Centre for Environmental Management
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Browsing Centre for Environmental Management by Author "Avenant, N. L."
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Item Open Access Investigating small mammal community structure as a possible indicator of improved habitat integrity in an area cleared of alien vegetation(University of the Free State, 2014-01) De Klerk, Jean J.; Kemp, M. E.; Avenant, N. L.Small mammal communities have been identified as possible indicators of the ecological integrity of different areas. Small mammal species are adapted to micro habitats and therefore can be affected by small-scale changes, which can be monitored to assist in biodiversity studies. Alien vegetation eradication programs have been ongoing across many areas of South Africa. These eradicated areas are believed to be able to restore to the original condition and therefore improving the biodiversity of the area. However, many ways of assessing ecological integrity are time consuming and expensive. By assessing the small mammal diversity and community structure in eradicated areas, judgments could be made about the success of implemented eradication programs. As small mammal surveys can be done readily, the ability to use them as indicators allows them to be implemented in all eradicated areas to indicate conditions of area over various time periods and can be utilized on a continual basis. This study investigates to which extent small mammal community structure (including the specific species present and the species richness) could indicate improved habitat integrity in areas cleared of alien vegetation. Small mammal communities in three areas, (i) area infested with Black Wattle (Acacia mearnsii), (ii) area cleared of Black Wattle and (iii) a control area which have no records of alien vegetation, were assessed. Data was captured using PVC live traps similar to Sherman and Willan traps. Traps were placed along transects in each area, once a month, from October to December 2013 for four consecutive days at a time. A total of 690 individual were caught during the 5400 trap nights of the study, with an overall trap success of 12.78%. In total five small mammal species were caught; one musk shrew (Crocidura flavescens) and four rodents. There was a significant difference between the number of small mammals caught between the three areas, with the control area and the cleared area being the most similar. Both the Shannon-Wiener and the Simpson’s diversity indexes were used, with the Shannon-Wiener indicating some significant differences between the areas and the Simpson’s indicating that there was not a significant difference between the areas. The Friedman Anova indicated a significant difference in the amount of species caught between the areas, with the Wilcoxon test indicating that there was significantly less species in the infested than in both the control and cleared areas; no difference was found between the cleared and the control areas. A similar difference in the total amount of individuals caught was also found. This was also found for the three most numerous species Rhabdomys pumilio, Micaelamys namaquensis, Otomys irroratus. Two species Saccostomus campestris and Crocidura flavescens were found in low numbers at both the control and cleared plots, but could not be found at the infested site. This study indicates that small mammal communities are different between the areas sampled with the infested area having the lowest species richness and abundance. The cleared area is not significantly different from the control area, but has a significantly higher species richness and abundance than the infested area, indicating that the area has improved and that small mammals could be used as an indicator of ecological integrity after alien eradication. No clear indicator species were identified, due to only five species being recorded. Rhabdomys pumilio dominated all areas sampled and has been identified to occur from very disturbed to pristine areas. Where more time and assistance is available, future studies will benefit from the inclusion of ecological integrity indices on other taxa, such as vegetation, alongside the small mammal communities. This would allow for correlations to be drawn and report on integrity at different levels of the ecosystem. As such the ecological integrity of the area can be determined using already proven indices to compare with the small mammal results. A further recommendation is that future small mammal studies should also include extended seasonal sampling including autumn and winter which have proved to yield higher trap success.Item Open Access Towards the development of a sustainable management strategy for Canis mesomelas and caracal on rangeland(University of the Free State, 2013-10) Du Plessis, Johannes Jurie; Avenant, N. L.; De Waal, H. O.English: South Africa has a long history of human-wildlife conflict with black-backed jackal Canis mesomelas and caracal Caracal caracal, especially in the small livestock industry. Recently, wildlife ranchers and cattle farmers have also started to report losses. Despite the excessive losses and widespread efforts to curb these conflicts there is no sustainable human predator conflict management (HPCM) strategy in place. Livestock owners still tackle the challenges individually or in small groups and concentrate mostly on elimination and precautionary techniques. Blanket-control and poisoning practices in many areas results in biodiversity being under constant threat, while stock losses do not decline. Current knowledge on aspects relating to black-backed jackal and caracal in South Africa (including ecology, economics, management techniques, predation rates, sociology) was collated and evaluated. Such information is needed for the development of a sustainable HPCM strategy for damage-causing black-backed jackal and caracal on livestock farms and wildlife ranches, and to inform policy and decision-making related to these species. There is a general lack of scientific information on virtually all the identified aspects, limiting the development of management strategies. Specific information gaps with regards to each aspect were identified and a conceptual model presented for the development of a sustainable HPCM plan for damage-causing black-backed jackal and caracal in South African rangeland. Most of the available ecological research on black-backed jackal and caracal are from spatially and temporally isolated studies, limited in scope, confined to protected areas and not focused on the development of sustainable management strategies. This results in a limited understanding of the ecological role of both black-backed jackal and caracal in South African ecosystems. A prerequisite for sustainable HPCM programs is a sound ecological understanding of the animals that are to be managed, and the ecosystems in which