Masters Degrees (Zoology and Entomology)
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Browsing Masters Degrees (Zoology and Entomology) by Author "Butler, H. J. B."
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Item Open Access Aspects of geophagia amongst dairy cattle in a feedlot system(University of the Free State, 2017-03) Wiid, Emmarentia Elsabe; Butler, H. J. B.English: Modern confinements imposed on animals limit their access to natural resources required for optimal nutrition. This lack of resources may lead to nutrient deficiencies and one of the hypotheses for the deliberate consumption of soil is to supplement mineral deficiencies. Counteraction of acidosis, detoxification, buffering of unpalatable plant compounds as well as the use of soil as anti-diarrhoeal agent are other suggested motivations for geophagy. By means of direct observation as well as camera traps, the behaviour of geophagy amongst dairy cows in a confined feedlot system was documented. In addition, soil analysis was done to determine the geochemistry of ingested as well as excreted soil. Geophagy amongst cows at Amperplaas constituted less than 2% of daily activity. The non-lactating individuals invested less time in this behaviour than lactating individuals and the frequency as well as time spent on this behaviour decreased as the lactation phases progressed. Recorded geophagy occurrences were most during winter and thereafter spring and peak soil ingestion occurred during mid-day. At Amperplaas, all but one of the mineral licks were situated on the undisturbed elevated areas underneath the fence wire or around the wooden and iron poles. The average size of a typical mineral lick was about 40 cm by 15 cm with a depth of 10 cm. The soil collected from the mineral licks was alkaline and classified as sandy clay loam. Quartz, Plagioclase and K-Feldspar were identified in all samples while Ilmenite was quantifiable in all but one of the control sites. Silica concentrations were supportive of quartz dominance in the soil collected from mineral licks as well as soil from the stomachs and faecal matter. The most recent mineral lick contained the lowest silica, arsenic, copper, lead, scandium, and zirconium content. But this site had elevated calcium, iron, potassium, magnesium, sodium and phosphorus as well as bromine, nickel, strontium and zinc levels. When offered soil combined with different minerals, the preference of most cows was sodium chloride mixture and thereafter calcium-phosphorus. When comparing the estimated amount of soil ingested per second with the excreted amount of soil, it appears that the daily excretion rate of soil is almost equal to the ingestion rate, therefore not posing any threat for sand impaction. Milk collected at Amperplaas had low levels of calcium as well as potassium and therefore, soil is possibly ingested to supplement this deficiency. Results of this study confirm the ability of some animals to detect deficiencies in the body and to attempt to correct these deficiencies from available resources. Results also support the theories that this nutritional wisdom is partly from cultural transmission as well as innate behaviour.Item Open Access Aspekte van die biologie van tuinduiwe (Columba livia) in die Bloemfonteinse stadsgebied(University of the Free State, 2007-05) Le Roux, Pieter Daniël Stephanus; Kok, O. B.; Butler, H. J. B.English: Owing to the increase of complaints in the city of Bloemfontein concerning the damage being caused to buildings by birds, different aspects of the biology of feral pigeons (Columba livia) was investigated. Close to 400 pigeons, which included nearly 50 lost racing pigeons, were collected on a regular basis within the city boundaries over a period of one year (March 2005 - February 2006). Although slightly more male birds were obtained, no significant variance from a balanced sex ratio in the population structure was distinguished. Feral pigeons moult continuously throughout the year at a relatively low intensity rate. Conspicuous peaks in the moulting of primary, secondary and tail feathers were observed for both sexes, however, the period for replacement was slower for females. Leucism was displayed by more than a quarter of the birds. Feral pigeons are more frequently infected with parasitic louse flies compared to local rock pigeons (Columba guinea), with the highest infection occurring during the summer months. Apart from measurements of the beak, the standard body measurements of adult males are significantly larger compared with their female counterparts. A similar trend applies in the different sexes of juvenile feral pigeons as well as racing pigeons. The seasonal variation in the body weight and visible fat deposits of adult feral pigeons probably coincides with the birds' breeding activity and the temporary availability of abundant food supplies. A prominent peak in the activity of the ovarian cycle of female birds, based on the weight and diameter of macroscopic follicles, coincides with the gonad cycle of male feral pigeons which occurs during the early winter months, followed by a smaller peak during spring. Based on the presence of nests, eggs and chicks, feral pigeons breed throughout the year with a decrease in breeding activity during the wetter summer months. Nest types vary from dried droppings on which eggs are laid to firmly-built, dry stick nests. After hatching from a typical clutch of two eggs the weight of the chicks increase daily on a linear scale. Both parents are involved in the hatching and raising of the chicks. Second