Spatio-temporal variation in the wintering associations of an alpine bird

Many animals make behavioural changes to cope with winter conditions, being gregariousness a common strategy. Several factors have been invoked to explain why gregariousness may evolve during winter, with individuals coming together and separating as they trade off the different costs and benefits of living in groups. These trade-offs may, however, change over space and time as a response to varying environmental conditions. Despite its importance, little is known about the factors triggering gregarious behaviour during winter and its change in response to variation in weather conditions is poorly documented. Here, we aimed at quantifying large-scale patterns in wintering associations over 23 years of the white-winged snowfinch Montifringilla nivalis nivalis. We found that individuals gather in larger groups at sites with harsh wintering conditions. Individuals at colder sites reunite later and separate earlier in the season than at warmer sites. However, the magnitude and phenology of wintering associations are ruled by changes in weather conditions. When the temperature increased or the levels of precipitation decreased, group size substantially decreased, and individuals stayed united in groups for a shorter time. These results shed light on factors driving gregariousness and points to shifting winter climate as an important factor influencing this behaviour.M.d.M.D. was financially supported by the (i) Spanish Ministry of Sciences, Innovation and Universities (no. CGL2016-79764-P) and (ii) a Spanish Ramon y Cajal grant no. RYC-2014-16263. M.B. was partly supported by the project Mediterranean Mosaics II funded by MAVA to Lipu

Estudio de la ecología trófica del águila perdicera Aquila fasciata: efectos de la dieta sobre la condición corporal, las tasas vitales y la demografía

[spa] En esta tesis se estudia con detalle la ecología trófica del águila perdicera en varias poblaciones de Europa Occidental, lo que permite testar una serie de hipótesis dentro del marco general de la teoría del forrajeo óptimo. En primer lugar, para estudiar la dieta se desarrollan nuevas metodologías basadas en el uso de biomarcadores intrínsecos como el análisis de isótopos estables en las plumas de los pollos, siendo una aproximación metodológica totalmente novedosa en estudios de dieta del águila perdicera. Los resultados muestran la utilidad de estos análisis como indicadores tróficos tanto a nivel individual, territorial, como poblacional, lo que ha permitido testar cuáles son los efectos de la composición de la dieta sobre la condición corporal de los pollos, y sobre las tasas vitales de las parejas territoriales en varias poblaciones con marcadas diferencias ecológicas y demográficas. En este sentido, se ha visto que un mayor consumo de presas preferidas por la especie, como el conejo o la perdiz, mejora algunos biomarcadores del estado de condición corporal de los pollos, mientras que un aumento en la diversidad trófica tiene efectos negativos. Asimismo, uno de los resultados más relevantes ha sido la relación positiva entre el consumo de presas preferidas y parámetros reproductores como la productividad, especialmente a nivel territorial. También se ha encontrado que los territorios con mayor diversidad trófica tienen menor productividad, e incluso menor supervivencia adulta, así como que los efectos de la dieta sobre la demografía a nivel poblacional parece una propiedad emergente de la relación entre dieta y tasas vitales a nivel territorial. En conjunto, los resultados obtenidos indican que existe una gran heterogeneidad en la dieta, en las estimas de condición y en los parámetros vitales del águila perdicera tanto entre territorios dentro de una misma población, como entre algunas poblaciones, y estas diferencias han permitido detectar patrones que relacionan la tipología de dieta con los parámetros vitales a diferentes escalas espacio-temporales. Tanto el desarrollo de nuevas técnicas de análisis de dieta, como el conocimiento generado de los efectos de la dieta sobre los parámetros vitales, aportan información muy relevante y útil de cara a establecer protocolos de monitoreo de la ecología trófica del águila perdicera que puedan ser empleados para su conservación. Este aspecto cobra una especial importancia en el área de estudio, debido a que el monitoreo de la dieta de depredadores terrestres, como el águila perdicera, podría servir en bioindicación para detectar el modo en el que la presión antrópica incide sobre el estado de conservación de los habitas y las comunidades en los ecosistemas mediterráneos en los que estas especies habitan.[eng] This thesis examines in detail the trophic ecology of Bonelli's eagle in several populations of Western Europe, which allows testing a number of hypotheses within the theoretical framework of the Optimal Foraging Theory. Firstly, in order to study Bonelli’s eagle diet we test the applicability of intrinsic biomarkers such as stable isotope analyses in nestling feathers, offering the first isotopic data for the Bonelli’s eagle. Our results show the usefulness of isotopic analyses as trophic indicators both at the individual, territorial and population levels. Then, by using isotopic analyses to assess main prey consumption, we tested which are the effects of diet composition on nestling body condition and on the main vital rates of territorial breeding pairs at different populations with marked ecological and demographic differences. In this regard, it has been shown that higher consumption of preferred prey species improved some nestling body condition biomarkers, while an increase in the diet diversity had an opposite effect. Moreover, a relevant result was the positive relationship between the consumption of preferred prey and reproductive parameters such as productivity, especially at the territory level. It has also been found that those territorial breeding pairs with higher diet diversity had lower productivity, and even lower adult survival. Moreover, the effects of diet on the populations’ demographic rates seem an emergent property of the relationship between diet and vital rates at the territory level. Overall, our results indicate that there is a high heterogeneity in diet, nestling body condition and territorial and population main vital parameters both between Bonelli's eagle territories within the same population, and among some populations. These differences have revealed patterns that relate diet with vital parameters at different spatial and temporal scales. Both the development of new techniques for diet analysis, as the generated knowledge of the effects of diet on vital parameters, provide very relevant and useful information in order to establish protocols for monitoring the feeding ecology of Bonelli's eagle that can be used for conservation. This aspect is particularly important in the study area, because the monitoring of the diet of a terrestrial predator such as Bonelli's eagle could serve in bioindication studies to detect how human pressure affects the conservation state of those habitats and communities in the Mediterranean ecosystems where the species inhabit

