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1
Schumaker, Nathan H. "Habitat connectivity and spotted owl population dynamics /." Thesis, Connect to this title online; UW restricted, 1995. http://hdl.handle.net/1773/5524.
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Barlow, Emily J. "Ecological and genetic perspectives on dispersal in European shags (Phalacrocorax aristotelis)." Thesis, University of Aberdeen, 2011. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=182248.
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Dispersal is a fundamental ecological and evolutionary process that can create demographic and genetic linkage between neighbouring and distant locations, influencing the dynamics, structure and ultimately the persistence of populations. To understand observed population dynamics and structure and to predict future change, accurate and comprehensive data are required describing the pattern and magnitude of dispersal and gene flow across all relevant spatial scales. However, this is a major empirical challenge. In this thesis, I aimed to obtain comprehensive empirical data quantifying natal dispersal patterns and population genetic structure across multiple spatial scales using the European shag (Phalacrocorax aristotelis) as a model species. I used a combination of field observations of shags individually ringed on the Isle of May, Scotland and molecular genetic techniques to accomplish these aims. By locating adult shags that had been ringed as chicks on the Isle of May at their breeding locations across eastern Scotland, I demonstrated divergent dispersal distributions at small versus large spatial scales. Using both mitochondrial DNA markers and a newly developed set of microsatellite markers, I quantified population genetic structure across a pan-European scale. This was weak across both molecular markers suggesting a role for occasional effective long-distance dispersal. However, a suite of evolutionary forces besides gene flow can create observed population genetic structure. Therefore, I quantified population genetic structure across populations in eastern Scotland, and quantitatively linked this indirect estimate of gene flow with my direct field observations of dispersal. Dispersal parameters derived explicitly from field observations and the spatial organisation of populations were shown to strongly influence observed population genetic structure. Overall, these data demonstrate the need to utilise both field observations and genetic methods to comprehensively estimate the extent and effectiveness of dispersal and highlight the importance of accurately quantifying long-distance dispersal in particular for predicting future change.
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Simmonds, Emily G. "Exploring the causes and consequences of phenological change in a wild bird population." Thesis, University of Oxford, 2017. http://ora.ox.ac.uk/objects/uuid:89fb7855-fdd8-4f92-915c-8dd9e51a0edd.
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Changes in climate shape biological populations. They can alter spatial distributions, the timing of life history events, and even the species themselves. We are now experiencing a period of rapid directional climate change, alongside seasonal fluctuations. This thesis investigates temporal changes in life history events, phenology, as a climate response. I explore the causes and population level consequences of change in breeding phenology of two wild bird populations from Wytham Woods, UK. I test how great tits (Parus major) and blue tits (Cyanistes caeruleus) achieve temporal synchrony between the peak demands of their breeding and the peak abundance of their prey species (winter moth caterpillars - Operophtera brumata) in an inter-annually variable environment. I demonstrate great tit (Parus major) incubation behaviour fine-tunes the timing of hatching in response to ambient temperatures right up until hatching (Chapter two). Temperatures within the nest box, however, appear to play little role in the breeding phenology of blue tits (Cyanistes caeruleus) (Chapter two). I discuss the merits and limitations of statistical approaches for cue identification (Chapter six), finding the method and time period of data used both affect the cue identified and predictive accuracy. The second part of this thesis explores the influence of a directionally changing environment on great tit phenology. I use an integral projection model (IPM) to predict population dynamics over the 21st century, showing that if the cues used by both interacting species change sufficiently closely, temporal synchrony can be maintained through both phenotypic plasticity and micro-evolution (Chapter 5). However, if the cues diverge mismatch will arise (Chapter 5) causing population declines when certain thresholds are passed (Chapter 4). This work contributes to understanding how phenological synchrony is achieved, how it might change in the future, and its population impacts. In Wytham Woods it appears that great tits have a great deal of flexibility in multiple components of their breeding cycle, allowing them to retain synchrony with their caterpillar prey in a fluctuating environment. These birds are relatively resilient to negative phenological impacts from climate change. Only if the cues used by the predator and prey completely diverge do we predict consistent declines in population size during this century.
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Aguillon, Stepfanie Maria. "The influence of personality on dispersal and population dynamics in a passerine bird." Thesis, The University of Arizona, 2014. http://hdl.handle.net/10150/323420.
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Dispersal influences the genetic and social composition of populations, yet it has been difficult to understand the mechanisms underlying dispersal and this limits our ability to understand how dispersal may be influencing population dynamics. Behavioral traits, such as aggression, have been implicated as drivers of both dispersal and population dynamics. However, the influence on both has never been addressed in a single system. Western bluebirds (Sialia mexicana) provide an excellent opportunity to address this question, as their dispersal propensity is dependent upon aggressive phenotype and we have detailed observations over a period of more than a decade. I show that natal dispersal is influenced by an interaction between father and son aggressive phenotypes, in addition to available resources on the natal territory. Furthermore, population density is influenced by resource availability and an interaction between population aggression and recruitment of offspring as breeders. Males that breed for multiple seasons once the population has reached saturation recruit a higher proportion of offspring into the population, as do males that are nonaggressive. Males that are nonaggressive are more likely to breed for multiple seasons, which suggests an added cost to aggressive behavior in this species. Both aggressive behavior and the availability of resources are mechanisms influencing dispersal of individuals that manifest at the population scale.
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Catlin, Daniel Herbert. "Population Dynamics of Piping Plovers (Charadrius melodus) on the Missouri River." Diss., Virginia Tech, 2003. http://hdl.handle.net/10919/27442.
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Habitat loss and predation are threatening many shorebird populations worldwide. While habitat preservation often is preferable, sometimes habitat needs to be restored or created in order to stave off immediate declines. The Great Plains population of piping plovers (Charadrius melodus) was listed as threatened in 1986, and habitat loss and predation appear to be limiting the growth of this population. On the Missouri River, piping plovers nest on sandbars, but the damming of the mainstem of the Missouri in the mid-twentieth century reduced the natural capacity of the Missouri River to create sandbar habitat. In 2004, the United States Army Corps of Engineers (USACE) implemented a habitat creation project on the Gavins Point Reach of the Missouri River (stretch of river immediately downriver from the Gavins Point Dam) in an effort to promote recovery of piping plovers and the endangered least tern (Sternula antillarum). The USACE built 3 sandbars in 2004 â 2005 and built another sandbar on Lewis and Clark Lake in 2007. We studied the population dynamics of piping plovers in relationship to this newly engineered habitat. We monitored 623 nests on 16 sandbar complexes, to evaluate habitat selection, determine the factors affecting nesting success, and compare nesting success between natural and engineered habitat. From these 623 nests, we banded 357 adults and 685 chicks to investigate the factors affecting adult and juvenile survival. We used a logistic-exposure model to calculate nest survival. Adult and juvenile survival was calculated using Cormack-Jolly-Seber based models in Program MARK. We used the estimates from these studies to create a matrix population model for piping plovers nesting on the Gavins Point Reach. We used this model to predict the effects of engineered habitat on the population growth rate.
Piping plovers selected for engineered sandbars and against natural and natural/modified habitats. Daily survival rate (DSR) on engineered habitats was significantly higher than on natural or natural modified habitats (log odds: 2.71, 95% CI: 1.20 â 6.08). Predator exclosures around nests did not affect DSR after controlling for the effects of date, nest age, and clutch size. Piping plover juvenile survival to recruitment was negatively related to nesting density on the relatively densely populated engineered sandbars. On the less dense natural sandbars, survival to recruitment was positively correlated with density. Adult survival did not appear to be related to density within our study. Movement within the study area was related also to density. Juveniles from densely populated engineered sandbars were more likely to leave engineered habitat to nest on natural sandbars than were juveniles hatched on less densely populated engineered sandbars. Movements among sandbars by breeding adults suggested that adults preferred engineered habitat. It is possible that juveniles moved to natural habitats because they were unable to compete with adults for the more desirable engineered habitats. Adults and juveniles emigrated from the study area at a higher rate after the 2006 breeding season, a year when water discharge was higher, nesting densities were higher, and reproductive success was lower (as a result of predation) than in the other years. Deterministic modeling suggested that engineered habitat significantly increased population growth. Decreased productivity over time and associated predicted negative population growth suggest that the amount of engineered habitat created was inadequate to sustain population growth, and/or that relatively high water discharge and nesting densities coupled with low reproductive rates and high emigration rates could lead to rapid declines in the plover population. Continued research is needed to determine the effects of these factors on long-term population growth. Our results suggest that habitat creation could be a viable short-term solution to population declines in shorebird populations limited by habitat loss, but high densities and increased predation associated with habitat creation indicate that other, long-term solutions may be required.Ph. D.
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Catlin, Daniel H. "Population Dynamics of Piping Plovers (Charadrius melodus) on the Missouri River." Diss., Virginia Tech, 2009. http://hdl.handle.net/10919/27442.