they operate. Without such an understanding it is difficult to predict the contribution of different management v interventions to mitigate damage and the effects on the behaviour and ecology of target animals. The study has also highlighted the overall lack of scientific estimations on the economics of black-backed jackal and caracal predation, and HPCM operations. Isolated pieces of evidence confirm that the current associated costs are high. A range of benefits and costs associated with these two species, which have not yet been quantified, are also emphasized. With reference to the human dimension there is insufficient information to understand the diversity of perceptions which various stakeholders may hold towards black-backed jackal, caracal and associated HPCM actions. Understanding these perceptions and its drivers are most important for the drafting of a sustainable HPCM strategy. Further, scientific information on HPCM methods for black-backed jackal and caracal in South Africa is lacking. Most information on these methods is contained in popular literature and very few refer specifically to the management of damage-causing black-backed jackal or caracal. A number of information gaps have been identified regarding the effectiveness of available HPCM methods to curb black-backed jackal and caracal predation under different South African conditions. Some major shortcomings have been identified in the availability of current predation information. The small number of available sources on livestock and wildlife predation is limiting an understanding of specifically black-backed jackal or caracal predation patterns. Better qualitative information on livestock and wildlife predation is needed to substantiate reported losses, and provide grounds for HPCM decisions. Moreover, it could also be used to better understand the dynamics of the predation which is necessary to develop sustainable HPCM strategies. Future research should be directed, coordinated and conducted systematically to ensure that the understanding of these damage-causing species is complemented and priority knowledge gaps filled in a focused way. Setting short and long-term goals is important, as well as the continuous feedback between participating scientists, livestock farmers, wildlife ranchers, conservation managers, legislation officials, the coordinator(s) and the public.Item Open Access The use of ecosystem parameters in predicting the risk of aicraft-wildlife collisions at Namibian airports(University of the Free State, 2014-01) Hauptfleisch, Morgan Lindo; Avenant, N. L.; Toerien, D.English: Human-wildlife conflict is affecting a number of aspects of society as a result of increased competition for resources such as food and space. To address the complexity, management of human wildlife conflict needs to be innovative to achieve a difficult but possible win-win solution for both humans and wildlife. As an important form of human-wildlife conflict, aircraft-wildlife collisions (AWCs), more commonly known as bird strikes, require even greater imagination and innovation to solve. AWCs have the potential to cause loss of life to humans, and annual losses in damages as a result of such collisions runs in excess of US$ 3 billion per year to the aviation industry. Due to lack of accurate reporting of AWCs in Namibia (and Africa as a whole) losses have been impossible to quantify locally. In addition to direct damage, airlines, airports and individuals have been litigated in Europe and the USA for indirect damages resulting from AWCs. A number of studies have identified an increasing trend in AWCs globally as a result of higher flight volumes and increases in risk bird populations. Flight safety in Africa is of concern internationally, and AWCs are an important safety aspect which need to be understood better. Very little empirical research on the extent or causes of AWCs in Africa have been published. At Namibia’s two major airports, Hosea Kutako International and Eros (domestic), 128 AWC incidents were recorded between 2006 and 2010. Although none led to human injury or death, two major incidents lead to costs in excess of N$ 20 million and N$ 1million respectively. Publications on AWC minimisation strategies and techniques on the continent are limited to South Africa and Uganda. This is problematic, as mitigation measures for AWCs in Africa are therefore mostly based on research in foreign ecosystems; while we know that local knowledge of AWC factors, such as bird and mammal population dynamics and climatic seasonality are critical to the success of AWC management. This study is the first scientific investigation into any aspect of AWCs in Namibia. It aims to understand the relationship between ecosystem components and their effect on the risk of aircraft-wildlife collisions occurring at Hosea Kutako and Eros airports. Monitoring of ecosystem components such as insects and small mammals are useful to airport wildlife management as they are relatively quick and inexpensive tools for determining ecosystem health and functioning and can indicate varying environmental contexts and responses. These ecosystem components and others such as vegetation and avian communities were explored. The study found that modelling the abovementioned ecosystem factors to predict the risk of AWCs would be marginally accurate, but still useful in understanding the system, as well as the effects of various management actions on that system. Systems modelling was found to have the potential to map the complexity of influences on AWCs and make them understandable to airport management in order to allow more informed decision making and resourcing regarding the management of AWC risk. The international obligation placed on airport staff to control wildlife hazards in the vicinity of airports is often difficult to fulfil, especially at smaller airports or in countries with inadequate resources and capacity. In addition to this, research into wildlife habitat, species and their habits at airports has predominantly originated in Europe and North America, and hence mitigation measures are most effective in these conditions, and less effective elsewhere. Based on the context of its literature and empirical research, this study proposes a toolkit which was designed to guide airports in Southern Africa to minimise risk of aircraftwildlife collisions. It is based on the understanding of ecosystems in the vicinity of the two airports on which this study was based, but also on the broader understanding of capacity and resources available to many Southern African countries. It also considers the recommended practices of ICAO, global best practice and promotes a multi-stakeholder management approach. Key words: Aircraft-wildlife collision, airport habitat, avifauna, bird strike, ecosystem, human-wildlife conflict, multi-stakeholder management, systems modelling, toolkit, wildlife hazard management.