No description available.

No description available.

Since European settlement, the woodlands and associated habitats, especially in the temperate zones of Australia, have been extensively cleared and converted to arable land and pastures. Much of the remaining vegetation in the agricultural zone occurs as small isolated patches prone to disturbance and degradation. Apart from habitat loss and fragmentation, altered fire regimes, periods of intense drought, and the introduction of exotic plants and animals, have contributed to the deterioration of most of the natural habitats across Australia, with a negative impact on the native wildlife, including birds. Many woodland bird species have undergone widespread declines, culminating in some local or even regional extinctions. In the mallee woodlands of south-east Australia two closely related species of whistlers (fam. Pachycephalidae) — Red-lored Whistler Pachycephala rufogularis and Gilbert’s Whistler P. inornata — have overlapping ranges, and in some areas they co-exist. These two species are morphologically and ecologically similar. However, despite the similarities, P. rufogularis has undergone greater declines in distribution and abundance than P. inornata. The ecology of these two species is poorly known, which renders adequate management impracticable. The major objectives of this thesis were to determine the key habitat requirements for the two species, to determine their habitat use, and to document the ecology and behaviour of the two species, particularly their foraging, and intra- and interspecific interactions. A sound knowledge of the ecology of the two species is needed to underpin appropriate actions for their management and conservation. Morphological features were measured from skins of P. rufogularis and P. inornata in the South Australian Museum collection, and from captured live birds, to detect if any aspect of the morphology could indicate possible niche partitioning between the two species. Also, the use of biometry as a tool for separating the sexes for P. rufogularis, for determining the species of the uncoloured immature birds and for sexing immatures, was evaluated. No morphological feature suggested niche partitioning. The biometry did not prove a very reliable tool for distinguishing sexes in adult P. rufogularis, but reliably identified the species of the uncoloured immatures. Sexing immatures based on biometrical data alone was not possible. Research was conducted in two main South Australian parks: Gluepot Reserve and Ngarkat Conservation Park. Ecological and behavioural data for P. rufogularis and P. inornata were collected by observing marked (colour-banded and radio-tagged) and unmarked individual birds of both species and sexes, over a two-year period from June 2004 to May 2006. The home ranges of P. rufogularis and P. inornata were determined by tracking the movements of birds in the landscape. Pachycephala rufogularis had much larger home ranges than P. inornata, especially when breeding. The striking differences in home range size between the two ecologically similar species might be related to differences in site fidelity. Pachycephala rufogularis at Gluepot was sedentary, being detected in the same locations throughout the year, and over several years. On the contrary, P. inornata generally showed poor site fidelity, being more mobile, and shifting home ranges between and within seasons. In the field the two species were segregated by habitat. Pachycephala rufogularis and P. inornata showed different habitat preferences, even in areas where they did not co-occur. Pachycephala rufogularis favoured low mallee with Triodia on sand dunes, while P. inornata favoured tall mallee with sparse shrub understorey in interdunes, but also other habitats, such as prickly Acacia thickets and Casuarina woodlands. However, both species used the mallee- Triodia with Callitris vegetation type. The key to coexistence in this habitat was a behavioural one, P. inornata acting as a subordinate species. Pachycephala rufogularis had strict habitat requirements, with the presence of Triodia being critical for the presence of the species. In contrast, P. inornata was more flexible in its habitat requirements, and used a broader range of vegetation types, being more of a habitat generalist. The investigation of habitat use from both a spatial and temporal perspective confirmed that both species actively selected habitat, and that the habitats they selected differed. The core areas of home ranges predominantly contained the preferred habitat for both species. In both species, core areas of home ranges of breeding individuals (where generally the nests were placed) contained preferred habitat in higher proportion than core areas of non-breeding birds. This suggests that during breeding, both species are more restricted to, and/or use more intensely the preferred habitat than when not breeding. The foraging behaviour did not differ consistently between the two species, both capturing insects mostly by snatching in canopy foliage, and also by gleaning on the vegetation, at different heights. However, the two species were already segregated by habitat. Thus the resource partitioning occurred spatially, at the macrohabitat level. In the instances when individuals of both species foraged in the same area and used the same resources, resource partitioning occurred at a temporal scale. Both species were generalists in foraging; therefore, a presumed foraging specialisation as a possible factor related to the decline of P. rufogularis was ruled out. Pachycephala rufogularis and P. inornata are unlikely to be competitors. Support for this argument came from the situation at Ngarkat, where P. inornata was absent. Despite this, P. rufogularis did not use a broader range of vegetation types in Ngarkat, as would be expected under ‘competitive release’. Instead the species maintained strict habitat requirements, specializing virtually on a single vegetation type. The rigid habitat requirements of P. rufogularis, together with its sedentary nature, render this species vulnerable to disturbances, such as wildfires. On the other hand, the apparent flexibility in habitat requirements and greater mobility may explain why P. inornata has been more successful than its sibling species. The information on habitat requirements, preference and use, and also on home ranges of P. rufogularis and P. inornata provided in this study should be included in future habitat suitability models and predictive models for these species, which will assist in their management. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1374821 / Thesis (Ph.D.) -- University of Adelaide, School of Earth and Environmental Sciences, 2009

Since European settlement, the woodlands and associated habitats, especially in the temperate zones of Australia, have been extensively cleared and converted to arable land and pastures. Much of the remaining vegetation in the agricultural zone occurs as small isolated patches prone to disturbance and degradation. Apart from habitat loss and fragmentation, altered fire regimes, periods of intense drought, and the introduction of exotic plants and animals, have contributed to the deterioration of most of the natural habitats across Australia, with a negative impact on the native wildlife, including birds. Many woodland bird species have undergone widespread declines, culminating in some local or even regional extinctions. In the mallee woodlands of south-east Australia two closely related species of whistlers (fam. Pachycephalidae) — Red-lored Whistler Pachycephala rufogularis and Gilbert’s Whistler P. inornata — have overlapping ranges, and in some areas they co-exist. These two species are morphologically and ecologically similar. However, despite the similarities, P. rufogularis has undergone greater declines in distribution and abundance than P. inornata. The ecology of these two species is poorly known, which renders adequate management impracticable. The major objectives of this thesis were to determine the key habitat requirements for the two species, to determine their habitat use, and to document the ecology and behaviour of the two species, particularly their foraging, and intra- and interspecific interactions. A sound knowledge of the ecology of the two species is needed to underpin appropriate actions for their management and conservation. Morphological features were measured from skins of P. rufogularis and P. inornata in the South Australian Museum collection, and from captured live birds, to detect if any aspect of the morphology could indicate possible niche partitioning between the two species. Also, the use of biometry as a tool for separating the sexes for P. rufogularis, for determining the species of the uncoloured immature birds and for sexing immatures, was evaluated. No morphological feature suggested niche partitioning. The biometry did not prove a very reliable tool for distinguishing sexes in adult P. rufogularis, but reliably identified the species of the uncoloured immatures. Sexing immatures based on biometrical data alone was not possible. Research was conducted in two main South Australian parks: Gluepot Reserve and Ngarkat Conservation Park. Ecological and behavioural data for P. rufogularis and P. inornata were collected by observing marked (colour-banded and radio-tagged) and unmarked individual birds of both species and sexes, over a two-year period from June 2004 to May 2006. The home ranges of P. rufogularis and P. inornata were determined by tracking the movements of birds in the landscape. Pachycephala rufogularis had much larger home ranges than P. inornata, especially when breeding. The striking differences in home range size between the two ecologically similar species might be related to differences in site fidelity. Pachycephala rufogularis at Gluepot was sedentary, being detected in the same locations throughout the year, and over several years. On the contrary, P. inornata generally showed poor site fidelity, being more mobile, and shifting home ranges between and within seasons. In the field the two species were segregated by habitat. Pachycephala rufogularis and P. inornata showed different habitat preferences, even in areas where they did not co-occur. Pachycephala rufogularis favoured low mallee with Triodia on sand dunes, while P. inornata favoured tall mallee with sparse shrub understorey in interdunes, but also other habitats, such as prickly Acacia thickets and Casuarina woodlands. However, both species used the mallee- Triodia with Callitris vegetation type. The key to coexistence in this habitat was a behavioural one, P. inornata acting as a subordinate species. Pachycephala rufogularis had strict habitat requirements, with the presence of Triodia being critical for the presence of the species. In contrast, P. inornata was more flexible in its habitat requirements, and used a broader range of vegetation types, being more of a habitat generalist. The investigation of habitat use from both a spatial and temporal perspective confirmed that both species actively selected habitat, and that the habitats they selected differed. The core areas of home ranges predominantly contained the preferred habitat for both species. In both species, core areas of home ranges of breeding individuals (where generally the nests were placed) contained preferred habitat in higher proportion than core areas of non-breeding birds. This suggests that during breeding, both species are more restricted to, and/or use more intensely the preferred habitat than