The influence of diet on nestling body condition of an apex predator: a multi-biomarker approach

Animal body condition refers to the health and physiological state of individuals, and multiple parameters have been proposed to quantify this key concept. Food intake is one of the main determinants of individual body condition and much debate has been generated on how diet relates to body condition. We investigated this relationship in free-living Bonelli’s eagle (Aquila fasciata) nestlings sampled at two geographically distant populations in Spain. Nestlings’ main prey consumption was estimated by isotopic analyses. A multi-biomarker approach, including morphometric and blood biochemical measures (i.e. hematocrit, plasma biochemistry and oxidative stress biomarkers), enabled us to integrate all the body condition measures taken. A greater consumption of a preferred prey [i.e. the European rabbit (Oryctolagus cuniculus)] improved nestling body condition, as indicated by lower levels of cholesterol in plasma, greater activity of enzymes mediating in protein catabolism, higher levels of tocopherol and glutathione, and less glutathione peroxidase activity, which also suggested lower degree of oxidative stress. On the other hand, increased diet diversity was positively correlated with higher levels of oxidized glutathione, which suggests that these nestlings had poorer body condition than those with a higher frequency of preferred prey consumption. Several factors other than diet [i.e. altitude of nesting areas, nestling sex and age, sampling time (before or after midday) and recent food ingestion] had an effect on certain body condition measures. Our study reveals a measurable effect of diet on a predator’s body condition and demonstrates the importance of considering the potential influence of multiple intrinsic and extrinsic factors when assessing animal body condition.This study was funded by projects CGL2007-64805 and CGL2010-17056 from the “Ministerio de Ciencia e Innovación, Gobierno de España”, the “Àrea d’Espais Naturals de la Diputació de Barcelona” and Miquel Torres S.A. J. Resano-Mayor was supported by a predoctoral grant from the “Departamento de Educación, Gobierno de Navarra; Plan de Formación y de I+D 2008–2009”.Peer Reviewe

The importance of seasonal environmental factors in the foraging habitat selection of Alpine Ring Ouzels Turdus torquatus alpestris

Species inhabiting mountain ecosystems are expected to be particularly vulnerable to environmental change, yet information on their basic ecology is often lacking. Knowledge from field-based empirical studies remains essential to refine our understanding of the impact of current habitat alterations and for the consequential development of meaningful conservation management strategies. This study focuses on a poorly investigated and vulnerable mountain bird species in Europe, the Ring Ouzel Turdus torquatus. Our aim was to identify the species’ key ecological requirements during the crucial period of nestling provisioning in the context of environmental change. We radiotracked and observed Alpine Ring Ouzels in a high-density population, investigating their pattern of foraging habitat selection in 2015 and 2017, and evaluated the transferability of these results over a wider geographical range across the SW Swiss Alps. Foraging birds selected, consistently in space and time, short grass swards (< 10 cm) with interspersed patches of accessible and penetrable soils, at intermediate moisture levels (around 40–65% volumetric water content). In Alpine ecosystems, this microhabitat configuration is typically widespread during the spring snowmelt, but extremely seasonal, with a rapid decrease in its availability over the course of the breeding season. This underlines the high vulnerability of the Ring Ouzel to environmental change: an earlier snowmelt could generate a temporal mismatch between the peak of the breeding effort and optimal foraging conditions; however, abandoning grazing activities on semi-wooded Alpine pastures may further decrease foraging habitat suitability through taller and denser grass swards, and subsequent woody vegetation encroachment. This study provides a mechanistic appraisal of the challenges Ring Ouzels will face in the future, as well as initial guidelines for targeted habitat management within timberline ecotones

Pollutant accumulation in nestlings of Bonelli's Eagle. Effects on health and influence of diet composition estimated through fatty acid signatures

