14 results on '"Avenant, N. L."'
Search Results
2. The microenvironment of house mice on Marion Island (sub-Antarctic)
- Author
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Avenant, N. L. and Smith, V. R.
- Published
- 2003
- Full Text
- View/download PDF
3. Among habitat variation in prey availability and use by caracal Felis caracal
- Author
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Avenant, N. L. and Nel, J. A. J.
- Published
- 2002
- Full Text
- View/download PDF
4. Developing a management information system for coordinated predation management in South Africa
- Author
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Kruger, Quinette, De Waal, H. O., Avenant, N. L., Kruger, Quinette, De Waal, H. O., and Avenant, N. L.
- Abstract
Predation on livestock and wildlife is the most prominent facet of human-wildlife conflict worldwide. Yet, it is the least understood, in part due to the disparity in methods used to collect data and report results relating to predation and predation management. Predation management is a highly controversial issue, and the lack of scientific information is a major concern and impediment for initiatives to devise effective and acceptable management strategies. The purpose of this study was twofold: (a) to conduct a detailed farm-level investigation into predation vs predation management in areas where high levels of predation had previously been reported, and (b) to develop a tool to provide livestock farmers and wildlife ranchers with a means of reporting predation and practices employed to curb the impact of predation. Building on the groundwork laid by previous studies in South Africa, this study aimed to provide a basis for improving our understanding of the dynamics of human-predator conflict on farm level as well as on a larger scale in an attempt to address some of the current research gaps. This study explored a succession of methods to collect information on predation and predation management on farm-level and develop a tool to collect such data. Initially, questionnaires were used to collect data, concurrent with the process of developing a digital data collection tool. The data collected by means of the questionnaires were used to test this tool (two mobile device applications). The challenges presented during the study and those associated with other methods of data collection played a central role in the data collection methodology developed in the study. At the onset of the study, questionnaires were used to collect information on predation experienced, predator control methods practised, as well as other factors known to influence predation, such as demographic information, physical and managerial characteristics of a farm, and husbandry practices. Tho, African Large Predator Research Unit, University of the Free State, Department of Animal, Wildlife and Grassland Sciences
- Published
- 2019
5. The use of ecosystem parameters in predicting the risk of aicraft-wildlife collisions at Namibian airports
- Author
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Hauptfleisch, Morgan Lindo, Avenant, N. L., Toerien, D., Hauptfleisch, Morgan Lindo, Avenant, N. L., and Toerien, D.
- Abstract
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, Afrikaans: Mens-wildlewe konflik is huidiglik ‘n probleem wat alle aspekte van die samelewing beinvloed as gevolg van verergende kompetisie vir hulpbronne soos voedsel en ruimte. Om hierdie komplekse probleem aan te spreek, moet die bestuur van mens-wildlewe konflik innoverend wees om ‘n moeilike maar wel moontlike wen-wen oplossing vir mens en dier te vind. Vliegtuig-wildlewe botsings (VWBs) is ‘n belangrike vorm van mens-wildlewe konflik en verg nog meer verbeelding en innovering om op te los. VWBs het die potensiaal om tot menslike lewensverlies te lei, en geldelike verliese weens sulke botsings beloop meer as US$ 3 miljard per jaar vir die globale lugvaartbedryf. Weens ‘n tekort aan akkurate verslagdiening van VWBs in Namibië (en Afrika as geheel) is dit onmoontlik om verliese lokaal te skat. Ongeag direkte verliese, word lugrederye, lughawens en individue voor die hof gedaag om indirekte kostes as gevolg van VWBs te eis. Menigde studies het ‘n globale toename in die volume VWBs gevind as gevolg van meer vlugte en toenames in risiko voël bevolkings. Vlugveiligheid in Afrika is ‘n internasionale bekommernis, en VWBs is een aspek wat nog swak verstaan word. Weinige empiriese navorsing oor die getalle of oorsake van VWBs in Afrika is al gepubliseer. Op Namibië se twee belangrikste en besigste lughawens, naamlik Hosea Kutako Internasionaal en Eros (plaaslik), is 128 VWB insidente tussen 2006 en 2010 aangemeld. Howel geen tot menslike beserings of lewensverlies gelei het nie, het twee groot insidente tot kostes van meer as N$ 20 miljoen en N$ 1 miljoen gelei. Publikasies oor VWB verminderings strategieë en tegnieke in Afrika is tans beperk tot Suid Afrika en Uganda. Dit veroorsaak probleme, omdat die meerderheid strategieë dus in Europa en Amerika ontwikkel is, vir ekosisteme wat anders as lokale ekosisteme funksioneer. Dit neem nie plaaslike kennis oor voël en soogdier bevolkingsdinamika, en seisoenaliteit in ag nie, faktore wat krities is tot suksesvolle VWB bestuu, Namibia Airports Company (NAC)
- Published
- 2014
6. Investigating small mammal community structure as a possible indicator of improved habitat integrity in an area cleared of alien vegetation
- Author
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De Klerk, Jean J., Kemp, M. E., Avenant, N. L., De Klerk, Jean J., Kemp, M. E., and Avenant, N. L.
