Modelling mountain bird distributions - Model consistency and transferability across different Alpine regions

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Programme and Abstracts

Edited by Zoltán Barta

U

O

E

TURKU 2017

FIN

11

th

Conference of the European Ornithologists’

Union

18 – 22 August 2017

Turku

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Oral sessions 73

1_{Lund University, Lund, Sweden}

Twice a year millions of long-distance migratory birds travel thousands of miles between their temperate breeding and tropical wintering grounds. Surviving exposure to pathogens in both of these environments presents a major challenge for the immune system. How migratory birds have adapted to cope with this high diversity of pathogens is currently unknown. Here we address this issue in a phylogenetic framework by testing whether Afro-Palearctic migratory Passerine birds have more diverse major histocompatibility compatibility (MHC) genes, allowing a wider range of pathogens to be recognised, than resident species in either Africa or the Palearctic. We found that, although most Afro-Palearctic migratory passerines originated from resident African species, their MHC diversity now more closely resembles that of Palearctic residents, suggesting that the migratory birds have evolved lower MHC diversity than their African ancestors. This initially surprising result may reflect the cost of high MHC diversity in terms of an increased risk of immuno-pathology. By enabling species to escape tropical pathogens during the breeding season, migration appears to have relaxed selection for high MHC diversity. Overall, our results underscore the potential role of pathogen avoidance in the evolution of migration.

Oral session 2: Distribution

15:00 SATURDAY, 19/08/2017 HALLXXI OS2.1

Climate change impacts on mountain birds: status and prospects

Davide Scridel1,2, Dan Chamberlain3, Paolo Pedrini1, Giuseppe Bogliani2, Mattia Brambilla1,4

1_{Museo delle Scienze (Sezione Zoologia dei Vertebrati), Trento, Italy;}2_{Università di Pavia (Dipartimento di}

Scienze della Terra e dell’Ambiente), Pavia, Italy;3Università di Torino, Torino, Italy;4Fondazione Lombardia per l’Ambiente (Settore Biodiversità e Aree Protette), Seveso, Italy

Although considered globally important areas for birds and biodiversity, mountain regions remain poorly studied despite their renowned susceptibility to climatic alterations. Basic knowledge of species inhabiting these regions is scarce, and even a univocal definition for mountain regions is debatable as interpretations vary across countries and institutions. These ambiguities may prevent the definition of effective large-scale conservation strategies, and it is urgent to define "mountain birds" and investigate the potential impact of climate change on such species. Here, we propose a definition of mountain birds, summarise reported impacts and discuss predictions of changes in species distribution according to climate scenarios. We introduce for the first time an objective classification of mountain bird specialists and generalists, present the results of a systematic review and meta-analysis of the effects of climate change on Holarctic mountain and upland birds, quantifying the general responses to climate change including altitudinal shifts, changes in life history traits and assessment of mitigation actions. Using Italy as a case-study, we then demonstrate how climate change has already affected patterns of bird distribution in the last 30-years by comparing a range of cold-adapted and closely related control species. Finally, we show how climate change will increase the potential conflict between anthropogenic activities and the conservation of high-elevation birds and habitats in the Alps and examine the potential future impacts of climate change on both broad distribution and fine-scale habitat suitability for a mountain specialist.

Modelling mountain bird distributions - Model consistency and transferability across different Alpine regions

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Oral sessions 74

1_{University of Turin, Turin, Italy;}2_{Museo delle Scienze di Trento, Trento, Italy;}3_{Fondazione Lombardia}

per l’Ambiente, Seveso, Italy

Conservation actions are often based on studies carried out in fairly restricted areas, yet these actions may be applied to much wider areas beyond the location of research. The extent to which birds respond to habitat in a consistent way across different regions may limit the efficacy of any conservation initiative that is intended to be applied over broad geographical areas. We address this issue in an Alpine context, considering (i) existing evidence of differences in environmental requirements (habitat, climate, topography) in different areas of the Alps and (ii) formally analysing consistency of climate and habitat associations and trends in altitudinal occurrence rates for Alpine species using data from bird surveys of altitudinal transects carried out in two separate Alpine regions, Piedmont and Trentino. Forest and grassland species showed a reasonable level of consistency in previously published models, although model outcomes were less consistent for forest-shrub ecotone species. Distributions of the majority of species along altitudinal gradients were consistent across regions. Furthermore, the environmental drivers were similar across regions for a given species. However, the magnitude of the effects of individual drivers varied. Cross-validation found good model performance for forest species, suggesting high model transferability, but poor model performance for grassland and especially forest-shrub ecotone species. These findings suggest that broad-scale models can be used to predict montane forest species occurrence across Alpine regions, but that a greater understanding of environmental requirements of higher altitude species is needed in order to develop more widely applicable predictive models.

Influence of device accuracy and choice of algorithm for species distribution modelling of seabirds: A case study using black-browed albatrosses

Jan O. Engler1, Petra Quillfeldt2, Janet R.D. Silk3, Richard A. Phillips3

1_{Dept. of Biology, Terrestrial Ecology Unit, Ghent University, Ghent, Belgium;}2_{Dept. of Animal Ecology}

and Systematics, Justus-Liebig-University, Giessen, Germany;3British Antarctic Survey, Natural Environment Research Council, Cambridge, UK

Species distribution models (SDM) based on tracking data from different devices are used increasingly to explain and predict seabird distributions. However, different tracking methods provide different data resolutions, ranging from <10m to >100km. To better understand the implications of this variation, we modeled the potential distribution of black-browed albatrosses Thalassarche melanophris from South Georgia that were simultaneously equipped with a Platform Terminal Transmitter (PTT) (high resolution) and a Global Location Sensor (GLS) logger (coarse resolution), and measured the overlap of the respective potential distribution for a total of nine different SDM algorithms. We found slightly better model fits for the PTT than for GLS data (AUC values 0.958±0.048 vs. 0.95±0.05) across all algorithms. The overlaps of the predicted distributions were higher between device types for the same algorithm, than among algorithms for either device type. Uncertainty arising from coarse-resolution location data is therefore lower than that associated with the modeling technique. Consequently, the choice of an appropriate algorithm appears to be more important than device type when applying SDMs to seabird tracking data. Despite their low accuracy, GLS data appear to be effective for analyzing the habitat preferences and distribution patterns of pelagic species.

Weather effects on population dynamics of common birds in the northern and southern parts of their distribution range