when not breeding. The foraging behaviour did not differ consistently between the two species, both capturing insects mostly by snatching in canopy foliage, and also by gleaning on the vegetation, at different heights. However, the two species were already segregated by habitat. Thus the resource partitioning occurred spatially, at the macrohabitat level. In the instances when individuals of both species foraged in the same area and used the same resources, resource partitioning occurred at a temporal scale. Both species were generalists in foraging; therefore, a presumed foraging specialisation as a possible factor related to the decline of P. rufogularis was ruled out. Pachycephala rufogularis and P. inornata are unlikely to be competitors. Support for this argument came from the situation at Ngarkat, where P. inornata was absent. Despite this, P. rufogularis did not use a broader range of vegetation types in Ngarkat, as would be expected under ‘competitive release’. Instead the species maintained strict habitat requirements, specializing virtually on a single vegetation type. The rigid habitat requirements of P. rufogularis, together with its sedentary nature, render this species vulnerable to disturbances, such as wildfires. On the other hand, the apparent flexibility in habitat requirements and greater mobility may explain why P. inornata has been more successful than its sibling species. The information on habitat requirements, preference and use, and also on home ranges of P. rufogularis and P. inornata provided in this study should be included in future habitat suitability models and predictive models for these species, which will assist in their management. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1374821 / Thesis (Ph.D.) -- University of Adelaide, School of Earth and Environmental Sciences, 2009

M.Sc. / Rivers always borrow a great part of their character from the terrestrial ecosystems – the catchments – through which they flow. A multitude of natural factors determines the health of a river ecosystem, however, together with these natural factors, the combined influences of urban development, pollution, bank erosion, deforestation (and ironically many forms of afforestation), and poor agricultural practices have so degraded our rivers that they are under severe threat. One particular group of organisms within river ecosystems that are affected by human-induced changes, are birds. Birds are rather adaptable organisms; many species are able to inhabit human environments very successfully. However, some bird species are highly specialized and adapted to specific environments, like riparian and riverine zones, and their absence or presence is a useful aid in indicating the ecological integrity of an area. In the past, management of aquatic ecosystems was based primarily on chemical water quality monitoring. However, it is impractical to monitor each component of river make-up in detail, therefore monitoring of biological components (biomonitoring) was also incorporated; using selected ecological indices that are representative of the larger ecosystem, and that are practical to measure. Common examples of biotic assemblages that have been incorporated into biomonitoring and used in biotic indices are aquatic macroinvertebrates, fish, plants and algae. Each assemblage is useful in its own particular way in providing us with an integrated view of the integrity of the ecological system as a whole. However, little research has been done on the potential of using birds in a suitable index to monitor changes in the environment. Because birds are so easily observed, their species so easily identified, and their distribution so widespread, it seems viable that birds could also be incorporated into an index of biotic integrity, and used for short- or long-term monitoring of river ecosystems. The river that was selected for the purposes of this study was the Sabie River, in Mpumalanga, South Africa. The Sabie River catchment falls within the Incomati River basin, which is an international drainage basin occupied by South Africa, Swaziland and Mozambique. Land use in the catchment is characterized by forestry, rural community activities (subsistence and small scale farming of livestock and fruit), and conservation activities, in particular the Kruger National Park. In order to gain better understanding of the functioning and composition of the instream and riparian zones of the Sabie River, certain indices were applied, namely the SASS 5 aquatic invertebrate index, together with the Index of Habitat Integrity (IHI). / Dr. G.M. Pieterse

This study compared the avian communities of treatment wetlands in South Florida called Stormwater Treatment Wetlands (STAs) to those in natural marshes and crop lands, and examined factors that influenced the size and structure of the avian communities within the STAs. The STAs contained a more abundant, rich and distinct avian community compared to reference land types. The STAs were dominated by wintering waterfowl, and therefore community patterns fluctuated more seasonally other land types. Within the STAs, density and richness in the fall and winter were much greater in the submerged aquatic vegetation than in the mixed emergent vegetation when waterfowl were present. The STAs maintain two vegetation treatments which enhanced their biodiversity value by supporting distinct avian communities with different migratory strategies This suggests the increase in treatment wetlands could partially offset the loss of natural wetlands, but avian communities in treatment wetlands are not surrogates for natural wetlands. / by Tyler J. Beck. / Thesis (M.S.)--Florida Atlantic University, 2013. / Includes bibliography. / Mode of access: World Wide Web. / System requirements: Adobe Reader.