Full textAbstract:
Habitat loss and predation are threatening many shorebird populations worldwide. While habitat preservation often is preferable, sometimes habitat needs to be restored or created in order to stave off immediate declines. The Great Plains population of piping plovers (Charadrius melodus) was listed as threatened in 1986, and habitat loss and predation appear to be limiting the growth of this population. On the Missouri River, piping plovers nest on sandbars, but the damming of the mainstem of the Missouri in the mid-twentieth century reduced the natural capacity of the Missouri River to create sandbar habitat. In 2004, the United States Army Corps of Engineers (USACE) implemented a habitat creation project on the Gavins Point Reach of the Missouri River (stretch of river immediately downriver from the Gavins Point Dam) in an effort to promote recovery of piping plovers and the endangered least tern (Sternula antillarum). The USACE built 3 sandbars in 2004 â 2005 and built another sandbar on Lewis and Clark Lake in 2007. We studied the population dynamics of piping plovers in relationship to this newly engineered habitat. We monitored 623 nests on 16 sandbar complexes, to evaluate habitat selection, determine the factors affecting nesting success, and compare nesting success between natural and engineered habitat. From these 623 nests, we banded 357 adults and 685 chicks to investigate the factors affecting adult and juvenile survival. We used a logistic-exposure model to calculate nest survival. Adult and juvenile survival was calculated using Cormack-Jolly-Seber based models in Program MARK. We used the estimates from these studies to create a matrix population model for piping plovers nesting on the Gavins Point Reach. We used this model to predict the effects of engineered habitat on the population growth rate.
Piping plovers selected for engineered sandbars and against natural and natural/modified habitats. Daily survival rate (DSR) on engineered habitats was significantly higher than on natural or natural modified habitats (log odds: 2.71, 95% CI: 1.20 â 6.08). Predator exclosures around nests did not affect DSR after controlling for the effects of date, nest age, and clutch size. Piping plover juvenile survival to recruitment was negatively related to nesting density on the relatively densely populated engineered sandbars. On the less dense natural sandbars, survival to recruitment was positively correlated with density. Adult survival did not appear to be related to density within our study. Movement within the study area was related also to density. Juveniles from densely populated engineered sandbars were more likely to leave engineered habitat to nest on natural sandbars than were juveniles hatched on less densely populated engineered sandbars. Movements among sandbars by breeding adults suggested that adults preferred engineered habitat. It is possible that juveniles moved to natural habitats because they were unable to compete with adults for the more desirable engineered habitats. Adults and juveniles emigrated from the study area at a higher rate after the 2006 breeding season, a year when water discharge was higher, nesting densities were higher, and reproductive success was lower (as a result of predation) than in the other years. Deterministic modeling suggested that engineered habitat significantly increased population growth. Decreased productivity over time and associated predicted negative population growth suggest that the amount of engineered habitat created was inadequate to sustain population growth, and/or that relatively high water discharge and nesting densities coupled with low reproductive rates and high emigration rates could lead to rapid declines in the plover population. Continued research is needed to determine the effects of these factors on long-term population growth. Our results suggest that habitat creation could be a viable short-term solution to population declines in shorebird populations limited by habitat loss, but high densities and increased predation associated with habitat creation indicate that other, long-term solutions may be required.Ph. D.
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Shephard, Jill, and n/a. "A Multi-Scale Approach to Defining Historical and Contemporary Factors Responsible for the Current Distribution of the White-bellied Sea-Eagle Haliaeetus leucogaster (Gmelin, 1788) in Australia." Griffith University. Australian School of Environmental Studies, 2004. http://www4.gu.edu.au:8080/adt-root/public/adt-QGU20041012.142221.
Full textAbstract:
The White-bellied Sea-Eagle Haliaeetus leucogaster is widespread in Australia, but has been the subject of conservation concern due to suggested localised declines and extinctions. Regionalised monitoring programmes have addressed some aspects of local concern, however a broader approach is needed to gain an understanding of large-scale processes affecting long-term persistence at scales equivalent to the species Australian range. Ultimately, the ability to predict change in population size over time accurately depends on the scale of analysis. By necessity, ecological studies using direct sampling techniques are often made across spatial scales smaller than a species geographic range and across relatively short time frames. This seems counter-intuitive considering that long-term species persistence is often dependent on large-scale processes. The principal aim of this thesis was to identify historical and contemporary forces responsible for the current pattern of population structure in H. leucogaster. This required a multi-scale approach, and the resulting research uses genetic, distributional and morphometric data. Haliaeetus leucogaster is a large territorial raptor that historically has been associated with coastal regions, lakes and perennial river systems. It has an extensive worldwide distribution from the western coast of India throughout the Indomalaysian region, Papua New Guinea and Australia. By virtue of the species' large-scale distribution, in Australia it is fairly cosmopolitan in its use of habitat and prey types. Haliaeetus leucogaster is monomorphic for adult plumage colouration, but in body size displays reversed sexual dimorphism with female birds significantly larger. A discriminant function based on 10 morphometric characters was 100% effective in discriminating between 19 males and 18 females that had been sexed using molecular genetic methods. Re-classification using a jackknife procedure correctly identified 92% of individuals. The discriminant function should be a viable alternative to genetic sexing or laparoscopy for a large proportion of individuals within the Australo-Papuan range of this species; and can also be used to identify a small proportion of "ambiguous" individuals for which reliable sexing will require those other techniques. I used mitochondrial (mtDNA) control region sequence data to investigate the current distribution of genetic variation in this species at the continental level and within and between specified regional units. I was specifically interested in identifying breaks in genetic connectivity between the west and east of the continent and between Tasmania and the Australian mainland. Overall, genetic diversity was low and there was no significant level of genetic subdivision between regions. The observed genetic distribution suggests that the population expanded from a bottleneck approximately 160 000 years ago during the late Pleistocene, and spread throughout the continent through a contiguous range expansion. There is insufficient evidence to suggest division of the population into different units for conservation management purposes based on the theoretical definition of the 'evolutionary significant unit'. It is clear from the analysis that there are signatures of both historical and contemporary processes affecting the current distribution. Given the suggestion that population expansion has been relatively recent, additional sampling and confirmation of the perceived pattern of population structure using a nuclear marker is recommended to validate conservation monitoring and management at a continental scale. To determine the existence of perceived population declines across ecological time scales, I analysed the Australian Bird Atlas Data to identify the extent and pattern of change in range and density of the species between three Atlas Periods (1901-1976, 1977-1981 and 1998-2001) using a new standardised frequency measure, the Occupancy Index (OI) for 1° blocks (approx. 100km2) across the continent. At the continental scale, there was no significant difference in the spatial extent of occupancy between Atlas Periods. However, there were considerable changes in frequency and range extent between defined regions, and there were distinct differences in the pattern of change in OI between coastal and inland blocks over time. Coastal blocks showed much more change than inland blocks, with a clear increase in the use of coastal blocks, accompanied by a decrease in inland blocks, during the 1977-1981 Atlas Period, relative to both other Atlas Periods. The over-riding factor associated with distributional shifts and frequency changes was apparently climatic fluctuation (the 1977-1981 period showing the influence of El Nino associated drought). The impression of abundance was strongly dependent on both the temporal and spatial scale of analysis. To test for correspondence between geographic variation in morphology and geographic variation in mtDNA I analysed morphometric data from 95 individuals from Australia and Papua New Guinea. First, the degree of morphometric variation between specified regions was determined. This was then compared with the pattern of genetic differentiation. There was a strong latitudinal cline in body dimensions. However, there was no relationship between morphometric variation and patterns of genetic variation at least for mtDNA. Females showed a pattern of isolation by distance based on morphometric characters whereas males did not. Three hypotheses to explain the pattern of morphometric variation were considered: phenotypic plasticity, natural selection and secondary contact between previously isolated populations. I conclude that the pattern of morphometric variation is best explained by the suggestion that there is sufficient local recruitment for natural selection to maintain the observed pattern of morphometric variation. This implies that gene flow may not be as widespread as the mtDNA analysis suggested. In this instance either the relatively recent colonisation history of the species or the inability of the mtDNA marker to detect high mutation rates among traits responsible for maintaining morphometric variation may be overestimating the levels of mixing among regions. As might be expected given the physical scale over which this study was conducted, the pattern of genetic, morphometric and physical distribution varied dependent on the scale of analysis. Regional patterns of genetic variation, trends in occupancy and density and morphometric variation did not reflect continental patterns, reinforcing the contention that extrapolation of data from local or regional levels is often inappropriate. The combined indirect methodologies applied in this study circumvent the restrictions imposed by direct ecological sampling, because they allow survey across large geographic and temporal scales effectively covering the entire Australian range of H. leucogaster. They also allow exploration of the evolutionary factors underpinning the species' current distribution.
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Shephard, Jill. "A Multi-Scale Approach to Defining Historical and Contemporary Factors Responsible for the Current Distribution of the White-bellied Sea-Eagle Haliaeetus leucogaster (Gmelin, 1788) in Australia." Thesis, Griffith University, 2004. http://hdl.handle.net/10072/367440.
