Release success of captive bred Cape Vultures (Gyps coprotheres) in the Magaliesberg Mountains, South Africa
- Authors: Hirschauer, Maggie
- Date: 2017
- Subjects: Vultures -- South Africa -- Magaliesburg , Vultures -- South Africa -- Behavior
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/4743 , vital:20720
- Description: The Cape Vulture, Gyps coprotheres, is currently classified as ‘endangered’. Endemic to southern Africa, its population has declined continuously over the past 40 years. The species is facing multiple anthropogenic threats. Notably, birds frequently collide with power lines and some cannot be released after treatment. This has led to the establishment of a captive breeding population with the hope that captive bred young can supplement wild populations and re-establish a now- abandoned breeding colony in the Magaliesberg Mountains, South Africa. This study aimed to follow the breeding behaviours of the captive colony and assess the appropriateness of chick rearing conditions. The study also aimed to monitor the behaviour, physical condition and dispersal of ten captive bred vultures after release in relation to their age. Behavioural observations of captive adult breeding and parental behaviours were conducted to establish whether chicks developed under comparable conditions to wild chicks. A high percentage of total colony copulation attempts (22 %) were extra-pair copulations. Four paired males formed ephemeral extra-pair relationships, two of which were homosexual. Chicks fledged earlier than wild chicks, on average at 128 days old. Wild and captive bred birds were observed at carcasses to compare competitive and feeding behaviours. Older birds, both wild and captive, fed the most efficiently. Preliminary evidence suggests females are more dominant and have higher display rates than males. Captive bred juvenile and four year old birds’ competitive and feeding behaviours (interaction rate, feeding rate, display rate, dominance, aggressiveness, and feeding efficiency) were the closest to, but still generally below, average values for same-aged wild birds. An index of body condition, body mass, and the prevalence of fault bars on the rectrices were used to assess their physical condition. After eight months, none of the ten birds had moved more than 8 km from the release site, nor had they foraged away from the vulture restaurant on site. Although altitude records of > 3100 m were recorded, their flight skills seemed inadequate. Future management considerations include the initiation of a pre-release exercise regime, the establishment of an acclimatization enclosure removed from the breeding site, and a varied or reduced post-release feeding schedule. Fledglings should be relocated and housed at the release enclosure until they are four years old.
- Full Text:
- Authors: Hirschauer, Maggie
- Date: 2017
- Subjects: Vultures -- South Africa -- Magaliesburg , Vultures -- South Africa -- Behavior
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/4743 , vital:20720
- Description: The Cape Vulture, Gyps coprotheres, is currently classified as ‘endangered’. Endemic to southern Africa, its population has declined continuously over the past 40 years. The species is facing multiple anthropogenic threats. Notably, birds frequently collide with power lines and some cannot be released after treatment. This has led to the establishment of a captive breeding population with the hope that captive bred young can supplement wild populations and re-establish a now- abandoned breeding colony in the Magaliesberg Mountains, South Africa. This study aimed to follow the breeding behaviours of the captive colony and assess the appropriateness of chick rearing conditions. The study also aimed to monitor the behaviour, physical condition and dispersal of ten captive bred vultures after release in relation to their age. Behavioural observations of captive adult breeding and parental behaviours were conducted to establish whether chicks developed under comparable conditions to wild chicks. A high percentage of total colony copulation attempts (22 %) were extra-pair copulations. Four paired males formed ephemeral extra-pair relationships, two of which were homosexual. Chicks fledged earlier than wild chicks, on average at 128 days old. Wild and captive bred birds were observed at carcasses to compare competitive and feeding behaviours. Older birds, both wild and captive, fed the most efficiently. Preliminary evidence suggests females are more dominant and have higher display rates than males. Captive bred juvenile and four year old birds’ competitive and feeding behaviours (interaction rate, feeding rate, display rate, dominance, aggressiveness, and feeding efficiency) were the closest to, but still generally below, average values for same-aged wild birds. An index of body condition, body mass, and the prevalence of fault bars on the rectrices were used to assess their physical condition. After eight months, none of the ten birds had moved more than 8 km from the release site, nor had they foraged away from the vulture restaurant on site. Although altitude records of > 3100 m were recorded, their flight skills seemed inadequate. Future management considerations include the initiation of a pre-release exercise regime, the establishment of an acclimatization enclosure removed from the breeding site, and a varied or reduced post-release feeding schedule. Fledglings should be relocated and housed at the release enclosure until they are four years old.
- Full Text:
The trophic ecology of waterbirds in a small temperate estuary: a stable isotope and lipid tracer approach
- Authors: Hean, Jeffrey William
- Date: 2016
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/54356 , vital:26557
- Description: Waterbirds are often overlooked as predators in aquatic ecosystems, despite the fact that waterbirds congregate in great numbers in and around waterways, notably estuaries. To fully appreciate the effect that aquatic feeding waterbird species may have on aquatic prey communities and the role that they play in estuarine food webs, stable isotopes and fatty acid profiles were employed to examine the seasonal diet of selected waterbirds in the Kowie Estuary, Eastern Cape Province, South Africa. Population counts were conducted every month for four seasons to examine the demography of waterbirds in the lower reaches of the estuary. The mean monthly energy consumption, along with dry matter intake of all waterbird species observed, were calculated and compared to similar estuaries in South Africa and elsewhere. Three duck species, one migrant sandpiper and one piscivore were selected for more detailed investigation at several temporal scales. This thesis has revealed that stable isotope analysis of waterbird tissues provides more informative data than fatty acid analysis for investigating waterbird diet and basal resource-tertiary consumer nutrient coupling. Stable δ15N and δ13C isotopes from several body tissues, in conjunction with SIAR models, were used to determine the seasonal diet of each waterbird species, while fatty acid profiles were investigated to examine the trophic transfer of fatty acids from basal resources to waterbird predators via the benthic fauna. Stable isotopes revealed that Cape Shoveller, Cape Teal and Yellow-Billed Duck shifted their diet over both long and short temporal scales, while the migratory Ruff and piscivorous Little Egret maintained a relatively consistent diet over time. Isopods, amphipods, copepods and Mysidacea were the main foods of all three duck species and the Ruff (>30%). Little Egret fed mainly on flathead mullet throughout the year. Fatty acid analysis revealed evidence for trophic transfer of specific fatty acids from basal resources to waterbirds in the Kowie Estuary but provided little information on seasonal diet of waterbirds. Waterbirds foraging in the Kowie Estuary appeared to shift their diet to coincide with resource abundance pulses, but also displayed seasonal dietary overlap. This study highlights the role that waterbirds play in aquatic food webs. The subject requires more attention so that we can better understand all the predatory drivers on aquatic communities.
- Full Text:
- Authors: Hean, Jeffrey William
- Date: 2016
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/54356 , vital:26557
- Description: Waterbirds are often overlooked as predators in aquatic ecosystems, despite the fact that waterbirds congregate in great numbers in and around waterways, notably estuaries. To fully appreciate the effect that aquatic feeding waterbird species may have on aquatic prey communities and the role that they play in estuarine food webs, stable isotopes and fatty acid profiles were employed to examine the seasonal diet of selected waterbirds in the Kowie Estuary, Eastern Cape Province, South Africa. Population counts were conducted every month for four seasons to examine the demography of waterbirds in the lower reaches of the estuary. The mean monthly energy consumption, along with dry matter intake of all waterbird species observed, were calculated and compared to similar estuaries in South Africa and elsewhere. Three duck species, one migrant sandpiper and one piscivore were selected for more detailed investigation at several temporal scales. This thesis has revealed that stable isotope analysis of waterbird tissues provides more informative data than fatty acid analysis for investigating waterbird diet and basal resource-tertiary consumer nutrient coupling. Stable δ15N and δ13C isotopes from several body tissues, in conjunction with SIAR models, were used to determine the seasonal diet of each waterbird species, while fatty acid profiles were investigated to examine the trophic transfer of fatty acids from basal resources to waterbird predators via the benthic fauna. Stable isotopes revealed that Cape Shoveller, Cape Teal and Yellow-Billed Duck shifted their diet over both long and short temporal scales, while the migratory Ruff and piscivorous Little Egret maintained a relatively consistent diet over time. Isopods, amphipods, copepods and Mysidacea were the main foods of all three duck species and the Ruff (>30%). Little Egret fed mainly on flathead mullet throughout the year. Fatty acid analysis revealed evidence for trophic transfer of specific fatty acids from basal resources to waterbirds in the Kowie Estuary but provided little information on seasonal diet of waterbirds. Waterbirds foraging in the Kowie Estuary appeared to shift their diet to coincide with resource abundance pulses, but also displayed seasonal dietary overlap. This study highlights the role that waterbirds play in aquatic food webs. The subject requires more attention so that we can better understand all the predatory drivers on aquatic communities.