or subsequent clutches are laid regularly throughout the year at the same nesting site. Rock and feral pigeons may interbreed, however this phenomenon is rarely documented. Agricultural crops including maize (Zea mays), sunflower (Helianthus annuus) and wheat (Triticum aestivum) are the most important components of the diet of feral pigeons living at the SASOL library on the campus of the University of the Free State. The diet of birds living within the city centre consists mainly of natural vegetation of which seeds of the Camdeboo stinkwood (Celtis africana) constitutes the most important component. The low percentage of animal matter consists largely of pupae of Diptera and egg cocoons of unidentified earthworms, while grit constitutes the largest component of inorganic matter. No significant statistical difference was found in the composition of the different sexes' diet. Under experimental conditions feral pigeons show a definite affinity towards maize in comparison with sorghum (Sorghum almum), sunflower and wheat. Associated with the latter, yellow food items are preferred above blue, green and red coloured items. Single birds eat on average more over a short term (10 minutes) than individuals which feed in groups, but almost equal amounts of food are ingested by individuals over a longer period (2 hours). Feral pigeons living on the university campus leave their nesting sites daily just after sunrise to go and feed on agricultural crops on the surrounding farmlands, returning approximately two hours later. Birds feeding in the city were mainly found on the ground during the early morning hours and to a lesser extent during the afternoon. The birds usually spend the hot midday hours in the shade. Lost racing pigeons regularly join local feral populations in urban areas. With the consideration of appropriate national and/or municipal laws, the shooting of feral pigeons with airguns and/or the provision of alpha-chloralose treated bait seems to be the most effective way in which their numbers in urban areas may be controlled. The introduction of natural enemies such as owls and/or falcons into urban areas could also be considered as a method of control of feral pigeon numbers.Item Open Access Colour variation of African bovidae: consequences for conservation and the wildlife ranching industry(University of the Free State, 2015-07) Olivier, Phillip Arnold; Butler, H. J. B.English: Colour variant game species have become a common sight on game farms and at auctions, as a result of their oddity and high monetary value. Currently there are more than 40 colour variants of African Bovidae. Even though these colour variants have become very sought after and profitable to farm with, it has been warned that colour variants do not contribute to conservation since colour variants normally do not survive in nature. Consequently the intentional breeding of colour variants is causing concern, as they may be a threat to conservation. The objective of this study was to collect data to facilitate decision making in the game ranching and conservation industry. Statistical analysis showed that there were significant behavioural differences between four springbok colour variants studied. Black springbok were less active and utilised much more shaded areas compared to other colour variants or normal coloured animals. The darker coloured animals presented less body surface area to the sun during the warmest times of the day than the white springbok. Springbok were also found to form herds based on phenotype, preferring to associate with homogenous individuals. This phenomenon was likely due to the odd-prey effect. Wildlife auction turnover grew from R62 million to over R1 billion in the last ten years. In conjunction with this growth, record prices for animals are being recorded every year. However in most cases colour variant game are reaching much higher prices than the normal coloured nonspecific's. Colour variants also achieve annual growth which is greater than inflation often providing better return on investment than stock market shares. Even though a normal Kalahari springbok ram set a new record at R1.2 million it was far exceeded by coffee coloured springbok that sold for R4 million. Financial gain then seems to be the main motivator behind the breeding of colour variants as they have become sought after by game ranchers. There is however concern amongst various stakeholders that the breeding of colour variant wildlife is unsustainable. This is as a result of the increasing opposition against the selective breeding of these animals and a general disinterest in these animals from end-users which include hunters and eco-tourists. No significant proof could be found during this study that there will be large-scale interest in the consumptive or non-consumptive use of colour variants. Little published scientific data is available concerning colour variants and most of the available information is in the form of popular magazine articles, newsletters and websites. The lack of published scientific data has resulted in a debate concerning colour variants. Opinions on this issue are much divided and can also evoke strong emotional responses from those involved; particularly from ranchers that are concerned their livelihoods may be threatened by any control measures. Most wildlife ranchers feel that they should be allowed to breed with any animal that provides the best return on investment and that, since colour variants are a natural phenomenon, they do not threaten conservation. Survey results showed that