In recent decades, New England agriculture has become increasingly characterized by small, diversified farming operations with values deeply rooted in community and conservation. In sharp contrast to large-scale, high-intensity agriculture currently typified by the majority of North American farms, New England farmers commonly prioritize ecologically beneficial production practices such as reduced chemical inputs, integrated pest management (IPM), low tillage, cover cropping and crop rotation, and retention of natural habitats like woody hedgerows and herbaceous strips. Public support and demand for local, sustainable food, evidenced by the success of CSA (Community Supported Agriculture) in the region, has helped to bolster this movement and increase the viability of these farms. In addition to boosting regional food production and self-sufficiency, these farms also present an opportunity for wildlife conservation. Shrubland bird species in particular may benefit from habitat created on these farms because of their preference for heterogeneous shrub and herbaceous vegetation and lower area sensitivity compared to other species, such as grassland obligates. In order to evaluate conservation potential and habitat associations of shrubland birds and other priority species on small, diversified farms, we conducted point counts and vegetation surveys across 23 farms in the Pioneer Valley, MA during the summers of 2017 and 2018. We used Poisson-binomial mixture models and canonical correspondence analysis (CCA) to assess the effects of a suite of microhabitat-, field-, and landscape-scale variables on the abundance of bird species. Our results confirmed that shrubland birds, including song sparrow (Melospiza melodia), gray catbird (Dumatella carolinensis), common yellowthroat (Geothlypis trichas) and American goldfinch (Spinus tristis), were the predominant species present, accounting for over 52% of the total observations. Species-habitat relationships were diverse; however, smaller field sizes, and increased cover of tall, dense, woody or nonproductive vegetation types were associated with higher abundance of shrubland species as well as lower abundance of crop pests such as European starling (Sturnus vulgaris) and house sparrow (Passer domesticus). These findings support the hypothesis that small, diversified farms are providing beneficial habitat for shrubland birds, as well as providing species-specific guidelines for farmers interested in conserving birds on their land. In order to place small, diversified farms into a regional conservation context and evaluate their contribution to shrubland bird conservation efforts in New England, we compared bird abundance, community composition, and conservation value of small, diversified farms to five established shrubland habitat types in the region: wildlife openings, two types of silvicultural openings (larger clearcuts and small forest openings created by group selection harvest), beaver meadows, and powerline rights-of-way. We compiled avian survey data from previous studies of each of the aforementioned habitat types conducted from 2002-2006 (powerline rights-of-way, wildlife openings, clearcuts, and beaver meadows) and 2014 (small forest openings). We then compared the relative bird abundance, community composition, and conservation value across all five habitat types (including farms) using Generalized Linear Models (GLMs), non-metric multidimensional scaling (NMDS) ordination, permutational multivariate analysis of variance (PERMANOVA), and calculated an Avian Conservation Significance (ACS) score for each habitat. The avian community composition of farms most closely resembled that of wildlife openings and harbored more open-habitat and generalist species such as American robin (Turdus migratorius), red-winged blackbird (Agelaius phoeniceus), and eastern kingbird (Tyrannus tyrannus). Several shrubland species were found to have higher relative abundances on farms than any of the other four habitats including song sparrow (Melospiza melodia), northern cardinal (Cardinalis cardinalis), and willow flycatcher (Empidonax traillii). Farms possessed a higher ACS score than powerline rights-of-way, small forest openings, and beaver meadows, but were lower than clearcuts and wildlife openings. Our results suggest that small, diversified farms support a unique suite of shrubland species, and while they certainly cannot replace managed shrubland habitats such as wildlife openings and clearcuts, they may complement these existing habitats in terms of their community composition and conservation value.

Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal.

