The foraging ecology of Wedge-tailed Shearwaters (Ardenna Pacifica) in the tropical Western Indian Ocean
- Authors: Keys, Danielle Zuanda
- Date: 2018
- Subjects: Birds of prey -- Behavior -- South Africa -- Western Cape , Animal behavior , Wildlife conservation
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/31251 , vital:31348
- Description: The distribution and abundance of prey largely influences how marine predators forage. Thus, understanding how marine predators respond to such changes becomes imperative when making decisions in marine spatial planning, especially in light of global climate change. Tropical marine systems are known for their relatively low productivity and high unpredictability of prey resources. Compared to higher latitudes, very few studies on seabirds have been implemented in the tropics. The Wedge-tailed Shearwater Ardenna pacifica is an Indo-Pacific tropical seabird with a wide distributional range. However, like many other seabirds, its population numbers are currently declining. Very little is known about the at-sea distribution of Wedge-tailed Shearwaters in the tropical western Indian Ocean. Therefore, this thesis investigates the foraging ecology of Wedge-tailed Shearwaters in the western Indian Ocean by tracking the fine scale movements of individuals at sea. This study was conducted in two different oceanic environments, namely D’Arros Island and Fouquet Island, St Joseph Atoll in the Amirantes Group in Seychelles archipelago as well as Réunion Island in the Mascarene archipelago during the Wedge-tailed Shearwaters breeding seasons. Here I aimed to investigate the foraging distribution of Wedge-tailed Shearwaters on Réunion Island in relation to different stages of the breeding period. I also compared the foraging ecology of all three populations, subjected to different abiotic and biotic factors. Furthermore, I investigated foraging site fidelity in individuals and repeatability within individual flight characteristics. To my knowledge, this is the first study to comprehensively investigate the foraging ecology of Wedge-tailed Shearwaters using global positioning system (GPS) loggers. This study demonstrated that the Wedge-tailed Shearwaters implement flexible foraging strategies throughout different stages of their breeding period and between different islands. In Réunion, during the shearwater breeding season, sexual segregation was prominent during early chick rearing and both sexes implemented dual foraging. As suggested by previous studies, it is likely that long trips were implemented for self-maintenance, whereas multiple short trips were implemented to meet the high energetic demands of the chicks. Several important foraging areas were identified for these Wedge-tailed Shearwaters. During incubation, shearwaters from Réunion faithfully foraged towards the south east of Madagascar near the East Madagascar Current and flew over large areas of the Mascarene Basin. During chick rearing, shearwaters significantly constricted their range closer to the colony and exploited deep waters on the south-west of Réunion Island. Shearwaters concentrated near oceanographic features such as the Pérouse Seamount (which is a known area of high productivity) as well as the Bourdonnais Ridge. There was no clear evidence for spatial or sexual segregation between individuals from the two study colonies in Seychelles during incubation and birds utilized a broader foraging range than birds from Réunion. This is likely to be the result of a large annual phytoplankton bloom which coincides with the shearwater breeding season in Seychelles, providing many foraging opportunities within the Seychelles Basin. The shearwaters from Seychelles exploited the Amirante Basin, East Somali Basin, and parts of the Seychelles archipelago. Shearwaters from D’Arros flew further east and foraged in the Mascarene Basin. Shearwaters from all populations foraged over deep, relatively unproductive waters with relatively high sea surface temperatures which are similar oceanographic features favoured by tuna. Foraging plasticity between individuals from different colonies was observed with varying flight bearings, flight durations and the maximum distances travelled from their respective colonies. Shearwaters displayed dissimilar levels of site fidelity, where shearwaters from Réunion faithfully foraged towards south east Madagascar, while shearwaters from Seychelles foraged over a wide range over the Seychelles Basin. Foraging effort for shearwaters from Fouquet was lower than shearwaters from Reunion and they spent less time at sea and foraged closer to their colony. These difference in behaviour responses between colonies may be advantageous to shearwaters, indicating that they may be able to respond to some level of environmental variability resulting from climate change and anthropogenic pressures. Lastly, during chick rearing, though shearwaters showed low levels of repeatability in flight characterising, foraging site fidelity was high amongst some of the individuals. Here we see that shearwaters continuously rely on permanent features, like seamounts and possibly fish aggregating devices, which are known to attract high abundances of tuna. Shearwaters may to some extent be relying on memory to find prey in a seemingly unpredictable environment. This study has helped us gain valuable insight about the foraging ecology of Wedge-tailed Shearwaters in the western Indian Ocean. Together with similar studies determining the at-sea behaviour of seabirds, better informed recommendations can be made to marine spatial planners as to where much needed pelagic marine protection should be implemented to preserve marine life in this fascinating part of the global ocean.