Thesis (MSc)--Stellenbosch University, 2015. / ENGLISH ABSTRACT: Forests in South Africa have had a long history of human utilization and disturbance, and are under threat from a variety of anthropogenic land use changes. Foremost of these are deforestation and forest degradation, impacting the species native to these forests. The aims of this study were to determine changes in the distribution of forest dependent bird species according to the South African Bird Atlas Project; to relate these changes to changes in land-use; to identify links between these changes; to determine the extent, location and causes of the decline of each forest dependent bird species; and to identify current risks to forest dependent bird species in South Africa. Range data on 57 forest dependent bird species from SABAP1 (1987-1992) and SABAP2 (2007-present) were analyzed. Of these, 28 species were found to have declining ranges. Thirty sites across South Africa were identified as being most at risk, with all having experienced a loss of more than 10 of the 57 forest dependent bird species between SABAP1 and SABAP2. The range change data of the 28 species with decreasing ranges were correlated with data on changes in land cover over the same time period to infer relationships between changes in land use and change in bird ranges. Occupancy modelling was done to determine which land cover types affect extinction and initial presence. Individual species characteristics were analyzed to determine links between characteristics and response to land use change. A pan-European trait-based risk assessment framework was applied to all 57 species to identify habitats and species most at risk, as well as the most important threats to species persistence. Results showed that natural vegetation decreased in 67% of sites, while plantations and cultivation increased in 50% of sites. Occupancy modelling showed extinction likelihood to increase with plantations in some species, while plantations mitigated extinction likelihood in other species. Urbanization and cultivation likewise mitigated extinction likelihood in some species. Natural vegetation was replaced by cultivation, while cultivation was replaced by urbanization. The number of species lost increased with a loss of natural vegetation. Twenty two of the thirty sites experienced deforestation of indigenous forests between 2000 and 2013/2014; changes in natural vegetation in these sites can be attributed primarily to deforestation, and a loss of plantations. While most at-risk sites were in the Eastern Cape, there was no geographic grouping of species loss or of land use change. Most species lost were birds of prey or insectivores, and species characteristics and habitat preferences determined the sites from which they were lost. The Cape parrot (Poicephalus robustus), rufous-chested sparrowhawk (Accipiter rufiventris) and the migratory Eurasian golden oriole (Oriolus oriolus) suffered the largest declines in range size and are thought to be most at risk. Montane forests were found to be more at risk than other forest types. The major risks facing montane forests were increased abundance of small predators, increased fire suppression, increased soil management, removal of deadwood and reduced diversity of tree species. These threats are all products of plantation forestry and local harvesting. Nesting risk was higher than foraging risk for all species, indicating that nesting habitat should be better preserved. Half of South Africa’s forest dependent bird species have declining ranges, with the loss of these species most prominent in the Eastern Cape. Natural vegetation loss, comprising mostly recent deforestation; increased cultivation and urbanization; and changes in plantation cover are thought to be the main factors determining these declines. Montane forests in particular should be better protected to preserve forest dependent species, and the negative effects of plantation forestry and local harvesting should be mitigated. / AFRIKAANSE OPSOMMING: Suid-Afrika het ‘n lang geskiedenis van woude wat deur mense gebruik, asook vernietig word. Woude word bedreig deur verskeie