- Abstract
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 ar
- Published
- 2014
7. Towards the development of a sustainable management strategy for Canis mesomelas and caracal on rangeland
- Author
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Du Plessis, Johannes Jurie, Avenant, N. L., De Waal, H. O., Du Plessis, Johannes Jurie, Avenant, N. L., and De Waal, H. O.
- Abstract
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, Afrikaans: Suid-Afrika het ‘n lang geskiedenis van konflik tussen mense en die rooijakkals Canis mesomelas en rooikat Caracal caracal. Alhoewel die meeste konflik in die verlede in die kleinvee industrie paasgevind het, is daar meer onglangs ook bewerings van bees- en wildboere dat hulle verliese as gevolg van hierdie twee predatore ervaar. Nieteenstaande die bomatige verliese en weidverspreide pogings om hierdie konflik te stop is daar geen volhoubare bestuurs strategie in plek. Vee eienaars probeer tans die probleem op hulle eie of in klein groepe oplos en daarvoor maak hulle meestal gebruik van metodes wat predator getalle uitdun en predasie voorkom. Oorhoofse beheer en gif word in baie areas gebruik. Hierdie metodes is egter selde suksesvol om veeverliese te verminder en in baie gevalle plaas dit net ekstra druk op die biodiversiteit in hierdie areas. Huidige kennis oor aspekte rakende die rooijakkals en die rooikat in Suid-Afrika (insluitende ekologie, ekonomie, bestuurs metodes, predasie getalle, sosiologie) is saamgevoeg en krities ondersoek. Hierdie inligting is nodig vir die opstel van ‘n volhoubare strategie vir die bestuur van die skade veroorsaakende rooijakkals en rooikat op vee- en wildsplase en om beleidvorming en besluitneming rakende hierdie twee spesies in te lig. Daar is ‘n algemene tekortkoming van wetenskaplike inligting oor feitlik al die geïdentifiseerde aspekte wat die ontwikkeling van suksesvolle bestuurs strategieë belemmer. Spesifieke inligtings tekorte ten opsigte van elke aspek is geïdentifiseer en ‘n konsep model word hiervolgens voorgestel van wat nodig is vir die ontwikkeling van ‘n volhoubare bestuurs plan vir skade veroorsakende rooijakkals en rooikat op vee- en wildsplase in Suid Afrika. Meeste van die ekologiese navorsing op beide die rooijakkals en rooikat is van geïsoleerde areas, is gedoen oor ‘n kort tydperk, het ‘n beperkte omvang, is meestal in natuurreservate uitgevoer en het nie gefokus op die ontwikkeling van volhoubare b
- Published
- 2013
8. The impact of predation on a sheep enterprise in the Free State Province
- Author
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Strauss, Andries Jacobus, De Waal, H. O., Avenant, N. L., Strauss, Andries Jacobus, De Waal, H. O., and Avenant, N. L.
- Abstract
The Free State Wool Sheep Project was initiated in 1998 at the Glen Agricultural Institute (AI) and a selection of 280 of the available Merino ewes were randomly divided in the following four production system treatments, namely: · Treatment SL-V(C) Spring Lambing season on Veld with a salt (NaCl) lick only (control) · Treatment SL-V&S Spring Lambing season on Veld with Supplementary feeding · Treatment SL-R&V Spring Lambing season on irrigated Rye-grass (Lolium multiflorum and L. perenne) and veld · Treatment AL-O&V Autumn Lambing season on Oats (Avena sativa) pasture in winter and Veld in summer and spring The broad aim of the Free State Wool Sheep Project was to “develop profitable and sustainable wool farming systems on the resource combination of Glen AI”. However, it was not foreseen at the conceptualization of the Project in 1998 that the impact of predation, mostly by black-backed jackal Canis mesomelas on the sheep flocks at Glen AI would soon reach the high levels experienced in later years. A Merino shearing flock (77 ewes in 2003) and a Dorper flock (219 ewes in 2003) at the Glen AI were also severely impacted by predation. These two flocks were managed in the same way as the Merino ewes in Treatment SL-V(C), therefore, it was decided to include the results of these two flocks also in this study. The impact of predation on reproduction and production performance of sheep flocks (Merino and Dorper) are reviewed and put into perspective for the period 1999 to 2007. Four categories of sheep losses were identified namely: predation, diseases, metabolic disorders or accidents and stock theft. Direct financial losses, veterinary and shearing cost, lick, labour and planted pasture cost were calculated for each of these categories of losses. The calculations were included in the review and served as basis for determining the extent to which financial losses ascribed to predation exceeded the financial losses due to diseases, metabolic disorders or accidents and, University of the Free State, ALPRU
- Published
- 2009
9. A critical evaluation of historical data on two damage causing predators, Canis mesomelas and Caracal caracal
- Author
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Gunter, Quinette, De Waal, H. O., Avenant, N. L., Gunter, Quinette, De Waal, H. O., and Avenant, N. L.