- Full Text:
A flight of fancy in the Chorister Robin-Chat (Cossypha dichroa) : an isotopic standpoint
- Wolmarans, Milena Helena Louise
- Authors: Wolmarans, Milena Helena Louise
- Date: 2015
- Subjects: Muscicapidae -- South Africa , Muscicapidae -- Food , Muscicapidae -- Habitat , Muscicapidae -- Habitat -- Conservation , Forest birds -- South Africa , Isotopes , Stable isotope tracers
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5920 , http://hdl.handle.net/10962/d1017207
- Description: Forested areas have been cited for their highly diverse floral and faunal assemblages, which are currently under threat from anthropogenic activities that restrict their range and deplete the resources produced within these naturally fragmented patches. Historically, up to 67 percent of avifaunal species associated with well-treed areas have undergone localised extinctions, consequentially affecting biodiversity as a measure of species richness and ecosystem functionality. To date, more than 900 of the bird species affiliated with forests are under threat and despite the theory surrounding functional redundancy, the mass extinction that is currently underway poses considerable limitations on the ecological integrity of these biomes. In South Africa, indigenous forest (one of the rarest biomes), occurs predominantly in small isolated patches along the eastern escarpment. With mountainous terrain emphasised as ‘prominent hotspots of extinction’, the limited dispersal and habitat sensitivity of montane forest fauna renders these species more prone to localised extinctions. BirdLife International, the IUCN and SABAP2 all indicate reductions in the range and abundance of the Chorister Robin-Chat (Cossypha dichroa) - an endemic forest specialist that is reported to move seasonally between high-altitude forest patches where they breed in summer, and lowland coastal forests where they overwinter. Beyond diet, body morphology and vocalisations, much of the information available on the altitudinal movements of C. dichroa is based on secondary sources and the assumptions therein. This study aimed to investigate the potential utilisation of δ13C and δ15N stable isotopes in determining the dietary niche width and altitudinal movements of C. dichroa. Feathers obtained in forested patches of the Limpopo, KwaZulu-Natal and Eastern Cape provinces exhibited a wide trophic niche width and generalised diet. Strong regional separation is apparent in the isotopic signatures suggesting little movement between provinces. A comparison of 13C-isotopes showed minimal variation that point to a uniformity in the carbon-base utilised by C. dichroa across their range. The 15N-signatures obtained in Limpopo, however, revealed a distinct trophic segregation between the northern-most Chorister populations and their southern counterparts. No altitudinal movements were detected in the isotopic signatures of recaptured Choristers, but more research is needed to investigate the long-term accuracy of these results and the breeding potential of resident Choristers in lowland coastal forests; especially when considering the reduced range and abundance reported for this endemic species.
- Full Text:
- Authors: Wolmarans, Milena Helena Louise
- Date: 2015
- Subjects: Muscicapidae -- South Africa , Muscicapidae -- Food , Muscicapidae -- Habitat , Muscicapidae -- Habitat -- Conservation , Forest birds -- South Africa , Isotopes , Stable isotope tracers
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5920 , http://hdl.handle.net/10962/d1017207
- Description: Forested areas have been cited for their highly diverse floral and faunal assemblages, which are currently under threat from anthropogenic activities that restrict their range and deplete the resources produced within these naturally fragmented patches. Historically, up to 67 percent of avifaunal species associated with well-treed areas have undergone localised extinctions, consequentially affecting biodiversity as a measure of species richness and ecosystem functionality. To date, more than 900 of the bird species affiliated with forests are under threat and despite the theory surrounding functional redundancy, the mass extinction that is currently underway poses considerable limitations on the ecological integrity of these biomes. In South Africa, indigenous forest (one of the rarest biomes), occurs predominantly in small isolated patches along the eastern escarpment. With mountainous terrain emphasised as ‘prominent hotspots of extinction’, the limited dispersal and habitat sensitivity of montane forest fauna renders these species more prone to localised extinctions. BirdLife International, the IUCN and SABAP2 all indicate reductions in the range and abundance of the Chorister Robin-Chat (Cossypha dichroa) - an endemic forest specialist that is reported to move seasonally between high-altitude forest patches where they breed in summer, and lowland coastal forests where they overwinter. Beyond diet, body morphology and vocalisations, much of the information available on the altitudinal movements of C. dichroa is based on secondary sources and the assumptions therein. This study aimed to investigate the potential utilisation of δ13C and δ15N stable isotopes in determining the dietary niche width and altitudinal movements of C. dichroa. Feathers obtained in forested patches of the Limpopo, KwaZulu-Natal and Eastern Cape provinces exhibited a wide trophic niche width and generalised diet. Strong regional separation is apparent in the isotopic signatures suggesting little movement between provinces. A comparison of 13C-isotopes showed minimal variation that point to a uniformity in the carbon-base utilised by C. dichroa across their range. The 15N-signatures obtained in Limpopo, however, revealed a distinct trophic segregation between the northern-most Chorister populations and their southern counterparts. No altitudinal movements were detected in the isotopic signatures of recaptured Choristers, but more research is needed to investigate the long-term accuracy of these results and the breeding potential of resident Choristers in lowland coastal forests; especially when considering the reduced range and abundance reported for this endemic species.
- Full Text:
Dietary aspects of establishing a mainland-based colony of the endangered African Penguin (Spheniscus demersus) in St Francis Bay, South Africa
- Authors: Voogt, Nina Margaret
- Date: 2014
- Subjects: African penguin -- South Africa -- Cape Saint Francis , African penguin -- Food -- South Africa -- Algoa Bay , African penguin -- Habitat suitability index models -- South Africa -- Cape Saint Francis , Stable isotopes
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5875 , http://hdl.handle.net/10962/d1013115
- Description: Cape St Francis, Eastern Cape, has been identified as one of four potential sites for establishing a mainland-based African penguin (Spheniscus demersus) colony. This thesis comprises three main components: a verification of a preparation method for stable isotope samples from penguin feathers; a dietary analysis of the penguins on Bird Island, Algoa Bay, though stable isotope analysis of whole blood and feathers (2012 and 2013); and an estimation of available fish surplus that could potentially support a colony of penguins at Cape St Francis. Each component contributes towards the next, all building towards answering the main research question: Will there be enough food around St Francis Bay to support a colony of penguins and sustain the already established fisheries industry within the bay? Stable isotope analysis of whole blood and feathers from breeding adults and whole blood from juveniles provided insight into the variability of African penguins’ diets at different stages in their life history. Stable isotope mixing models indicated that the predicted proportions that each prey species could potentially contribute to diet conflicted with published stomach sample data. This might arise from inaccurate trophic enrichment factors used in the model, or from systematic biases in the published stomach sampling techniques, or both. Dietary sexual dimorphism was not demonstrated by the isotope signatures of breeding penguins. Based on official catch data, the fisheries activity on the south coast, and especially around the potential colony site at St Francis, is much lower than around the west coast’s penguin colonies. The model provided a first-order estimate for fish supply around the potential colony site at St Francis both at a large coastal scale and a local small scale. At both scales the estimate indicated an ample availability of fish at current fishing levels. The model in Chapter 4 can also be applied to refining the assessments of other potential colony sites on the south coast. In conclusion, the south coast is a promising area for a new colony of penguins in terms of food availability. There is relatively low fishing activity in the area and, as suggested by the large-scale model in Chapter 4, an ample fish resource. The final chapter briefly discusses factors that need to be considered before attempting to establish a mainland-based colony of African penguins.