Full textAbstract:
The White-bellied Sea-Eagle Haliaeetus leucogaster is widespread in Australia, but has been the subject of conservation concern due to suggested localised declines and extinctions. Regionalised monitoring programmes have addressed some aspects of local concern, however a broader approach is needed to gain an understanding of large-scale processes affecting long-term persistence at scales equivalent to the species Australian range. Ultimately, the ability to predict change in population size over time accurately depends on the scale of analysis. By necessity, ecological studies using direct sampling techniques are often made across spatial scales smaller than a species geographic range and across relatively short time frames. This seems counter-intuitive considering that long-term species persistence is often dependent on large-scale processes. The principal aim of this thesis was to identify historical and contemporary forces responsible for the current pattern of population structure in H. leucogaster. This required a multi-scale approach, and the resulting research uses genetic, distributional and morphometric data. Haliaeetus leucogaster is a large territorial raptor that historically has been associated with coastal regions, lakes and perennial river systems. It has an extensive worldwide distribution from the western coast of India throughout the Indomalaysian region, Papua New Guinea and Australia. By virtue of the species' large-scale distribution, in Australia it is fairly cosmopolitan in its use of habitat and prey types. Haliaeetus leucogaster is monomorphic for adult plumage colouration, but in body size displays reversed sexual dimorphism with female birds significantly larger. A discriminant function based on 10 morphometric characters was 100% effective in discriminating between 19 males and 18 females that had been sexed using molecular genetic methods. Re-classification using a jackknife procedure correctly identified 92% of individuals. The discriminant function should be a viable alternative to genetic sexing or laparoscopy for a large proportion of individuals within the Australo-Papuan range of this species; and can also be used to identify a small proportion of "ambiguous" individuals for which reliable sexing will require those other techniques. I used mitochondrial (mtDNA) control region sequence data to investigate the current distribution of genetic variation in this species at the continental level and within and between specified regional units. I was specifically interested in identifying breaks in genetic connectivity between the west and east of the continent and between Tasmania and the Australian mainland. Overall, genetic diversity was low and there was no significant level of genetic subdivision between regions. The observed genetic distribution suggests that the population expanded from a bottleneck approximately 160 000 years ago during the late Pleistocene, and spread throughout the continent through a contiguous range expansion. There is insufficient evidence to suggest division of the population into different units for conservation management purposes based on the theoretical definition of the 'evolutionary significant unit'. It is clear from the analysis that there are signatures of both historical and contemporary processes affecting the current distribution. Given the suggestion that population expansion has been relatively recent, additional sampling and confirmation of the perceived pattern of population structure using a nuclear marker is recommended to validate conservation monitoring and management at a continental scale. To determine the existence of perceived population declines across ecological time scales, I analysed the Australian Bird Atlas Data to identify the extent and pattern of change in range and density of the species between three Atlas Periods (1901-1976, 1977-1981 and 1998-2001) using a new standardised frequency measure, the Occupancy Index (OI) for 1° blocks (approx. 100km2) across the continent. At the continental scale, there was no significant difference in the spatial extent of occupancy between Atlas Periods. However, there were considerable changes in frequency and range extent between defined regions, and there were distinct differences in the pattern of change in OI between coastal and inland blocks over time. Coastal blocks showed much more change than inland blocks, with a clear increase in the use of coastal blocks, accompanied by a decrease in inland blocks, during the 1977-1981 Atlas Period, relative to both other Atlas Periods. The over-riding factor associated with distributional shifts and frequency changes was apparently climatic fluctuation (the 1977-1981 period showing the influence of El Nino associated drought). The impression of abundance was strongly dependent on both the temporal and spatial scale of analysis. To test for correspondence between geographic variation in morphology and geographic variation in mtDNA I analysed morphometric data from 95 individuals from Australia and Papua New Guinea. First, the degree of morphometric variation between specified regions was determined. This was then compared with the pattern of genetic differentiation. There was a strong latitudinal cline in body dimensions. However, there was no relationship between morphometric variation and patterns of genetic variation at least for mtDNA. Females showed a pattern of isolation by distance based on morphometric characters whereas males did not. Three hypotheses to explain the pattern of morphometric variation were considered: phenotypic plasticity, natural selection and secondary contact between previously isolated populations. I conclude that the pattern of morphometric variation is best explained by the suggestion that there is sufficient local recruitment for natural selection to maintain the observed pattern of morphometric variation. This implies that gene flow may not be as widespread as the mtDNA analysis suggested. In this instance either the relatively recent colonisation history of the species or the inability of the mtDNA marker to detect high mutation rates among traits responsible for maintaining morphometric variation may be overestimating the levels of mixing among regions. As might be expected given the physical scale over which this study was conducted, the pattern of genetic, morphometric and physical distribution varied dependent on the scale of analysis. Regional patterns of genetic variation, trends in occupancy and density and morphometric variation did not reflect continental patterns, reinforcing the contention that extrapolation of data from local or regional levels is often inappropriate. The combined indirect methodologies applied in this study circumvent the restrictions imposed by direct ecological sampling, because they allow survey across large geographic and temporal scales effectively covering the entire Australian range of H. leucogaster. They also allow exploration of the evolutionary factors underpinning the species' current distribution.Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
Australian School of Environmental Studies
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SICURELLA, BEATRICE CARLOTTA. "Analysis of the consequences of climate change and habitat modification on migratory birds." Doctoral thesis, Università degli Studi di Milano-Bicocca, 2015. http://hdl.handle.net/10281/69740.
Full textAbstract:
Habitat alteration and climate change are among the anthropogenic factors that contribute most to the current global decline of biodiversity. Due to their sensitivity to environmental conditions, birds are considered excellent indicators of global change. In particular, long-distance migrants are likely more sensitive to global change than residents or short-distance migrants because they suffer from changes in ecological conditions both at their breeding and wintering quarters The aim of this thesis is to investigate the effects of climate change and habitat modification on population dynamics of migratory birds.
The first part of this thesis includes papers investigating the effects of environmental conditions experienced by two long-distance migratory species, the Barn Swallow Hirundo rustica and the Common Swift Apus apus, at their breeding quarters in Northern Italy on their population dynamics. We observed that both the presence of livestock farming and the extent of hayfields close to the breeding site affected colony size of Barn Swallows and that recent variation in these conditions has probably concurred to worsen the demographic decline that this population has suffered. We also investigated the effect of the rearing environment on the survival and growth of Common Swift nestlings in a part of the breeding range of this species where these effects have never been investigated so far. We observed that nestlings’ growth is influenced not only by competition for resources with nest mates, but also by meteorological conditions. However, the effects we documented were different from those observed in more northern parts of the breeding range of the species, thus suggesting geographical variation in the susceptibility of this widespread species to general ecological conditions.
In the second part of this thesis we aimed at identifying migration routes and wintering quarters of small-sized migrant birds, and at evaluating the effect of environmental conditions experienced during migration and wintering on population dynamic. We followed two different and complementary approaches. First, we took advantage of the large number of ring recoveries available for the Barn Swallow throughout more than a century to identify changes in the timing of migration and main migration routes of individuals breeding in Europe. Second, we applied miniaturized tracking devices to 94 Barn Swallows to precisely identify, for the first time, timing of migration and position of the wintering areas of each individual. We could also evaluate the impact of the application of these instruments on survival and breeding success. In a further study we combined information on wintering grounds and migration routes with long-term data on population dynamic from Northern Italy and found that environmental conditions encountered during wintering and spring migration are the factors that influence most year-to-year variation in population consistency. Finally, we analyzed a long-term series of ringing data on a short-distance migrant, the European Robin Erithacus rubecula and found that winter temperatures at the breeding grounds influenced spatial and temporal variation in migration propensity and distance among individuals.
Overall, our researches confirmed that global change is already affecting bird populations by acting at different stages of their life-cycle. We showed that variations in ecological conditions at breeding quarters seem to influence breeding performances of individuals, while condition experienced during migration and wintering seem to affect their survival. Effective conservation measures for migratory species should therefore aim at protecting both breeding and wintering areas as well as stopover sites along migration routes. The novel analytic frameworks we developed may also be suitable for investigating the effects of climate change on migration across a broad range of species.
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Doxa, Aggeliki. "Complex population dynamics in a changing environment : the impact of density dependence and environmental factors on the vital rates and dynamics of two long-lived bird species." Paris, Muséum national d'histoire naturelle, 2009. http://www.theses.fr/2009MNHN0001.