Resumen del trabajo presentado al 23rd Annual Meeting of the Society of Environmental Toxicology and Chemistry, celebrado en Glasgow (Escocia) del 12 al 16 de mayo de 2013.-- et al.The accumulation of persistent pollutants like organochlorine compounds (OC) in raptors has been related to toxic effects on adults, while nestlings have received less attention. Nestlings usually demand high amounts of energy that can be obtained from fat consumption, with the potential for mobilization of stored OC. The accumulation of OC depends on the diet composition, which can be estimated from fatty acid (FA) signatures in plasma. Bonelli’s Eagle (Aquila fasciata) is an endangered raptor with high dietary variablity, and therefore high inter-territorial differences in potential OC intake. The aims of this study were i) to analyse OC accumulation in nestlings from three regions in Spain, ii) to compare plasma OC profiles with FA signatures as diet indicators, and iii) to asses the effects of OC accumulation on fitness. Nestlings from 57 territories in Catalunya, Andalucía and Castilla y León were bled and measured to calculate body condition. Plasma was used to quantify OC, FA, vitamins, carotenoids and biochemical parameters, while cellular pellet was used to measure oxidative stress biomarkers. PCB congener and FA (after calculation of log ratios referred to 18:0) matrixes were classified in three principal components each (63 and 81% of variance, respectively). Nestlings from Catalunya, the most industrialized region, showed the highest values for ?PCB, toxic equivalents (TEQ) (p?0.005) and the PCB component related to the dioxin-like congener 126 (p=0.07). No relationship was observed between OC and FA signatures, suggesting that plasma FA profiles are limited as diet indicators to relate to pollutant accumulation. OC profiles significantly explained the variability shown by fitnessrelated responses (RDA Monte Carlo test: p=0.04). ?PCB and TEQ were selected by permutation tests as significant explaining variables (marginal variance=0.032). Both variables affected plasma vitamins and carotenoids, being negatively correlated (Spearman) to retinol, lutein and zeaxanthin (p?0.038). TEQ also caused oxidative stress through the increase of total glutathione levels (p=0.01) and the inhibition of superoxide dismutase and lactate dehydrogenase activities (p?0.048). Organochlorine insecticides were homogeneously distributed across regions and had almost no effects. Our results suggest that OC accumulation in Bonelli’s Eagle nestlings may cause health problems ultimately compromising individual viability.Peer Reviewe

Pollutant accumulation patterns in nestlings of an avian top predator: biochemical and metabolic effects

The exposure to persistent pollutants such as organochlorine compounds (OCs) or metals has been associated with declines in top predator populations, which can accumulate high amounts of these pollutants from their prey. However, understanding how variation in OC and metal accumulation in wild species affects their biochemical and physiological responses is a big challenge, especially for endangered predators like the Bonelli's eagle (Aquila fasciata). This bird of prey is an interesting study model because the differences in diet composition among populations and territories can account for important pollutant uptake variations. We compared OC and metal accumulation in blood of Bonelli's eagle nestlings from three populations across Spain as a function of origin, age class (nestlings vs. adults), sex and number of siblings per nest, and related accumulation patterns to responses indicative of body condition, biochemistry and antioxidant status. Nestlings from Catalonia, the most industrialized area, showed the highest concentrations of PCBs and arsenic, and the lowest concentrations of zinc. The two former substances, together with DDTs, exerted an overall influence on nestling's physiology. PCBs and arsenic were associated with reduced retinol levels, pointing to oxidative damage in exposed individuals, which was also consistent with the low zinc levels in individuals from the polluted region. Increased plasma DDT levels were related to reduced body condition and lower levels of triglycerides. Mercury accumulation in Castile and Leon was higher in nestlings that were alone in the nest than in nestlings that shared it with a sibling; this suggests an increased mercury uptake from secondary prey in territories where preferred prey (i.e. rabbits) are scarce, which are also the territories where productivity is reduced. Overall, the results reveal a spatial variation in pollutant accumulation patterns and associated physiological effects, and suggest the major role that territory quality may have in such patterns.Study financed by the Spanish Ministry of Economy and Competitiveness (project ref. CGL2010-17056 to JR and Juan de la Cierva contract to MEOS) and Navarra Government (PhD fellowship of the I + D Plan 2008–2009 to JRM).Peer Reviewe

Diet–demography relationships in a long-lived predator: from territories to populations