although many respondents did not consider colour variants to be a threat to conservation the majority did not support breeding of such colour variant wildlife. The vast majority of respondents indicated that financial gain was the main reason for the popularity of colour variants. Many stakeholders also expressed great concern about potential damage being done to the conservation and eco-tourism image of South Africa as many, specifically foreign hunters, consider colour variants wildlife to be unnatural. The ultimate conclusion of this study is that the existence of colour variants does not pose a threat to conservation but it is rather the management of these animals which pose a potential threat to conservation of South Africa’s wildlife as well as South Africa’s conservation image.Item Open Access Enzootic geophagy by elephants (Loxodonta Africana) in relation to geochemical composition of mineral licks in Addo Elephant National Park, South Africa(University of the Free State, 2022) Darker, Kristen Nadine; Butler, H. J. B.Geophagy, the deliberate ingestion of soil, is a common occurrence amongst various animal species including mammalian herbivores such as elephants. Despite the documented instances of soil-eating, and several nonexclusive hypotheses, the real motivation behind the phenomenon remains controversial. In this study, six camera traps were set up throughout Addo Elephant National Park, South Africa at selected geophagy sites which captured visitation frequency as well as the demographic trend of elephant groups during site visits from April 2019 to May 2020. The geochemical and mineralogical composition of soils at these selected geophagy sites were analysed using X-ray diffractometry (XRD) and X-ray fluorescence spectrometry (XRF). Furthermore, the spatial distribution of five collared elephants (three matriarchs and two males) in relation to the six geophagy sites were investigated using kernel density estimations (KDE). Females had larger home ranges that incorporated more geophagy sites than males. Visitation frequency to geophagy sites were estimated using 500 m buffer zones from the centre of each site. Individuals visited at least three or more geophagy sites throughout the study period. Overall, essential elements Na, Ca and Mn were identified as main drivers for geophagic behaviour in the elephants of AENP. These essential elements (Na, Ca and Mn) are important for certain physiological demands such as bone and tusk growth in elephants and reproductive (pregnancy and lactation) demands in females. Geophagy is considered to be a contributing factor of movement patterns and area utilisation and may have important implications for conservation and management.Item Open Access An examination of non-mammalian cynodont cranial endocasts(University of the Free State, 2010-09) Du Plessis, Dewald; Botha-Brink, J.; Butler, H. J. B.English: The palaeoneurology (study of the nervous system of extinct animals) of nonmammalian cynodonts, which were the ancestors of mammals, is poorly understood. It is thought that the relative brain size of cynodonts increased with time, and that this change significantly affected their physiology and behaviour. Forty-four cynodont skulls belonging to eleven genera from Permian, Triassic and Jurassic strata were scanned and analysed using neutron computerized tomography (NCT), at the SAFARI-1 Nuclear Research Reactor of the Nuclear Energy Corporation of South Africa (Necsa). Data concerning the endocranial casts was hereby obtained in a non-destructive manner. Four specimens, namely Galesaurus, Platycraniellus, Langbergia and Tritylodon produced successful scans and were used for further study. Measurements of the cranial material were used to calculate the size of the brain endocasts and the approximate body masses were determined from an equation using skull length. The encephalization quotient (EO), a measure of brain size relative to body size, was determined for each specimen using brain volume and body mass. Changes in the position of the brain inside the skull, and an overall increase in size of the brain in the more derived cynodonts indicate some development towards the mammalian condition. Taxonomic variation regarding the shape and size of the olfactory bulbs and other parts of the brain endocasts is discussed and related to differences in ecology or behaviour. The relatively deep and large olfactory bulbs in some cynodonts may be an adaptation to either nocturnal behaviour, dietary or habitat preferences. Relatively large cranial endocasts in Galesaurus, Platycraniellus, Massetognathus, Tritylodon, Chiniquodon and the tritheledonts may be related to habitat preference or social behaviour. The basal epicynodonts Galesaurus and Platycraniellus have the largest cranial endocasts of all the cynodonts studied. Their large cranial endocasts may be related to behavioural or ecological preferences, but the results require confirmation from a larger sample size. The present study provides an important foundation from which further cranial endocast studies on cynodonts can be developed.Item Open Access Livestock, leopards and brown hyaenas: conflicts of cohabitation in the Roodewalshoek Conservancy, Mpumalanga(University of the Free State, 2012-01) Van As, Michelle; Butler, H. J. B.English: Conflict between livestock farmers and predators has been an ongoing battle since the breeding of domestic animals were first attempted by man. Insufficient data on the dynamics of predators, especially in regions outside formal protected areas where they are perceived