- Full Text:
- Authors: Voogt, Nina Margaret
- Date: 2014
- Subjects: African penguin -- South Africa -- Cape Saint Francis , African penguin -- Food -- South Africa -- Algoa Bay , African penguin -- Habitat suitability index models -- South Africa -- Cape Saint Francis , Stable isotopes
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5875 , http://hdl.handle.net/10962/d1013115
- Description: Cape St Francis, Eastern Cape, has been identified as one of four potential sites for establishing a mainland-based African penguin (Spheniscus demersus) colony. This thesis comprises three main components: a verification of a preparation method for stable isotope samples from penguin feathers; a dietary analysis of the penguins on Bird Island, Algoa Bay, though stable isotope analysis of whole blood and feathers (2012 and 2013); and an estimation of available fish surplus that could potentially support a colony of penguins at Cape St Francis. Each component contributes towards the next, all building towards answering the main research question: Will there be enough food around St Francis Bay to support a colony of penguins and sustain the already established fisheries industry within the bay? Stable isotope analysis of whole blood and feathers from breeding adults and whole blood from juveniles provided insight into the variability of African penguins’ diets at different stages in their life history. Stable isotope mixing models indicated that the predicted proportions that each prey species could potentially contribute to diet conflicted with published stomach sample data. This might arise from inaccurate trophic enrichment factors used in the model, or from systematic biases in the published stomach sampling techniques, or both. Dietary sexual dimorphism was not demonstrated by the isotope signatures of breeding penguins. Based on official catch data, the fisheries activity on the south coast, and especially around the potential colony site at St Francis, is much lower than around the west coast’s penguin colonies. The model provided a first-order estimate for fish supply around the potential colony site at St Francis both at a large coastal scale and a local small scale. At both scales the estimate indicated an ample availability of fish at current fishing levels. The model in Chapter 4 can also be applied to refining the assessments of other potential colony sites on the south coast. In conclusion, the south coast is a promising area for a new colony of penguins in terms of food availability. There is relatively low fishing activity in the area and, as suggested by the large-scale model in Chapter 4, an ample fish resource. The final chapter briefly discusses factors that need to be considered before attempting to establish a mainland-based colony of African penguins.
- Full Text:
Quantifying crop damage by Grey crowned crane balearica regulorum regulorum and evaluating changes in crane distribution in the North Eastern Cape, South Africa
- Authors: Van Niekerk, Mark Harry
- Date: 2011
- Subjects: Cranes (Birds) -- South Africa -- Eastern Cape , Cranes (Birds) -- Geographical distribution -- South Africa -- Eastern Cape , Cranes (Birds) -- Behavior -- South Africa -- Eastern Cape , Cranes (Birds) -- Food -- South Africa -- Eastern Cape , Corn -- Effect of grazing on -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5749 , http://hdl.handle.net/10962/d1005436 , Cranes (Birds) -- South Africa -- Eastern Cape , Cranes (Birds) -- Geographical distribution -- South Africa -- Eastern Cape , Cranes (Birds) -- Behavior -- South Africa -- Eastern Cape , Cranes (Birds) -- Food -- South Africa -- Eastern Cape , Corn -- Effect of grazing on -- South Africa -- Eastern Cape
- Description: Complaints of crop damage by cranes on planted maize in the North Eastern Cape, South Africa, have been increasing since the mid-1990‘s, and in some instances severe losses have been reported. Crop damage by the Grey Crowned Crane Balearica regulorum regulorum near the town of Maclear (31º04´S 28º22´E), has been quantified over two growing seasons, and assessed relative to losses caused by foraging Cape Crows Corvus capensis and other feeding damage assumed to be caused by insects. Twelve fields were selected based on previous patterns of crop depredation. Maize seed in seven of the fields was treated with the chemical ‗Gaucho‘ and five fields were planted with untreated maize. In order to determine the source of losses, twenty quadrats (4 m x 4 m) randomly distributed within each field were visited on average every second day, for a period of up to twenty eight days. Results indicate that seed treatments do act as a deterrent to feeding by both cranes and crows, however crane damage is generally insignificant compared to other sources of damage. My study also reviewed past sightings data of the Grey Crowned Crane in an effort to determine if the conversion of former grassland to plantations in this region may have increased foraging activity in maize fields. The data did not allow for clear-cut conclusions regarding changes in distribution or population trends. Conclusions provide direct input into the management of agricultural areas by enabling landowners to take steps to mitigate crop damage. These mitigation measures may either involve the application of seed treatments, or the planting of low risk crops in high risk areas. Future studies should consider the ppossible detrimental effects of chemical seed treatments on crane biology.
- Full Text:
- Authors: Van Niekerk, Mark Harry
- Date: 2011
- Subjects: Cranes (Birds) -- South Africa -- Eastern Cape , Cranes (Birds) -- Geographical distribution -- South Africa -- Eastern Cape , Cranes (Birds) -- Behavior -- South Africa -- Eastern Cape , Cranes (Birds) -- Food -- South Africa -- Eastern Cape , Corn -- Effect of grazing on -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5749 , http://hdl.handle.net/10962/d1005436 , Cranes (Birds) -- South Africa -- Eastern Cape , Cranes (Birds) -- Geographical distribution -- South Africa -- Eastern Cape , Cranes (Birds) -- Behavior -- South Africa -- Eastern Cape , Cranes (Birds) -- Food -- South Africa -- Eastern Cape , Corn -- Effect of grazing on -- South Africa -- Eastern Cape
- Description: Complaints of crop damage by cranes on planted maize in the North Eastern Cape, South Africa, have been increasing since the mid-1990‘s, and in some instances severe losses have been reported. Crop damage by the Grey Crowned Crane Balearica regulorum regulorum near the town of Maclear (31º04´S 28º22´E), has been quantified over two growing seasons, and assessed relative to losses caused by foraging Cape Crows Corvus capensis and other feeding damage assumed to be caused by insects. Twelve fields were selected based on previous patterns of crop depredation. Maize seed in seven of the fields was treated with the chemical ‗Gaucho‘ and five fields were planted with untreated maize. In order to determine the source of losses, twenty quadrats (4 m x 4 m) randomly distributed within each field were visited on average every second day, for a period of up to twenty eight days. Results indicate that seed treatments do act as a deterrent to feeding by both cranes and crows, however crane damage is generally insignificant compared to other sources of damage. My study also reviewed past sightings data of the Grey Crowned Crane in an effort to determine if the conversion of former grassland to plantations in this region may have increased foraging activity in maize fields. The data did not allow for clear-cut conclusions regarding changes in distribution or population trends. Conclusions provide direct input into the management of agricultural areas by enabling landowners to take steps to mitigate crop damage. These mitigation measures may either involve the application of seed treatments, or the planting of low risk crops in high risk areas. Future studies should consider the ppossible detrimental effects of chemical seed treatments on crane biology.
