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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] 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
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Evaluation of the network of protection areas for the feeding of scavengers in Spain

Evaluation of the network of protection areas for the feeding of scavengers in Spain

Protected areas are one of the most common strategies for wildlife conservation worldwide. However, their effectiveness is rarely evaluated. In Europe, after the outbreak of bovine spongiform encephalopathy, a restrictive sanitary regulation prohibited the abandonment of dead livestock in extensive farming in the field, which led to negative consequences for scavengers. As an attempt to mitigate this negative impact, a new regulation was approved to allow farmers to leave extensive livestock carcasses in the so-called "Protection areas for the feeding of necrophagous species of European interest" (PAFs). General aims of this study were to quantify (i) the proportion of breeding distribution of targeted scavenger species overlapping PAFs; (ii) the extensive livestock carrion biomass available inside PAFs; (iii) the proportion of breeding distribution of non-targeted scavenger species falling within PAFs; (iv) the overlap between the home range of vultures and PAFs, as well as the extent to which vultures move through different administrative units; and (v) the savings in greenhouse gas emissions in relation to the pre-PAF scenario. Results show that the implementation of the new sanitary regulation by means of areas for the feeding of scavengers could mean an important improvement in scavenger conservation and a noteworthy reduction of greenhouse gas emissions. However, some gaps related to the distribution of endangered facultative scavengers were identified. Moreover, given that vultures are highly mobile organisms, the design and management of these feeding areas should be coordinated at both the supra-regional and supra-national scales. informacion[at] Morales-Reyes et al (2016) Evaluation of the network of protection areas for the feeding of scavengers in Spain: from biodiversity conservation to greenhouse gas emission savings. J Appl Ecol doi:10.1111/1365-2664.12833