Made available in DSpace on 2014-06-11T19:30:55Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-02-25Bitstream added on 2014-06-13T19:01:01Z : No. of bitstreams: 1 bispo_aa_dr_sjrp.pdf: 1875837 bytes, checksum: 6139dc36c7ba0eb1ab24a12c0fbae7ad (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / A fragmentação florestal é uma das principais ameaças a diversidade de aves sendo responsável por grande parte das extinções de espécies em florestas tropicais. Os efeitos da fragmentação florestal sobre a diversidade de espécies em remanescentes devem ser analisados em diferentes escalas com a finalidade de uma melhor interpretação de suas conseqüências sobre cada espécie ou grupo de espécies. Desta forma, este estudo procurou responder três perguntas que geraram as hipóteses de trabalho desenvolvidas em cada capítulo. 1) Quais espécies ocorrem na região noroeste do estado de São Paulo? 2) Como a paisagem do entorno dos remanescentes florestais influencia a riqueza e os grupos funcionais de aves? 3) Na escala do fragmento, como as variáveis ambientais influenciam a riqueza de espécies e a distribuição dos grupos funcionais nos remanescentes florestais? As respostas dessas perguntas seguem um gradiente de relação, de um fator regional até o local. Foram registradas 328 espécies para a região. As origens dos registros permitiram supor que os exclusivamente históricos foram de espécies que não ocorram mais localmente. Essas espécies apresentaram uma forte relação com as categorias propostas, sendo que 75% delas possuem algum tipo de dependência com o ambiente florestal, 63% estão categorizadas como ameaçadas de extinção para o estado de São Paulo e 34% pertencem a algum centro de endemismo. Na escala da paisagem, a distância adotada como paisagem de entorno e os requerimentos ecológicos de cada grupo funcional são responsáveis pelas relações com os componentes da paisagem. Na escala do fragmento, as similaridades entre os remanescentes florestais de acordo com as variáveis estruturais e os grupos funcionais nem sempre foram concordantes. As relações positivas entre o tamanho de área e porcentagem de área nuclear com a riqueza... / Forest fragmentation is one of the major threats to bird diversity and is responsible for most of the extinctions of species in tropical forests. The effects of forest fragmentation on the species diversity in forest remnants should be analyzed at different scales in order to a better interpretation of the consequences for each species or species groups. The presented thesis was therefore structured in three chapters that address questions which reflect these differente scales 1) Which species occur in the northwestern region of the state of São Paulo? 2) How influences the landscapes the species richness and the functional groups of birds? 3) How are species richness and distribution of functional groups in forest remnants influenced by environmental variables on the patch scale? The answers to these questions follow a gradient, of a regional to a local scale. The records of our assessment and former studies, performed in this region, include 328 species for the northwestern region, but show discrepancies in species composition between the former and the present status. Some species have thus apparently vanished regionally. We structured the records in three categories representing forest dependence, threat status, and endemism. The species that have regionally vanished show a strong relationship with the categories: 75% depend somehow on the forest habitat, 63% are categorized as endangered in the state of São Paulo, and 34% are endemic to four endemism centers. At the landscape scale, the surrounding landscape and the ecological requirements of each functional group describe the relations of bird functional groups and bird species richness to the components of the landscape. On patch scale the multivariate analysis showed that the similarities between remnants according structural variable and functional groups, sometimes disagree. The positive relationship... (Complete abstract click electronic access below)

Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal

The local extinction of habitat patches and dispersal between the patches are important processes structuring animal populations in heterogeneous environments. Understanding these two processes is crucial for the conservation of wildlife populations in landscapes impacted by human land-use. Approximately 50% of the subtropical rainforest in South East Queensland, Australia has been lost to deforestation over the last 100 years. While large areas of rainforest are reserved, little is known about the distribution and population status of rainforest birds within smaller remnants in the region. The overall research problem for this thesis was to understand how deforestation and fragmentation of subtropical rainforest affects the occurrence of rainforest birds and the effective dispersal of a rainforest-restricted species, the logrunner (Orthonyx temminckii). Understanding why some bird species are lost from habitat patches while others remain will lead to improved conservation of extinction prone species in fragmented landscapes. Although the mechanisms underlying local extinctions are well established in temperate systems, the relative importance of local and regional processes on species occurrence in subtropical and tropical rainforests is poorly understood. Chapter 2 investigated the relative effects of life history and scale of habitat modification on avian site occupancy using observational data collected at 46 rainforest sites in South East Queensland. A probabilistic model for the joint site occupancy of 29 bird species was used to evaluate hypotheses for the effects of avian life history traits on the occurrence of multiple species. The single-species occurrence models incorporated habitat effects on detection, which may be especially important in rainforests because dense vegetation and idiosyncratic occurrence of species can interfere with sampling. Occupancy rates for each species were modelled to determine the relative influence of process operating at the stand, landscape and patch scales. The life history analysis indicated taxonomic Family, body mass, migratory strategy and feeding