Full textAbstract:
Un des principaux enjeux actuels en dynamique des populations est de fournir des outils adaptés pour prédire efficacement l’impact des changements globaux sur les espèces. Les interactions entre les populations et leur environnement peuvent être complexes, et leurs effets sur la variation des paramètres démographiques peuvent être décalés dans le temps. Les modèles de projection du risque d’extinction des populations ou de leur capacité à s’adapter à des modifications rapides des conditions environnementales nécessitent donc d’incorporer ce type de complexité dans leur structure pour qu’ils soient robustes. Cette thèse vise à identifier les aspects à prendre en compte dans l’analyse de l’impact des paramètres intrinsèques, comme la densité-dépendance, et des facteurs externes, comme le climat, sur les traits d’histoire de vie de l’espèce considérée et sur la dynamique des populations. Pour illustrer ces aspects, le Pélican frisé (Pelecanus crispus) et le Pélican blanc (Pelecanus onocrotalus) ont été choisis comme espèces modèles. D’après cette analyse, la densité-dépendance peut interagir avec les variations extrêmes de l’environnement, et influençer significativement le risque d’extinction. En outre, les variations temporelles de la densité et des facteurs climatiques peuvent influencer sur les patrons de survie, et générer de la synchronisation au sein et entre les populations. Enfin, les interactions entre espèces qui coopèrent durant la période de la reproduction et qui répondent différemment aux changements climatiques peuvent être cruciales pour la compréhension de ces changements sur les dynamiques de ces espècesOne of the challenges of modern population ecology is to provide the effective tools for population dynamics predictions in a rapidly changing environment. Reliable estimations of the effects of environmental variation on species dynamics require to integrate the effects of populations intrinsic parameters (e. G. , density) as well as external environmental factors. Importantly, these interacting effects are influenced by current and past conditions of the system, at both local and global scales. The present thesis aims to illustrate some of the aspects that need to be considered when assessing the impact of density and climatic factors on life history traits and on population dynamics, by using the example of two long-lived bird species, the Dalmatian pelican (Pelecanus crispus) and the Great white pelican (Pelecanus onocrotalus). The analyses showed that patterns of density-dependence can significantly interact with severe environmental stochasticity, producing unpredicted effects on population extinction risk. Large-scale climatic factors together with population density may similarly influence the survivorship of different population segments, resulting to spatial and temporal synchronisation between and within populations. Finally, interactions between until now cooperative species that are differently affected by climatic change may be a critical aspect for their future capacity to effectively respond to changing conditions
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Gustafson, Tomas. "Bird communities and vegetation on Swedish wet meadows : importance of management regimes and landscape composition /." Uppsala : Swedish University of Agricultural Sciences, 2006. http://diss-epsilon.slu.se/archive/00001234/.
Full textAbstract:
Thesis (doctoral)--Swedish University of Agricultural Sciences, 2006.Title from PDF file as viewed on 11/28/2006. Includes bibliographical references. Also available in print. Print version includes appendices.
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McDermott, Molly E. "Breeding and post-breeding forest bird community dynamics in regenerating clearcuts and two-age harvests in the central Appalachians." Morgantown, W. Va. : [West Virginia University Libraries], 2007. https://eidr.wvu.edu/etd/documentdata.eTD?documentid=5328.
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Thesis (M.S.)--West Virginia University, 2007.Title from document title page. Document formatted into pages; contains viii, 133 p. : ill. (some col.), col. maps. Includes abstract. Includes bibliographical references.
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Carboneras, Malet Carles. "Bird population dynamics in the wintering season: the case of the mediterranean Gull Larus melanodephalus = Dinàmiques poblacionals en ocells durant la hivernada: el cas de la Gavina Capnegra Larus melanocephalus." Doctoral thesis, Universitat de Barcelona, 2016. http://hdl.handle.net/10803/386447.
Full textAbstract:
The winter period is typically associated with harsh weather conditions and reduced food availability, which may lead to increased mortality. In birds, a common strategy to avoid such risks is to migrate to more favourable grounds, but its demographic costs are largely unknown. The wintering season remains a black box in our knowledge of the life cycle of birds. From the perspective of a wintering area, I study the population ecology of a migratory species, based on the hypothesis that winter aggregations of birds constitute true populations, instead of random aggregations of individuals. I look at the population composition, structure and dynamics across several spatial scales, and the link between the wintering and breeding areas through connecting migratory routes.
My study model is a population of wintering Mediterranean Gulls Larus melanocephalus made of birds from multiple origins, a significant proportion of which have been individually marked with individually-coded colour-rings in their natal or breeding colonies. The study system constitutes the species’ main winter quarters globally and is situated on the Mediterranean coast of E-NE Spain.
Capture-recapture analyses reveal high estimates of apparent local interannual survival after the first year (0.81 on average), indicating a high individual winter site-fidelity that does not vary with age. This attachment to the wintering area models the distribution of individuals, shaping them into a spatially structured population with metapopulation dynamics, as each subpopulation has independent demography, determined by area-specific survival and low levels of dispersal.
Using a probability model, I infer the migratory route followed by first-winter birds; the most likely path is a combination of fluvial and coastal routes, seeking minimal distance along favourable terrain. In the focus species, wintering populations are made of individuals from different sex and age classes, in one of the few documented cases of nondifferential migration. Exceptionally, the species also exhibits synheimy (the population in each distinct wintering area is made of birds from all the breeding populations), possibly as a result of its recent history. Individual choice of wintering area is made in the first migration according to a probability rule determined by distance, and is maintained through life.
On a local scale, I find a very high turnover of individuals and a frequent movement, in no particular direction, among sites. The low monthly probability of local residency (0.56) contrasts with the species’ strong site-fidelity to the general wintering area. Individual turnover shows that a single site may be visited by a large proportion of the regional (43%) and global (18%) populations every season. Thus, the population home range extends over an area much larger than a single locality or a protected area, showing evidence of a mismatch between the distribution of protected areas and the spatial needs of the population.
Compared with data from 60 years ago, Mediterranean Gulls have undergone a huge expansion of their breeding distribution range (750% area increase) while the wintering distribution has increased only moderately (25%). The global population size has remained stable, indicating that its growth may be limited by events taking place in the wintering season. As the breeding distribution continues to expand, where breeding and wintering populations come in contact, they interact little and follow independent dynamics.
This work contributes to a better understanding of bird population dynamics in the wintering season and shows how the detailed study of a species’ ecology during one part of the annual cycle can help comprehend what happens during the rest of the year. The ‘view from the winter quarters’ can bring important and complementary information to the study of birds during the breeding period.Des de la perspectiva d’una àrea d’hivernada, el meu estudi es centra en l’ecologia de poblacions d’una espècie migratòria, a partir de la hipòtesi que els agrupaments hivernals d’ocells constitueixen veritables poblacions. Investigo la composició, estructura i dinàmiques de la població a diverses escales espacials, i el lligam entre les àrees de reproducció i hivernada connectades mitjançant les rutes migratòries. El meu model d’estudi és una població hivernant de Gavines Capnegres Larus melanocephalus formada per individus provinents de diversos orígens, una fracció dels quals han estat marcats individualment amb anelles de colors. El sistema d’estudi a la costa catalana constitueix la principal àrea d’hivernada de l’espècie a nivell mundial. Mitjançant anàlisis de captura-recaptura, estimo alts nivells de supervivència interanual local (0,81), indicatius d’una alta fidelitat a l’àrea d’hivernada que no canvia amb l’edat individual. La població s’estructura espacialment com a metapoblació, amb subpoblacions independents demogràficament. Un model probabilístic permet inferir la ruta migratòria dels ocells joves en llur primera migració; aquesta és una combinació de rutes fluvials i costaneres, cercant la mínima distància sobre terreny favorable. A escala local, l’espècie mostra alts nivells de rotació d’individus i freqüents moviments entre localitats, sense destí concret, i una baixa probabilitat de residència local (0,56). Les necessitats espacials de la població, superiors a una sola localitat, demostren la falta d’adequació amb la distribució de les àrees protegides per a espècies amb alta mobilitat. Comparant els darrers 60 anys, la distribució reproductora ha experimentat una espectacular expansió (increment areal, 750%) mentre que la distribució hivernal ha augmentat de manera moderada (25%). La població mundial ha romàs estable, indicant que el seu creixement pot estar limitat per esdeveniments de l’època hivernal. Allà on entren en contacte les poblacions reproductora en expansió i la hivernant, interactuen poc i mantenen dinàmiques independents. Aquest treball contribueix a millorar la comprensió de les dinàmiques poblacionals durant l’hivern i demostra com l’estudi de l’ecologia durant una part del cicle anual pot ajudar a comprendre el que succeeix la resta de l’any. La ‘visió des dels quarters d’hivernada’ pot aportar una informació important i complementària als estudis durant l’època reproductora.
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Delgado, Ana Margarida dos Santos. "Os efeitos da intensificação agrícola na comunidade de aves das estepes cerealíferas." Doctoral thesis, ISA, 2013. http://hdl.handle.net/10400.5/6156.