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- Date Issued: 2018
The management of chacma baboons and humans in a peri-urban environment: a case study from Nelson Mandela Metropolitan University's George Campus
- Authors: Botes, Peet
- Date: 2016
- Subjects: Human-animal relationships , Animal behavior , Human beings , Bestiality
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: http://hdl.handle.net/10948/5135 , vital:20812
- Description: Conflicts between humans and baboons (Papio ursinus) have become a significant management challenge on Nelson Mandela Metropolitan University’s (NMMUs) George Campus, which is located in peri-urban George in the Garden Route, of the Western Cape of South Africa. Current management policy, although required to be ‘scientifically’ based, largely relies on studies done outside the Garden Route. This study addresses the question of how the management of human-baboon relations could be improved on the campus. A case study was undertaken which aimed at addressing the cohabitation of baboons and humans on the NMMU campus, specifically human-baboon resource selection and interaction. The research methodology and the related analytical tools were primarily quantitative but were supplemented by some qualitative data drawn from interviews. Data collected was used to determine landscape features acting as Keystone Resource Areas (KRAs) for both humans and baboons on the campus. Relationships between the frequency and location of negative interactions, and resident-baboon distribution on the campus were also determined. Two key findings emerged from the research. First, residences, non-residence buildings and waste disposal stations act as KRAs for both humans and baboons. Second, the frequency of negative interaction correlates with the time spent by residents and baboons at residences, where common negative interactions between baboons and humans are known to occur. It is postulated that cohabitation on the NMMU George Campus is causing the habituation of baboons, a loss of fear of humans and association of humans with high energy foods. As a result, present cohabitation contributes to negative human-baboon relations in the George area. To ensure sustainable co-existence between humans and baboons on the George Campus, management should implement zonation and wildlife monitoring to reverse the loss of baboon fear of humans and better limit the availability of human-derived foods. In addition, management should consider giving stakeholders co-management roles to foster and facilitate knowledge and responsibility partnerships, and subsequently correct any misunderstandings related to human-baboon relations on the campus. Recommendations for further research include sampling beyond campus boundaries to compensate for regional variations in baboon behaviour and the biophysical environment.
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- Date Issued: 2016
Avoidance-related behaviour, bleeding times and the quality of meat from sheep slaughtered at a commercial and a municipal abattoir
- Authors: Njisane, Yonela Zifikile
- Date: 2012
- Subjects: Mutton -- Quality , Sheep -- Quality , Slaughtering and slaughter-houses -- South Africa , Animal behavior , Dorper sheep , Meat -- Quality , Sheep -- Carcasses -- Handling
- Language: English
- Type: Thesis , Masters , MSc Agric (Animal Science)
- Identifier: vital:11818 , http://hdl.handle.net/10353/d1004195 , Mutton -- Quality , Sheep -- Quality , Slaughtering and slaughter-houses -- South Africa , Animal behavior , Dorper sheep , Meat -- Quality , Sheep -- Carcasses -- Handling
- Description: The objective of the study was to determine the avoidance-related behaviour, bleeding times and the quality of meat from sheep of different gender, breed (Dorper, Merino, and their crosses) and age groups, slaughtered at a commercial and municipal abattoir. Castrates and ewes of different age groups (1= <10months, 2= 11-12months, and 3= >12months) and breeds were used. From the commercial abattoir, 90 castrates and 110 ewes were used, while 66 castrates and 19 ewes were obtained from the municipal abattoir. Meat samples were obtained to determine meat colour, ultimate pH, temperature, cooking loss and tenderness. Correlations between bleeding times and meat quality variables were also determined. The two abattoirs differed in terms of technology and the procedures used, and this brought about different response behaviours in sheep at slaughter, bleeding times at exsanguination and the quality of meat produced. Animal-related factors (breed, gender and age classes) had no effect on the avoidance-related behaviour of sheep slaughtered at the commercial abattoir, while these factors affected those sheep slaughtered at the municipal abattoir. These factors also had an effect on the quality of meat produced at both abattoirs. Gender and weight of the animals had effects on the bleeding times at exsanguination at both abattoirs. Bleeding times did no correlate with any of the meat quality variables, but correlations among meat quality variables were observed. Avoidance-related behaviour, bleeding times, and the quality of mutton from sheep slaughtered at a commercial and a municipal abattoir was affected by breed, age, and gender.