strata had large effects on avian site occupancy, whereas abundance traits such as mean density and extent of occurrence showed little predictive ability. After accounting for correlated extinction risk attributed to life history, the degradation of stand structure at the local scale was more important for species richness than habitat modification at landscape or patch scales. While individual species showed various responses to the different scales of habitat modification, the distribution of many species was limited by vegetation structure at the landscape scale. Maintaining stand basal area and restoring degraded rainforests at the local scale will increase the probability of occupancy for members of the rainforest bird community. However, revegetation and retention of forest cover at the landscape scale may be necessary for the successful colonisation of many species. Chapter 3 introduced a predictive hypothesis-driven approach for quantifying the relative contribution of historic and contemporary processes to genetic connectivity. Current analytic frameworks in population genetics have difficulty evaluating meaningful hypotheses about spatial processes in dynamic landscapes. Confronting genetic data with models of historic and contemporary landscapes allowed the identification of dispersal processes operating in naturally heterogeneous and human-altered systems. Two measures of indirect gene flow were estimated from microsatellite polymorphism among 11 logrunner populations. Of particular interest was how much information in the genetic data was attributable to processes occurring in a reconstructed historic landscape and a contemporary human-modified landscape. A linear mixed model was used to estimate appropriate sampling variance from non-independent data and information-theoretic model selection provided strength of evidence for alternate hypotheses. The historic and contemporary landscapes explained an equal proportion of variation in genetic differentiation and there was considerable evidence for a temporal shift in dispersal pattern. Migration rates estimated from genealogical information were primarily influenced by contemporary landscape change. Landscape heterogeneity appeared to facilitate gene flow prior to European settlement, but contemporary deforestation is rapidly becoming the most important barrier to logrunner dispersal. Understanding asymmetric dispersal is becoming an important consideration for the conservation metapopulations. Populations acting as net exporters of dispersing animals may be able to rescue local populations from extinction and allow metapopulations to persist in degraded landscapes impacted by habitat loss. In Chapter 4, I estimated bidirectional migration rates from genetic data to infer dispersal among 11 logrunner populations. The first question posed was, does logrunner dispersal correspond to the source-sink or balanced model of dispersal? The second question involved determining the strength of evidence for two hypotheses about how landscape structure has affected asymmetric dispersal. Hypothesis one proposed that asymmetric dispersal was primarily influenced by naturally occurring habitat heterogeneity. Hypothesis two asserted that asymmetric dispersal was predominantly influenced by anthropogenic landscape change. The data were confronted with the alternate hypotheses using linear mixed models and landscape covariates extracted from digital maps. The results showed the direction of asymmetric dispersal was consistent with source-sink population structure. I also discovered that the asymmetry in dispersal was influenced more by anthropogenic landscape change than by naturally occurring habitat heterogeneity. Intact landscapes were net exporters of dispersing logrunners while landscapes heavily impacted by rainforest clearing were net importers of individuals. Elevated immigration rates into landscapes impacted by rainforest clearing appeared to arrest population declines in accordance with the rescue effect. The primary conclusion emerging from the study of patch occupancy and dispersal was that logrunner populations in South East Queensland conformed to a mainland-island metapopulation. Asymmetric dispersal from the largest expanse of upland rainforest appeared to prevent fragmented rainforests in close proximity from going locally extinct. While the distribution of logrunners was limited by the spatial configuration of rainforest patches, other rainforest birds exhibited variable responses to scale of habitat modification. The most consistent pattern was several species dropping-out of the community in degraded stands affected by selective timber harvest. Deforestation at the landscape scale also played a role in the extremely low patch occupancy rates of Albert’s lyrebirds (Menura alberti) and green catbirds (Ailuroedus crassirostris).

The local extinction of habitat patches and dispersal between the patches are important processes structuring animal populations in heterogeneous environments. Understanding these two processes is crucial for the conservation of wildlife populations in landscapes impacted by human land-use. Approximately 50% of the subtropical rainforest in South East Queensland, Australia has been lost to deforestation over the last 100 years. While large areas of rainforest are reserved, little is known about the distribution and population status of rainforest birds within smaller remnants in the region. The overall research problem for this thesis was to understand how deforestation and fragmentation of subtropical rainforest affects the occurrence of rainforest birds and the effective dispersal of a rainforest-restricted species, the logrunner (Orthonyx temminckii). Understanding why some bird species are lost from habitat patches while others remain will lead to improved conservation of extinction prone species in fragmented landscapes. Although the mechanisms underlying local extinctions are well established in temperate systems, the relative importance of local and regional processes on species occurrence in subtropical and tropical rainforests is poorly understood. Chapter 2 investigated the relative effects of life history and scale of habitat modification on avian site occupancy using observational data