- Full Text:
The ecology and conservation of Mackinder's eagle owls (Bubo capensis mackinderi) in central Kenya in relation to agricultural land-use and cultural attitudes
- Authors: Ogada, Darcy L
- Date: 2008
- Subjects: Cape eagle owl -- Kenya Cape eagle owl -- Habitat -- Kenya Cape eagle owl -- Breeding -- Kenya Cape eagle owl -- Nutrition -- Kenya Bubo -- Kenya Wildlife conservation -- Kenya Biodiversity conservation -- Kenya
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5668 , http://hdl.handle.net/10962/d1005353
- Description: The loss of habitat to agriculture is a worldwide problem for biodiversity conservation. One species that has seemingly been able to adapt to the conversion of forests to farmlands is Mackinder’s eagle owl (Bubo capensis mackinderi), which inhabits highland areas, but little is known of its ecology, especially outside of protected areas. This study examined the impact of agricultural practices and farmer’s attitudes on the foraging and population ecology of the Mackinder’s eagle owl in central Kenya. Owl territories were monitored monthly from June 2004- October 2006 for signs of occupancy, breeding activity, mortality and to collect data on food resources. Nest site characteristics were measured for all known nests. Because previous studies showed an affinity for rodents, small mammals were trapped monthly using mark-recapture methodology. In each territory, the type and amount of farm crops were measured each month and farmers were interviewed about their knowledge and beliefs about owls. Mackinder’s eagle owls in central Kenya lived at extremely high density 0.87 owl pairs/km². This density was high compared to other populations of Mackinder’s eagle owl and to Eurasian eagle owl (Bubo bubo) populations in Europe. Breeding success was 48% over three years and this compared well with other species of eagle owl inhabiting human-disturbed areas. All nests and roosts were located in river valleys, and all successful nest sites were located on cliffs or other inaccessible rocky terrain. Nest sites were located adjacent to farms, which provided for both open hunting and an abundance of prey. Breeding activity was concentrated after the rainy seasons and this was likely linked to prey availability after the rains. Agricultural activities generally had a positive effect on rodent populations. Small mammal trapping results revealed that rodents were over 14 times more abundant in farms than in adjacent grassland habitat. This population of Mackinder’s eagle owl had a very catholic diet and consumed mostly mammalian prey species including hares, giant rats, root rats, grooved-tooth rats and small rodents. Small rodents accounted for almost half of the owls’ diet and when their numbers increased, owls responded by consuming more of them, indicating the importance of farming activities to this population of owls. Other populations of eagle owl inhabiting human-disturbed areas had diet widths positively related to levels of habitat disturbance. This result supported optimal foraging theory that more productive environments have predators with more specialized diets, while patchy environments have generalist predators. The ecology of this population of Mackinder’s eagle owls was heavily influenced by human agricultural activities, which generally had a positive effect on their population. Farming activities changed rapidly both within and between seasons as plots were small and neighbouring farmers planted various crops at different times of the year and this was enhanced by irrigation in some areas. Year-round availability of forage within farms had a positive effect on owl prey species, some of which increased relative to the type and amount of crops found in farms. However, 57% of owl injuries and mortalities that occurred were related either directly or indirectly to human activities. Cultural prejudices against owls remain the biggest threat to this population’s long-term persistence. Farmer education was shown to play a significant role in overcoming negative beliefs about owls. Because Mackinder’s eagle owls are highly adaptable to anthropomorphic landscape changes, largely due to their adaptability as food generalists, they are one of the few top predators remaining in this highly disturbed agricultural system. However, populations within agricultural areas remain especially vulnerable to negative human attitudes towards owls due to their close association with human activities.
- Full Text:
- Authors: Ogada, Darcy L
- Date: 2008
- Subjects: Cape eagle owl -- Kenya Cape eagle owl -- Habitat -- Kenya Cape eagle owl -- Breeding -- Kenya Cape eagle owl -- Nutrition -- Kenya Bubo -- Kenya Wildlife conservation -- Kenya Biodiversity conservation -- Kenya
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5668 , http://hdl.handle.net/10962/d1005353
- Description: The loss of habitat to agriculture is a worldwide problem for biodiversity conservation. One species that has seemingly been able to adapt to the conversion of forests to farmlands is Mackinder’s eagle owl (Bubo capensis mackinderi), which inhabits highland areas, but little is known of its ecology, especially outside of protected areas. This study examined the impact of agricultural practices and farmer’s attitudes on the foraging and population ecology of the Mackinder’s eagle owl in central Kenya. Owl territories were monitored monthly from June 2004- October 2006 for signs of occupancy, breeding activity, mortality and to collect data on food resources. Nest site characteristics were measured for all known nests. Because previous studies showed an affinity for rodents, small mammals were trapped monthly using mark-recapture methodology. In each territory, the type and amount of farm crops were measured each month and farmers were interviewed about their knowledge and beliefs about owls. Mackinder’s eagle owls in central Kenya lived at extremely high density 0.87 owl pairs/km². This density was high compared to other populations of Mackinder’s eagle owl and to Eurasian eagle owl (Bubo bubo) populations in Europe. Breeding success was 48% over three years and this compared well with other species of eagle owl inhabiting human-disturbed areas. All nests and roosts were located in river valleys, and all successful nest sites were located on cliffs or other inaccessible rocky terrain. Nest sites were located adjacent to farms, which provided for both open hunting and an abundance of prey. Breeding activity was concentrated after the rainy seasons and this was likely linked to prey availability after the rains. Agricultural activities generally had a positive effect on rodent populations. Small mammal trapping results revealed that rodents were over 14 times more abundant in farms than in adjacent grassland habitat. This population of Mackinder’s eagle owl had a very catholic diet and consumed mostly mammalian prey species including hares, giant rats, root rats, grooved-tooth rats and small rodents. Small rodents accounted for almost half of the owls’ diet and when their numbers increased, owls responded by consuming more of them, indicating the importance of farming activities to this population of owls. Other populations of eagle owl inhabiting human-disturbed areas had diet widths positively related to levels of habitat disturbance. This result supported optimal foraging theory that more productive environments have predators with more specialized diets, while patchy environments have generalist predators. The ecology of this population of Mackinder’s eagle owls was heavily influenced by human agricultural activities, which generally had a positive effect on their population. Farming activities changed rapidly both within and between seasons as plots were small and neighbouring farmers planted various crops at different times of the year and this was enhanced by irrigation in some areas. Year-round availability of forage within farms had a positive effect on owl prey species, some of which increased relative to the type and amount of crops found in farms. However, 57% of owl injuries and mortalities that occurred were related either directly or indirectly to human activities. Cultural prejudices against owls remain the biggest threat to this population’s long-term persistence. Farmer education was shown to play a significant role in overcoming negative beliefs about owls. Because Mackinder’s eagle owls are highly adaptable to anthropomorphic landscape changes, largely due to their adaptability as food generalists, they are one of the few top predators remaining in this highly disturbed agricultural system. However, populations within agricultural areas remain especially vulnerable to negative human attitudes towards owls due to their close association with human activities.
- Full Text:
The biology of suburban olive thrushes (Turdus olivaceus olivaceus) in the Eastern Cape, South Africa
- Authors: Bonnevie, Bo Tørris
- Date: 2005
- Subjects: Thrushes , Turdus , Thrushes -- South Africa -- Eastern Cape , Turdus -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5651 , http://hdl.handle.net/10962/d1005333 , Thrushes , Turdus , Thrushes -- South Africa -- Eastern Cape , Turdus -- South Africa -- Eastern Cape
- Description: This study investigated the biology of the Olive Thrush Turdus olivaceus olivaceus in Grahamstown, South Africa from 1998 to 2003. Behavioural differences between males and females, parent-young interactions, development of fledglings, and the role of song and moult in territorial behaviour were investigated. Comparisons of biometrics, moult and survival were made using Olive Thrush ringing data from other regions. There were no significant differences in mass, wing length or survival rate between the Eastern and Western Cape provinces, but primary wing moult started earlier in the Western Cape and coincided with the end of the main breeding periods in both provinces. Both males and females of breeding pairs remained in and defended their territories throughout the year, but there was some evidence that territorial defence was strongest during the breeding periods. Roughly, every 100 eggs laid produce 50 fledglings. Out of these 20 to 30 reach the age of independence at approximately 50 days, and only five of these juvenile birds reach maturity. Adult survival was estimated at 80%, with a mean life expectancy of 4.5 years and a conservative estimate of maximum lifespan of 11 years. Using ringing data and museum specimens, the Olive Thrush was compared with the Karoo Thrush Turdus smithi, a former race of the Olive Thrush. Olive Thrushes had shorter bills and wings, but were heavier than Karoo Thrushes from the Cradock district. There were also differences in bill and eye-ring colouration between these populations. No morphological differences were found between the sexes in either species.