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- Date Issued: 2012
The management of extralimital giraffe (Giraffa Camelopardalis) in the mosaic thicket of Southern Cape, South Africa
- Authors: Cornelius, Andri Judith
- Date: 2010
- Subjects: Giraffe -- South Africa -- Eastern Cape , Giraffe -- Food -- South Africa -- Eastern Cape , Giraffe -- Ecology -- South Africa -- Eastern Cape , Animal behavior , Animal-plant relationships -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: vital:10749 , http://hdl.handle.net/10948/1345 , Giraffe -- South Africa -- Eastern Cape , Giraffe -- Food -- South Africa -- Eastern Cape , Giraffe -- Ecology -- South Africa -- Eastern Cape , Animal behavior , Animal-plant relationships -- South Africa -- Eastern Cape
- Description: The giraffe at Nyaru were found to be browsers who made little use of graze during the study period. They utilized a diversity of 20 browse species. Two species, Acacia karroo and Acacia cyclops, formed the bulk of the giraffe diet throughout the year. A definite seasonal dietary shift was evident. A. karroo was favoured in summer and autumn and formed the main food species in spring, summer and autumn. A. cyclops was favoured throughout the study, but its contribution to the diet increased during winter when less A. karroo was consumed. This seasonal shift is related to the deciduous nature of Acacia karroo. Although a seasonal shift in species contribution to giraffe diet has been observed in many other giraffe feeding studies, no studies on giraffe feeding have been done in the Mosaic Thicket of the southern Cape. The ecological browsing capacity for giraffe in thicket was estimated to be between 0.020 BU/ha and 0.095 BU/ha. The browsing capacity for giraffe at Nyaru, based on the available phytomass 2–5 m above the ground, was estimated using those species that formed the bulk of the giraffe diet, and amounted to 0.063 BU/ha. A maximum of three giraffe could thus be stocked on the 157 ha of suitable giraffe habitat on Nyaru. This stocking rate recommendation lies within the range commonly recommended by local consultants for giraffe introductions into the southern Cape. Their recommendations are, however, not based on quantitative assessments such as performed in this study. The recommendation of this study should not be applied as a fixed ecological capacity for giraffe in thicket, but should be seen as a starting point in the adaptive management cycle. Ongoing monitoring of parameters, such as herbaceous composition and phytomass; as well as the condition of key browse species, is strongly advocated. A. karroo was browsed significantly more and carried significantly fewer pods per tree at a heavily used site compared to a lightly used site. Heavy browsing thus appears to affect the reproductive success of A. karroo significantly. Fewer pods are likely to lead to lower regeneration and thus reduced density of A. karroo. Whether A. karroo will maintain its dominance within the thicket vii community in the long run will be related to how individual plants survive and reproduce and if some can escape from herbivory. Fewer G. occidentalis were clumped with other species at the heavily used site compared to the lightly used site. This could possibly be attributed to the fact that intense browsing pressure at the heavily used site caused protective clumps to be eaten away, thus exposing G. occidentalis to higher ungulate browsing. Previous studies have found that nurse shrubs protect G. occidentalis against ungulate browsing. G. occidentalis was browsed significantly more at the heavily used site compared to the lightly used site. There was a general trend of fewer fruits at the heavily used site compared to the lightly used site, while fruits were absent on G. occidentalis growing alone at the heavily used site. This suggests a negative effect of heavy browsing on plant reproductive success and emphasizes the importance of nurse plants for the successful recruitment and hence long term prevalence of G. occidentalis in Mosaic Thicket.
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- Date Issued: 2010