Exposure of wetlands important for nonbreeding waterbirds to sea-level rise in the Mediterranean.

Sea-level rise (SLR) is expected to cause major changes to coastal wetlands, which are among the world's most vulnerable ecosystems and are critical for nonbreeding waterbirds. Because strategies for adaptation to SLR, such as nature-based solutions and designation of protected areas, can locally reduce the negative effects of coastal flooding under SLR on coastal wetlands, it is crucial to prioritize adaptation efforts, especially for wetlands of international importance for biodiversity. We assessed the exposure of coastal wetlands important for nonbreeding waterbirds to projected SLR along the Mediterranean coasts of 8 countries by modeling future coastal flooding under 7 scenarios of SLR by 2100 (from 44- to 161-cm rise) with a static inundation approach. Exposure to coastal flooding under future SLR was assessed for 938 Mediterranean coastal sites (≤30 km from the coastline) where 145 species of nonbreeding birds were monitored as part of the International Waterbird Census and for which the monitoring area was delineated by a polygon (64.3% of the coastal sites monitored in the Mediterranean region). Thirty-four percent of sites were threatened by future SLR, even under the most optimistic scenarios. Protected study sites and study sites of international importance for waterbirds were, respectively, 1.5 and 2 times more exposed to SLR than the other sites under the most optimistic scenario. Accordingly, we advocate for the development of a prioritization scheme to be applied to these wetlands for the implementation of strategies for adaptation to SLR to anticipate the effects of coastal flooding. Our study provides major guidance for conservation planning under global change in several countries of the Mediterranean region.

Exposición de los humedales de importancia para las aves acuáticas no reproductoras al incremento del nivel del mar en el Mediterráneo Resumen Se espera que el incremento en el nivel del mar (INM) cause cambios importantes en los humedales costeros, los cuales se encuentran entre los ecosistemas más vulnerables y son críticos para las aves acuáticas no reproductoras. Es crucial la priorización de los esfuerzos de adaptación, especialmente en los humedales con importancia internacional para la biodiversidad, ya que las estrategias de adaptación ante el INM, como las soluciones basadas en la naturaleza y la designación de áreas protegidas, pueden reducir localmente los efectos negativos de las inundaciones costeras por INM en los humedales costeros. Evaluamos la exposición de los humedales costeros con importancia para las aves acuáticas no reproductoras ante el INM proyectado en las costas del Mediterráneo en ocho países con un modelo de inundaciones costeras en el futuro bajo siete escenarios de INM para el año 2100 (de 44 a 161 cm) con un enfoque de inundación estática. Evaluamos la exposición a las inundaciones costeras bajo el INM futuro en 938 sitios costeros del Mediterráneo (≤ 30 km a partir de la costa), en donde monitoreamos a 145 especies de aves no reproductoras como parte del Censo Internacional de Aves Acuáticas y para los cuales el área de monitoreo estuvo delineada con un polígono (64.3% de los sitios costeros monitoreados en la región Mediterránea). El 34% de los sitios se vio amenazado por el INM en el futuro, incluso con los escenarios más optimistas. Los sitios de estudio protegidos y los sitios de estudio de importancia internacional para las aves acuáticas estuvieron expuestos 1.5 y 2 veces más al INM que otros sitios con el escenario más optimista. De acuerdo con esto, abogamos por el desarrollo de un esquema de priorización para aplicarse en estos humedales para la implementación de estrategias de adaptación al INM para anticipar los efectos de las inundaciones costeras. Nuestro estudio proporciona información importante para la planeación de la conservación bajo el cambio global en varios de los países del Mediterráneo.

Differential survival throughout the full annual cycle of a migratory bird presents a life-history trade-off.

Long-distance migrations are among the most physically demanding feats animals perform. Understanding the potential costs and benefits of such behaviour is a fundamental question in ecology and evolution. A hypothetical cost of migration should be outweighed by higher productivity and/or higher annual survival, but few studies on migratory species have been able to directly quantify patterns of survival throughout the full annual cycle and across the majority of a species' range. Here, we use telemetry data from 220 migratory Egyptian vultures Neophron percnopterus, tracked for 3,186 bird months and across approximately 70% of the species' global distribution, to test for differences in survival throughout the annual cycle. We estimated monthly survival probability relative to migration and latitude using a multi-event capture-recapture model in a Bayesian framework that accounted for age, origin, subpopulation and the uncertainty of classifying fates from tracking data. We found lower survival during migration compared to stationary periods (ß = -0.816; 95% credible interval: -1.290 to -0.318) and higher survival on non-breeding grounds at southern latitudes (<25°N; ß = 0.664; 0.076-1.319) compared to on breeding grounds. Survival was also higher for individuals originating from Western Europe (ß = 0.664; 0.110-1.330) as compared to further east in Europe and Asia, and improved with age (ß = 0.030; 0.020-0.042). Anthropogenic mortalities accounted for half of the mortalities with a known cause and occurred mainly in northern latitudes. Many juveniles drowned in the Mediterranean Sea on their first autumn migration while there were few confirmed mortalities in the Sahara Desert, indicating that migration barriers are likely species-specific. Our study advances the understanding of important fitness trade-offs associated with long-distance migration. We conclude that there is lower survival associated with migration, but that this may be offset by higher non-breeding survival at lower latitudes. We found more human-caused mortality farther north, and suggest that increasing anthropogenic mortality could disrupt the delicate migration trade-off balance. Research to investigate further potential benefits of migration (e.g. differential productivity across latitudes) could clarify how migration evolved and how migrants may persist in a rapidly changing world.

