Littérature scientifique sur le sujet « Bird population dynamics »
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Articles de revues sur le sujet "Bird population dynamics"
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Galloway, Terry D., et Robert J. Lamb. « Population Dynamics of Chewing Lice (Phthiraptera) Infesting Birds (Aves) ». Annual Review of Entomology 66, no 1 (7 janvier 2021) : 209–24. http://dx.doi.org/10.1146/annurev-ento-041420-075608.
Texte intégralRésumé :
In the past 25 years, studies on interactions between chewing lice and their bird hosts have increased notably. This body of work reveals that sampling of live avian hosts, collection of the lice, and the aggregated distributions of louse infestations pose challenges for assessing louse populations. The number of lice on a bird varies among host taxa, often with host size and social system. Host preening behavior limits louse abundance, depending on bill shape. The small communities of lice (typically one–four species) that live on individual birds show species-specific patterns of abundance, with consistently common and rare species, and lower year-to-year population variability than other groups of insects. Most species of lice appear to breed continuously on their hosts, with seasonal patterns of abundance sometimes related to host reproduction and molting. Competition may have led to spatial partitioning of the host by louse species, but seldom contributes to current patterns of abundance.
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Galloway, Terry D., et Robert J. Lamb. « Population Dynamics of Chewing Lice (Phthiraptera) Infesting Birds (Aves) ». Annual Review of Entomology 66, no 1 (7 janvier 2021) : 209–24. http://dx.doi.org/10.1146/annurev-ento-041420-075608.
Texte intégralRésumé :
In the past 25 years, studies on interactions between chewing lice and their bird hosts have increased notably. This body of work reveals that sampling of live avian hosts, collection of the lice, and the aggregated distributions of louse infestations pose challenges for assessing louse populations. The number of lice on a bird varies among host taxa, often with host size and social system. Host preening behavior limits louse abundance, depending on bill shape. The small communities of lice (typically one–four species) that live on individual birds show species-specific patterns of abundance, with consistently common and rare species, and lower year-to-year population variability than other groups of insects. Most species of lice appear to breed continuously on their hosts, with seasonal patterns of abundance sometimes related to host reproduction and molting. Competition may have led to spatial partitioning of the host by louse species, but seldom contributes to current patterns of abundance.
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Virkkala, Raimo, et Ari Rajasärkkä. « Climate change affects populations of northern birds in boreal protected areas ». Biology Letters 7, no 3 (8 décembre 2010) : 395–98. http://dx.doi.org/10.1098/rsbl.2010.1052.
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Human land-use effects on species populations are minimized in protected areas and population changes can thus be more directly linked with changes in climate. In this study, bird population changes in 96 protected areas in Finland were compared using quantitative bird census data, between two time slices, 1981–1999 and 2000–2009, with the mean time span being 14 years. Bird species were categorized by distribution pattern and migratory strategy. Our results showed that northern bird species had declined by 21 per cent and southern species increased by 29 per cent in boreal protected areas during the study period, alongside a clear rise (0.7–0.8°C) in mean temperatures. Distribution pattern was the main factor, with migratory strategy interacting in explaining population changes in boreal birds. Migration strategy interacted with distribution pattern so that, among northern birds, densities of both migratory and resident species declined, whereas among southern birds they both increased. The observed decline of northern species and increase in southern species are in line with the predictions of range shifts of these species groups under a warming climate, and suggest that the population dynamics of birds are already changing in natural boreal habitats in association with changing climate.
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Matsyura, О. V. « КОМПЛЕКСНА ОЦІНКА ДИНАМІКИ ЧИСЕЛЬНОСТІ УГРУПОВАНЬ КОЛОНІАЛЬНИХ НАВКОЛОВОДНИХ ПТАХІВ (НА ПРИКЛАДІ ДЕЯКИХ ОСТРОВІВ СИВАШУ) ». Biological Bulletin of Bogdan Chmelnitskiy Melitopol State Pedagogical University 1, no 3 (25 décembre 2011) : 85. http://dx.doi.org/10.15421/20111_38.
