Tracking data highlight the importance of human-induced mortality for large migratory birds at a flyway scale

Human-induced direct mortality affects huge numbers of birds each year, threatening hundreds of species worldwide. Tracking technologies can be an important tool to investigate temporal and spatial patterns of bird mortality as well as their drivers. We compiled 1704 mortality records from tracking studies across the African-Eurasian flyway for 45 species, including raptors, storks, and cranes, covering the period from 2003 to 2021. Our results show a higher frequency of human-induced causes of mortality than natural causes across taxonomic groups, geographical areas, and age classes. Moreover, we found that the frequency of human-induced mortality remained stable over the study period. From the human-induced mortality events with a known cause (n = 637), three main causes were identified: electrocution (40.5 %), illegal killing (21.7 %), and poisoning (16.3 %). Additionally, combined energy infrastructure-related mortality (i.e., electrocution, power line collision, and wind-farm collision) represented 49 % of all human-induced mortality events. Using a random forest model, the main predictors of human-induced mortality were found to be taxonomic group, geographic location (latitude and longitude), and human footprint index value at the location of mortality. Despite conservation efforts, human drivers of bird mortality in the African-Eurasian flyway do not appear to have declined over the last 15 years for the studied group of species. Results suggest that stronger conservation actions to address these threats across the flyway can reduce their impacts on species. In particular, projected future development of energy infrastructure is a representative example where application of planning, operation, and mitigation measures can enhance bird conservation

Pushed by increasing air temperature and tailwind speed: weather selectivity of raptors migrating across the Aegean Sea

A vast number of raptors migrates between the Western Palearctic and Africa every autumn. Species and/or populations ofmigratory raptors that choose to cross theMediterranean Sea need to overcome an extended ecological barrier,which is particularly extensive in the area of east–central and eastMediterranean.We tested the selectivity of two raptor species to weather and phenology analyzing the data collected on a small Greek island throughout four different years.Weather selectivity of the two species shows both similarities and differences. The intensity of migration of both studied species is positively correlated with air temperature. The European Honey Buzzard selects days with strong tailwind assistance that helps to reduce flight time over sea thus decreasingmortality risk and energy consumption during this sea crossing. On the other hand, theWesternMarsh Harrier seems to be less wind selective reaching the island in good numbers also with headwinds, probably because of its higher ability in using powered-flapping flight

Broad‐front migration leads to strong migratory connectivity in the lesser kestrel (Falco naumanni)

Aim: Migratory animals regularly move between often distant breeding and non‐breeding ranges. Knowledge about how these ranges are linked by movements of individuals from different populations is crucial for unravelling temporal variability in population spatial structuring and for identifying environmental drivers of population dynamics acting at different spatio‐temporal scales. We performed a large‐scale individual‐based migration tracking study of an Afro‐Palaearctic migratory raptor, to determine the patterns of migratory connectivity of European breeding populations. Location: Europe, Africa. Methods: Migration data were recorded using different devices (geolocators, satellite transmitters, Global Positioning System dataloggers) from 87 individuals breeding in the three core European populations, located in the Iberian, Italian and Balkan peninsulas. We estimated connectivity by the Mantel correlation coefficient (rM), and computed both the degree of separation between the non‐breeding areas of individuals from the same population (i.e. the population spread) and the relative size of the non‐breeding range (i.e. the non‐breeding range spread). Results: European lesser kestrels migrated on a broad front across the Mediterranean Sea and Sahara Desert, with different populations using different routes. Iberian birds migrated to western Sahel (Senegal, Mauritania, western Mali), Balkan birds migrated chiefly to central‐eastern Sahel (Niger, Nigeria, Chad), whereas Italian ones spread from eastern Mali to Nigeria. Spatial differentiation of non‐breeding areas led to a strong migratory connectivity (rM = .58), associated with a relatively high population (637 km) and non‐breeding range (1,149 km) spread. Main conclusions: Our comprehensive analysis of the non‐breeding distribution of European lesser kestrel populations revealed a strong migratory connectivity, a rare occurrence in long‐distance avian migrants. The geographical conformation of the species’ breeding and non‐breeding ranges, together with broad‐front migration across ecological barriers, promoted the differentiation of migratory routes and non‐breeding areas. Strong connectivity could then arise because of both high population spread and broad non‐breeding range.CLH; FCC Energía/Enerstar Villena S.A.; Alcalá de Henares Municipality; EDF Énergies Nouvelles S.A.; EuroNatur; Fundación Iberdrola España, Grant/Award Number: Project Migra; MAVA Foundation; French Ministry of Ecology, Grant/Award Number: Lesser Kestrel National Action Plan; Greek Green Fund; European Commission, Grant/Award Number: LIFE11 NAT/IT/000068, LIFE11 NAT/BG/000360 and NAT/GR/001011; Córdoba Zoo; Seiit‐R‐4; Consejería de Agricultura, Medio Ambiente y Desarrollo Rural de Castilla‐La Mancha; MIUR, Grant/Award Number: PRIN 2010‐2011/20180‐TZKHC