collected at 46 rainforest sites in South East Queensland. A probabilistic model for the joint site occupancy of 29 bird species was used to evaluate hypotheses for the effects of avian life history traits on the occurrence of multiple species. The single-species occurrence models incorporated habitat effects on detection, which may be especially important in rainforests because dense vegetation and idiosyncratic occurrence of species can interfere with sampling. Occupancy rates for each species were modelled to determine the relative influence of process operating at the stand, landscape and patch scales. The life history analysis indicated taxonomic Family, body mass, migratory strategy and feeding strata had large effects on avian site occupancy, whereas abundance traits such as mean density and extent of occurrence showed little predictive ability. After accounting for correlated extinction risk attributed to life history, the degradation of stand structure at the local scale was more important for species richness than habitat modification at landscape or patch scales. While individual species showed various responses to the different scales of habitat modification, the distribution of many species was limited by vegetation structure at the landscape scale. Maintaining stand basal area and restoring degraded rainforests at the local scale will increase the probability of occupancy for members of the rainforest bird community. However, revegetation and retention of forest cover at the landscape scale may be necessary for the successful colonisation of many species. Chapter 3 introduced a predictive hypothesis-driven approach for quantifying the relative contribution of historic and contemporary processes to genetic connectivity. Current analytic frameworks in population genetics have difficulty evaluating meaningful hypotheses about spatial processes in dynamic landscapes. Confronting genetic data with models of historic and contemporary landscapes allowed the identification of dispersal processes operating in naturally heterogeneous and human-altered systems. Two measures of indirect gene flow were estimated from microsatellite polymorphism among 11 logrunner populations. Of particular interest was how much information in the genetic data was attributable to processes occurring in a reconstructed historic landscape and a contemporary human-modified landscape. A linear mixed model was used to estimate appropriate sampling variance from non-independent data and information-theoretic model selection provided strength of evidence for alternate hypotheses. The historic and contemporary landscapes explained an equal proportion of variation in genetic differentiation and there was considerable evidence for a temporal shift in dispersal pattern. Migration rates estimated from genealogical information were primarily influenced by contemporary landscape change. Landscape heterogeneity appeared to facilitate gene flow prior to European settlement, but contemporary deforestation is rapidly becoming the most important barrier to logrunner dispersal. Understanding asymmetric dispersal is becoming an important consideration for the conservation metapopulations. Populations acting as net exporters of dispersing animals may be able to rescue local populations from extinction and allow metapopulations to persist in degraded landscapes impacted by habitat loss. In Chapter 4, I estimated bidirectional migration rates from genetic data to infer dispersal among 11 logrunner populations. The first question posed was, does logrunner dispersal correspond to the source-sink or balanced model of dispersal? The second question involved determining the strength of evidence for two hypotheses about how landscape structure has affected asymmetric dispersal. Hypothesis one proposed that asymmetric dispersal was primarily influenced by naturally occurring habitat heterogeneity. Hypothesis two asserted that asymmetric dispersal was predominantly influenced by anthropogenic landscape change. The data were confronted with the alternate hypotheses using linear mixed models and landscape covariates extracted from digital maps. The results showed the direction of asymmetric dispersal was consistent with source-sink population structure. I also discovered that the asymmetry in dispersal was influenced more by anthropogenic landscape change than by naturally occurring habitat heterogeneity. Intact landscapes were net exporters of dispersing logrunners while landscapes heavily impacted by rainforest clearing were net importers of individuals. Elevated immigration rates into landscapes impacted by rainforest clearing appeared to arrest population declines in accordance with the rescue effect. The primary conclusion emerging from the study of patch occupancy and dispersal was that logrunner populations in South East Queensland conformed to a mainland-island metapopulation. Asymmetric dispersal from the largest expanse of upland rainforest appeared to prevent fragmented rainforests in close proximity from going locally extinct. While the distribution of logrunners was limited by the spatial configuration of rainforest patches, other rainforest birds exhibited variable responses to scale of habitat modification. The most consistent pattern was several species dropping-out of the community in degraded stands affected by selective timber harvest. Deforestation at the landscape scale also played a role in the extremely low patch occupancy rates of Albert’s lyrebirds (Menura alberti) and green catbirds (Ailuroedus crassirostris).