Early and accumulated experience shape migration and flight in Egyptian vultures.

Two types of experience affect animals' behavioral proficiencies and, accordingly, their fitness: early-life experience, an animal's environment during its early development, and acquired experience, the repeated practice of a specific task.1,2,3,4,5,6,7,8 Yet, how these two experience types and their interactions affect different proficiencies is still an open question. Here, we study the interactions between these two types of experience during migration, a critical and challenging period.9,10 We do so by comparing migratory proficiencies between birds with different early-life experiences and explain these differences by testing fine-scale flight mechanisms. We used data collected by GPS transmitters during 127 autumn migrations of 65 individuals to study the flight proficiencies of two groups of Egyptian vultures (Neophron percnopterus), a long-distance, soaring raptor.11,12 The two groups differed greatly in their early-life experience, one group being captive bred and the other wild hatched.13 Both groups improved their migratory performance with acquired experience, exhibiting shorter migration times, longer daily progress, and improved flight skills, specifically more efficient soaring-gliding behavior. The observed improvements were mostly apparent for captive-bred vultures, which were the least efficient during their first migration but were able to catch up in their migratory performance already in the second migration. Thus, we show how the strong negative effects of early-life experience were offset by acquired experience. Our findings uncover how the interaction between early-life and acquired experiences may shape animals' proficiencies and shed new light on the ontogeny of animal migration, suggesting possible effects of sensitive periods of learning on the acquisition of migratory skills.

Plasma cholinesterase activity: A benchmark for rapid detection of pesticide poisoning in an avian scavenger.

Poisoning due to exposure to organophosphate and carbamate pesticides is a common threat for many wildlife species, especially for scavengers such as vultures. The Griffon vulture population (Gyps fulvus), for instance, is deteriorating in the Eastern Mediterranean, and is considered to be critically endangered in Israel, where 48 out of 107 (45 %) known injury/mortality cases in 2010-2021 were caused by poisoning. Lack of specific clinical indications, together with levels of organophosphate or carbamate pesticides too low to detect, challenge the ability to diagnose and treat such poisoning events. The activity of cholinesterase (ChE) in plasma has the potential to serve as an effective biomarker for monitoring exposure to anticholinesterase pesticides in live vultures. Yet, the applicability of this approach has been limited by intra- and inter-species variations in ChE basal levels. The present study aims to provide a benchmark for ChE activity levels in healthy Griffons and their intra-species variation. Blood samples from free-roaming (n = 231) and captive (n = 63) Griffons were collected during routine monitoring, and ChE levels were determined using a colorimetric method. We established that the ChE in the plasma of Griffons reflects mostly acetylcholinesterase as the dominant form. ChE levels in healthy Griffons are 0.601 ± 0.011 U/ml (mean ± SE), while Griffons with suspected or confirmed pesticide poisoning display much lower levels of ChE activity (typically <0.3 U/ml). We also characterized the age dependence of ChE activity, as well as differences among groups from different locations or origins. Our study provides a rapid diagnostic tool for the detection of exposure to organophosphate and carbamate pesticides that should facilitate the lifesaving treatment and the conservation of this species. Moreover, our protocols can be adapted to other species and geographical areas, addressing pesticide poisoning worldwide and contributing to the protection of endangered species and their ecological functions (e.g. sanitation by scavengers).

Examination of Eurasian griffon vultures (Gyps fulvus fulvus) in Israel for exposure to environmental toxicants using dried blood spots.

The griffon vulture (Gyps fulvus) is one of seven species of Old World Gyps vultures found over a wide range from the Iberian peninsula in the west through the Balkans, Turkey, and the Middle East to India in the east. The population of the griffon vultures in Israel has suffered a dramatic decrease, and in recent years productivity has been severely reduced. In this study, whole-blood samples taken from 25 apparently healthy griffon vultures at various stages of maturity were examined to investigate whether the vultures are being excessively exposed to environmental contaminants that might deleteriously affect their reproduction. Five groups of environmental contaminants, comprising toxic elements, organochlorine pesticides, polychlorinated biphenyls, polybrominated diphenyl ethers, and perfluorinated compounds, were monitored in dried blood spots. Results of the analyses showed low levels of exposure of griffon vultures to environmental contaminants compared with the sparse data available on griffon vultures and other diurnal raptors in other countries.

Decision-making by a soaring bird: time, energy and risk considerations at different spatio-temporal scales.

Natural selection theory suggests that mobile animals trade off time, energy and risk costs with food, safety and other pay-offs obtained by movement. We examined how birds make movement decisions by integrating aspects of flight biomechanics, movement ecology and behaviour in a hierarchical framework investigating flight track variation across several spatio-temporal scales. Using extensive global positioning system and accelerometer data from Eurasian griffon vultures (Gyps fulvus) in Israel and France, we examined soaring-gliding decision-making by comparing inbound versus outbound flights (to or from a central roost, respectively), and these (and other) home-range foraging movements (up to 300 km) versus long-range movements (longer than 300 km). We found that long-range movements and inbound flights have similar features compared with their counterparts: individuals reduced journey time by performing more efficient soaring-gliding flight, reduced energy expenditure by flapping less and were more risk-prone by gliding more steeply between thermals. Age, breeding status, wind conditions and flight altitude (but not sex) affected time and energy prioritization during flights. We therefore suggest that individuals facing time, energy and risk trade-offs during movements make similar decisions across a broad range of ecological contexts and spatial scales, presumably owing to similarity in the uncertainty about movement outcomes.This article is part of the themed issue 'Moving in a moving medium: new perspectives on flight'.