- Full Text:
- Authors: Bonnevie, Bo Tørris
- Date: 2005
- Subjects: Thrushes , Turdus , Thrushes -- South Africa -- Eastern Cape , Turdus -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5651 , http://hdl.handle.net/10962/d1005333 , Thrushes , Turdus , Thrushes -- South Africa -- Eastern Cape , Turdus -- South Africa -- Eastern Cape
- Description: This study investigated the biology of the Olive Thrush Turdus olivaceus olivaceus in Grahamstown, South Africa from 1998 to 2003. Behavioural differences between males and females, parent-young interactions, development of fledglings, and the role of song and moult in territorial behaviour were investigated. Comparisons of biometrics, moult and survival were made using Olive Thrush ringing data from other regions. There were no significant differences in mass, wing length or survival rate between the Eastern and Western Cape provinces, but primary wing moult started earlier in the Western Cape and coincided with the end of the main breeding periods in both provinces. Both males and females of breeding pairs remained in and defended their territories throughout the year, but there was some evidence that territorial defence was strongest during the breeding periods. Roughly, every 100 eggs laid produce 50 fledglings. Out of these 20 to 30 reach the age of independence at approximately 50 days, and only five of these juvenile birds reach maturity. Adult survival was estimated at 80%, with a mean life expectancy of 4.5 years and a conservative estimate of maximum lifespan of 11 years. Using ringing data and museum specimens, the Olive Thrush was compared with the Karoo Thrush Turdus smithi, a former race of the Olive Thrush. Olive Thrushes had shorter bills and wings, but were heavier than Karoo Thrushes from the Cradock district. There were also differences in bill and eye-ring colouration between these populations. No morphological differences were found between the sexes in either species.
- Full Text:
The ecology of the red-billed quelea Quelea Quelea (Linnaeus) and other granivorous birds at Eastern Cape feedlots
- Whittington-Jones, Craig Alun
- Authors: Whittington-Jones, Craig Alun
- Date: 2002
- Subjects: Quelea quelea -- South Africa -- Eastern Cape Granivores -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5618 , http://hdl.handle.net/10962/d1003286
- Description: Red-billed Quelea Quelea quelea have expanded their range in the Eastern Cape and now occur throughout the year in new areas. Recent changes in agricultural practice have probably been a contributing factor as flocks are larger than previously recorded and were more often associated with artificial food sources than natural grasses. Ringing and census data indicate that quelea have reduced movements during the non-breeding season and may display strong fidelity (over successive years) to dry season quarters with reliable food supplies. Although the recapture/recovery rate for quelea in the Eastern Cape (1.0-2.5%) was higher than the national average, it was still lower than expected and there may be considerable movement between nearby feeding sites. Some quelea breed locally, but most disperse during summer and their numbers at the feedlots were generally highest in winter and spring. The breeding season of quelea is later than other ploceids in the region and post-nuptial moult overlaps with winter. Replacement of primary wing feathers is relatively slow (124 days), and this is considered an adaptation to minimise disruption of flight capabilities and insulation. Significantly more quelea in the Eastern Cape have breeding plumage suffused with pink than in other southern African populations. However, during the non-breeding season there is apparently considerable intermixing between local populations and those from further north and the existence of a local sub-species is not supported. Seeds of two grass species, Echinochloa sp. and Urochloa panicoides, and two weed species, Amaranthus sp. and Chenopodium sp., were important in the diet of both quelea and Laughing Doves Streptopelia senegalensis. Maize comprised a large proportion of the diet of these species and losses at one ostrich feedlot were estimated at over R 17 000 in two years. Dependence on artificial food sources was generally greatest in winter and spring, but economically significant damage was not confined to this period. Alpha-chloralose showed good potential for reducing numbers of problem birds at livestock feedlots. However, the dynamic nature of problem bird populations favours a non-lethal management approach. Reduction of feed loss through manipulation of the ostrich ration could provide a relatively cheap and effective alternative to lethal control if applied appropriately.
- Full Text:
- Authors: Whittington-Jones, Craig Alun
- Date: 2002
- Subjects: Quelea quelea -- South Africa -- Eastern Cape Granivores -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5618 , http://hdl.handle.net/10962/d1003286
- Description: Red-billed Quelea Quelea quelea have expanded their range in the Eastern Cape and now occur throughout the year in new areas. Recent changes in agricultural practice have probably been a contributing factor as flocks are larger than previously recorded and were more often associated with artificial food sources than natural grasses. Ringing and census data indicate that quelea have reduced movements during the non-breeding season and may display strong fidelity (over successive years) to dry season quarters with reliable food supplies. Although the recapture/recovery rate for quelea in the Eastern Cape (1.0-2.5%) was higher than the national average, it was still lower than expected and there may be considerable movement between nearby feeding sites. Some quelea breed locally, but most disperse during summer and their numbers at the feedlots were generally highest in winter and spring. The breeding season of quelea is later than other ploceids in the region and post-nuptial moult overlaps with winter. Replacement of primary wing feathers is relatively slow (124 days), and this is considered an adaptation to minimise disruption of flight capabilities and insulation. Significantly more quelea in the Eastern Cape have breeding plumage suffused with pink than in other southern African populations. However, during the non-breeding season there is apparently considerable intermixing between local populations and those from further north and the existence of a local sub-species is not supported. Seeds of two grass species, Echinochloa sp. and Urochloa panicoides, and two weed species, Amaranthus sp. and Chenopodium sp., were important in the diet of both quelea and Laughing Doves Streptopelia senegalensis. Maize comprised a large proportion of the diet of these species and losses at one ostrich feedlot were estimated at over R 17 000 in two years. Dependence on artificial food sources was generally greatest in winter and spring, but economically significant damage was not confined to this period. Alpha-chloralose showed good potential for reducing numbers of problem birds at livestock feedlots. However, the dynamic nature of problem bird populations favours a non-lethal management approach. Reduction of feed loss through manipulation of the ostrich ration could provide a relatively cheap and effective alternative to lethal control if applied appropriately.