- Abstract
English: The study focused on monthly hunt reports of two problem animal control clubs in the Mossel Bay district of the erstwhile Cape Province, namely the Cooper Jagklub and the Mosselbaai Sentrale Jagklub. These reports were the most complete set of data retrieved by ALPRU and also covered a substantial period from 1976 to 1992. The study was successful in creating computer software (ALPRU Predator Database) to capture and analyse historical data on predator control activities. Original handwritten records were manually captured on the ALPRU Predator Database and transformed during export to the ArcGIS environment. A large number of data tables and maps were generated for evaluation. Historical data were used with a view to: - Investigate whether it was possible to establish the measure of success of predator management practices used in the past. - To test the capacity and performance of the computer software for further application as a tool in predator management. The computer programmes could filter out specific sets of data for separate analysis. In the present study only maps showing stock losses as a result of predation and predators killed in control operations, were analysed. The two different sets of data were filtered out for the study period of 16 years, for separate years and for every month in a selection of three years, 1985 to 1987. The software highlighted several important issues and shortcomings in the dataset, namely: - The historical monthly hunt reports and especially the way in which the data were recorded, were never intended for further analysis. - Positive identification of the specific locations of farms proved to be especially difficult and time-consuming. - The data were incomplete regarding specific information which prevented definitive conclusions being drawn. - The format in which data regarding predator control activities is recorded and reported needs to be improved. - Despite the shortcomings in the dataset, the software proved, Afrikaans: Die studie was toegespits op die maandelikse jagverslae van twee probleemdierbeheerklubs in die Mosselbaaidistrik van die voormalige Kaapprovinsie, naamlik die Cooper Jagklub en die Mosselbaai Sentrale Jagklub. Hierdie verslae was die volledigste wat herwin kon word deur ALPRU en het ook ‘n redelike lang periode gedek vanaf 1976 tot 1992. Die studie was suksesvol in die skep van sagteware (ALPRU Predator Database) om historiese data oor roofdierbeheer vas te vang en te ontleed. Oorspronklike handgeskrewe rekords is met die hand ingevoer op die ALPRU Predator Database en tydens die uitvoer na die ArcGIS omgewing getransformeer. ’n Groot aantal tabelle en kaarte is geskep vir evaluasie. Historiese data is gebruik ten einde: - Ondersoek in te stel na die moontlikheid om die mate van sukses te bepaal wat in die verlede met roofdier bestuurspraktyke behaal is. - Die kapasiteit en verrigting van die sagteware te bepaal as hulpmiddel vir toekomstige toepassing in roofdierbestuur. Die sagteware kan spesifieke data selekteer vir afsonderlike ontleding. In die huidige studie is slegs kaarte ontleed ten opsigte van veeverliese as gevolg van predasie en roofdiere gedood tydens beheeroperasies. Hierdie datastelle is geselekteer vir die studietydperk van 16 jaar, vir afsonderlike jare en ook vir elke maand gedurende ‘n geselekteerde periode van drie jaar, 1985 tot 1987. Die sagteware beklemtoon verskeie belangrike sake en tekortkominge in die data, naamlik: - Die historiese maandelikse jagverslae en veral die wyse waarop die data aangeteken is, was nooit bedoel vir verdere ontleding nie. - Positiewe identifikasie van die spesifieke lokaliteit van plase was veral baie moeilik en tydrowend. - Die data was onvolledig ten opsigte van spesifieke inligting wat dit moeilik maak om finale afleidings te maak. - Die formaat waarin data ten opsigte van roofdierbeheer aangeteken en rapporteer word, benodig aansienlike verbetering. - Ten spyte van die tekortkominge in die datastel, National Research Foundation (NRF), Read Meat Producers Organisation (RPO), National Wool Growers Association (NWGA), South African Mohair Growers Assocation (SAMGA), African Large Predator Research Unit (ALPRU and its Canis-Caracal Programme)
- Published
- 2008
10. Assessing the ecological integrity of a grassland ecosystem: the applicability and rapidity of the SAGraSS method
- Author
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Kaiser, W., primary, Avenant, N. L., additional, and Haddad, C. R., additional
- Published
- 2009
- Full Text
- View/download PDF
11. The microenvironment of house mice on Marion Island (sub-Antarctic)
- Author
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Avenant, N. L., primary and Smith, V. R., additional
- Published
- 2002
- Full Text
- View/download PDF
12. Home‐range use, activity, and density of caracal in relation to prey density
- Author
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Avenant, N. L, primary and Nel, J. A. J, additional