Assessing exposure to wind turbines of a migratory raptor through its annual life cycle across continents

Unsustainable fossil fuel emissions have prompted a global shift towards renewable energy sources, such as wind. This has led to a strong expansion of wind power generation infrastructures, often conflicting with biodiversity conservation. Relatively large flying animals, such as birds and bats, have frequently been reported to collide with wind turbines, resulting in casualties that can depress population size and lead to local extinctions. Migratory species that move across continents through their year-round displacements may be especially at risk. We comprehensively assessed wind turbine exposure for a colonial migratory raptor of European conservation interest, the lesser kestrel Falco naumanni, based on the distribution and size of >1800 colonies and a large GPS-tracking dataset (>350 individuals) for three distinct biogeographical populations (from Iberian, Italian, and Balkan peninsulas). 26 % of the European population has at least one wind turbine within the foraging areas around colony sites, Italian colonies being most at risk. The main European network of protected areas, the Natura 2000 network, failed to mitigate the potential negative impact of wind turbines on breeding populations. GPS-tracking revealed that exposure was negligible in the African non-breeding areas (Sahel region), particularly high during migration, and lower during breeding for Iberian and Balkan individuals but not for Italian ones. Different countries should prioritize different measures to mitigate collision risk with wind power generation infrastructures. This case study can be leveraged by conservationists and renewable energy stakeholders to mitigate conflicts between biodiversity conservation and expected wind energy infrastructure development in the near future.This study was partly funded by the European Commission through the LIFE programme (LIFE17 NAT/IT/000586 LIFE FALKON) and by the Italian Ministry for University and Research (PRIN 2017 funding scheme, grant number 20178T2PSW to D. Rubolini). Lesser kestrel monitoring and tracking data in France were funded by the Plan national d'Actions pour le Faucon Crécerellette, by Office Français pour la Biodiversité (Migralion), and by OSU-OREME (SO ECOPOP). Most of the information on GPS-tagged birds in Spain originates from the MIGRA programme developed by SEO/BirdLife with the support of Fundación Iberdrola España and with the collaboration of GREFA, Córdoba Zoo, Alcalá de Henares Municipality, Global Nature Foundation and the European Commission (LIFE15 NAT/ES/000734 Steppe Farming), besides several Spanish environmental administrations and the collaboration of numerous field technicians and collaborators. The activity of GREFA was also supported by the Ministerio Para la Transición Ecológica y el Reto Demográfico. In Extremadura (Spain) tag deployment was conducted within the framework of LIFE project Gestión de ZEPA Urbanas en Extremadura (LIFE 15/NAT/ES/001016 ZEPAURBAN), while in Andalucía (Spain) tags were deployed within the framework of the “KESTRELS MOVE” project (CGL2016 79249 P, AEI/FEDER, UE). At the time of analyses and writing, L. López-Ricaurte and D. García-Silveira were supported by projects MERCURIO (rPID2020-115793GB, AEI/FEDER, UE) and SUMHAL (European Regional Development Fund LIFEWATCH-2019-09-CSIC-13, MICINN, POPE 2014-2020). Logistic and technical support in the field was provided by ICTS-RBD. I. Catry was funded by contract 2021.03224.CEECIND from FCT (Fundação para a Ciência e Tecnologia), J. Gameiro was supported by a post-doc scholarship (BIOPOLIS 2022-13), T. Catry was funded by contract 2021.00573.CEECIND from FCT (Fundação para a Ciência e Tecnologia). The authors acknowledge the support of NBFC to CNR, funded by the Italian Ministry of University and Research, PNRR, Missione 4 Componente 2, “Dalla ricerca all'impresa”, Investimento 1.4, Project CN00000033

Tracking data highlight the importance of human-induced mortality for large migratory birds at a flyway scale

Human-induced direct mortality affects huge numbers of birds each year, threatening hundreds of species worldwide. Tracking technologies can be an important tool to investigate temporal and spatial patterns of bird mortality as well as their drivers. We compiled 1704 mortality records from tracking studies across the African-Eurasian flyway for 45 species, including raptors, storks, and cranes, covering the period from 2003 to 2021. Our results show a higher frequency of human-induced causes of mortality than natural causes across taxonomic groups, geographical areas, and age classes. Moreover, we found that the frequency of human-induced mortality remained stable over the study period. From the human-induced mortality events with a known cause (n = 637), three main causes were identified: electrocution (40.5 %), illegal killing (21.7 %), and poisoning (16.3 %). Additionally, combined energy infrastructure-related mortality (i.e., electrocution, power line collision, and wind-farm collision) represented 49 % of all human-induced mortality events. Using a random forest model, the main predictors of human-induced mortality were found to be taxonomic group, geographic location (latitude and longitude), and human footprint index value at the location of mortality. Despite conservation efforts, human drivers of bird mortality in the African-Eurasian flyway do not appear to have declined over the last 15 years for the studied group of species. Results suggest that stronger conservation actions to address these threats across the flyway can reduce their impacts on species. In particular, projected future development of energy infrastructure is a representative example where application of planning, operation, and mitigation measures can enhance bird conservation.publishedVersio