Differential heat tolerance in nestlings suggests sympatric species may face different climate change risks

For endotherms, a major threat of climate change will be the increasing frequency of extreme climate events, including heat waves. Thus, the ability of different species to tolerate high environmental temperatures is likely to have important consequences for ecology and population dynamics. We investigated the impacts of exposure to high temperatures on survival, mass gain and physiological stress of nestlings of 2 sympatric bird species subjected to the same climatic conditions in the Mediterranean basin. Results showed species-specific responses to high temperatures. Whilst hyperthermia or acute dehydration caused 36% mortality among lesser kestrels Falco naumanni, none occurred among European rollers Coracias garrulus. Within survivors, high maximum daily temperatures significantly reduced mass gain, especially among kestrels. Moreover, mass loss during heat events was shown to result in carry-over fitness costs only for lesser kestrels, by decreasing fledging condition and likely impacting post-fledging survival. High nest temperatures strongly elevated physiological stress levels of kestrels. Overall, rollers exhibited greater resilience to heat than kestrels, surviving nest temperatures up to 50°C and recovering from mass losses, suggesting that nestling development is flexible enough to cope with the constraints imposed by occasional heat waves. Although predicted increases in the frequency of extreme temperatures can accentuate lethal and sublethal fitness costs for both species, the higher thermal tolerance of rollers makes them more resilient. Our results highlight that sympatric species are not equally at risk when facing climate change and suggest that successfully predicting species response to global warming will require a better understanding of species-specific thermal tolerance

Timing is critical : consequences of asynchronous migration for the performance and destination of a long-distance migrant

Background Migration phenology is shifting for many long-distance migrants due to global climate change, however the timing and duration of migration may influence the environmental conditions individuals encounter, with potential fitness consequences. Species with asynchronous migrations, i.e., with variability in migration timing, provide an excellent opportunity to investigate how of the conditions individuals experience during migration can vary and affect the migratory performance, route, and destination of migrants. Methods Here, we use GPS tracking and accelerometer data to examine if timing of autumn migration influences the migratory performance (duration, distance, route straightness, energy expenditure) and migration destinations of a long-distance, asynchronous, migrant, the white stork (Ciconia ciconia). We also compare the weather conditions (wind speed, wind direction, and boundary layer height) encountered on migration and examine the influence of wind direction on storks' flight directions. Results From 2016 to 2020, we tracked 172 white storks and obtained 75 complete migrations from the breeding grounds in Europe to the sub-Saharan wintering areas. Autumn migration season spanned over a 3-month period (July-October) and arrival destinations covered a broad area of the Sahel, 2450 km apart, from Senegal to Niger. We found that timing of migration influenced both the performance and conditions individuals experienced: later storks spent fewer days on migration, adopted shorter and more direct routes in the Sahara Desert and consumed more energy when flying, as they were exposed to less supportive weather conditions. In the Desert, storks' flight directions were significantly influenced by wind direction, with later individuals facing stronger easterly winds (i.e., winds blowing to the west), hence being more likely to end their migration in western areas of the Sahel region. Contrastingly, early storks encountered more supportive weather conditions, spent less energy on migration and were exposed to westerly winds, thus being more likely to end migration in eastern Sahel. Conclusions Our results show that the timing of migration influences the environmental conditions individuals face, the energetic costs of migration, and the wintering destinations, where birds may be exposed to different environmental conditions and distinct threats. These findings highlight that on-going changes in migration phenology, due to environmental change, may have critical fitness consequences for long-distance soaring migrants.Peer reviewe

Connectivity between countries established by landbirds and raptors migrating along the African–Eurasian flyway

The conservation of long-distance migratory birds requires coordination between the multiple countries connected by the movements of these species. The recent expansion of tracking studies is shedding new light on these movements, but much of this information is fragmented and inaccessible to conservation practitioners and policy makers. We synthesized current knowledge on the connectivity established between countries by landbirds and raptors migrating along the African–Eurasian flyway. We reviewed tracking studies to compile migration records for 1229 individual birds, from which we derived 544 migratory links, each link corresponding to a species’ connection between a breeding country in Europe and a nonbreeding country in sub-Saharan Africa. We used these migratory links to analyze trends in knowledge over time and spatial patterns of connectivity per country (across species), per species (across countries), and at the flyway scale (across all countries and all species). The number of tracking studies available increased steadily since 2010 (particularly for landbirds), but the coverage of existing tracking data was highly incomplete. An average of 7.5% of migratory landbird species and 14.6% of raptor species were tracked per country. More data existed from central and western European countries, and it was biased toward larger bodied species. We provide species- and country-level syntheses of the migratory links we identified from the reviewed studies, involving 123 populations of 43 species, migrating between 28 European and 43 African countries. Several countries (e.g., Spain, Poland, Ethiopia, Democratic Republic of Congo) are strategic priorities for future tracking studies to complement existing data, particularly on landbirds. Despite the limitations in existing tracking data, our data and results can inform discussions under 2 key policy instruments at the flyway scale: the African–Eurasian Migratory Landbirds Action Plan and the Memorandum of Understanding on the Conservation of Migratory Birds of Prey in Africa and Eurasia.Fundação para a Ciência e Tecnologia - FCTinfo:eu-repo/semantics/publishedVersio