The local extinction of habitat patches and dispersal between the patches are important processes structuring animal populations in heterogeneous environments. Understanding these two processes is crucial for the conservation of wildlife populations in landscapes impacted by human land-use. Approximately 50% of the subtropical rainforest in South East Queensland, Australia has been lost to deforestation over the last 100 years. While large areas of rainforest are reserved, little is known about the distribution and population status of rainforest birds within smaller remnants in the region. The overall research problem for this thesis was to understand how deforestation and fragmentation of subtropical rainforest affects the occurrence of rainforest birds and the effective dispersal of a rainforest-restricted species, the logrunner (Orthonyx temminckii). Understanding why some bird species are lost from habitat patches while others remain will lead to improved conservation of extinction prone species in fragmented landscapes. Although the mechanisms underlying local extinctions are well established in temperate systems, the relative importance of local and regional processes on species occurrence in subtropical and tropical rainforests is poorly understood. Chapter 2 investigated the relative effects of life history and scale of habitat modification on avian site occupancy using observational data collected at 46 rainforest sites in South East Queensland. A probabilistic model for the joint site occupancy of 29 bird species was used to evaluate hypotheses for the effects of avian life history traits on the occurrence of multiple species. The single-species occurrence models incorporated habitat effects on detection, which may be especially important in rainforests because dense vegetation and idiosyncratic occurrence of species can interfere with sampling. Occupancy rates for each species were modelled to determine the relative influence of process operating at the stand, landscape and patch scales. The life history analysis indicated taxonomic Family, body mass, migratory strategy and feeding strata had large effects on avian site occupancy, whereas abundance traits such as mean density and extent of occurrence showed little predictive ability. After accounting for correlated extinction risk attributed to life history, the degradation of stand structure at the local scale was more important for species richness than habitat modification at landscape or patch scales. While individual species showed various responses to the different scales of habitat modification, the distribution of many species was limited by vegetation structure at the landscape scale. Maintaining stand basal area and restoring degraded rainforests at the local scale will increase the probability of occupancy for members of the rainforest bird community. However, revegetation and retention of forest cover at the landscape scale may be necessary for the successful colonisation of many species. Chapter 3 introduced a predictive hypothesis-driven approach for quantifying the relative contribution of historic and contemporary processes to genetic connectivity. Current analytic frameworks in population genetics have difficulty evaluating meaningful hypotheses about spatial processes in dynamic landscapes. Confronting genetic data with models of historic and contemporary landscapes allowed the identification of dispersal processes operating in naturally heterogeneous and human-altered systems. Two measures of indirect gene flow were estimated from microsatellite polymorphism among 11 logrunner populations. Of particular interest was how much information in the genetic data was attributable to processes occurring in a reconstructed historic landscape and a contemporary human-modified landscape. A linear mixed model was used to estimate appropriate sampling variance from non-independent data and information-theoretic model selection provided strength of evidence for alternate hypotheses. The historic and contemporary landscapes explained an equal proportion of variation in genetic differentiation and there was considerable evidence for a temporal shift in dispersal pattern. Migration rates estimated from genealogical information were primarily influenced by contemporary landscape change. Landscape heterogeneity appeared to facilitate gene flow prior to European settlement, but contemporary deforestation is rapidly becoming the most important barrier to logrunner dispersal. Understanding asymmetric dispersal is becoming an important consideration for the conservation metapopulations. Populations acting as net exporters of dispersing animals may be able to rescue local populations from extinction and allow metapopulations to persist in degraded landscapes impacted by habitat loss. In Chapter 4, I estimated bidirectional migration rates from genetic data to infer dispersal among 11 logrunner populations. The first question posed was, does logrunner dispersal correspond to the source-sink or balanced model of dispersal? The second question involved determining the strength of evidence for two hypotheses about how landscape structure has affected asymmetric dispersal. Hypothesis one proposed that asymmetric dispersal was primarily influenced by naturally occurring habitat heterogeneity. Hypothesis two asserted that asymmetric dispersal was predominantly influenced by anthropogenic landscape change. The data were confronted with the alternate hypotheses using linear mixed models and landscape covariates extracted from digital maps. The results showed the direction of asymmetric dispersal was consistent with source-sink population structure. I also discovered that the asymmetry in dispersal was influenced more by anthropogenic landscape change than by naturally occurring habitat heterogeneity. Intact landscapes were net exporters of dispersing logrunners while landscapes heavily impacted by rainforest clearing were net importers of individuals. Elevated immigration rates into landscapes impacted by rainforest clearing appeared to arrest population declines in accordance with the rescue effect. The primary conclusion emerging from the study of patch occupancy and dispersal was that logrunner populations in South East Queensland conformed to a mainland-island metapopulation. Asymmetric dispersal from the largest expanse of upland rainforest appeared to prevent fragmented rainforests in close proximity from going locally extinct. While the distribution of logrunners was limited by the spatial configuration of rainforest patches, other rainforest birds exhibited variable responses to scale of habitat modification. The most consistent pattern was several species dropping-out of the community in degraded stands affected by selective timber harvest. Deforestation at the landscape scale also played a role in the extremely low patch occupancy rates of Albert’s lyrebirds (Menura alberti) and green catbirds (Ailuroedus crassirostris).