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<p>The problem of the mathematical analysis of the number dynamics of the nesting waterbirds for the islands of the south of Ukraine is examined. The algorithm of the evaluation of changes in the number of island birds is proposed. Data of the long-term monitoring of the number of birds were analyzed according to this algorithm. The necessity of the implementation of the statistical indices together with the graphic representation of island birds’ turnover is proved. The trends of population dynamics are determined for the key species. The discussed procedure of the complex evaluation is proposed for the management planning of the island bird species and their habitats.</p> <p>The performed analysis of the number dynamics of the key-stone breeding island birds showed that, with the exception of little tern, the population status and the prognosis of number are sufficiently favorable. From the data of long-term monitoring we came up with the conclusion about the existence of island habitats with carrying capacity to maintain the additional number of breeding birds. In the case of unfavorable conditions like strengthening of anthropogenic press, concurrent interrelations, deficiency of feed resources or drastic reduction of breeding biotopes, the birds due to turnover are capable to successfully react even without reducing their number and breeding success. The extinction rate of the breeding bird species from the island sites directly correlates with the number of breeding species. For the species with equal abundance, the extinction probability is higher for birds, whose numbers are unstable and characterized by significant fluctuations. This testifies the urgency of the constant monitoring and analysis of the number dynamics of breeding bird species in region.</p> <p>The suggested procedure of analysis is recommended for drawing up of management plans and performing of prognoses of number of breeding island bird species. More detail analysis with use of quantitative data on breeding birds will be the next step of the study of the island birds’ turnover. The results of the analysis of population dynamics assist to count the minimal population size for the colonization of new islands and stable existence of bird communities. Detailed analysis will allow to estimate the effect of competition on population and to determine the competitive variability inside and between the species breeding on islands.</p> <p><em>Key words: Ukraine, colonial waterbirds, islands, dynamics of number, analysis</em></p> <p> </p>
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JHA, Kaushalendra Kumar, et Craig R. MCKINLEY. « Composition and Dynamics of Migratory and Resident Avian Population in Wintering Wetlands from Northern India ». Notulae Scientia Biologicae 7, no 1 (20 mars 2015) : 1–15. http://dx.doi.org/10.15835/nsb719484.
Texte intégralRésumé :
Twelve wetlands occurring in four different ecozones in Uttar Pradesh (UP), India, were selected for studying the winter composition and dynamics of avian populations. Wetland information was collected from office records of the UP Forest department. Bird populations were estimated by transect method and block-in-flock-in-sector method for woodland and aquatic birds, respectively. Across the twelve selected wetlands a total of 486,182 individuals belonging to 161 species of birds on 15,592 ha were recorded during the winter of 2010-11. The data were analyzed to assess the relationship between wetland characteristics and avian populations. Aquatic vegetation, surrounding vegetation, water availability and climate were found as important factors related to avian populations. January was found to be the peak of bird assemblage, while winter times before and after January were the waxing and waning period, respectively. Species richness and species diversity of aquatic birds varied between 18-58 and 1.90-3.20, respectively, and of all bird species between 23-109, and 1.73-3.81, respectively. The density of aquatic birds ranged between 17-384 ha-1. The most common migratory birds in wetlands were Northern Pintail, Common Teal and Greylag Goose. Common resident birds included Asian Openbill, Darter, Little Egret, Common Coot, Little Cormorant, Grey Heron, Purple Heron, Indian Pond Heron, Common Moorhen, Purple Swamphen, Cattle Egret, Indian Sarus Crane and White-throated Kingfisher. For improved conservation of aquatic avian fauna, management prescriptions are suggested for wetlands under current management which could also be extended to other wetlands, whereas conservation of avian fauna to be the emphasis.
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Sakhvon, V. V., et M. E. Nikiforov. « Features of formation bird population structure in Minsk in the time aspect ». Proceedings of the National Academy of Sciences of Belarus, Biological Series 66, no 4 (10 novembre 2021) : 412–25. http://dx.doi.org/10.29235/1029-8940-2021-66-4-412-425.
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The structure of bird population of urbanized areas is determined by the diversity of habitats within the city, the diversity of bird species in suburban biotopes, and regional processes of dispersal of birds closely associated with human settlements. The analysis of the dynamics of the breeding bird species richness in Minsk showed that its formation progressed in different ways. All in all, since 1946, 141 bird species have been recorded nesting (including allegedly) in the territory of Minsk.The breeding bird assemblages is dominated by dendrophilous (45.0 % of all species) as well as wetland and semi-aquatic (29,3 %) bird species, with more than half of all the breeding bird species (50.3 %) associated with trees and shrubs. In different periods, the breeding bird species richness varied, by now, it has noticeably increased (from 77 to 132 species). This happened due to the expansion of the administrative boundaries of the city with the inclusion of bird species of suburban habitats, an increase in the diversity of habitats suitable for bird nesting (for example, the formation of large water bodies) as well as due to active colonization of urban ecosystems by various bird species. At the same time, after 2000, 9 bird species stopped nesting and 17 bird species started nesting. Active processes of synurbization of some bird species on the European continent observed in recent decades have become the reason for the addition of new species to the avifauna in Minsk, although the basis of the current structure of bird population was formed back in 1986–1999. At the same time, the synurbized groups of various bird species may be of autochthonous, allochthonous, or mixed origin.