Large expert-curated database for benchmarking document similarity detection in biomedical literature search

Document recommendation systems for locating relevant literature have mostly relied on methods developed a decade ago. This is largely due to the lack of a large offline gold-standard benchmark of relevant documents that cover a variety of research fields such that newly developed literature search techniques can be compared, improved and translated into practice. To overcome this bottleneck, we have established the RElevant LIterature SearcH consortium consisting of more than 1500 scientists from 84 countries, who have collectively annotated the relevance of over 180 000 PubMed-listed articles with regard to their respective seed (input) article/s. The majority of annotations were contributed by highly experienced, original authors of the seed articles. The collected data cover 76% of all unique PubMed Medical Subject Headings descriptors. No systematic biases were observed across different experience levels, research fields or time spent on annotations. More importantly, annotations of the same document pairs contributed by different scientists were highly concordant. We further show that the three representative baseline methods used to generate recommended articles for evaluation (Okapi Best Matching 25, Term Frequency-Inverse Document Frequency and PubMed Related Articles) had similar overall performances. Additionally, we found that these methods each tend to produce distinct collections of recommended articles, suggesting that a hybrid method may be required to completely capture all relevant articles. The established database server located at https://relishdb.ict.griffith.edu.au is freely available for the downloading of annotation data and the blind testing of new methods. We expect that this benchmark will be useful for stimulating the development of new powerful techniques for title and title/abstract-based search engines for relevant articles in biomedical research.Peer reviewe

LesserKestrel_chick_data

Biometries (mass and wing lenght) and posterior recruitment in the population of Lesser Kestrel (Falco naumanni) chicks ringed as fledglings between 2003 and 2014 in Castro Verde Portugal. Information on brood (clutch size, laying date) of each chick is also provided

Easy but ephemeral food: exploring the trade-offs of agricultural practices in the foraging decisions of Lesser Kestrels on farmland

Capsule:Cereal harvesting creates high-quality but ephemeral foraging habitats for invertebrate predators. Aims: To investigate how cereal harvesting affects foraging decisions and hunting success of Lesser Kestrels. Methods: Habitat selection in response to changing availability of cereal fields (as patches being harvested are turned into stubble) was assessed by transects around colonies to count foraging birds. Focal observations of foraging kestrels were performed to assess hunting success and intake rate before and after harvesting. We performed transects to count Orthoptera to evaluate the impact of cereal cutting on prey abundance. Results: Harvesting impacted prey accessibility due to a temporary flush of prey, which resulted in a significant reduction in foraging time and an increase in the intake rate of kestrels. Accordingly, patches being harvested became the most preferred habitat. Nonetheless, harvesting likely caused high orthopteran mortality and dispersal leading to a gradual decline in prey abundance in stubbles. Lower prey abundance increased foraging time and reduced intake rate, and stubbles became avoided by foraging individuals. Conclusion: Although harvesting significantly increases foraging opportunities for Lesser Kestrels through intake rate maximization, patches being harvested represent an ephemeral high-quality habitat and its benefits are relatively short-lived as cereals are converted into low-quality stubbles

Data from: Mechanisms and fitness consequences of laying decisions in a migratory raptor

Seasonal decline in breeding performance is a commonly observed pattern in birds, but disentangling the contributions of environmental conditions (“timing” hypothesis) and individual quality (“quality” hypothesis) to such a pattern is challenging. Moreover, despite the strong selection for early breeding, the individual optimization model predicts that each individual has an optimal breeding window. We investigated the causes and consequences of laying decisions in the lesser kestrel (Falco naumanni) by combining a long-term dataset on reproductive traits with information on food availability. A marked seasonal decline was found in breeding success, mostly mediated by a decline in clutch size. The “timing” hypothesis, supported by the decline in consumption of mole crickets, key prey for prelaying females, seems to explain the seasonal trend in clutch size, as this pattern was recorded in both higher (adults) and lower (yearlings) quality individuals. Contrarily, the higher proportion of yearlings breeding late in the season, rather than a decay in food availability during chick rearing, seems to drive the decline in fledging success, giving support to the “quality” hypothesis. Advanced breeding and increased clutch size, as proxies of reproductive effort, were not offset by lower survival. Low repeatability in both these traits suggests that individual quality is a dynamic attribute and reproduction costs are minimized by individual optimization. Understanding the mechanisms driving individual breeding decisions is critical to anticipate species’ ability to cope with environmental changes. Here, we show that lesser kestrels failing the prelaying food window opportunity compromise reproductive performance, mostly regardless of their individual quality

grasshoppers_transects_abundance

Mean number of grasshoppers counted in walked transects in fallow grassland patches around Lesser Kestrel (Falco naumanni) colonies between 2012 and 2015

LessserKestrel_breeding_parameters_ringed_birds_dataset

Breeding parameters, age and recapture data of Lesser Kestrels (Falco naumanni) ringed between 2003 and 2014 at Castro Verde, Portuga

LesserKestrel_female_mass_wing

Weight and wing length of female Lesser Kestrels (Falco naumanni) captured during the incubation period between 2003 and 2014 in Castro Verde, Portugal