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Doutoramento em Engenharia Florestal e dos Recursos Naturais - Instituto Superior de AgronomiaThis study evaluates the agricultural intensification effects on steppe bird populations of cereal fields and fallows. Through the analysis of landscape dynamics between 2002–2011, a gradient of agricultural intensification was identified in selected areas of Baixo Alentejo. In cereal fields, total bird abundance of steppe and resident birds decreased along the intensification gradient. During the breeding season, this trend should be related to an increase in height and density of vegetation structure in intensive areas. Food availability is not influenced by intensification. In extensive areas, the bird abundance is influenced by differences associated to the type of cereal and vegetation structure. In fallows, the abundance of steppe and resident birds is affected by intensification. Wintering and breeding species are influenced by fallow age and livestock presence. The multi-scale analysis of local management and landscape composition effects on steppe bird community in cereal fields showed that local component is more important in winter. In fallows, both components are equally important for steppe bird community. Between-year variations (2002-2008) in Tetrax tetrax population densities were shown to be influenced by agricultural intensification and rainfall
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Villard, Marc-Andre Carleton University Dissertation Biology. "Spatio-temporal dynamics of forest bird patch populations in agricultural landscapes." Ottawa, 1991.
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Smith, Melanie Anne. "Predicting northern goshawk dynamics using an individual-based spatial model." CONNECT TO THIS TITLE ONLINE, 2007. http://etd.lib.umt.edu/theses/available/etd-05312007-161744/.
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Colles, Frances M. "Population structure and dynamics of Campylobacter populations carried by wild birds and chickens reared in a free-range woodland environment." Thesis, University of Oxford, 2006. http://ora.ox.ac.uk/objects/uuid:3dc7cdfb-29f6-4681-b8db-cb71129cd946.
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Ingestion of contaminated chicken meat is a major cause of Campylobacteriosis in Europe and the USA. The environment, including wild birds, is considered to be an important reservoir for chicken colonization. The aims of this study were to determine the population structure of Campylobacter amongst chicken and wild bird sources on a single farm, and to establish the extent to which genotypes flow between them and ultimately infect humans, using MLST and antigen sequence typing. A pilot study amongst farm animals and wild birds in Lancashire demonstrated that Campylobacter genotypes from human disease were common on the farm and could be isolated from more than one animal source. Between 30-50% of wild geese and Starlings were shedding Campylobacter, with a seasonal peak in shedding rate in Spring. Genotypes were divergent from those previously isolated from human disease, retail meat and farm animal sources, with the majority being restricted to the host source. The carriage rate of Campylobacter was between 70- 100% amongst 78 free-range poultry flocks tested at 56 days of age. Up to seven genotypes were found to co-exist within a flock, and genotypes varied throughout the year on a random basis. Some Campylobacter strains were isolated from one farm site only, but a small percentage of them had spread nationally and were stable over a period of a decade. A total of 23% of Campylobacter isolates from free-range chickens were indistinguishable to those from human disease, and 5% were indistinguishable from wild birds. A total of 6% of genotypes isolated from wild birds were indistinguishable from those isolated from human disease. Wild birds could not be completely disregarded as a potential reservoir of Campylobacter for both humans and poultry, but their role is likely to be limited.
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Cattadori, Isabella M. C. "Temporal dynamics and spatial patterns of galliform birds in Trentino - Italy." Thesis, University of Stirling, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.311690.
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Kirby, Jeff. "Distribution and dynamics of wintering waders in Britain with particular reference to weather." Thesis, Open University, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.295548.
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Hargrove, Lori Jean. "Limits to species' distributions spatial structure and dynamics of breeding bird populations along an ecological gradient /." Diss., [Riverside, Calif.] : University of California, Riverside, 2010. http://proquest.umi.com/pqdweb?index=0&did=2019822781&SrchMode=1&sid=2&Fmt=2&VInst=PROD&VType=PQD&RQT=309&VName=PQD&TS=1273860879&clientId=48051.
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Thesis (Ph. D.)--University of California, Riverside, 2010.Includes abstract. Available via ProQuest Digital Dissertations. Title from first page of PDF file (viewed May 14, 2010). Includes bibliographical references. Also issued in print.
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Ronget, Victor. "The relationships linking age and body mass to vital rates : a comparative perspective in birds and mammals." Thesis, Lyon, 2018. http://www.theses.fr/2018LYSE1304/document.
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Les individus varient en termes de taux de survie et de taux de reproduction. Les variations de ces taux vitaux peuvent être reliées aux caractéristiques des individus tel que la masse et l’âge. Des modèles démographiques ont été développé pour prendre en compte ces variations dans les populations naturelles et permettre de faire des prédictions pour gérer les populations naturelles. Cependant, la quantité de données démographiques nécessaire pour construire ces modèles n’est pas disponible dans toutes les populations. Pour surmonter ce problème, j’ai pendant ma thèse décrit les patrons généraux des relations reliant l’âge et la masse aux taux vitaux chez les mammifères et les oiseaux. En utilisant les données de la littérature, j’ai pu décrire les patrons généraux de ces relations et mis en évidence les facteurs biologiques pouvant expliquer les variations de ces relations entre les espèces et les populations. Dans un premier temps je me suis concentrer sur le lien entre la masse des individus et leurs taux vitaux. J’ai montré un effet positif de la masse des jeunes sur la survie des jeunes. J’ai ensuite mis évidence l’effet des différentes causes de mortalité sur cette relation avec par exemple un effet négatif de la prédation sur l’intensité de cette relation. J’ai ensuite montré un effet positif de la masse de la mère sur la masse du jeune et enfin que la probabilité de reproduction d’une femelle est impactée positivement par sa masse. Dans une seconde partie, je me suis concentré sur le lien entre l’âge et la survie chez les mammifères. Pour décrire ce lien, nous avons construit une base de données MALDDABA compilant les relations reliant l’âge aux taux vitaux chez les populations naturelles de mammifères que nous avons extraits de tables de vie issues de la littérature. En utilisant ces données, nous avons démontré que les femelles vivent en moyenne plus longtemps que les mâles chez les mammifères en milieu naturelles. J’ai enfin décrit les avantages at les inconvénients des différentes métriques de longévité et proposé de nouvelles méthodes pour décrire la relation entre l’âge et le taux de mortalité. Avec cette thèse, je mets en avant l’utilisation des approches comparatives pour mieux comprendre quels sont les facteurs qui influence la dynamique des populations naturellesIndividuals varies in terms of survival and reproduction. Most of those variations in vital rates can be linked to individual characteristics such as age or body mass. Demographic models were developed to make prediction on those trait-structured populations and are now often used to manage wild populations. However, the amount of data needed to perform those models is not available for every populations. To overcome this issue, I tried in my thesis to assess the general patterns for the relationships linking age and body mass to the vital rates in birds and mammals. By comparing relationship extracted in the literature, I was then able to assess the general effect of body or age on vital rates as well as the biological factor explaining the variation of those relationships between species and populations. I first assess how body mass influence vital rates in birds and mammals. I demonstrated the positive effect of offspring body mass on offspring survival and showed how the relative importance of each causes of mortality influence this relationship, with for instance a negative effect of the predation rate on the intensity of the relationship. I also showed that mother body mass is positively related to offspring body mass and that heavier mother are also more likely to reproduce. On a second part I focused on describing the relationship between age and survival for mammals. We built a database MALDDABA compiling all relationships linking vital rates to age for wild mammals from life tables reported in the literature. Using life table data compiled in the database I was able to demonstrate that females live on average longer than males in wild populations of mammals. I then critically assess the metrics of longevity and provide new insight to describe the relationship between mortality and age. With my thesis I provided new views on the uses of comparative approach to highlight the major factors influencing the population dynamic in the wild
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Roos, Staffan. "Nest predation processes and farmland birds : habitat selection and population dynamics of predators and prey /." Uppsala : Dept. of Conservation Biology, Swedish Univ. of Agricultural Sciences, 2004. http://epsilon.slu.se/s301.pdf.
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Wretenberg, Johan. "The decline of farmland birds in Sweden /." Uppsala : Department of Conservation Biology, Swedish University of Agricultural Sciences, 2006. http://epsilon.slu.se/2006113.pdf.
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Einarsson, Olafur. "Breeding biology of the Whooper Swan and factors affecting its breeding success, with notes on its social dynamics and life cycle in the wintering range." Thesis, University of Bristol, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.361163.
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Latimer, Christopher Edward. "Avian population and community dynamics in response to vegetation restoration on reclaimed mine lands in southwest Virginia." Thesis, Virginia Tech, 2003. http://hdl.handle.net/10919/32773.
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Coal surface-mining is often implicated for its negative impacts on native flora and fauna. However, some studies suggest that, in reclaiming land after mining, there may be potential to create early successional habitat needed by many avian species currently in decline throughout eastern North America. I evaluated nest-site selection and nest success for on reclaimed mine lands in southwest Virginia during the summers of 2010 and 2011. For this nest-site analysis, I focused on 2 bird species common to reclaimed mine lands in southwest Virginia: field sparrows (Spizella pusillia) and indigo buntings (Passerina cyanea). In addition, I assessed bird community attributes in relation to various surface-mine reclamation regimens over a 5-year period from 2007-2011.