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Odintseva, A. A., et O. A. Odintsev. « Seasonal Dynamics of the Bird Population of Omsk City ». Biology Bulletin 48, no 7 (décembre 2021) : 1030–40. http://dx.doi.org/10.1134/s1062359021070220.
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Sæther, Bernt-Erik, Russell Lande, Steinar Engen, Henri Weimerskirch, Magnar Lillegård, Res Altwegg, Peter H. Becker et al. « Generation time and temporal scaling of bird population dynamics ». Nature 436, no 7047 (juillet 2005) : 99–102. http://dx.doi.org/10.1038/nature03666.
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Ruffino, Lise, Diane Zarzoso-Lacoste et Eric Vidal. « Assessment of invasive rodent impacts on island avifauna : methods, limitations and the way forward ». Wildlife Research 42, no 2 (2015) : 185. http://dx.doi.org/10.1071/wr15047.
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Bird conservation is nowadays a strong driving force for prioritising rodent eradications, but robust quantitative estimates of impacts are needed to ensure cost-effectiveness of management operations. Here, we review the published literature to investigate on what methodological basis rodent effects on island bird communities have been evaluated for the past six decades. We then discuss the advantages and limitations of each category of methods for the detection and quantification of impacts, and end with some recommendations on how to strengthen current approaches and extend our knowledge on the mechanisms of impacts. Impact studies (152 studies considered) emphasised seabirds (67%), black rats (63%) and the Pacific Ocean (57%). Among the most commonly used methods to study rodent impacts on birds were the observation of dead eggs or empty nests while monitoring bird breeding success, and the analyses of rodent diets, which can both lead to misleading conclusions if the data are not supported by direct field evidence of rodent predation. Direct observations of rodent–bird interactions (19% of studies) are still poorly considered despite their potential to reveal cryptic behaviours and shed light on the mechanisms of impacts. Rodent effects on birds were most often measured as a change or difference in bird breeding parameters (74% of studies), while estimates of bird population growth rates (4%) are lacking. Based on the outcomes of this literature review, we highlight the need for collecting unbiased population-level estimates of rodent impacts, which are essential prerequisites for predicting bird population growth scenarios and prioritising their conservation needs. This could be achieved by a more systematic integration of long-term monitoring of bird populations into rodent management operations and modelling bird population dynamics. We also strongly recommend including various complementary methods in impact assessment strategies to unravel complex interactions between rodents and birds and avoid faulty evidence. Finally, more research should be devoted to a better understanding of the cases of non-impacts (i.e. long-term coexistence) and those impacts mediated by mechanisms other than predation and ecosystem-level processes.
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Layton-Matthews, Kate, Michael Griesser, Christophe F. D. Coste et Arpat Ozgul. « Forest management affects seasonal source-sink dynamics in a territorial, group-living bird ». Oecologia 196, no 2 (juin 2021) : 399–412. http://dx.doi.org/10.1007/s00442-021-04935-6.
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AbstractThe persistence of wildlife populations is under threat as a consequence of human activities, which are degrading natural ecosystems. Commercial forestry is the greatest threat to biodiversity in boreal forests. Forestry practices have degraded most available habitat, threatening the persistence of natural populations. Understanding population responses is, therefore, critical for their conservation. Population viability analyses are effective tools to predict population persistence under forestry management. However, quantifying the mechanisms driving population responses is complex as population dynamics vary temporally and spatially. Metapopulation dynamics are governed by local dynamics and spatial factors, potentially mediating the impacts of forestry e.g., through dispersal. Here, we performed a seasonal, spatially explicit population viability analysis, using long-term data from a group-living territorial bird (Siberian jay, Perisoreus infaustus). We quantified the effects of forest management on metapopulation dynamics, via forest type-specific demography and spatially explicit dispersal, and how forestry impacted the stability of metapopulation dynamics. Forestry reduced metapopulation growth and stability, through negative effects on reproduction and survival. Territories in higher quality natural forest contributed more to metapopulation dynamics than managed forests, largely through demographic processes rather than dispersal. Metapopulation dynamics in managed forest were also less resilient to disturbances and consequently, may be more vulnerable to environmental change. Seasonal differences in source-sink dynamics observed in managed forest, but not natural forests, were caused by associated seasonal differences in dispersal. As shown here, capturing seasonal source-sink dynamics allows us to predict population persistence under human disturbance and to provide targeted conservation recommendations.