menslike grondgebruike en veranderinge. Die mees vooraanstaande van die bedreigings is ontbossing en woud verdunning, wat ‘n invloed het op inheemse spesies in die woude. Die doelwitte van hierdie studie was om veranderinge in die verspreiding van bos-afhanklike voëlspesies vas te stel volgens die Suid Afrikaanse Voël Atlas Projek; om hierdie veranderinge te verband met veranderinge in grondgebruik; om verbande tussen hierdie veranderinge te identifiseer; om die mate, die plek en die oorsake van die agteruitgang van elke bos-afhanklike voëlspesies te bepaal; en om huidige risiko's aan die bos afhanklik voëlspesies in Suid-Afrika te identifiseer. Trefwydte inligting oor 57 woud afhanklike voëlspesies van SABAP1 (1987-1992) en SABAP2 (2007-nou) was geanaliseer. Daar was gevind dat vanuit die spesies, het 28 ‘n afneming in trefwydte ervaar. Dertig terreine in Suid-Afrika was uitgeken as dié met die hoogste risiko, met ‘n verlies van meer as 10 van die 57 woud afhanklike voëlspesies tussen SABAP1 en SABAP2. Die trefwydte inligting van die 28 spesies met ‘n afnemende trefwydte was gekorreleer met inligting oor veranderinge in grond bedekking oor dieselfde tydperk om verhoudings tussen veranderinge in grond gebruik en veranderinge in voël trefwydtes aftelei. Besetting modellering was gedoen om te bepaal watter tipes grond bedekking beinvloed uitwissing en aanvanklike teenwoordigheid. Kenmerke van individuele spesies is ontleed om verbande tussen kenmerke en reaksie op verandering in grondgebruik te bepaal. ‘n Pan-Europese eienskap gebaseerde risiko-analise raamwerk is toegepas op die 57 spesies om die spesies en habitatte met die grootse risiko te identifiseer, asook die belangrikste bedreigings vir spesies-volharding. Die resultate het gewys dat natuurlike plantegroei het verminder in 67% van terreine, terwyl plantasie en verbouing vermeerder het in 50% van terreine. Besetting-modellering het gewys dat waarskynlikheid van uitwissing vermeerder met plantasies in sommige spesies, terwyl plantasies die waarskynlikheid van uitwissing verminder het in ander spesies. Verstedeliking en verbouing het ook die waarskynlikheid van uitwissing verminder in sommige spesies. Natuurlike plantegroei was vervang deur verbouing, terwyl verbouing vervang is deur verstedeliking. Die aantal spesies verlies het vermeerder met die vermindering van natuurlike plantegroei. Twee en twintig van die dertig terreine het ontbossing van inheemse woude ervaar tussen 2000 en 2013/2014. Veranderinge in natuurlike plantegroei in die terreine is meestal as gevolg van ontbossing, en ‘n vermindering van plantasies. Terwyl meeste van die hoë risiko terreine in die Oos-Kaap was, was daar geen geografiese groepering van spesies vermindering of grondgebruik veranderinge nie. Meeste spesies wat vernietig is was roofvoëls of insectivore, en spesies kenmerke en habitat voorkeure het die terreine bepaal waaruit hulle verloor is. Die grootpapegaai (Poicephalus robustus), rooiborssperwer (Accipiter rufiventris) en die trekvoël Europese wielewaal (Oriolus oriolus) het die grootste vermindering in trefwydte grootte ervaar, en is vermoedelik die grootste risiko. Bergwoude was gevind om meer in gevaar te wees as ander woud tipes. Die grootste risikos wat bergwoude beïnvloed het was ‘n toenemende hoeveelheid klein roofdiere, verhoogde vuur onderdrukking, verhoogde grondbestuur, verwydering van dooie hout, en verlaagde diversiteit van boomspesies. Hierdie bedreigings is almal as gevolg van plantasie bosbou en plaaslike oes. Nes-risiko was hoër as kos soek risiko vir alle spesies, wat aandui dat nes-habitat beter bewaar moet word. Die helfte van Suid-Afrika se woud-afhanklike-voëlspesies het dalende trefwydtes, met die verlies van hierdie spesies mees opvallend in die Oos-Kaap. Die verlies van natuurlike plantegroei, as gevolg van onlangse ontbossing; verhoogde verbouing en verstedeliking; en veranderinge in plantasie bedekking is vermoedelik die hooffaktore wat die vermindering van voëlspesies veroorsaak. Veral bergwoude moet beter beskerm word om woud-afhanklike-voëlspesies te bewaar en die negatiewe invloede van plantasiebosbou en plaaslike oes te verminder.