- Full Text:
Ecology and breeding biology of Lanner Falcons in the Eastern Cape Province, South Africa
- Authors: Stephenson, Alan
- Date: 2001
- Subjects: Birds -- Breeding , Birds -- South Africa -- Eastern Cape , Birds -- Ecology , Falcons -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5667 , http://hdl.handle.net/10962/d1005352 , Birds -- Breeding , Birds -- South Africa -- Eastern Cape , Birds -- Ecology , Falcons -- South Africa -- Eastern Cape
- Description: Lanner Falcons Falco biarmicus are the commonest large falcons in Africa and this study in the coastal area of the Eastern Cape Province, South Africa investigated their ecology from 1984 to 2000. Lanners have recently been categorised as near-threatened and this study was initiated to ascertain if the population was stable. Breeding success of a small population, in different habitat types, was monitored intensively from 1997 to 2000, and the factors that inhibited breeding were investigated. The earliest onset of incubation was 17 July and the latest 16 August, with 2.2 young fledged per breeding pair over the four-year period. Incubation lasted 32 days and young fledged after 42-45 days. All nest sites were on cliffs with a mean height of 114 m, a mean vertical face of 53 m; 45% of the nests were in ravens’ nests. The aspect of cliff sites also influenced breeding success. Radio tracking was used to determine home range, habitat use and hunting methods, with prey species identified. Home ranges were between 66 km² and 249 km². Preferred prey was domestic chickens, pigeons and small birds during the breeding season. Foraging ranges were smaller in intensively cultivated areas with seed crops. Data obtained from ringing returns showed that no long distance movements occurred in this region, but two juveniles dispersed 152 km and 127 km. Conservation aspects with possible threats to Lanner Falcons such as poisons, electrocutions and direct persecution are discussed with some recommendations made for future research. Evidence from this study indicates that Lanner breeding success is not limited by nest site availability, but by rainfall timing and prey availability. Lanners foraged more in open areas than areas with tall vegetation, and benefited from intensive agriculture. This population appeared to be healthy and in no danger of declining in the near future.
- Full Text:
- Authors: Stephenson, Alan
- Date: 2001
- Subjects: Birds -- Breeding , Birds -- South Africa -- Eastern Cape , Birds -- Ecology , Falcons -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5667 , http://hdl.handle.net/10962/d1005352 , Birds -- Breeding , Birds -- South Africa -- Eastern Cape , Birds -- Ecology , Falcons -- South Africa -- Eastern Cape
- Description: Lanner Falcons Falco biarmicus are the commonest large falcons in Africa and this study in the coastal area of the Eastern Cape Province, South Africa investigated their ecology from 1984 to 2000. Lanners have recently been categorised as near-threatened and this study was initiated to ascertain if the population was stable. Breeding success of a small population, in different habitat types, was monitored intensively from 1997 to 2000, and the factors that inhibited breeding were investigated. The earliest onset of incubation was 17 July and the latest 16 August, with 2.2 young fledged per breeding pair over the four-year period. Incubation lasted 32 days and young fledged after 42-45 days. All nest sites were on cliffs with a mean height of 114 m, a mean vertical face of 53 m; 45% of the nests were in ravens’ nests. The aspect of cliff sites also influenced breeding success. Radio tracking was used to determine home range, habitat use and hunting methods, with prey species identified. Home ranges were between 66 km² and 249 km². Preferred prey was domestic chickens, pigeons and small birds during the breeding season. Foraging ranges were smaller in intensively cultivated areas with seed crops. Data obtained from ringing returns showed that no long distance movements occurred in this region, but two juveniles dispersed 152 km and 127 km. Conservation aspects with possible threats to Lanner Falcons such as poisons, electrocutions and direct persecution are discussed with some recommendations made for future research. Evidence from this study indicates that Lanner breeding success is not limited by nest site availability, but by rainfall timing and prey availability. Lanners foraged more in open areas than areas with tall vegetation, and benefited from intensive agriculture. This population appeared to be healthy and in no danger of declining in the near future.
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Raptor communities in hill habitats in south-eastern Zimbabwe
- Authors: Davison, Bruce
- Date: 1998
- Subjects: Birds of prey -- Zimbabwe , Birds of prey -- Ecology -- Zimbabwe
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5751 , http://hdl.handle.net/10962/d1005438 , Birds of prey -- Zimbabwe , Birds of prey -- Ecology -- Zimbabwe
- Description: The interrelationships between species composition, resource-use and availability, breeding and competition were studied in two hill habitat raptor communities in a conserved reserve and an unprotected communal land in Zimbabwe in 1995 and 1996. The conserved Lonestar Study Area (LSA) and the unprotected Communal Land Study area (CLSA) had 38 and 31 raptor species, high and normal diversities for the area sizes respectively. An estimated 147 pairs of 21 raptor species bred in 40km² in the LSA compared to only 26 pairs of 22 raptor species per 40km² in the CLSA. Six species (African Hawk Eagle Hieraaetus spilogaster, Black Eagle Aquila verreauxii, Crowned Eagle Stephanoaetus coronatus, Little Banded Goshawk Accipiter badius, Barn Owl Tyto alba,and Barred Owl Glancidium capense made up 69% of breeding raptors in the LSA, while African Hawk Eagles, Little Banded Goshawks, Barn Owls and Barred Owls made up 58% of the breeding raptors in the CLSA. The abundance of Black, Crowned and African Hawk Eagles in the LSA was linked to abundant hyrax, Heterohyrax brucei and Procavia capensis and juvenile bushbuck Tragelaphus prey, and the high reproduction rates of Natal Francolin Francolinus natalensis (0.7 per ha when not breeding). Little Banded Goshawk and Barn Owl abundances were linked to their ability to change prey preferences according to prey availability. A fairly high rate of breeding attempts by eagles in the LSA in both years (60 - 76% of all pairs per year)was probably also linked to prey abundance, Most breeding failures were predator related, and were more common in areas of relatively low nesting densities indicating lower parental vigilance there. High eagle breeding densities were associated with small mean territory sizes in the LSA (7.7 - 10.7km² for the main eagle species). Eagles in the LSA usually nested closer to another eagle species than a conspecific, resulting in regular distributions of nests and no territory overlap within species. Differences in daily flight activity of eagles in both study areas, and in the onset of breeding between LSA eagles probably reduced interspecific aggression. Interspecific competition food and nest sites amongst LSA eagles was possibly lessened by slight ditferences in resource selection. Raptor resources were mostly unaffected by human activities in either study area during the study period. Differences in the raptor communities were probably as a result of natural habitat differences. The CLSA raptors potentially face resource loss through forest clearing and hunting. An expansion of the present CAMPFIRE program will protect the CLSA raptors.
- Full Text:
- Authors: Davison, Bruce
- Date: 1998
- Subjects: Birds of prey -- Zimbabwe , Birds of prey -- Ecology -- Zimbabwe
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5751 , http://hdl.handle.net/10962/d1005438 , Birds of prey -- Zimbabwe , Birds of prey -- Ecology -- Zimbabwe
- Description: The interrelationships between species composition, resource-use and availability, breeding and competition were studied in two hill habitat raptor communities in a conserved reserve and an unprotected communal land in Zimbabwe in 1995 and 1996. The conserved Lonestar Study Area (LSA) and the unprotected Communal Land Study area (CLSA) had 38 and 31 raptor species, high and normal diversities for the area sizes respectively. An estimated 147 pairs of 21 raptor species bred in 40km² in the LSA compared to only 26 pairs of 22 raptor species per 40km² in the CLSA. Six species (African Hawk Eagle Hieraaetus spilogaster, Black Eagle Aquila verreauxii, Crowned Eagle Stephanoaetus coronatus, Little Banded Goshawk Accipiter badius, Barn Owl Tyto alba,and Barred Owl Glancidium capense made up 69% of breeding raptors in the LSA, while African Hawk Eagles, Little Banded Goshawks, Barn Owls and Barred Owls made up 58% of the breeding raptors in the CLSA. The abundance of Black, Crowned and African Hawk Eagles in the LSA was linked to abundant hyrax, Heterohyrax brucei and Procavia capensis and juvenile bushbuck Tragelaphus prey, and the high reproduction rates of Natal Francolin Francolinus natalensis (0.7 per ha when not breeding). Little Banded Goshawk and Barn Owl abundances were linked to their ability to change prey preferences according to prey availability. A fairly high rate of breeding attempts by eagles in the LSA in both years (60 - 76% of all pairs per year)was probably also linked to prey abundance, Most breeding failures were predator related, and were more common in areas of relatively low nesting densities indicating lower parental vigilance there. High eagle breeding densities were associated with small mean territory sizes in the LSA (7.7 - 10.7km² for the main eagle species). Eagles in the LSA usually nested closer to another eagle species than a conspecific, resulting in regular distributions of nests and no territory overlap within species. Differences in daily flight activity of eagles in both study areas, and in the onset of breeding between LSA eagles probably reduced interspecific aggression. Interspecific competition food and nest sites amongst LSA eagles was possibly lessened by slight ditferences in resource selection. Raptor resources were mostly unaffected by human activities in either study area during the study period. Differences in the raptor communities were probably as a result of natural habitat differences. The CLSA raptors potentially face resource loss through forest clearing and hunting. An expansion of the present CAMPFIRE program will protect the CLSA raptors.