Thèses sur le sujet "Bird population dynamics"
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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.
Texte intégralRésumé :
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, et 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.
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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.
Texte intégralRésumé :
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.
Texte intégralRésumé :
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.
Texte intégralRésumé :
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
Livres sur le sujet "Bird population dynamics"
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Telfair, Raymond Clark. Cattle egret (Bubulcus ibis) population trends and dynamics in Texas, 1954-1990. Austin, TX (4200 Smith School Road, Austin 78744) : Nongame and Urban Program, Fisheries and Wildlife Division, Texas Parks and Wildlife Dept., 1993.
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1936-, Grant Peter R., dir. Evolutionary dynamics of a natural population : The large cactus finch of the Galápagos. Chicago : University of Chicago Press, 1989.
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B, Franklin Alan, et American Ornithologists' Union, dir. Population dynamics of the California spotted owl (Strix occidentalis occidentalis) : A meta-analysis. Washington, D.C : American Ornithologists' Union, 2004.
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Harmata, Alan R. Population dynamics of key raptors nesting in the Kevin Rim area : Challenge cost share progress report 1996 to Bureau of Land Management, Great Falls District. [Bozeman, Mont.] : [Montana State University, Department of Biology, Fish & Wildlife Program], 1997.
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Rosenberg, Daniel H. Harlequin duck population dynamics : Measuring recovery from the Exxon Valdez Oil Spill. Anchorage, AK : EVOS Trustee Council, 2005.
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Rosenberg, Daniel H. Harlequin duck population dynamics : Measuring recovery from the Exxon Valdez Oil Spill. Anchorage, AK : EVOS Trustee Council, 2005.
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Harmata, Alan R. Population dynamics of key raptor species in the Kevin Rim Raptor Study Area, 2001 : Challenge cost share progress report to : Bureau of Land Management, Great Falls District. Bozeman, Mont.] : [Montana State University, Department of Ecology, Fish & Wildlife Program], 2001.
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Harmata, Alan R. Population dynamics of key raptor species in the Kevin Rim Raptor Study Area, 2000 : Challenge cost share progress report to : Bureau of Land Management, Great Falls District. Bozeman, Mont.] : [Montana State University, Department of Biology, Fish & Wildlife Program], 2000.
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Harmata, Alan R. Population dynamics of key raptor species in the Kevin Rim Area : Challenge cost share progress report 1997 and 1998 to Bureau of Land Management, Great Falls District. Bozeman, Mont.] : [Montana State University, Department of Biology, Fish & Wildlife Program], 1998.
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Harmata, Alan R. Population dynamics of key raptor species in the Kevin Rim Raptor Study Area, 1999 : Challenge cost share progress report to : Bureau of Land Management, Great Falls District. Bozeman, Mont.] : [Montana State University, Department of Biology, Fish & Wildlife Program], 1999.
Trouver le texte intégralChapitres de livres sur le sujet "Bird population dynamics"
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Bourski, O. V. « Bird Population Dynamics in Relation to Habitat Quality ». Dans The GeoJournal Library, 52–60. Dordrecht : Springer Netherlands, 1996. http://dx.doi.org/10.1007/978-94-009-0343-2_6.
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Francis, Charles M., et David R. Wells. « The Bird Community at Pasoh : Composition and Population Dynamics ». Dans Pasoh, 375–93. Tokyo : Springer Japan, 2003. http://dx.doi.org/10.1007/978-4-431-67008-7_27.
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Dhondt, André A., Erik Matthysen, Frank Adriaensen et Marcel M. Lambrechts. « Population Dynamics and Regulation of a High Density Blue Tit Population ». Dans Population Biology of Passerine Birds, 39–53. Berlin, Heidelberg : Springer Berlin Heidelberg, 1990. http://dx.doi.org/10.1007/978-3-642-75110-3_3.
