the human–wildlife conflict that takes place locally. The urban aspect of the large grey, water and white-tailed mongoose ecology is also understudied, and we recommend further research be targeted. The spatial ecology of water mongoose in the urban green space matrix of the Upper Highway Area of eThekwini, KZN, was subsequently investigated. This was to compare aspects of their ecology between fragmented natural farmland and urban mosaic using similar methods. Water mongooses occurred at a high density in the fragmented green Durban Metropolitan Open Space System (D’MOSS). Insight into the spatial ecology of urban water mongoose (home range, core area utilisation, overlap and habitat use) determined using GPS telemetry data from 14 water mongooses from July 2018 - October 2019. Water mongooses had constricted spatial movements that were highly dependent on natural refugia, and individuals intentionally avoided built-up areas of the urban matrix. The confined nature of these green spaces consequently resulted in home range sizes that were significantly smaller than their farmland conspecifics. However, the species behavioural plasticity and generalist nature has allowed the species to occur at higher population densities in the green spaces of the urban matrix of the Upper Highway Area. Furthermore, the effects of urban sprawl on the dietary ecology of water mongooses using faecal analyses was conducted. Water mongooses scat samples (n = 104) were opportunistically collected and with the aid of members of the Kloof Conservancy during the study. Urban water mongooses consume a diverse array of dietary items (9 categories), which is dominated by three categories (relative frequency of occurrence: crustaceans 35.7%, invertebrates 19.9%, small mammals 19.1% and other 25.2%). Seasonal variation in the diet only occurred for crustaceans and invertebrates with the other dietary categories consumed equally throughout the seasons. Additionally, it was demonstrated that urban water mongooses are supplementing their diets with anthropogenic waste (chicken bones, plastic particulates and cigarette butts). The broad diversity in dietary categories and supplementation of anthropogenic waste demonstrates the generalist opportunistic feeding behaviour and adaptability of the species in an urban matrix. An online questionnaire survey was conducted to investigate socio-ecological attitudes and general perspectives towards mammalian mesocarnivores across a land-use gradient (rural–urban) from the uMgungundlovu to eThekwini Municipalities of KZN. Significant trends were assessed using the frequency of responses. The public held a range of different perspectives. Overall, respondents viewed mesocarnivores as non-threatening and vital for the environment. However, black-backed jackals (Canis mesomelas) were commonly identified as a problematic pest species, that subsequently are targets of predator control pressures by rural participants. The survey also identified that smaller, behaviourally flexible species (mongoose species and cape genet Genetta tigrina) were commonly sighted and are potentially increasing in both land-use types in the absence of competition and predatory control. Vehicle collisions are the primary cause of mesocarnivore fatality reported by participants of the survey. The impact of mesocarnivores was perceived differently along a land–use gradient which links to levels of interaction. The study emphasises the importance of citizen science and community engagement when attempting to understand the drivers of human–wildlife interactions and potential mitigation strategies. The present multifaceted study has improved our understanding of solitary members of the Herpestidae family and how anthropogenic changes affect them across a land-use gradient. Furthermore, the behavioural flexibility and adaptability of mongooses in enabling them to persist at differing degrees of anthropogenic pressure were evident. However, the size class of mammalian mesocarnivores remains understudied in Africa, and this is of concern in a rapidly developing region.