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A comparative study of the Grey-headed Sparrow (Passer griseus L) and the House Sparrow (Passer domesticus L) in Malawi
- Authors: Nhlane, Martin Edwin Darwin
- Date: 1997
- Subjects: English sparrow Sparrows
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5654 , http://hdl.handle.net/10962/d1005337
- Description: The House Sparrow Passer domesticus, an introduced species, and the Grey-headed Sparrow Passer griseus, an indigenous species, are sympatric in Malawi. Their distribution in the country and any possible interactions were studied, principally in southern Malawi. A morphological analysis of museum specimens confirmed that grey-headed sparrows in Malawi belong to the Northern Grey-headed Sparrow Passer griseus as distinct from the Southern Grey-headed Sparrow Passer diffusus. This species was widely distributed in the, country in association with human dwellings, both in rural areas as well as urban centres. In the northern region Greyheaded Sparrows were more abundant in the urban centres than rural areas, but in the central and southern regions numbers in the rural and urban areas were more or less the same. In Blantyre City, where they are in sympatry with the House Sparrow, they were found in the low density and industrial areas and were absent from the high density areas. The House Sparrow, arrived in Malawi in 1967 at Chileka in the southern region. Since then it has spread northwards, moving from the southern to the central and northern regions. House Sparrow numbers were found to be progressively larger in the southern region and lowest in the northern region. House Sparrows were found at sites where food was readily available, as in the immediate vicinity of houses. In the central and northern regions they were restricted mainly to urban areas. In the southern region, they occur both in rural and urban areas, probably as a reflection of the larger period of colonization in the south. In the northern region their movement has apparently been restricted by geographical barriers. In Blantyre City Grey-headed Sparrows preferred areas where tree density was high and house density was low, while House Sparrows preferred areas where house density was high and tree density was low. There was a positive correlation between Greyheaded Sparrow numbers and tree density and a negative correlation with house density. House Sparrow abundance was negatively correlated with tree density and positively correlated with house density. Grey-headed Sparrows bred in the rainy season, whereas House Sparrows bred throughout the year. There were differences in nest site selection: Grey-headed Sparrows used artificial structures such as fencing poles, and wooden telephone or electricity poles. The House Sparrow used mostly buildings and nested in crevices, holes in walls and between the walls and rafters. Nest height also differed- Grey-headed Sparrows nested at heights ranging from 1 - 8 m while House Sparrow nests were at heights of 1 - 5 m. Moult data suggests that although the House Sparrows breed throughout the year, they moult at a particular time of the year when breeding is less common. Grey-headed Sparrows were found to moult mainly from May to September in southern Africa and from June to September in central Africa. In both cases the breeding season extends over a similar period from about October to April/May of the following year. Peak moult periods differed between the House Sparrows and Grey-headed Sparrows. House Sparrows moulted mainly in the first half of the year, and Greyheaded Sparrows in the second six months. The clutch sizes of the two species were similar (mean 3.9 eggs for the House Sparrow and 3.4 for the Grey-headed Sparrow). The clutch size of the House Sparrow varied seasonally and was larger from November to May. The average incubation period for the House Sparrow was 11.5 days and the fledging period 15.4 days. The Grey-headed Sparrow fledging period was 14.7 days. Chick mortality of the House Sparrow at Chikunda farm was attributed to starvation resulting from brood reduction, abandonment, predation, low birth weight, accidental deaths and parasitism by fly larvae. Both Grey-headed and House Sparrows fed their young on insect food. Male House Sparrows fed actively initially, but their contribution declined from about day five onwards. In the Grey-headed Sparrow, both parents fed their young equally throughout the nestling period. House Sparrows fed on the ground near houses; Grey-headed Sparrows fed both on the ground away from houses and in tree canopies. The Grey-headed Sparrow walked as it fed on the ground as opposed to the House sparrow which hopped. Grey-headed Sparrows fed mainly as pairs and singletons while House Sparrows fed as family groups. Larger feeding groups of Grey-headed Sparrows were seen in the northern region at areas where food was plentiful. Where the two sparrows were seen feeding together, there was no direct competition for food. Where individual distance was violated; male House Sparrows displaced Grey-headed Sparrows which landed too close to them. Overall it appears that the distribution of the two species is determined more by their responses to habitat conditions than by interspecific interactions.
- Full Text:
- Authors: Nhlane, Martin Edwin Darwin
- Date: 1997
- Subjects: English sparrow Sparrows
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5654 , http://hdl.handle.net/10962/d1005337
- Description: The House Sparrow Passer domesticus, an introduced species, and the Grey-headed Sparrow Passer griseus, an indigenous species, are sympatric in Malawi. Their distribution in the country and any possible interactions were studied, principally in southern Malawi. A morphological analysis of museum specimens confirmed that grey-headed sparrows in Malawi belong to the Northern Grey-headed Sparrow Passer griseus as distinct from the Southern Grey-headed Sparrow Passer diffusus. This species was widely distributed in the, country in association with human dwellings, both in rural areas as well as urban centres. In the northern region Greyheaded Sparrows were more abundant in the urban centres than rural areas, but in the central and southern regions numbers in the rural and urban areas were more or less the same. In Blantyre City, where they are in sympatry with the House Sparrow, they were found in the low density and industrial areas and were absent from the high density areas. The House Sparrow, arrived in Malawi in 1967 at Chileka in the southern region. Since then it has spread northwards, moving from the southern to the central and northern regions. House Sparrow numbers were found to be progressively larger in the southern region and lowest in the northern region. House Sparrows were found at sites where food was readily available, as in the immediate vicinity of houses. In the central and northern regions they were restricted mainly to urban areas. In the southern region, they occur both in rural and urban areas, probably as a reflection of the larger period of colonization in the south. In the northern region their movement has apparently been restricted by geographical barriers. In Blantyre City Grey-headed Sparrows preferred areas where tree density was high and house density was low, while House Sparrows preferred areas where house density was high and tree density was low. There was a positive correlation between Greyheaded Sparrow numbers and tree density and a negative correlation with house density. House Sparrow abundance was negatively correlated with tree density and positively correlated with house density. Grey-headed Sparrows bred in the rainy season, whereas House Sparrows bred throughout the year. There were differences in nest site selection: Grey-headed Sparrows used artificial structures such as fencing poles, and wooden telephone or electricity poles. The House Sparrow used mostly buildings and nested in crevices, holes in walls and between the walls and rafters. Nest height also differed- Grey-headed Sparrows nested at heights ranging from 1 - 8 m while House Sparrow nests were at heights of 1 - 5 m. Moult data suggests that although the House Sparrows breed throughout the year, they moult at a particular time of the year when breeding is less common. Grey-headed Sparrows were found to moult mainly from May to September in southern Africa and from June to September in central Africa. In both cases the breeding season extends over a similar period from about October to April/May of the following year. Peak moult periods differed between the House Sparrows and Grey-headed Sparrows. House Sparrows moulted mainly in the first half of the year, and Greyheaded Sparrows in the second six months. The clutch sizes of the two species were similar (mean 3.9 eggs for the House Sparrow and 3.4 for the Grey-headed Sparrow). The clutch size of the House Sparrow varied seasonally and was larger from November to May. The average incubation period for the House Sparrow was 11.5 days and the fledging period 15.4 days. The Grey-headed Sparrow fledging period was 14.7 days. Chick mortality of the House Sparrow at Chikunda farm was attributed to starvation resulting from brood reduction, abandonment, predation, low birth weight, accidental deaths and parasitism by fly larvae. Both Grey-headed and House Sparrows fed their young on insect food. Male House Sparrows fed actively initially, but their contribution declined from about day five onwards. In the Grey-headed Sparrow, both parents fed their young equally throughout the nestling period. House Sparrows fed on the ground near houses; Grey-headed Sparrows fed both on the ground away from houses and in tree canopies. The Grey-headed Sparrow walked as it fed on the ground as opposed to the House sparrow which hopped. Grey-headed Sparrows fed mainly as pairs and singletons while House Sparrows fed as family groups. Larger feeding groups of Grey-headed Sparrows were seen in the northern region at areas where food was plentiful. Where the two sparrows were seen feeding together, there was no direct competition for food. Where individual distance was violated; male House Sparrows displaced Grey-headed Sparrows which landed too close to them. Overall it appears that the distribution of the two species is determined more by their responses to habitat conditions than by interspecific interactions.