The local extinction of habitat patches and dispersal between the patches are important processes structuring animal populations in heterogeneous environments. Understanding these two processes is crucial for the conservation of wildlife populations in landscapes impacted by human land-use. Approximately 50% of the subtropical rainforest in South East Queensland, Australia has been lost to deforestation over the last 100 years. While large areas of rainforest are reserved, little is known about the distribution and population status of rainforest birds within smaller remnants in the region. The overall research problem for this thesis was to understand how deforestation and fragmentation of subtropical rainforest affects the occurrence of rainforest birds and the effective dispersal of a rainforest-restricted species, the logrunner (Orthonyx temminckii). Understanding why some bird species are lost from habitat patches while others remain will lead to improved conservation of extinction prone species in fragmented landscapes. Although the mechanisms underlying local extinctions are well established in temperate systems, the relative importance of local and regional processes on species occurrence in subtropical and tropical rainforests is poorly understood. Chapter 2 investigated the relative effects of life history and scale of habitat modification on avian site occupancy using observational data collected at 46 rainforest sites in South East Queensland. A probabilistic model for the joint site occupancy of 29 bird species was used to evaluate hypotheses for the effects of avian life history traits on the occurrence of multiple species. The single-species occurrence models incorporated habitat effects on detection, which may be especially important in rainforests because dense vegetation and idiosyncratic occurrence of species can interfere with sampling. Occupancy rates for each species were modelled to determine the relative influence of process operating at the stand, landscape and patch scales. The life history analysis indicated taxonomic Family, body mass, migratory strategy and feeding strata had large effects on avian site occupancy, whereas abundance traits such as mean density and extent of occurrence showed little predictive ability. After accounting for correlated extinction risk attributed to life history, the degradation of stand structure at the local scale was more important for species richness than habitat modification at landscape or patch scales. While individual species showed various responses to the different scales of habitat modification, the distribution of many species was limited by vegetation structure at the landscape scale. Maintaining stand basal area and restoring degraded rainforests at the local scale will increase the probability of occupancy for members of the rainforest bird community. However, revegetation and retention of forest cover at the landscape scale may be necessary for the successful colonisation of many species. Chapter 3 introduced a predictive hypothesis-driven approach for quantifying the relative contribution of historic and contemporary processes to genetic connectivity. Current analytic frameworks in population genetics have difficulty evaluating meaningful hypotheses about spatial processes in dynamic landscapes. Confronting genetic data with models of historic and contemporary landscapes allowed the identification of dispersal processes operating in naturally heterogeneous and human-altered systems. Two measures of indirect gene flow were estimated from microsatellite polymorphism among 11 logrunner populations. Of particular interest was how much information in the genetic data was attributable to processes occurring in a reconstructed historic landscape and a contemporary human-modified landscape. A linear mixed model was used to estimate appropriate sampling variance from non-independent data and information-theoretic model selection provided strength of evidence for alternate hypotheses. The historic and contemporary landscapes explained an equal proportion of variation in genetic differentiation and there was considerable evidence for a temporal shift in dispersal pattern. Migration rates estimated from genealogical information were primarily influenced by contemporary landscape change. Landscape heterogeneity appeared to facilitate gene flow prior to European settlement, but contemporary deforestation is rapidly becoming the most important barrier to logrunner dispersal. Understanding asymmetric dispersal is becoming an important consideration for the conservation metapopulations. Populations acting as net exporters of dispersing animals may be able to rescue local populations from extinction and allow metapopulations to persist in degraded landscapes impacted by habitat loss. In Chapter 4, I estimated bidirectional migration rates from genetic data to infer dispersal among 11 logrunner populations. The first question posed was, does logrunner dispersal correspond to the source-sink or balanced model of dispersal? The second question involved determining the strength of evidence for two hypotheses about how landscape structure has affected asymmetric dispersal. Hypothesis one proposed that asymmetric dispersal was primarily influenced by naturally occurring habitat heterogeneity. Hypothesis two asserted that asymmetric dispersal was predominantly influenced by anthropogenic landscape change. The data were confronted with the alternate hypotheses using linear mixed models and landscape covariates extracted from digital maps. The results showed the direction of asymmetric dispersal was consistent with source-sink population structure. I also discovered that the asymmetry in dispersal was influenced more by anthropogenic landscape change than by naturally occurring habitat heterogeneity. Intact landscapes were net exporters of dispersing logrunners while landscapes heavily impacted by rainforest clearing were net importers of individuals. Elevated immigration rates into landscapes impacted by rainforest clearing appeared to arrest population declines in accordance with the rescue effect. The primary conclusion emerging from the study of patch occupancy and dispersal was that logrunner populations in South East Queensland conformed to a mainland-island metapopulation. Asymmetric dispersal from the largest expanse of upland rainforest appeared to prevent fragmented rainforests in close proximity from going locally extinct. While the distribution of logrunners was limited by the spatial configuration of rainforest patches, other rainforest birds exhibited variable responses to scale of habitat modification. The most consistent pattern was several species dropping-out of the community in degraded stands affected by selective timber harvest. Deforestation at the landscape scale also played a role in the extremely low patch occupancy rates of Albert’s lyrebirds (Menura alberti) and green catbirds (Ailuroedus crassirostris).