For migrant birds, the non-breeding season can greatly influence survival and future reproductive success. Knowledge of annual and overwinter survival, the degree of site fidelity and habitat use in the non-breeding season, migration ecology, routes and stopovers, and whether these differ with age or sex is fundamental to understanding population dynamics, vulnerability to anthropogenic habitat degradation, and consequently for understanding the severe widespread declines of migrant bird species. The degree to which a migrant is a winter specialist or generalist is likely to be central to understanding population dynamics. I studied survival rates and the wintering and migration ecology of a declining Palearctic migrant, the whinchat Saxicola rubetra, wintering in West Africa, to establish how the non-breeding season may influence migrant population dynamics. Whinchats were extremely site faithful to both within and between years, holding distinct winter territories and returning to those territories in subsequent winters, despite the opportunity to relocate. Overwinter survival was very high and annual survival was comparable to or higher than that reported on the breeding grounds. Because our power to detect resident and dispersing birds was high, survival rates likely estimated true survival well. Habitat characteristics varied widely across territories and territories were smaller if more perching shrubs and maize were present. Most individuals showed a tolerance or even preference for human modified habitats. Some individuals may have multiple wintering sites. There was no evidence of dominance-based habitat occupancy or any differences in winter ecology, site fidelity, survival and most aspects of migratory behaviour between age and sex classes. Migratory connectivity occurred only on a large-scale and individual migratory behaviour was also varied. Fundamentally, the results suggest a generalist strategy in the non-breeding season within their wintering habitat of open savannah, most likely as an adaption to stochastic site selection within the wintering range for juveniles undertaking their first migration plus changing and unpredictable conditions both within and between years. Consequently, wintering conditions may not significantly limit whinchat populations and mortality is probably highest during active migration. Notably, non-specialist migrants such as whinchats may have some resilience at the population-level to the increasing anthropogenic habitat modification occurring in Africa, suggesting that conditions during migration and in Europe may be driving declines; yet establishing the currently unknown thresholds of any resilience is likely to be fundamental for the future conservation migrants.

Forest fragmentation is caused by the clearing of patches of indigenous vegetation for agriculture, urban development, and other human land uses. Such action results in patches of remnant natural vegetation being surrounded by altered vegetation. I investigate the effects of forest fragmentation and matrix type on avian diversity and assemblage structure in forest patches of the historically fragmented Karkloof / Balgowan forest range, KwaZulu-Natal, South Africa. This study compares the bird assemblage diversity and composition of indigenous forest patches surrounded by commercial forestry (Gilboa complex) with that surrounded by natural grassland matrix (Balgowan complex). Insularisation of Afromontane Mistbelt forest in KwaZulu-Natal has led to loss of species where forest fragments support fewer bird species than comparably sized patches of mainland forest. Small fragments within natural grassland have fewer bird species per unit area than larger fragments. Forest patch area-dependent density compensation is evident and bird assemblages appear saturated. Bird assemblages are characterised by a non-random species distribution pattern where area-dependent processes are dominant, and the loss of species from fragments follows a deterministic sequence. In forests in the plantation-dominated matrix no island-effect is detectable and it appears that forest patches are converging on the same bird species richness, regardless of forest size. No density compensation is evident and bird assemblages are not saturated. The sequence of species loss from forest patches is not as predictable, where a random yet prominent colonisation process exists. As commercial plantations provide suitable habitat cover for movement of forest birds, colonisation of both distant and small indigenous forest patches has been possible, reducing the effects of area-dependent extinction in the forest patches but also resulting in lower species richness in larger patches. Bird species of the Karkloof / Balgowan forest range appear to be fragmentation adapted, and most species are resilient to further landscape change. Certain species are however more prone to local extinction than others. The major predictors of extinction risk are body size, abundance status, and feeding guild. Patch area is the dominant force governing traits in the natural Balgowan complex where larger species with low natural abundance and an insectivorous diet are most prone to local extinction. In the Gilboa complex the nature of the plantation matrix appears to be masking the species natural responses to fragmentation making it difficult to predict which species are most at risk. In order to preserve maximum bird diversity, including high-risk species, the largest intact forest units (≥302ha) must be conserved. Evidently, the nature of the matrix affects avifaunal diversity and distribution in forest patches, and plantations have the capacity to significantly alter bird assemblage structure and composition in indigenous forest patches. Forest fragments must be considered as integrated parts of a complex landscape mosaic, and this study emphasises the importance of understanding landscape-scale processes. Knowledge of ecological and life history traits proves valuable for predicting community level response to landscape change. / Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 2001.