as problem animals, make control methods almost impossible. Due to complaints of predation by cattle farmers in the unspoiled Roodewalshoek Conservancy, the dynamics of livestock predation was investigated. Specific emphasis was placed on the relationship between the ecological traits of leopard, brown hyaena and natural prey species and the consequences thereof on livestock losses. Investigations were carried out by means of motion-sensing camera traps, combined with seasonal field observations of all physical signs of animals. The presence of recorded prey species showed a monthly variation, with some prey species present all year round while others showed definite periods of occurrence. Rainfall seemed to have some influence on the occurrence of such species. Most small potential prey species was observed continuously during the winter months and only sporadically during the summer. Medium sized potential prey species that occurred on a constant basis throughout the year in the study area included bushbuck, Chacma baboons and common grey duikers. Sporadic occurrence of impala and mountain reedbuck were encountered mostly during the mid-summer months, especially during December. All species classified as large prey were continuously present throughout the year, except for the aardvark which showed a sporadic presence and were mostly observed during mid-summer. Large predators were continually observed in the conservancy except in late summer during the month of January and reached highest numbers during early autumn, mid-winter and in the height of summer. All the other predators, including small and medium-sized predators, were present on a frequent basis except during late summer and only reached a high in mid-winter and early spring. It was also evident that, when the presence of large predators in the study area increased, the presence of other predators diminished. The majority of calves (59%) were killed by predators during the wet summer months, while only 41% of calves were predated upon during winter months with low precipitation. Lunar cycles seem to play a distinctive role in livestock predation with almost two thirds of calves lost to predators when moonlight intensity was low. Even though sufficient occurrences of natural prey could be found in the Roodewalshoek Conservancy, predation on livestock persists during the calving season. Regarding the key predator of livestock in the conservancy, both leopards and brown hyaenas were almost equally accountable and displayed alternating periods of calf predation. Instances of predation where the problem animal could be identified, implicated brown hyaenas in 48% and leopards in 52% of livestock losses. During times when brown hyaenas were responsible for the most calf losses, predation caused by leopards was low. High incidences of leopard predation consequently resulted in lowered brown hyaena predation. This could be due to inter-predator competition for shared resources. The behaviour of surplus-killing by both predator species is indicative of the ability to fully exploit all the available resources in their area. The relatively large number of livestock lost to predation each year may be due to a combination of several factors. These include the lack of predator control in adjacent game farms and other protected areas, continuous presence of livestock, leopards and brown hyaenas as well as the open, unattended system in which livestock is kept in the Roodewalshoek Conservancy.Item Open Access Parasite induced behavioural changes in fish(University of the Free State, 2011-05) Grobbelaar, Andri; Van As, J. G.; Butler, H. J. B.; Van As, L. L.English: Numerous studies have been conducted on the hypothesis of parasites influencing the behaviour of their hosts. Many authors have been bias in trying to prove that this is a form of manipulation and that parasites increase their transmission success by changing host behaviour. Not much research has been conducted in Africa regarding parasite induced behaviour. During the present study fish were collected from the Okavango and Orange-Vaal River Systems, respectively situated in Botswana and South Africa. Within these ecologically diverse systems a wide variety of fish were found to be infected with diplostomatid metacercariae occurring inside their eyes and / or brains. These digenetic trematodes are known to cause blindness and other pathological effects, known as diplostomiasis, especially in fish reared in aquaculture. Diplostomatids have a three-host life cycle which involves different species of snails, fishes and piscivorous birds. Fish act as the second intermediate hosts and need to be eaten by a piscivorous bird in order for the diplostomatids to be trophically transmitted and the life cycle to be completed. Seven different metacercarial types and cysts were identified and some were collected from both the eyes and brains of infected fish species. The results signified a moderate prevalence of these parasites amongst the different fish species, whilst the intensity of infection proved to be low. No marked altered pathology was observed in infected fish brains but noticeable histopathological changes were noted within eyes infected with diplostomatid cysts. To determine the effect these infections have on the behaviour of natural populations of fish, two behavioural experiments were conducted. The results indicate that infected fish show similar behaviour than uninfected fish and therefore the null hypothesis (Ho) is accepted.Item Open Access Population dynamics management of invasive