The local extinction of habitat patches and dispersal between the patches are important processes structuring animal populations in heterogeneous environments. Understanding these two processes is crucial for the conservation of wildlife populations in landscapes impacted by human land-use. Approximately 50% of the subtropical rainforest in South East Queensland, Australia has been lost to deforestation over the last 100 years. While large areas of rainforest are reserved, little is known about the distribution and population status of rainforest birds within smaller remnants in the region. The overall research problem for this thesis was to understand how deforestation and fragmentation of subtropical rainforest affects the occurrence of rainforest birds and the effective dispersal of a rainforest-restricted species, the logrunner (Orthonyx temminckii). Understanding why some bird species are lost from habitat patches while others remain will lead to improved conservation of extinction prone species in fragmented landscapes. Although the mechanisms underlying local extinctions are well established in temperate systems, the relative importance of local and regional processes on species occurrence in subtropical and tropical rainforests is poorly understood. Chapter 2 investigated the relative effects of life history and scale of habitat modification on avian site occupancy using observational data collected at 46 rainforest sites in South East Queensland. A probabilistic model for the joint site occupancy of 29 bird species was used to evaluate hypotheses for the effects of avian life history traits on the occurrence of multiple species. The single-species occurrence models incorporated habitat effects on detection, which may be especially important in rainforests because dense vegetation and idiosyncratic occurrence of species can interfere with sampling. Occupancy rates for each species were modelled to determine the relative influence of process operating at the stand, landscape and patch scales. The life history analysis indicated taxonomic Family, body mass, migratory strategy and feeding strata had large effects on avian site occupancy, whereas abundance traits such as mean density and extent of occurrence showed little predictive ability. After accounting for correlated extinction risk attributed to life history, the degradation of stand structure at the local scale was more important for species richness than habitat modification at landscape or patch scales. While individual species showed various responses to the different scales of habitat modification, the distribution of many species was limited by vegetation structure at the landscape scale. Maintaining stand basal area and restoring degraded rainforests at the local scale will increase the probability of occupancy for members of the rainforest bird community. However, revegetation and retention of forest cover at the landscape scale may be necessary for the successful colonisation of many species. Chapter 3 introduced a predictive hypothesis-driven approach for quantifying the relative contribution of historic and contemporary processes to genetic connectivity. Current analytic frameworks in population genetics have difficulty evaluating meaningful hypotheses about spatial processes in dynamic landscapes. Confronting genetic data with models of historic and contemporary landscapes allowed the identification of dispersal processes operating in naturally heterogeneous and human-altered systems. Two measures of indirect gene flow were estimated from microsatellite polymorphism among 11 logrunner populations. Of particular interest was how much information in the genetic data was attributable to processes occurring in a reconstructed historic landscape and a contemporary human-modified landscape. A linear mixed model was used to estimate appropriate sampling variance from non-independent data and information-theoretic model selection provided strength of evidence for alternate hypotheses. The historic and contemporary landscapes explained an equal proportion of variation in genetic differentiation and there was considerable evidence for a temporal shift in dispersal pattern. Migration rates estimated from genealogical information were primarily influenced by contemporary landscape change. Landscape heterogeneity appeared to facilitate gene flow prior to European settlement, but contemporary deforestation is rapidly becoming the most important barrier to logrunner dispersal. Understanding asymmetric dispersal is becoming an important consideration for the conservation metapopulations. Populations acting as net exporters of dispersing animals may be able to rescue local populations from extinction and allow metapopulations to persist in degraded landscapes impacted by habitat loss. In Chapter 4, I estimated bidirectional migration rates from genetic data to infer dispersal among 11 logrunner populations. The first question posed was, does logrunner dispersal correspond to the source-sink or balanced model of dispersal? The second question involved determining the strength of evidence for two hypotheses about how landscape structure has affected asymmetric dispersal. Hypothesis one proposed that asymmetric dispersal was primarily influenced by naturally occurring habitat heterogeneity. Hypothesis two asserted that asymmetric dispersal was predominantly influenced by anthropogenic landscape change. The data were confronted with the alternate hypotheses using linear mixed models and landscape covariates extracted from digital maps. The results showed the direction of asymmetric dispersal was consistent with source-sink population structure. I also discovered that the asymmetry in dispersal was influenced more by anthropogenic landscape change than by naturally occurring habitat heterogeneity. Intact landscapes were net exporters of dispersing logrunners while landscapes heavily impacted by rainforest clearing were net importers of individuals. Elevated immigration rates into landscapes impacted by rainforest clearing appeared to arrest population declines in accordance with the rescue effect. The primary conclusion emerging from the study of patch occupancy and dispersal was that logrunner populations in South East Queensland conformed to a mainland-island metapopulation. Asymmetric dispersal from the largest expanse of upland rainforest appeared to prevent fragmented rainforests in close proximity from going locally extinct. While the distribution of logrunners was limited by the spatial configuration of rainforest patches, other rainforest birds exhibited variable responses to scale of habitat modification. The most consistent pattern was several species dropping-out of the community in degraded stands affected by selective timber harvest. Deforestation at the landscape scale also played a role in the extremely low patch occupancy rates of Albert’s lyrebirds (Menura alberti) and green catbirds (Ailuroedus crassirostris).

