10 research outputs found

    Seasonal variation and tracking of climate niche of a migratory bird

    Get PDF
    Migratory birds inhabit different areas during breeding and non-breeding seasons. Depending on the time of the year, they may utilize different resources available in seasonal habitats, but also are subjected to changing climate regimes during their annual life cycle. Migratory birds may adopt ecological niche tracking to cope with different environmental conditions between breeding and non-breeding grounds. The American White Pelican (Pelecanus erythrorhynchos, hereafter ‘AWPE’) is a short-distance migrant between the Gulf of Mexico coastal regions (nonbreeding grounds) and the Northern Great Plains (breeding grounds) of Canada and the US. The American White Pelican is a piscivore, feeding on fish, crayfish, and salamanders in inland freshwater wetlands. Cold, icy winter weather conditions substantially reduce and limit food resource availability at the breeding grounds during winters. Thus, we hypothesize that AWPEs would migrate between the breeding and non-breeding grounds to track climatic conditions that allow easier availability of resources. However, the niche tracking strategies have not been tested in AWPEs mainly due to the lack of reliable tracking data. Our objectives were to test whether the niche tracking or niche switching hypothesis would better explain seasonal variations in ecological niche overlap of AWPEs using the GPS locations of 19 tracked migrating birds, which had GPS locations at both breeding and non-breeding grounds. We estimated overlap of climate niche to test for seasonal niche tracking behaviors at both individual and population levels. Our results indicate that six out of 13 GPS-tracked AWPE individuals tracked climatic niche during the annual migration cycle. The analysis of the combined data of all 19 tracked AWPEs demonstrated that AWPEs tracked seasonal climate niche at the population level. Cold winter temperatures below zero (℃) may freeze the water surface of wetlands and shallow waterbodies, preventing AWPEs from acquiring sufficient food. The coupling of winter food resources with winter climatic conditions may result in climate niche tracking. Variation in climate niche tracking among individuals may offer ecological plasticity for AWPEs to cope with climatic changes

    Synergistic Effects of Climate and Land-Cover Change on Long-Term Bird Population Trends of the Western USA: A Test of Modeled Predictions

    Get PDF
    Climate and land-use change are predicted to lead to widespread changes in population dynamics, but quantitative predictions on the relative effects of these stressors have not yet been examined empirically. We analyzed historical abundance data of 110 terrestrial bird species sampled from 1983 to 2010 along 406 Breeding Bird Survey (BBS) across the northwestern USA. Using boosted-regression trees, we modeled bird abundance at the beginning of this interval as a function of (1) climate variables, (2) Landsat-derived landcover data, (3) the additive and interactive effects of climate and land-cover variables. We evaluated the capacity of each model set to predict observed 27-year bird population trends. On average, 45 species significantly declined over the period observed and only 8 increased (mean trend = -0.84%/year). Climate change alone significantly predicted observed abundance trends for 44/108 species (mean 0.37 ± 0.09 [SD]), land-cover changes alone predicted trends for 47/108 species (mean r = 0.36 ±0.09), and the synergistic effects predicted 59/108 species (mean r = 0.37 ±0.11). However, for 37 of these species, including information on land-cover change increased prediction success over climate data alone. Across stressors, species with trends that were predicted accurately were more likely to be in decline across the western USA. For instance, species with high correlations between predicted and observed abundances (> r = 0.6) were declining at rates that were on average >2%/ year. We then provide the first empirical evidence that abundance models based on land cover and climate have the capacity to predict the species most likely to be at risk from climate and land-use change. However, for many species there were substantial discrepancies between modeled and observed trends. Nevertheless, our results highlight that climate change is already influencing bird populations of the western U.S. and that such effects often operate synergistically with land-cover change to affect population decline

    A Broad Assessment of Factors Determining Culicoides imicola Abundance: Modelling the Present and Forecasting Its Future in Climate Change Scenarios