For both species, I found estimates of daily nest success to be higher than other estimates reported in the literature; however, empirical estimates of adult and juvenile survival are needed to provide better estimates of population status. For field sparrows, models of avian nest success support the hypothesis that a tradeoff exists between nest concealment and a view of the surroundings for field sparrows. For indigo buntings, year explained the most variation in nest success, with much lower estimates of daily nest survival in 2010, possibly as a result of increased precipitation.
I also assessed avian community dynamics in relation to vegetation changes on reclaimed mine sites and observed a total of 96 species throughout the 4 years of sampling. Local species persistence and species turnover were comparable to another
continental scale study conducted using breeding bird survey (BBS) data. Observed changes in community vital rates were likely a result of changes in certain habitat attributes over the 5-year period. Lastly, seven species were unique to certain cover types, suggesting the need to consider landscape level processes when developing restoration guidelines for reclaimed coal surface-mines.Master of Science
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Latimer, Chris E. "Avian population and community dynamics in response to vegetation restoration on reclaimed mine lands in southwest Virginia." Thesis, Virginia Tech, 2012. http://hdl.handle.net/10919/32773.
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Coal surface-mining is often implicated for its negative impacts on native flora and fauna. However, some studies suggest that, in reclaiming land after mining, there may be potential to create early successional habitat needed by many avian species currently in decline throughout eastern North America. I evaluated nest-site selection and nest success for on reclaimed mine lands in southwest Virginia during the summers of 2010 and 2011. For this nest-site analysis, I focused on 2 bird species common to reclaimed mine lands in southwest Virginia: field sparrows (Spizella pusillia) and indigo buntings (Passerina cyanea). In addition, I assessed bird community attributes in relation to various surface-mine reclamation regimens over a 5-year period from 2007-2011.
For both species, I found estimates of daily nest success to be higher than other estimates reported in the literature; however, empirical estimates of adult and juvenile survival are needed to provide better estimates of population status. For field sparrows, models of avian nest success support the hypothesis that a tradeoff exists between nest concealment and a view of the surroundings for field sparrows. For indigo buntings, year explained the most variation in nest success, with much lower estimates of daily nest survival in 2010, possibly as a result of increased precipitation.
I also assessed avian community dynamics in relation to vegetation changes on reclaimed mine sites and observed a total of 96 species throughout the 4 years of sampling. Local species persistence and species turnover were comparable to another continental scale study conducted using breeding bird survey (BBS) data. Observed changes in community vital rates were likely a result of changes in certain habitat attributes over the 5-year period. Lastly, seven species were unique to certain cover types, suggesting the need to consider landscape level processes when developing restoration guidelines for reclaimed coal surface-mines.Master of Science
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Reif, V. (Vitali). "Birds of prey and grouse in Finland:do avian predators limit or regulate their prey numbers?" Doctoral thesis, University of Oulu, 2008. http://urn.fi/urn:isbn:9789514288050.
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Relationships between predators and prey may affect population dynamics of both parties. Predators may also serve as a link between populations of different prey, e.g., small game and small mammals. I used available data on the diet and reproduction of birds of prey (mainly common buzzards Buteo buteo and goshawks Accipiter gentilis) and video surveillance of their nests, as well as multiannual data on numbers of grouse and small mammals for studying food habits and population dynamics of raptors and their links with population fluctuations of voles and grouse (capercaillie Tetrao urogallus, black grouse Tetrao tetrix and hazel grouse Bonasa bonasia) in western Finland during 1980–1990s when grouse and vole numbers fluctuated in regular cycles.
Microtus voles were the main prey of the buzzards which partly switched their diet to small game (juvenile grouse and hares) in years when vole numbers declined. The nesting rate of buzzards also correlated with vole abundance, but the productivity rate and brood size tended to lag behind the vole cycle. This mismatch between the buzzards' functional and numerical responses resulted in a fairly small impact of buzzards on juvenile grouse, which did not correlate with vole density. The productivity of goshawks followed the fluctuations of grouse density closely whereas the occupancy rate of goshawk territories did so with a two-year lag. The annual numerical ratio of goshawk to grouse was inversely related to grouse density, suggesting that this predator may be a destabilising factor for grouse population dynamics. However, the goshawks' kill rate of grouse showed no clear relations to grouse density. In June–July, these birds of prey (including hen harriers Circus cyaneus) usually killed a relatively small number of grouse chicks. Losses to raptors constituted up to one quarter of grouse juvenile mortality during the two months. We did not find a strong effect of avian predators on grouse juvenile mortality. In boreal forests, predators and other factors of grouse mortality do not operate as one, and there is probably no single factor responsible for the reproductive success of grouse.
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Miguet, Paul. "Influence de l’hétérogénéité du paysage sur la distribution et la dynamique des populations." Thesis, Montpellier 2, 2013. http://www.theses.fr/2013MON20152.
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L'objectif de cette thèse est de comprendre comment l'hétérogénéité du paysage (i.e. composition, structuration spatiale et dynamique temporelle) affecte les populations, notamment dans les paysages agricoles, fortement structurés par la mosaïque des parcelles et les rotations culturales. Nous abordons cette question à la fois de manière théorique (en simulant des dynamiques de populations dans des paysages aux propriétés spatiales et temporelles contrôlées) mais également empirique (en analysant la sélection d'habitat par la communauté de passereaux des paysages agricoles).Nous avons ainsi montré que la composition, la configuration spatiale et la dynamique temporelle étaient toutes trois importantes pour expliquer les dynamiques de population, et que la nature des réponses à l'hétérogénéité dépendait des traits des espèces (taux de croissance, dispersion, échelle de réponse au paysage). L'analyse sur la communauté de passereaux a montré que la composition en cultures influençait la sélection d'habitat chez certaines espèces, mais nos données ne nous ont pas permis de mettre en avant un effet significatif de la structuration spatiale des cultures sur les passereaux. Une analyse plus fine pour l'Alouette des champs (Alauda arvensis) a montré un effet positif de la diversité des cultures à l'échelle du territoire, expliqué par une complémentarité fonctionnelle entre les cultures, suggérant que des petites parcelles et un mélange des cultures dans le paysage seraient bénéfiques pour cette espèce. L'effet de la structuration spatiale et temporelle des cultures sur les populations mériterait d'être testé de façon plus approfondie à l'échelle adéquate sur de nombreux taxons. Une meilleure connaissance de l'effet des propriétés de la matrice cultivée sur les processus permettrait de prédire l'évolution des populations face à des modifications du paysage à l'aide de modèles mécanistes, et offrirait de nouvelles opportunités pour gérer la biodiversitéThe aim of this thesis is to understand how landscape heterogeneity (i.e. composition, configuration and temporal dynamics) affects populations, especially in farmlands, highly structured by the crop mosaic and rotations. We answer this question theoretically (simulating population dynamics in landscapes with controlled spatial and temporal properties) and empirically (analysing habitat selection by the farmland bird community).We found that landscape composition, configuration and temporal dynamics were all important to explain population dynamics and that the response to landscape heterogeneity depended on species traits (growth rate, dispersal, scale of response to the landscape). The analyse of farmland birds data revealed that crop composition influenced habitat selection for some species, but did not reveal a significant effect of crop configuration on birds. A finer analyse on Skylark showed a positive effect of crop diversity at the territory scale explained by a functional complementation among crops. It suggested that small fields and crop well mixed in the landscape would be beneficial for this species. The effect of spatial and temporal crop heterogeneity should be studied in depth at the right scale on many taxa. A good understanding of the effect of the cultivated matrix on processes would allow us to predict the change in populations when modifying the landscape and would offer new opportunities to manage biodiversity
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McLean, Nina Margaret. "Life in a changing world: climate change impacts on common European birds." Phd thesis, Canberra, ACT : The Australian National University, 2018. http://hdl.handle.net/1885/143430.
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Anthropogenic climate change is predicted to be a major cause of
extinctions. Therefore, a major aim of climate change ecology is
to understand how species are being impacted and identify which
species are most at risk. However, the ability to make these
broad generalisations requires large-scale comparative analyses
based on appropriate assumptions. This thesis investigates how
European birds respond to changes in climate, the validity of
several common assumptions, and identifies which species or
populations are most at risk based on multiple long-term
datasets.
Our understanding of how different responses relate and how they
affect population persistence is lacking. A conceptual
hierarchical framework is introduced in chapter one to better
understand and predict when climate-induced trait changes
(phenology or physiology) impact demographic rates (survival or
reproduction), and subsequently population dynamics. I synthesise
the literature to find hypotheses about life-history and
ecological characteristics that could predict when population
dynamics will likely be affected. An example shows that, although
earlier laying with warmer temperatures was associated with
improved reproduction, this had no apparent effect on population
trends in 35 British birds. Number of broods partly explains
which species are most at risk of temperature-induced population
declines.