The local extinction of habitat patches and dispersal between the patches are important processes structuring animal populations in heterogeneous environments. Understanding these two processes is crucial for the conservation of wildlife populations in landscapes impacted by human land-use. Approximately 50% of the subtropical rainforest in South East Queensland, Australia has been lost to deforestation over the last 100 years. While large areas of rainforest are reserved, little is known about the distribution and population status of rainforest birds within smaller remnants in the region. The overall research problem for this thesis was to understand how deforestation and fragmentation of subtropical rainforest affects the occurrence of rainforest birds and the effective dispersal of a rainforest-restricted species, the logrunner (Orthonyx temminckii). Understanding why some bird species are lost from habitat patches while others remain will lead to improved conservation of extinction prone species in fragmented landscapes. Although the mechanisms underlying local extinctions are well established in temperate systems, the relative importance of local and regional processes on species occurrence in subtropical and tropical rainforests is poorly understood. Chapter 2 investigated the relative effects of life history and scale of habitat modification on avian site occupancy using observational data collected at 46 rainforest sites in South East Queensland. A probabilistic model for the joint site occupancy of 29 bird species was used to evaluate hypotheses for the effects of avian life history traits on the occurrence of multiple species. The single-species occurrence models incorporated habitat effects on detection, which may be especially important in rainforests because dense vegetation and idiosyncratic occurrence of species can interfere with sampling. Occupancy rates for each species were modelled to determine the relative influence of process operating at the stand, landscape and patch scales. The life history analysis indicated taxonomic Family, body mass, migratory strategy and feeding strata had large effects on avian site occupancy, whereas abundance traits such as mean density and extent of occurrence showed little predictive ability. After accounting for correlated extinction risk attributed to life history, the degradation of stand structure at the local scale was more important for species richness than habitat modification at landscape or patch scales. While individual species showed various responses to the different scales of habitat modification, the distribution of many species was limited by vegetation structure at the landscape scale. Maintaining stand basal area and restoring degraded rainforests at the local scale will increase the probability of occupancy for members of the rainforest bird community. However, revegetation and retention of forest cover at the landscape scale may be necessary for the successful colonisation of many species. Chapter 3 introduced a predictive hypothesis-driven approach for quantifying the relative contribution of historic and contemporary processes to genetic connectivity. Current analytic frameworks in population genetics have difficulty evaluating meaningful hypotheses about spatial processes in dynamic landscapes. Confronting genetic data with models of historic and contemporary landscapes allowed the identification of dispersal processes operating in naturally heterogeneous and human-altered systems. Two measures of indirect gene flow were estimated from microsatellite polymorphism among 11 logrunner populations. Of particular interest was how much information in the genetic data was attributable to processes occurring in a reconstructed historic landscape and a contemporary human-modified landscape. A linear mixed model was used to estimate appropriate sampling variance from non-independent data and information-theoretic model selection provided strength of evidence for alternate hypotheses. The historic and contemporary landscapes explained an equal proportion of variation in genetic differentiation and there was considerable evidence for a temporal shift in dispersal pattern. Migration rates estimated from genealogical information were primarily influenced by contemporary landscape change. Landscape heterogeneity appeared to facilitate gene flow prior to European settlement, but contemporary deforestation is rapidly becoming the most important barrier to logrunner dispersal. Understanding asymmetric dispersal is becoming an important consideration for the conservation metapopulations. Populations acting as net exporters of dispersing animals may be able to rescue local populations from extinction and allow metapopulations to persist in degraded landscapes impacted by habitat loss. In Chapter 4, I estimated bidirectional migration rates from genetic data to infer dispersal among 11 logrunner populations. The first question posed was, does logrunner dispersal correspond to the source-sink or balanced model of dispersal? The second question involved determining the strength of evidence for two hypotheses about how landscape structure has affected asymmetric dispersal. Hypothesis one proposed that asymmetric dispersal was primarily influenced by naturally occurring habitat heterogeneity. Hypothesis two asserted that asymmetric dispersal was predominantly influenced by anthropogenic landscape change. The data were confronted with the alternate hypotheses using linear mixed models and landscape covariates extracted from digital maps. The results showed the direction of asymmetric dispersal was consistent with source-sink population structure. I also discovered that the asymmetry in dispersal was influenced more by anthropogenic landscape change than by naturally occurring habitat heterogeneity. Intact landscapes were net exporters of dispersing logrunners while landscapes heavily impacted by rainforest clearing were net importers of individuals. Elevated immigration rates into landscapes impacted by rainforest clearing appeared to arrest population declines in accordance with the rescue effect. The primary conclusion emerging from the study of patch occupancy and dispersal was that logrunner populations in South East Queensland conformed to a mainland-island metapopulation. Asymmetric dispersal from the largest expanse of upland rainforest appeared to prevent fragmented rainforests in close proximity from going locally extinct. While the distribution of logrunners was limited by the spatial configuration of rainforest patches, other rainforest birds exhibited variable responses to scale of habitat modification. The most consistent pattern was several species dropping-out of the community in degraded stands affected by selective timber harvest. Deforestation at the landscape scale also played a role in the extremely low patch occupancy rates of Albert’s lyrebirds (Menura alberti) and green catbirds (Ailuroedus crassirostris).