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Oversea migration of white storks through the water barriers of the straits of Gibraltar

Soaring landbirds typically exploit atmospheric uplift as they fly overland, displaying a highly effective energy-saving locomotion. However, large water bodies lack thermal updrafts, potentially becoming ecological barriers that hamper migration. The effects of a sea surface on the migratory performance of GPS-tagged white storks (Ciconia ciconia) were assessed before, during and after they crossed the straits of Gibraltar. Oversea movements involved only flapping and gliding and were faster, traversed in straighter, descending trajectories and resulted in higher movement-related energy expenditure levels than overland, supporting the water barrier hypothesis. Overland movements at both sides of the sea straits resulted in tortuous routes and ascending trajectories with pre-crossing flights showing higher elevations and more tortuous routes than post-crossing, thus supporting the barrier negotiation hypothesis. Individual positions at both ends of the sea narrow were predicted by zonal winds and storks´ location at entry in the European hinterland, and birds did not show compensational movements overland in anticipation to subsequent wind displacements oversea. The length of the water narrow at departure shore, the elevation therein and the winds on route affected major components of sea crossing performance (such as distances and times overwater, minimum elevations, climb angles, speeds and energy expenditure), supporting the departure position and oversea winds hypotheses. In summary, this study provides a prime example at high temporal resolution of how birds adjust their behavior and physiology as they interact with the changing conditions of the travelling medium, reallocating resources and modifying their movement to overcome an ecological barrier. informacion[at]ebd.csic.es: Blas et al (2020) Overland and oversea migration of white storks through the water barriers of the straits of Gibraltar. Scientific Reports 10: 20760. DOI 10.1038/s41598-020-77273-x. See Spanish press release


www.nature.com/articles/s41598-020-77273-x
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Invasive plants and urban development: a bad combination for coastal vegetation

Invasive plants and urban development: a bad combination for coastal vegetation

Land-use intensification and biological invasions are two of the most important global change pressures driving biodiversity loss. However, their combined impacts on biological communities have been seldom explored, which may result in misleading ecological assessments or mitigation actions. Based on an extensive field survey of 445 paired invaded and control plots of coastal vegetation in SW Spain, the joint effects of land-use intensification (agricultural and urban intensification) and invasion on the taxonomic and functional richness, mean plant height and leaf area of native plants were explored. The survey covered five invasive species with contrasting functional similarity and competitive ability in relation to the native community. The response of native communities for the overall and invader-specific datasets was modelled, and it was determined whether invader-native functional differences could influence the combined impacts of land-use intensification and invasion. Overall, urban intensification reduced taxonomic richness more strongly at invaded plots (synergistic interactive effects). In contrast, functional richness loss caused by urban intensification was less pronounced at invaded plots (antagonistic interactive effects). Overall models showed also that urban intensification led to reduced mean leaf area, while agriculture was linked to higher mean plant height. When exploring invader-specific models, the combined effects of agricultural and urban intensification with invasion were found to be heterogeneous. At invaded plots, invader-native functional differences accounted for part of this variability. These findings demonstrate the importance of considering the interactive effects of global change pressures for a better assessment and management of ecosystems. informacion[at]ebd.csic.es: Gutiérrez-Cánovas et al (2020) Combined effects of land-use intensification and plant invasion on native communities. Oecologia DOI 10.1007/s00442-020-04603-1


https://www.ncbi.nlm.nih.gov/pubmed/31982953