- Full Text:
A study of the Pycnonotus bulbul species complex in Southern Africa
- Authors: Lloyd, Penn
- Date: 1995
- Subjects: Bulbuls -- Ecology -- South Africa -- Eastern Cape , Songbirds -- Ecology -- South Africa -- Eastern Cape , Birds -- Ecology -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5782 , http://hdl.handle.net/10962/d1005470 , Bulbuls -- Ecology -- South Africa -- Eastern Cape , Songbirds -- Ecology -- South Africa -- Eastern Cape , Birds -- Ecology -- South Africa -- Eastern Cape
- Description: The three Pycnonotus bulbuls endemic to Africa, P. barbatus, P. nigricans and P. capensis, occupy mutually exclusive distributions in southern Africa. These species are closely related and appear to occupy very similar ecological niches, only in different regions. Using a multifaceted approach, this study attempts to explain the ecology of this species complex. All three species show similar physiological responses to temperature extremes, and are therefore unlikely to be directly limited by environmental temperature. However, their distributions are highly correlated to a complex of environmental variables, particularly winter minimum temperatures, the coefficient of variation in mean annual rainfall, and the seasonality of rainfall. This combination of environmental parameters can be used to predict the distributions of at least one of the species, P. nigricans, accurately. An analysis of the vocalizations and behaviour of the three species revealed that, whilst P. capensis has a number of recognizably different vocalizations, those of P. barbatus and P. nigricans are very similar. The three have nearly identical behaviours, particularly courtship and pre-copulatory behaviours. The mate recognition systems of the three are therefore extremely similar. P. barbatus is territorial during the breeding season, and exhibits highly structured-variation in male territorial song at the level of the local neighbourhood. The literature pertaining to song dialects is reviewed, and a new hypothesis is postulated to explain song-matching in terms of neighbour/stranger discrimination and the possible existence of cooperative territory defence. A survey of the eastern Cape region, where all three species come into contact, showed that extensive hybridization is taking place between each species pair. Phenotypically, this hybridization is restricted to narrow hybrid zones, that are considered to be stable in both time and place. The evolutionary and ecological significance of these zones to the distributions of the species is discussed, and it is proposed that the zones are maintained by selection acting on differentially-adapted genomes along an environmental gradient.
- Full Text:
- Authors: Lloyd, Penn
- Date: 1995
- Subjects: Bulbuls -- Ecology -- South Africa -- Eastern Cape , Songbirds -- Ecology -- South Africa -- Eastern Cape , Birds -- Ecology -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5782 , http://hdl.handle.net/10962/d1005470 , Bulbuls -- Ecology -- South Africa -- Eastern Cape , Songbirds -- Ecology -- South Africa -- Eastern Cape , Birds -- Ecology -- South Africa -- Eastern Cape
- Description: The three Pycnonotus bulbuls endemic to Africa, P. barbatus, P. nigricans and P. capensis, occupy mutually exclusive distributions in southern Africa. These species are closely related and appear to occupy very similar ecological niches, only in different regions. Using a multifaceted approach, this study attempts to explain the ecology of this species complex. All three species show similar physiological responses to temperature extremes, and are therefore unlikely to be directly limited by environmental temperature. However, their distributions are highly correlated to a complex of environmental variables, particularly winter minimum temperatures, the coefficient of variation in mean annual rainfall, and the seasonality of rainfall. This combination of environmental parameters can be used to predict the distributions of at least one of the species, P. nigricans, accurately. An analysis of the vocalizations and behaviour of the three species revealed that, whilst P. capensis has a number of recognizably different vocalizations, those of P. barbatus and P. nigricans are very similar. The three have nearly identical behaviours, particularly courtship and pre-copulatory behaviours. The mate recognition systems of the three are therefore extremely similar. P. barbatus is territorial during the breeding season, and exhibits highly structured-variation in male territorial song at the level of the local neighbourhood. The literature pertaining to song dialects is reviewed, and a new hypothesis is postulated to explain song-matching in terms of neighbour/stranger discrimination and the possible existence of cooperative territory defence. A survey of the eastern Cape region, where all three species come into contact, showed that extensive hybridization is taking place between each species pair. Phenotypically, this hybridization is restricted to narrow hybrid zones, that are considered to be stable in both time and place. The evolutionary and ecological significance of these zones to the distributions of the species is discussed, and it is proposed that the zones are maintained by selection acting on differentially-adapted genomes along an environmental gradient.
- Full Text:
The biology of the South African cliff swallow hirundo spilodera
- Authors: Earlé, Roy Anthony
- Date: 1986
- Subjects: Hirundo pyrrhonota Birds -- Breeding -- South Africa Birds -- Behavior -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5631 , http://hdl.handle.net/10962/d1004927
- Description: The general biology of the South African Cliff Swallow Hirundo spilodera was studied over a two year period in the central Orange Free State. This species is highly colonial, nesting mostly on man-made structures such as concrete road bridges. Adult birds were usually faithful to their breeding colony and very few individuals changed colonies. The Cliff Swallow had a surprisingly large vocal repertoire for a swallow and contact calls of the young were individually recognizable. Three species-specific ectoparasites parasitized the Cliff Swallow but none seemed to have a noticeable negative effect on the swallows. Breeding started earlier in larger colonies than in smaller ones and conspecific brood parasitism was a common feature in some colonies. Individual pairs made up to four breeding attempts per season. The findings of this study are compared with the available information on other members of the Hirundinidae and the advantages and costs of Cliff Swallow coloniality are discussed.
- Full Text:
- Authors: Earlé, Roy Anthony
- Date: 1986
- Subjects: Hirundo pyrrhonota Birds -- Breeding -- South Africa Birds -- Behavior -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5631 , http://hdl.handle.net/10962/d1004927
- Description: The general biology of the South African Cliff Swallow Hirundo spilodera was studied over a two year period in the central Orange Free State. This species is highly colonial, nesting mostly on man-made structures such as concrete road bridges. Adult birds were usually faithful to their breeding colony and very few individuals changed colonies. The Cliff Swallow had a surprisingly large vocal repertoire for a swallow and contact calls of the young were individually recognizable. Three species-specific ectoparasites parasitized the Cliff Swallow but none seemed to have a noticeable negative effect on the swallows. Breeding started earlier in larger colonies than in smaller ones and conspecific brood parasitism was a common feature in some colonies. Individual pairs made up to four breeding attempts per season. The findings of this study are compared with the available information on other members of the Hirundinidae and the advantages and costs of Cliff Swallow coloniality are discussed.
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