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Speziale, Karina L. « Continental analysis of invasive birds : South America. » Dans Invasive birds : global trends and impacts, 296–303. Wallingford : CABI, 2020. http://dx.doi.org/10.1079/9781789242065.0296.
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Burger, Joanna, et Michael Gochfeld. « Overview of Ecotoxicology for Birds ». Dans Habitat, Population Dynamics, and Metal Levels in Colonial Waterbirds, 229–44. Boca Raton : Taylor & Francis, 2016. | Series : CRC marine science series ; 36 : CRC Press, 2016. http://dx.doi.org/10.1201/9780429159435-11.
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Burger, Joanna, et Michael Gochfeld. « Effects of Metals in Birds ». Dans Habitat, Population Dynamics, and Metal Levels in Colonial Waterbirds, 245–75. Boca Raton : Taylor & Francis, 2016. | Series : CRC marine science series ; 36 : CRC Press, 2016. http://dx.doi.org/10.1201/9780429159435-12.
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Burnett, Jessica L., et Craig R. Allen. « Continental analysis of invasive birds : North America. » Dans Invasive birds : global trends and impacts, 279–95. Wallingford : CABI, 2020. http://dx.doi.org/10.1079/9781789242065.0279.
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McCallum, D. Archibald. « Variable Cone Crops, Migration, and Dynamics of a Population of Mountain Chickadees (Parus Gambeli) ». Dans Population Biology of Passerine Birds, 103–16. Berlin, Heidelberg : Springer Berlin Heidelberg, 1990. http://dx.doi.org/10.1007/978-3-642-75110-3_8.
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Burger, Joanna, et Michael Gochfeld. « Heavy Metals in Fish, Lower Trophic Levels, and Passerine Birds ». Dans Habitat, Population Dynamics, and Metal Levels in Colonial Waterbirds, 277–310. Boca Raton : Taylor & Francis, 2016. | Series : CRC marine science series ; 36 : CRC Press, 2016. http://dx.doi.org/10.1201/9780429159435-13.
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Shochat, Eyal, Susannah Lerman et Esteban Fernández-Juricic. « Birds in Urban Ecosystems : Population Dynamics, Community Structure, Biodiversity, and Conservation ». Dans Agronomy Monographs, 75–86. Madison, WI, USA : American Society of Agronomy, Crop Science Society of America, Soil Science Society of America, 2015. http://dx.doi.org/10.2134/agronmonogr55.c4.
Texte intégralActes de conférences sur le sujet "Bird population dynamics"
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Grimm, Brian A., Brooke A. Lahneman, Peter B. Cathcart, Robert C. Elgin, Greg L. Meshnik et John P. Parmigiani. « Autonomous Unmanned Aerial Vehicle System for Controlling Pest Bird Population in Vineyards ». Dans ASME 2012 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/imece2012-89528.
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Pest birds have long been a significant source of crop loss for grape growers, especially during the critical weeks leading up to harvest when grape sugar levels are high. In Oregon’s Willamette Valley, vineyards have seen a marked increase in crop loss in the last few years despite widespread use of intrusive gas cannons/shotguns and expensive netting systems. In order to deter this pest bird population, we have created an Unmanned Aerial Vehicle (UAV) package capable of autonomous flight, which incorporates common pest bird scare tactics into this dynamic platform. The system has been designed to launch, complete its mission waypoints, and land completely under autonomous control. By using this autonomous guidance system, we are able to employ visual, auditory, and predator mimicry pest bird control techniques in such a way as to discourage habituation. While radio controlled UAVs have been used for bird control in airport settings for many years, these systems require a trained operator to constantly guide the aircraft. The autonomous UAV system was designed for operation by an existing vineyard employee with minimal training. To capture widely accepted pest bird control techniques and management culture of Willamette Valley vineyards and gain information for design, implementation, and industry acceptance of this UAV project, we surveyed the owners of 225 local vineyards. Survey results indicated that vineyard owners are open to implementing innovative pest bird control methods that do not affect the terroir of their vineyards and that could replace the use of netting, which they do not view favorably despite its being the most effective pest bird control method to date. Results also indicated that pest birds are most damaging to a vineyard’s perimeter and that many vineyards employ someone to patrol this perimeter with a shotgun loaded with cracker shells. The UAV system is able to traverse the airspace above this perimeter without interfering with neighboring homes or beneficial predators in the area. By using proven pest bird control methods in an autonomous UAV system, we designed a device that brings an innovative solution to vineyard owners.