    Get PDF
    Bluetongue (BT) is still present in Europe and the introduction of new serotypes from endemic areas in the African continent is a possible threat. Culicoides imicola remains one of the most relevant BT vectors in Spain and research on the environmental determinants driving its life cycle is key to preventing and controlling BT. Our aim was to improve our understanding of the biotic and abiotic determinants of C. imicola by modelling its present abundance, studying the spatial pattern of predicted abundance in relation to BT outbreaks, and investigating how the predicted current distribution and abundance patterns might change under future (2011–2040) scenarios of climate change according to the Intergovernmental Panel on Climate Change. C. imicola abundance data from the bluetongue national surveillance programme were modelled with spatial, topoclimatic, host and soil factors. The influence of these factors was further assessed by variation partitioning procedures. The predicted abundance of C. imicola was also projected to a future period. Variation partitioning demonstrated that the pure effect of host and topoclimate factors explained a high percentage (>80%) of the variation. The pure effect of soil followed in importance in explaining the abundance of C. imicola. A close link was confirmed between C. imicola abundance and BT outbreaks. To the best of our knowledge, this study is the first to consider wild and domestic hosts in predictive modelling for an arthropod vector. The main findings regarding the near future show that there is no evidence to suggest that there will be an important increase in the distribution range of C. imicola; this contrasts with an expected increase in abundance in the areas where it is already present in mainland Spain. What may be expected regarding the future scenario for orbiviruses in mainland Spain, is that higher predicted C. imicola abundance may significantly change the rate of transmission of orbiviruses

    Long-term organic farming and floral diversity promotes stability of bee communities in agroecosystems

    Get PDF
    Increasing bee diversity promotes pollination services on farms. Yet, given the high turnover in pollinator communities, without knowledge of how pollinator communities assemble, it is difficult to conserve or increase bee diversity. Thus, a mechanistic understanding of factors mediating pollinator community assembly could promote pollinator conservation measures. To assess the determinants of pollinator community assembly and structure, we surveyed bee communities and floral resources on 36 farms ranging from 0 to 43 years in organic production. We used niche-based and stochastic species abundance models to characterise the mechanisms driving community assembly, and an additive partition of beta diversity to evaluate resource and species turnover (i.e. community structure). We then used statistical models to assess whether resource turnover or time in organic production altered community assembly and beta diversity, and a jackknife analysis to assess the sensitivity of top models to resource and species identity. We show that bee communities on farms that practiced organic methods for longer assembled by niche-based rather than stochastic processes and had less turnover in bee species across years. Because our model of niche-based processes assumes resource use, these results indicate bee communities reflect underlying species-specific resource preferences (e.g. floral and/or nesting resources) and that longer periods of organic management reduced dissimilarity mediated by species replacement. Our jackknife approach then examined the role of species identity effects in beta diversity, showing changes in floral resources increased dissimilarity driven by bee species loss, but only in landscapes simplified by urbanisation. This jackknife analysis then indicated that landscape resource replacement which was not driven by particular landscape classes, mediated bee species replacement wherein dissimilarity was driven by a generalist native bee, suggesting bee life history (e.g. flexibility in resource use) and landscape complementarity, rather than identity, underlie patterns identified using the beta diversity equations. Our results show bee communities assemble by niche-based processes, evidenced by collinearity in resource and bee species turnover. Because niche-based assembly indicates ecosystem health, farmers who adopt crop diversification and practice organic methods for longer may promote pollinator diversity and stability leading to improved pollination in farms. Read the free Plain Language Summary for this article on the Journal blog

    2õ curso de maestro de educación infantil de adaptación al EEES, módulo inicial : guía del alumno, curso 2008-2009

    No full text
    Publicación realizada al amparo de los Proyectos de Innovación Educativa tipo A-2, en el contexto de la Convergencia Europea (R-232/2008, de 22 de abril 2008 de la Universidad de Murcia), financiados por la Universidad de Murcia y por la Comunidad Autónoma de la Región de Murcia.Módulo inicial de adaptación al Espacio Europeo de Educación Superior (EEES), destinado al alumnado de segundo curso de la Titulación de Maestro en Educación Infantil, orientado a la adquisición de competencias profesionales. Se presentan las guías docentes de las asignaturas a cursar, horarios, programación de seminarios y talleres y recomendaciones para la elaboración de trabajos científicos..MurciaBiblioteca Regional de Murcia. Fondo Regional; Avda. Juan Carlos I, 17; 30008 Murcia; +34968366590; +34968366600; [email protected]
    corecore