It is often assumed that populations within species respond
similarly to climate change, and therefore a single value will
reflect species-specific responses. Chapter two explores inter-
and intra-specific variation in body condition responses to six
climatic variables in 46 species over 21 years and 80 sites. Body
condition is sensitive to all six variables (primarily in a
non-linear way), and declines with warmer temperatures. I find
that species signals might not exist as populations of the same
species are no more alike than populations of different species.
Decreased body condition is typically assumed to have detrimental
consequences on species’ vital rates and population dynamics,
but this assumption has rarely been tested. Expanding on chapter
two, chapter three shows that temperature-induced declines in
body condition have no apparent consequences on demography and
population dynamics. Instead, temperature has strong effects on
reproductive success and population growth rates via unknown
traits and demographic rates.
Much of the literature investigating climatic impacts assumes
that temporal trends accurately reflect responses to climate
change, and therefore investigate trait changes over time. In
chapter four, I use two long-term datasets to demonstrate that,
for four different types of trait responses, trait variation
through time cannot be assumed to be due to warming.
Non-temperature causal agents are important in explaining
temporal trends, often resulting in reinforced effects.
Consequently, the roles of climatic and non-climatic effects need
to be understood to better predict those species most at risk.
This thesis lays the foundations for more holistic climate change
research that encompasses relationships among multiple response
types, species and populations. Such knowledge will be vital for
future conservation efforts.
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Payo, Payo Ana. "Effects of environmental variability and perturbations on seabirds' population dynamics = Efectos de la variabilidad ambiental y las perturbaciones en la dinámica de poblaciones de las aves marinas." Doctoral thesis, Universitat de Barcelona, 2017. http://hdl.handle.net/10803/404751.
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The overarching aim of my thesis was to assess the role of environmental variability and specially of perturbations in the population dynamics of social vertebrates.
Our results emphasize the need to collect individual, population and metapopulation data at long term and large spatial scales. Such information is crucial to understand wild animal populations respond to environmental variability and perturbations.
We demonstrate that environmental variability and perturbations induce complex responses and lead to covariance processes within demographic traits at different spatio-temporal scales.
As expected for long-lived species, perturbations encouraged species to halt breeding investment in order to ensure future survival. However, under strong perturbation regimes an unknown population resilience threshold is surpassed and foregoing reproduction is insufficient to buffer population changes.
Cumulative effects of perturbations magnified population decreases across large spatio-temporal scales. Consecutive perturbations are potentially useful tools to effectively manage overabundant species. However, caution must be taken because their long-term consequences are still poorly understood.
Severe environmental conditions caused both lethal and non-lethal responses on populations. Non-lethal responses include changes in foraging behaviour, development cultural innovations such non-random dispersal movements or colonization of novel environments.
Individuals responded differentially to environmental variability and consecutive perturbations depending on their individual quality, age, experience and cohort of birth. Such differential responses resulted in severe selection filters and represent a structuring force — potentially destabilizing population dynamics.
Processes underlying the strong early-life selection pressures on early life survival are not limited to the rearing period, first winter is also critical. Consecutive cohort effects driven by density dependence and climate influence early-life survival of long-lived species, but that influence faded at older ages.
Experienced individuals act as an information repository. They are more likely to engage large distance dispersal and colonize new environments. Populations that include older individuals are more likely to be able to effectively and rapidly adapt to environmental change, at least in long lived, social species that exhibit social learning.
Colonisations are temporally and spatially unpredictable and respond to an accumulation of perturbations exceeding an unknown threshold for colonising new patches. The temporal mismatch between perturbations and colonisations events suggests that colonisers need a longer prospecting period to compensate for the lack of public information.
Non-lethal, density independent perturbations, such as predators’ presence, can drive changes in populations age structure and, therefore in the population reproductive value, through selection for young and inexperienced individuals with lower breeding success.
We provide strong evidences showing that consecutive perturbations, non-lethal effects and non-random individuals’ responses across different life stages are more important than previously thought. These results are especially relevant for understanding how populations will respond to the predicted increases in magnitude and frequency of perturbations as a consequence of global change.La tesis evalúa los efectos de la variabilidad ambiental y las perturbaciones en poblaciones naturales a diferentes escalas espacio-temporales. Todos los resultados mostrados proporcionan información útil para el modelado poblacional y metapoblacional. En particular, proporcionamos fuertes evidencias que demuestran que las perturbaciones consecutivas, los efectos no letales y las respuestas diferenciales de los individuos a lo largo de las distintas etapas de la vida son más importantes de lo que se pensaba anteriormente. Estos resultados son especialmente relevantes para entender cómo las poblaciones naturales responderán a los incrementos previstos en la magnitud y la frecuencia de las perturbaciones como consecuencia del cambio global.
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Brooks, Bonnie Louise. "The breeding distribution, population dynamics, and habitat availability and suitability of an upper Midwest loggerhead shrike population." 1988. http://catalog.hathitrust.org/api/volumes/oclc/19571160.html.
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Thesis (M.S.)--University of Wisconsin-Madison.Cover title. "Perf. rpt, MN E-1-18, study 440." eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.
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Hanzelka, Jan. "Vliv prostředí na vnitrodruhové rozdíly ve změnách početnosti polních ptáků." Master's thesis, 2012. http://www.nusl.cz/ntk/nusl-305078.
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Farmland bird populations in Europe have been in decline for a long time. Agricultural intensification and growing a large share of crops that provide suboptimal breeding habitat could be the main causes of the observed decline. To explore these possible drivers, I focused on population trends of farmland bird species in different habitats in the Czech Republic over the periods 1982-1990 and 1990-2010. Specifically, I focused on the variability in trends within each species in respect to the differences in landscape management between the lowlands and mid-altitude areas before and after 1990. The expected effect of intensive farming in the lowlands until 1990 was reflected by a strong decline in populations of Northern Lapwing and Yellowhammer. The influence of less intensive farming in mid-altitude areas causing moderate population decline was confirmed rather by shrubs and trees species than farmland specialists. After 1990, less intensive farming in the lowlands should reduce the decline, which may have occurred, but compelling comparison of population trends between the two time periods was not possible for most species due to the lack of data. On the contrary, more intensive population decline in mid-altitudes after 1990, which should be the response to arable land abandonment, was not...
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Schwarzkopf, Yonathan. "Complex Phenomena in Social and Financial Systems: From Bird Population Growth to the Dynamics of the Mutual Fund Industry." Thesis, 2011. https://thesis.library.caltech.edu/5988/2/thesis_final.pdf.
Full textAbstract:
This work explores different aspects of the statics and dynamics of the mutual fund industry. In addition, we answer a major question in the field of complex systems; the anomalous growth fluctuations observed for systems as diverse as breeding birds, city population and GDP.
We study how much control is concentrated in the hands of the largest mutual funds by studying the size distribution empirically. We show that it indicates less concentration than, for example, personal income. We argue that the dominant economic factor that determines the size distribution is market efficiency and we show that the mutual fund industry can be described using a random entry, exit and growth process.
Mutual funds face diminishing returns to scale as a result of convex trading costs yet there is no persistence nor a size dependence in their performance. To solve this puzzle we offer a new framework in which skillful profit maximizing fund managers compensate for decreasing performance by lowering their fees. We show that mutual fund behavior depends on size such that bigger funds charge lower fees and trade less frequently in more stocks. We present a reduced form model that is able to describe quantitatively this behavior.
We conclude with an investigation of the growth of mutual funds due to investor funds flows. We show that funds exhibit the same unusual growth fluctuations that have been observed for phenomena as diverse as breeding bird populations, the size of U.S. firms, the GDP of individual countries and the scientific output of universities. To explain this we propose a remarkably simple additive replication model. To illustrate how this can emerge from a collective microscopic dynamics we propose a model based on stochastic influence dynamics over a scale-free contact network.
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Hodder, Grace Violet. "The Impact of Habitat Alteration on the Population Dynamics of a Declining Woodland Bird in the Mount Lofty Ranges." Thesis, 2020. http://hdl.handle.net/2440/126624.