Rapports d'organisations sur le sujet "Bird population dynamics"
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Wideman, Jr., Robert F., Nicholas B. Anthony, Avigdor Cahaner, Alan Shlosberg, Michel Bellaiche et William B. Roush. Integrated Approach to Evaluating Inherited Predictors of Resistance to Pulmonary Hypertension Syndrome (Ascites) in Fast Growing Broiler Chickens. United States Department of Agriculture, décembre 2000. http://dx.doi.org/10.32747/2000.7575287.bard.
Texte intégralRésumé :
Background PHS (pulmonary hypertension syndrome, ascites syndrome) is a serious cause of loss in the broiler industry, and is a prime example of an undesirable side effect of successful genetic development that may be deleteriously manifested by factors in the environment of growing broilers. Basically, continuous and pinpointed selection for rapid growth in broilers has led to higher oxygen demand and consequently to more frequent manifestation of an inherent potential cardiopulmonary incapability to sufficiently oxygenate the arterial blood. The multifaceted causes and modifiers of PHS make research into finding solutions to the syndrome a complex and multi threaded challenge. This research used several directions to better understand the development of PHS and to probe possible means of achieving a goal of monitoring and increasing resistance to the syndrome. Research Objectives (1) To evaluate the growth dynamics of individuals within breeding stocks and their correlation with individual susceptibility or resistance to PHS; (2) To compile data on diagnostic indices found in this work to be predictive for PHS, during exposure to experimental protocols known to trigger PHS; (3) To conduct detailed physiological evaluations of cardiopulmonary function in broilers; (4) To compile data on growth dynamics and other diagnostic indices in existing lines selected for susceptibility or resistance to PHS; (5) To integrate growth dynamics and other diagnostic data within appropriate statistical procedures to provide geneticists with predictive indices that characterize resistance or susceptibility to PHS. Revisions In the first year, the US team acquired the costly Peckode weigh platform / individual bird I.D. system that was to provide the continuous (several times each day), automated weighing of birds, for a comprehensive monitoring of growth dynamics. However, data generated were found to be inaccurate and irreproducible, so making its use implausible. Henceforth, weighing was manual, this highly labor intensive work precluding some of the original objectives of using such a strategy of growth dynamics in selection procedures involving thousands of birds. Major conclusions, solutions, achievements 1. Healthy broilers were found to have greater oscillations in growth velocity and acceleration than PHS susceptible birds. This proved the scientific validity of our original hypothesis that such differences occur. 2. Growth rate in the first week is higher in PHS-susceptible than in PHS-resistant chicks. Artificial neural network accurately distinguished differences between the two groups based on growth patterns in this period. 3. In the US, the unilateral pulmonary occlusion technique was used in collaboration with a major broiler breeding company to create a commercial broiler line that is highly resistant to PHS induced by fast growth and low ambient temperatures. 4. In Israel, lines were obtained by genetic selection on PHS mortality after cold exposure in a dam-line population comprising of 85 sire families. The wide range of PHS incidence per family (0-50%), high heritability (about 0.6), and the results in cold challenged progeny, suggested a highly effective and relatively easy means for selection for PHS resistance 5. The best minimally-invasive diagnostic indices for prediction of PHS resistance were found to be oximetry, hematocrit values, heart rate and electrocardiographic (ECG) lead II waves. Some differences in results were found between the US and Israeli teams, probably reflecting genetic differences in the broiler strains used in the two countries. For instance the US team found the S wave amplitude to predict PHS susceptibility well, whereas the Israeli team found the P wave amplitude to be a better valid predictor. 6. Comprehensive physiological studies further increased knowledge on the development of PHS cardiopulmonary characteristics of pre-ascitic birds, pulmonary arterial wedge pressures, hypotension/kidney response, pulmonary hemodynamic responses to vasoactive mediators were all examined in depth. Implications, scientific and agricultural Substantial progress has been made in understanding the genetic and environmental factors involved in PHS, and their interaction. The two teams each successfully developed different selection programs, by surgical means and by divergent selection under cold challenge. Monitoring of the progress and success of the programs was done be using the in-depth estimations that this research engendered on the reliability and value of non-invasive predictive parameters. These findings helped corroborate the validity of practical means to improve PHT resistance by research-based programs of selection.