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dc.contributor.advisorKok, O. B.
dc.contributor.advisorVan der Linde, T. C. de K.
dc.contributor.authorKok, Alettta Catharina
dc.date.accessioned2018-03-19T11:21:05Z
dc.date.available2018-03-19T11:21:05Z
dc.date.issued1999-11
dc.identifier.urihttp://hdl.handle.net/11660/8052
dc.description.abstractEnglish: Owing to the world-wide increase in air traffic the number and intensity of collisions between birds and aircraft have increased accordingly. Bird strikes are not only responsible for considerable physical damage and fmancial losses, but also endanger human lives unnecessarily. Aspects of the ecology of avifauna at the Bloemfontein airport were, therefore, investigated in order to reduce hazards posed by birds at inland airports. Plant surveys conducted during 1994 and 1995 confirm the classification of the study area as a chy Cymbopogon-Themeda veld type. Based on botanical composition and basal cover the veld is in a relatively good condition. Regularly mowed experimental plots were characterised by a greater variety of plant species consisting of a lower percentage of climax grasses and a larger component of pioneer grasses, forbs and dwarf shrubs compared to undisturbed tall grass areas. A total of 270 pitfall traps were used over a continuous period of 15 months to determine the diversity, relative abundance and seasonal variation of terrestrial invertebrates in the study area. Members of seven classes, 23 orders and 57 families were identified of which insects comprised the most important component by far. As .opposed to this, flying and plantliving invertebrates which were monitored on a monthly basis by means of sweep-nets were represented by only two classes, comprising 13 orders and 70 families. Mouse trapping and incidental catches of smaller vertebrates in pitfall traps suggest a limited presence of amphibia, reptiles and small mammals. Broadly speaking significantly more invertebrates were collected during the wet than during the dry season. Evidently, the opposite trend applies with regard to the sampling of reptiles and small mammals. Although no direct relationship between catches and rainfall as environmental factor could be demonstrated, a significant correlation with temperature was indicated. Over a period of eleven years approximately 5 000 individuals representing 51 bird species which, potentially, posed a threat to aviation were collected at the Bloemfontein airport. More than half of the species concerned can be considered as I medium-sized terrestrial birds of which the crowned plover (Vane/Ius coronatus) is by far the most important. A similar species composition occurred at the Kimberley airport, in contrast to the greater percentage of water associated birds at the Johannesburg airport. Indirectly, food availability appears to be one of the main environmental factors involved in the presence of, amongst others, the five dominant bird species at the Bloemfontein airport. Analyses of the stomach contents of 3 544 bird carcasses from the Bloemfontein airport, supplemented by 906 stomach contents from the Johannesburg and Kimberley airports, indicate that insects can generally be considered the main food source of the birds concerned. Based on dry mass composition the Isoptera, followed by the Coleoptera and Orthoptera, constitute the most important component in the diet. The Isoptera, more specifically the harvester telmite (Hodotermes mossambicusi), is, moreover, the only important prey taxon showing a conspicuous utilisation peak during the relative food shortage of the dry season. Evidently, temporary superabundant food sources which periodically come about in grassland habitats are opportunistically utilised by the birds. Indications are that habitat manipulation at airports can serve as an effective long-term bird control strategy. Based on the superabundant availability of invertebrate prey species in short grass areas compared to that in tall grass, a socalled tall grass policy would not only lead to the reduction of available food sources, but would also hamper the prey searching abilities of the largely insectivorous avifauna. According to results obtained, chemical manipulation can also be successfully employed to limit the presence of harvester termites, the staple food of the majority of terrestrial bird species in grassland habitat, thereby bringing about a reduction in bird numbers. At the same time, a five layered model is discussed setting out the responsibilities of all the role players associated with the implementation of a successful bird control programme. Key words: Airport, avifauna, bird hazard, feeding ecology, harvester termites, pitfall trapping, grassland, habitat manipulation, management.en_ZA