- Published
- 1998
- Full Text
- View/download PDF
13. The influence of fire on rodent abundance at the N'washitshumbe enclosure site, Kruger National Park, South Africa.
- Author
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MacFadyen, D. N., Avenant, N. L., van der Merwe, M., and Bredenkamp, G. J.
- Subjects
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RODENT populations , *FUELBREAKS , *MAMMALS , *BIODIVERSITY , *NATURE conservation - Abstract
The relative population numbers of rodents were studied in nine habitats in and outside the N'washitshumbe enclosure site, Kruger National Park, before and after burning the firebreaks that surround the enclosure. Trap success was exceptionally high, and the field work is suspected to have coincided with a Mastomys population explosion. This genus dominated the small mammal communities before and after the burn, and never disappeared from the burnt patches. Its numbers also did not crash directly after the burn, as have been reported in most other studies. Movement from the burnt areas was observed, which may have had a significant impact on the numbers of rodents caught both inside the enclosure and in the more natural areas outside. Our study suggests that fire can be investigated as a tool to keep rodent densities down in areas where they are nuisance animals, especially when used in conjunction with models that forecast outbreaks of Mastomys. It also emphasizes the value of long-term studies informing management strategies for animal damage control and biodiversity and ecosystem conservation. [ABSTRACT FROM AUTHOR]
- Published
- 2012
- Full Text
- View/download PDF
14. The diet and impact of house mice on a sub-Antarctic island.
- Author
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Smith, V. R., Avenant, N. L., and Chown, S. L.
- Subjects
MICE ,RODENTS ,INVERTEBRATES ,DEVELOPMENTAL biology ,EARTHWORMS ,SEA birds - Abstract
An analysis of the stomach contents of house mice (Mus musculus L.) at three sites on Marion Island (47°S, 38°E) over a 1-year period showed that the mice feed mostly on terrestrial macroinvertebrates but that plants (mainly seed) are an important component of the diet in mid- to late summer. Larvae of a flightless moth, weevil larvae and adults and, at one of the sites, earthworms were the invertebrate items that showed the highest importance value over the year. Diet diversity was slightly lower in summer and autumn than in winter and spring. Diet variety was lowest in midsummer and highest in either autumn or winter, depending on the site. Mean stomach-content mass was significantly higher in midwinter than during the rest of the year. When offered prey of different types and sizes, mice selected moth larvae first in 92% of the trials; earthworms or weevil adults were most frequently selected second, and weevil larvae fourth. An introduced slug species was selected only once, as the last choice and only part of it was eaten. With both moth larvae and earthworms, the heaviest individual offered was almost always chosen first. Surprisingly, mice never consumed more than about half of the seed offered to them and their condition deteriorated severely during the trials with seed; in a third of the trials with two types of seed, the mice completely ignored the seed. The impact of mice predation on invertebrates was assessed at two of the sites – a dry mire and a coastal biotic herbfield that is influenced by seabird and seal manuring. Moth larvae and adults, weevil larvae and adults, earthworms, spiders and flies made up >90% of the animal remains in the stomach contents over the year and, on average, the mice daily consumed 45 g (dry mass) ha
–1 of those invertebrates at the mire and 194 g ha–1 at the biotic site. Moth larvae made up a substantial proportion of these amounts; average daily consumption was 30 g ha–1 at the mire and 107 g ha–1 at the biotic site. In terms of the amount consumed in relation to biomass, the heaviest impact of mice at both sites was on weevil adults; at the biotic site mice daily consumed 13% of weevil adult biomass in autumn and nearly 6 times the annual average biomass over the year. At the mire, slightly more than the annual average weevil adult biomass was consumed over the year. The consumption of invertebrates by mice found in this study (1992/1993) was about 20% greater than in 1979/1980. The most striking changes in annual average consumption rate between 1979/1980 and 1992/1993 were for weevil larvae (increased nearly fourfold) and earthworms (increased sixfold at the biotic site and threefold at the mire). In contrast, the consumption of spiders at both sites decreased between 1979/1980 and 1992/1993. [ABSTRACT FROM AUTHOR]- Published
- 2002
- Full Text
- View/download PDF
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