rock hyraxes, procavia capensis (Pallas, 1766), in the central Free State, South Africa(University of the Free State, 2017-02) Wiid, Roelof E.; Butler, H. J. B.Frequent reports of rock hyrax (Procavia capensis) invasions in residential areas prompted an investigation of this problem in order to identify possible solutions. From reports, problem areas in South Africa were identified, and sites within the Free State Province were selected for this study. At these sites, rock hyrax populations demonstrate an unusual annual increase. This increase has led to a food and habitat shortage, forcing individuals into residential areas in search of additional refuges and food sources. In order to manage populations, several preventive as well as control methods have been assessed and implemented. Population densities were determined using the Lincoln index and the Robson–Whitlock technique. Results obtained when both methods were used showed a positive correlation of R=0.88, calculated with Pearson’s correlation coefficient. Wild populations were included in the study for comparison purposes. Additional resources within residential areas have facilitated populations to grow much larger, in some instances exceeding the natural limits (30 – 40 individuals) by 175 - 225 %. This influx contributes to human–wildlife conflict. With the use of translocation, populations were reduced within three months. The introduction of natural predators for rock hyrax population control appears to have positive results, but will have to be monitored on a regular basis. Preventive measures have shown various levels of success. Different combinations of these measures proved to have different levels of effectiveness. A combination of wire fences higher than 1.8 m, an overhang at the top and dogs from the working and/or terrier groups seemed to be most effective. The strategy to capture and translocation individuals, for the rapid reduction of the population, has been successful. Results show that the establishment of translocated populations was not successful owing to high predation rates.Item Open Access Social organisation and reproductive behaviour of sable antelope (Hippotragus niger Harris, 1838): implications for captive management(University of the Free State, 2015-07) Jacobs, Nadine; Butler, H. J. B.English: Sable antelope (Hippotragus niger) are considered to be one of the most profitable wildlife species in southern Africa favoured by photographers and trophy hunters. Intensive wildlife production of sable antelope is practiced to improve reproductive rate which would normally be retarded by deficiencies and mortalities in extensive management systems. Intensive wildlife production refers to the management of wildlife in a fenced area where management practices such as the provision of dietary supplementation and water (throughout the year), the control of parasites and the provision of health care are implemented in order to increase productivity. Up to now studies investigating the effects of captivity on social and reproductive behaviour of sable antelope, have been focused on populations in zoos and conservancies where management practices are centred on conservation. Additionally, no published scientific data is available concerning the effects of intensive management practices used in the wildlife ranching industry of South Africa. The main objective of this study was therefore to determine the effects of management strategies practiced specifically in intensive wildlife production in South Africa, on aspects of social and reproductive behaviour of sable antelope. To determine the effects of different management strategies, the social and reproduction behaviour of three sable antelope populations under different management regimes were investigated. Interactions pertaining to reproductive behaviour, territorial displays, and agonistic behaviour were evaluated and compared between populations. The success of management strategies practiced was evaluated by determining the reproductive rate of each population. To determine why these behavioural patterns were affected, differences in the activity pattern and range use of breeding herds and territorial males of populations were also assessed. Populations in intensively managed systems showed 100% calving and survival rates compared to a 75% survival rate observed for the extensively managed population. Though the implementation of intensive management strategies resulted in increased production, it also resulted in increased rates of agonistic interactions. However, the occurrence of aggressive displays that could result in injury was not abnormally high in the intensively managed populations compared to that observed in the extensively managed population. However, in the two intensive populations agonistic interactions directed at immature individuals were not only more numerous but also contained a larger percentage of aggressive displays. Increased rates of agonistic behaviour were primarily as a result of the provision of dry feed. Other factors that could have influenced the rate of agonistic interactions in both the extensively and intensively managed populations included, the artificial provision of water, activities that result in decreased personal space, the rate of territorial displays and limited resources. Therefore it can be concluded that though intensive management strategies definitely succeed in increasing productivity, in practice these strategies could adversely affect aspects of social behaviour of sable antelope in intensively managed systems.