Understanding the mechanisms that shape animal population dynamics is of fundamental interest in ecology, evolution and conservation biology. Food supply is an important limiting factor in most animal populations and may have demographic consequences. Optimal foraging theory predicts greater consumption of preferred prey and less diet diversity when food is abundant, which may benefit key fitness parameters such as productivity and survival. Nevertheless, the correspondence between individual resource use and demographic processes in populations of avian predators inhabiting large geographic areas remains largely unexplored, particularly in complex ecosystems such as those of the Mediterranean basin. Based on a long-term monitoring program of the diet and demography of Bonelli’s eagle Aquila fasciata in western Europe, here we test the hypothesis that a predator’s diet is correlated to its breeding productivity and survival at both the territorial and population levels, and ultimately to its population growth rate. At the territorial level, we found that productivity increased with greater consumption of European rabbits Oryctolagus cuniculus, the Bonelli’s eagle’s preferred prey, and pigeons, an important alternative prey for this predator. The survival of territorial pairs was negatively affected by higher diet diversity, which probably reflected the inability to find sufficient high quality prey. Diet effects at the population level were similar but more noticeable than at the territorial level, i.e. a greater consumption of rabbits, together with lesser consumption of small-to-medium avian species (‘other birds’; non-preferred prey), increased productivity, while greater diet diversity and lower consumption of rabbits was associated with reduced survival and population growth rate. Overall, our study illustrates how the diet of a predator species can be closely related to key individual vital rates, which, in turn, leave a measurable fingerprint on population dynamics within and among populations across large spatial scales

Temperature Aware and Defect-Probability Driven Test Scheduling for System-on-Chip

The high complexity of modern electronic systems has resulted in a substantial increase in the time-to-market as well as in the cost of design, production, and testing. Recently, in order to reduce the design cost, many electronic systems have employed a core-based system-on-chip (SoC) implementation technique, which integrates pre-defined and pre-verified intellectual property cores into a single silicon die. Accordingly, the testing of manufactured SoCs adopts a modular approach in which test patterns are generated for individual cores and are applied to the corresponding cores separately. Among many techniques that reduce the cost of modular SoC testing, test scheduling is widely adopted to reduce the test application time. This thesis addresses the problem of minimizing the test application time for modular SoC tests with considerations on three critical issues: high testing temperature, temperature-dependent failures, and defect probabilities. High temperature occurs in testing modern SoCs and it may cause damages to the cores under test. We address the temperature-aware test scheduling problem aiming to minimize the test application time and to avoid the temperature of the cores under test exceeding a certain limit. We have developed a test set partitioning and interleaving technique and a set of test scheduling algorithms to solve the addressed problem. Complicated temperature dependences and defect-induced parametric failures are more and more visible in SoCs manufactured with nanometer technology. In order to detect the temperature-dependent defects, a chip should be tested at different temperature levels. We address the SoC multi-temperature testing issue where tests are applied to a core only when the temperature of that core is within a given temperature interval. We have developed test scheduling algorithms for multi-temperature testing of SoCs. Volume production tests often employ an abort-on-first-fail (AOFF) approach which terminates the chip test as soon as the first fault is detected. Defect probabilities of individual cores in SoCs can be used to compute the expected test application time of modular SoC tests using the AOFF approach. We address the defect-probability driven SoC test scheduling problem aiming to minimize the expected test application time with a power constraint. We have proposed techniques which utilize the defect probability to generate efficient test schedules. Extensive experiments based on benchmark designs have been performed to demonstrate the efficiency and applicability of the developed techniques

Pollutant accumulation patterns in nestlings of an avian top predator: biochemical and metabolic effects

The exposure to persistent pollutants such as organochlorine compounds (OCs) or metals has been associated with declines in top predator populations, which can accumulate high amounts of these pollutants from their prey. However, understanding how variation in OC and metal accumulation in wild species affects their biochemical and physiological responses is a big challenge, especially for endangered predators like the Bonelli's eagle (Aquila fasciata). This bird of prey is an interesting study model because the differences in diet composition among populations and territories can account for important pollutant uptake variations. We compared OC and metal accumulation in blood of Bonelli's eagle nestlings from three populations across Spain as a function of origin, age class (nestlings vs. adults), sex and number of siblings per nest, and related accumulation patterns to responses indicative of body condition, biochemistry and antioxidant status. Nestlings from Catalonia, the most industrialized area, showed the highest concentrations of PCBs and arsenic, and the lowest concentrations of zinc. The two former substances, together with DDTs, exerted an overall influence on nestling's physiology. PCBs and arsenic were associated with reduced retinol levels, pointing to oxidative damage in exposed individuals, which was also consistent with the low zinc levels in individuals from the polluted region. Increased plasma DDT levels were related to reduced body condition and lower levels of triglycerides. Mercury accumulation in Castile and Leon was higher in nestlings that were alone in the nest than in nestlings that shared it with a sibling; this suggests an increased mercury uptake from secondary prey in territories where preferred prey (i.e. rabbits) are scarce, which are also the territories where productivity is reduced. Overall, the results reveal a spatial variation in pollutant accumulation patterns and associated physiological effects, and suggest the major role that territory quality may have in such patterns