dc.description.abstractAfrikaans: Weens die wêreldwye toename in lugverkeer het die aantal en intensiteit van botsings tussen voëls en vliegtuie ooreenstemmend verhoog. Raakvlieginsidente is nie alleen vir aansienlike fisiese skade en finansiële verliese verantwoordelik nie, maar stelook menselewens onnodiglik in gevaar. Ondersoek is gevolglik ingestel na aspekte van die ekologie van avifauna op die Bloemfontein-lughawe ten einde die voëlgevaar op binnelandse lughawens te probeer bekamp. Plantopnames wat gedurende 1994 en 1995 uitgevoer IS, bevestig die klassifikasie van die studiegebied as 'n droë Cymbopogon-Themeda-veldtipe. Gebaseer op botaniese samestelling en basale bedekking verkeer die veld oor die algemeen in 'n goeie toestand. Eksperimentele persele wat periodiek kort gesny is, word gekenmerk deur 'n groter verskeidenheid plantsoorte, bestaande uit 'n kleiner persentasie klimaksgrasse en 'n groter komponent pioniersgrasse, kruide en dwergstruike in vergelyking met onversteurde langgras-gebiede. Altesaam 270 putvalle wat oor 'n aaneenlopende tydperk van 15 maande gemonitor is, is gebruik om die diversiteit, relatiewe voorkoms en seisoensvariasie I van grondlewende invertebrate in die studiegebied te bepaal. Lede van sewe klasse, 23 ordes en 57 families is geïdentifiseer waarvan insekte veneweg die belangrikste komponent uitgemaak het. Hielteenoor is vlieënde en plantlewende invertebrate wat in die ooreenstemmende tydperk op 'n maandelikse basis deur middel van veegnette gemonitor is, deur slegs twee klasse, waarby 13 ordes en 70 families betrokke was, verteenwoordig. Muisvalvangste en toevallige vangste van kleinere vertebrate in putvalle dui op 'n beperkte teenwoordigheid van amfibieë, reptiele en klein soogdiere. Globaal gesien is betekenisvol meer invertebrate gedurende die nat as die droë seisoen versamel. Klaarblyklik geld die teenoorgestelde tendens met betrekking tot 'die bemonstering van reptiele en klein soogdiere. Geen direkte verband tussen vangste en reënval as omgewingsfaktor kon aangetoon word nie, maar wel met temperatuur. Nagenoeg 5 000 individue van 51 voëlsoorte wat potensiële gevaar VII lugvaart ingehou het, is oor 'n tydperk van elf jaar op die Bloemfontein-lughawe versamel. Meer as die helfte van die voëlsoorte kan as grondlewende spesies van mediumgrootte beskou word waarvan die kroonkiewiet (Vanellus corona/lts) veneweg die belangrikste is. 'n Soortgelyke spesiesamestelling het op die Kimberley-lughawe voorgekom in teenstelling met die groter persentasie watergeassosieerde voëlsoorte op die Johannesburg-lughawe. Indirek blyk voedselbeskikbaarheid een van die belangrikste omgewingsfaktore in die voorkoms van onder andere die vyf dominante voëlsoorte op die Bloemfontein-lughawe te wees. Maaginhoud-ontledings van 3 544 voëlkarkasse afkomstig vanaf die Bloemfontein-lughawe, aangevul met 906 maaginhoude van die Johannesburg- en Kimberley-lughawe, dui aan dat insekte oor die algemeen as die hoofvoedselbron van die betrokke voëls beskou kan word. Gebaseer op droëmassa-samestelling vorm die Isoptera, gevolg deur die Coleoptera en Orthoptera, die belangrikste komponente in die dieet. Die Isoptera, meer spesifiek grootgrasdraertermiete (Hodotermes mossambicus), is ook die enigste van die belangrike prooitaksa wat 'n opvallende benuttingspiek gedurende die relatiewe voedselskaarste van die droë seisoen ope'nbaar. Klaarblyklik word tydelik oorvloedige voedselbronne wat periodiek in grasveldhabitatte tot stand kom op 'n opportunistiese wyse deur die voëls benut. Aanduidings bestaan dat habitatmanipulasie as doeltreffende langtermynvoëlbeheerstrategie op lughawens kan dien. Gebaseer op die oorvloedige beskikbaarheid van invertebraat-prooisoorte in kortgras-gebiede vergeleke met dié in lang gras, sou 'n sogenoemde langgras-beleid nie alleen tot die beperking van die beskikbare voedselvoonaad aanleiding gee nie, maar prooi-opsporing van die oorwegend insekvretende avifauna ook effektief bemoeilik. Volgens verkreë resultate kan chemiese manipulasie ook suksesvol aangewend word om die voorkoms van grootgrasdraertermiete, die stapelvoedsel van die meerderheid grohdlewende voëlsoorte in 'n grasveldhabitat, te beperk om sodoende 'n afname in voëlgetalle te bewerkstellig. 'n Vyf-vlak model word terselfdertyd bespreek om die verantwoordelikhede van alle rolspelers wat met die uitvoering van 'n doeltreffende voëlbeheerprogram gemoeid is, uiteen te sit.af
dc.language.isoafaf
dc.publisherUniversity of the Free Stateen_ZA
dc.subjectAirporten_ZA
dc.subjectAvifaunaen_ZA
dc.subjectBird hazarden_ZA
dc.subjectFeeding ecologyen_ZA
dc.subjectHarvester termitesen_ZA
dc.subjectPitfall trappingen_ZA
dc.subjectGrasslanden_ZA
dc.subjectHabitat manipulationen_ZA
dc.subjectManagementen_ZA
dc.subjectAnimals -- South Africa -- Bloemfonteinen_ZA
dc.subjectAirports -- Bird control -- South Africa -- Bloemfonteinen_ZA
dc.subjectAirports -- Environmental aspects -- South Africa -- Bloemfonteinen_ZA
dc.subjectThesis (Ph.D. (Zoology and Entomology))--University of the Free State, 1999en_ZA
dc.titleAspekte van die ekologie van avifauna op 'n binnelandse lughaweaf
dc.typeThesisen_ZA
dc.rights.holderUniversity of the Free Stateen_ZA


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