Considering the high rate of endemism in Madagascan organisms, which are mostly restricted to forest ecosystems, and the accelerating rate of deforestation affecting the island, it is critical to understand the effects of forest fragmentation on Malagasy biota to allow for better management of species within ecosystems. Ecological and human-induced changes have led to the disappearance of forest from vast areas of the island, including on the central High Plateau. The Ambohitantely Special Reserve, located on the central High Plateau at 1500 m asl, was selected as the study site for research on the effects of forest fragmentation on forestependent bird species in Madagascar. The Ambohitantely special Reserve covers 5600 ha of which 50% are natural forest, 35% are anthropogenic grassland savannah and 15% are exotic plantations. The forest, described as East Malagasy moist montane forest, is 2737 ha in area, of which 1487 ha are comprised of 513 forest fragments scattered around the largest block totalling 1250 ha. To investigate the effects of forest fragmentation on forest-dependent bird species, seven forest fragments were selected, ranging from 0.64 ha to 136 ha, in addition to the largest block, referred to as the control site. The bird species composition and relative abundance in different-sized fragments were assessed in reference to the control site, by using a combination of two standardized sampling methods: mistnetting and point-counts. A total of 1804 mistnet-days were accrued, 1026 in the control site and 778 in the seven forest fragments, leading to the capture of 491 birds of 26 species. A total of 160 point-counts was made at 39 different sample plots totalling 53 h 29 min of censusing, and a record of 30 species. A total of 72 bird species including 54 breeding forest affinities of the avifauna of Ambohitantely were defined with reference to 32 forest sites scattered across Madagascar. The species composition in all fragments are fully nested subsets of the control site and the species distribution in the fragments does not represent random subsets of the control site. The analysis of the bird communities in different size fragments indicates that the occurrence of bird species reflects a regular pattern of species extinction in relation to decreasing size of forest fragment. Species composition is discussed in reference to Ambohitantely's long history of isolation that may have led to extirpation of bird species from this site. The higher bird taxa decrease in number or totally disappear as a result of their ecological specialization. Equally, they are the most affected by edge effects (e. g. Atelornis pittoides). The main ecological trends in disappearance or extinction of species is a decrease in the number of small-bodied insectivorous understorey species and mid- and upper-stratum small-bodied insectivorous and nectarivorous species. Insectivorous species are particularly affected by forest fragmentation and three forest-dependent species found in Ambohitantely Forest are particularly sensitive to forest fragmentation: Newtonia amphichroa, Calicalicus madagascariensis, and Cyanolanius madagascarinus. The biological (flora species composition and forest structure) and the physical (temperature, moisture, and light) changes generated by the fragmentation of the forest have a greater impact on highly specialized foraging guilds and this explains the pattern of current bird species composition in Ambohitantely Forest. The influence of forest fragmentation on the altitudinal migration process is debated and conservation measures such as the establishment of forest corridors are proposed to improve the protection of biota found in the Ambohitantely Special Reserve. / Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 1995.