Full textAbstract:
Biotic invasions are among the main drivers of ecosystem change and contribute to species declines. In the southern hemisphere, perennial native understorey plants have been largely outcompeted by fast-growing annual crop grasses and herbs. This significant compositional change has altered patterns of seed production. Granivores such as the diamond firetail (Stagonopleura guttata) are likely to be affected by such alterations. This species has been declining nationally since large-scale land-clearance prior to 1980. Focussed, species-specific research is required to identify the threats and their interactions that contribute to ongoing declines. This thesis examined an isolated meta-population in the Mount Lofty Ranges (MLR), South Australia, subsisting in heavily degraded grassy woodland dominated by exotic annual grasses. The hypothesis that changes in grass seed phenology associated with invasion by exotic annual species has resulted in seasonal food shortages was tested. An assessment of the seed resources available to ground-foragers in the southern MLR confirmed that introduced, annual species dominate the understorey. Total seed biomass was over seven times greater in spring (4.08 g m-2) than in autumn, when biomass was just 0.53 g m-2. High spring seed biomass was predominantly produced by annual grasses. The subsequent drop in biomass coincided with breaking autumn rains, implicating mass-germination as the cause. Variation in seed biomass was attributed to seasonal changes in the seed abundance of annual weedy grasses and forbs. Diet analyses found that S. guttata diets mirrored the abundance and diversity of seasonal resources. However, during winter, when grass seed biomass was scarce, S. guttata relied heavily on the seeds of the drooping sheoak (Allocasuarina verticillata). A mark-resight study determined that S. guttata populations were affected by seasonal resource fluctuations. Stagonopleura guttata encounters were strongly correlated with seed abundance and S. guttata densities reflected seed biomasses. To further explore the reason for low numbers of S. guttata in autumn and winter, an in-field food supplementation experiment was conducted. The food-supplemented population had significantly higher survival than the non-supplemented population, indicating that food is limiting for S. guttata. Juveniles were less efficient foragers than adults, highlighting their vulnerability during times of seed scarcity. However, food supplementation appeared to increase the proportion of juveniles that survived their first winter. The transition of independent fledglings from spring/summer breeding into young breeding adults is critical for recruitment and is likely to be hampered by winter food shortages. Overall densities of S. guttata in the southern MLR were 0.023–0.062 birds/ha, lower than the minimum viable population estimate of 0.069 birds/ha. As such, this meta-population is not sustainable at current densities. To improve the persistence of S. guttata, it is essential that the grassy woodlands of the region are managed to create consistent, year-round food resources, particularly during winter. This requires the restoration of perennial native grasses in the understorey that seed more consistently and over longer time periods than annuals. In addition, rehabilitation of A. verticillata, a key resource, will improve food availability during times of scarcity.Thesis (Ph.D.) -- University of Adelaide, School of Biological Sciences, 2020
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(9738650), Dante P. Francomano. "Soundscape dynamics in the social-ecological systems of Tierra del Fuego." Thesis, 2020.
Find full textAbstract:
Human society is presently beset by an array of anthropogenic social-ecological crises that threaten the sustainability of the social-ecological systems that sustain our livelihoods. While research alone will not rectify these issues, it can help to answer key questions that must be addressed to develop effective solutions. To address such questions in a cohesive, compelling manner, social-ecological research can be bounded, structured, and distilled through innumerable organizing principles or theoretical frameworks. For this dissertation, I focused on the geographic region of Tierra del Fuego and sought to draw from the array of disciplines and methods that use sound as a lens for biological, ecological, and/or social inquiry. I also endeavored to consider various temporal, spatial, and organizational scales while investigating a selection of topics with a) specific importance in the social-ecological systems of Tierra del Fuego and b) general relevance to global social-ecological challenges. Chapter 1 provides an introduction to the dissertation, and Chapter 6 serves as a conclusion.
The objective of Chapter 2, “Biogeographical and analytical implications of temporal variability in geographically diverse soundscapes”, was to provide some guidance to passive acoustic monitoring (PAM) practitioners on how to design appropriate temporal sampling schemes based on the temporal variability of the sounds one wishes to measure and the power and storage limitations of acoustic recorders. We first quantified the temporal variability of several soundscape measurements and compared that variability across sites and times of day. We also simulated a wide range of temporal sampling schemes in order to model their representativeness relative to continuous sampling.
For Chapter 3, “Sentinels for sentinels: passive acoustic and camera trap monitoring of sensitive penguin populations”, we tested the utility of PAM to monitor behavior and abundance of Magellanic (Spheniscus magellanicus) and southern rockhopper penguins (Eudyptes chrysocome) at different spatial and temporal scales. We conducted in situ observations of the acoustic behavior of each species, and we compared acoustic metrics with penguin counts from narrowly focused camera traps and larger-extent observations of colony density.
Chapter 4, “Acoustic monitoring shows invasive beavers (Castor canadensis) increase avian diversity in Tierra del Fuego”, is focused on impacts of the invasive North American beaver (Castor canadensis) on Fuegian bird communities. We sought to determine how bird communities might differ between intact riparian forests, beaver ponds, and beaver meadows created by pond drainage. We conducted PAM and classic avian point counts under each of these conditions across seasons to test for differences between impact conditions and to compare the two methodologies.
For Chapter 5, “Human-nature connection and soundscape perception: insights from Tierra del Fuego, Argentina”, we evaluated the relationship between soundscape perception and nature relatedness by conducting surveys and soliciting responses to soundscape audio prompts. We also examined the potential for any demographic influences on nature relatedness or soundscape perception in the context of local social tensions.
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Dail, David (David Andrew). "Conditioning of unobserved period-specific abundances to improve estimation of dynamic populations." Thesis, 2012. http://hdl.handle.net/1957/28224.
Full textAbstract:
Obtaining accurate estimates of animal abundance is made difficult by the fact that most
animal species are detected imperfectly. Early attempts at building likelihood models that
account for unknown detection probability impose a simplifying assumption unrealistic for
many populations, however: no births, deaths, migration or emigration can occur in the
population throughout the study (i.e., population closure). In this dissertation, I develop
likelihood models that account for unknown detection and do not require assuming population closure. In fact, the proposed models yield a statistical test for population closure.
The basic idea utilizes a procedure in three steps: (1) condition the probability of the observed data on the (unobserved) period- specific abundances; (2) multiply this conditional
probability by the (prior) likelihood for the period abundances; and (3) remove (via summation) the period- specific abundances from the joint likelihood, leaving the marginal
likelihood of the observed data. The utility of this procedure is two-fold: step (1) allows
detection probability to be more accurately estimated, and step (2) allows population
dynamics such as entering migration rate and survival probability to be modeled. The
main difficulty of this procedure arises in the summation in step (3), although it is greatly
simplified by assuming abundances in one period depend only the most previous period (i.e., abundances have the Markov property). I apply this procedure to form abundance
and site occupancy rate estimators for both the setting where observed point counts are
available and the setting where only the presence or absence of an animal species is ob-
served. Although the two settings yield very different likelihood models and estimators,
the basic procedure forming these estimators is constant in both.Graduation date: 2012
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Huffer, Damien Garrett. "The ties that bind : population dynamics, mobility, and kinship during the mid-holocene in Northern Vietnam." Phd thesis, 2012. http://hdl.handle.net/1885/155785.
Full textAbstract:
During the mid-Holocene in Northern Vietnam, domestic rice, dogs, and pigs were introduced into Southeast Asia by populations genetically derived from Central China who interbred and traded with indigenous populations. Mortuary practices also changed substantially, indirectly suggesting a change in social structure and migration between communities, as well as possible changes to activity and mobility patterns. To investigate how the adoption of agriculture and increased long distance exchange affected daily life at individual and community levels, this thesis utilizes the skeletal assemblages from Man Bac (c. 3,800BP) and Con Co Ngua (c. 5,600BP). They represent the largest and best preserved mid-Holocene samples from Northern Vietnam, and have been analysed elsewhere to investigate broader topics such as the population history of Southeast Asia, palaeohealth and dietary change during the purported Neolithic Demographic Transition. To comprehend how daily life changed during this poorly understood time period, three aims, with associated hypotheses, were proposed: 1) To assess overall population mobility during the northern Vietnamese Neolithic transition over individual lifetime and diachronically by comparing strontium isotopic, musculo-skeletal stress marker (enthesis) and cross-sectional geometric data between individuals, sexes and samples; 2) To assess what relationship, if any, existed between social identity as reflected in burial treatment by kin at death, genetic kinship itself, and activity patterns; and 3) To answer questions of community-level social organization, the special treatment in death of first-generation migrants, and sex-based differences in activity/mobility patterns within one community; Man Bac. Social structure was approached through genetic kinship analysis assessed using cranial and dental nonmetric traits. Individual migration histories were approached through strontium isotopic analysis, as well as preliminary assessment of isotopic variation across the landscape. Mobility and activity patterns were assessed via standardized musculo{u00AD}skeletal stress marker analysis, as well as external and medullary long bone cross-sectional geometry. The cross-sectional geometry research also involved creation of a new method to more accurately assess medullary contours without using CT Scanning. Results suggest that the introduction of agriculture, as well as genetic heterogeneity in the case of Man Bac, did not result in a markedly different kinship structure, with both cemeteries containing small, unsegregated kin groups. Preliminary isotopic data indicates that first-generation migrants were present in both communities, but only males migrated into Man Bac, most of whom received high-status burials with exotic grave goods, and some of whom are suggested to have fathered locally born descendants. Diachronic comparison of the biomechanical data suggests minimal changes to type or intensity of activity or terrestrial mobility, suggesting that continued broad spectrum hunting and gathering (and hypothesized water-craft usage) outweighed the contribution of agricultural activities. Intra-community biomechanical analysis suggested different activity patterns for males and females in both populations. Although all results presented are preliminary, this research adds much to our current understanding of daily life during the agricultural transition in Southeast Asia. Beyond that, it demonstrates that significant insights into ancient social identity and community life can be gained by combining and comparing different strands of bioarchaeological data.