Unravelling trophic subsidies of agroecosystems for biodiversity conservation: food consumption and nutrient recycling by waterbirds in Mediterranean rice fields

Winners and losers of land use change: A systematic review of interactions between the world’s crane species ( Gruidae ) and the agricultural sector

While agricultural intensification and expansion are major factors driving loss and degradation of natural habitat and species decline, some wildlife species also benefit from agriculturally managed habitats. This may lead to high population densities with impacts on both human livelihoods and wildlife conservation. Cranes are a group of 15 species worldwide, affected both negatively and positively by agricultural practices. While eleven species face critical population declines, numbers of common cranes (Grus grus) and sandhill cranes (Grus canadensis) have increased drastically in the last 40 years. Their increase is associated with higher incidences of crane foraging on agricultural crops, causing financial losses to farmers. Our aim was to synthesize scientific knowledge on the bilateral effects of land use change and crane populations. We conducted a systematic literature review of peer‐reviewed publications on agriculture‐crane interactions (n = 135) and on the importance of agricultural crops in the diet of cranes (n = 81). Agricultural crops constitute a considerable part of the diet of all crane species (average of 37%, most frequently maize (Zea mays L.) and wheat (Triticum aestivum L.)). Crop damage was identified in only 10% of all agriculture‐crane interactions, although one‐third of interactions included cranes foraging on cropland. Using a conceptual framework analysis, we identified two major pathways in agriculture‐crane interactions: (1) habitat loss with negative effects on crane species dependent on specific habitats, and (2) expanding agricultural habitats with superabundant food availability beneficial for opportunistic crane species. The degree to which crane species can adapt to agricultural land use changes may be an important factor explaining their population response. We conclude that multi‐objective management needs to combine land sparing and land sharing strategies at landscape scale. To support viable crane populations while guaranteeing sustainable agricultural production, it is necessary to include the perspectives of diverse stakeholders and streamline conservation initiatives and agricultural policy accordingly.

Variación estacional de aves en el humedal de Trumao, centro-sur de Chile

RESUMEN En este estudio se describe el ensamble de aves del humedal de Trumao y su variación estacional según régimen hidrológico durante primavera 2017 y verano 2018 (no inundado) e inviernos 2017 y 2018 (inundado) y se evalúa el tipo de hábitat. Se registraron 29 especies de aves con una abundancia total de 2,341 individuos. El número total de especies acumuladas observadas para el período inundado y no inundado correspondió a 16 y 22 especies, respectivamente, siendo Chroicocephalus maculipennis (Lichtenstein, 1823) (Gaviota cáhuil) la especie dominante durante el período de estudio. El índice de similitud de Sorensen entre los períodos de inundación y no inundación del humedal fue de 73.2%, mientras que la similitud de Bray-Curtis resultó en un 32.65%. Al compararse el periodo invernal inundado (4 m profundidad) y el periodo estival no inundado (1 m profundidad), el índice de diversidad registró diferencias estadísticamente significativas, en cambio, la abundancia no presentó diferencias significativas. El análisis SIMPER arrojó que entre el periodo invernal inundado y el periodo estival no inundado las especies que mostraron un mayor porcentaje de disimilitud en su abundancia entre estas temporadas fueron la Gaviota cáhuil y Loro choroy [Enicognathus leptorhynchus (King, 1831)]. El uso de hábitat en el humedal de Trumao, por parte de las aves, fue altamente variable, tanto estacional como espacialmente, resultado esperable para este tipo de ecosistemas. Finalmente, nuestros resultados nos indican que las aves ocupan los humedales según fluctuaciones estacionales y según el hábitat que se encuentre disponible, sin embargo, la abundancia no se ve afectada por los cambios hidrológicos. Con estos resultados es fundamental seguir realizando más investigaciones en el humedal para determinar el uso (nidificación, alimentación, reproducción) que realizan las aves en los distintos hábitats para de esta manera generar medidas de protección y conservación para la gestión del humedal de Trumao.

Aspergillosis, Avian Species and the One Health Perspective: The Possible Importance of Birds in Azole Resistance

The One Health context considers health based on three pillars: humans, animals, and environment. This approach is a strong ally in the surveillance of infectious diseases and in the development of prevention strategies. Aspergillus spp. are fungi that fit substantially in this context, in view of their ubiquity, as well as their importance as plant pathogens, and potentially fatal pathogens for, particularly, humans and avian species. In addition, the emergence of azole resistance, mainly in Aspergillus fumigatus sensu stricto, and the proven role of fungicides widely used on crops, reinforces the need for a multidisciplinary approach to this problem. Avian species are involved in short and long distance travel between different types of landscapes, such as agricultural fields, natural environments and urban environments. Thus, birds can play an important role in the dispersion of Aspergillus, and of special concern, azole-resistant strains. In addition, some bird species are particularly susceptible to aspergillosis. Therefore, avian aspergillosis could be considered as an environmental health indicator. In this review, aspergillosis in humans and birds will be discussed, with focus on the presence of Aspergillus in the environment. We will relate these issues with the emergence of azole resistance on Aspergillus. These topics will be therefore considered and reviewed from the “One Health” perspective.

Flexible Behavior of the Black-Tailed Godwit Limosa limosa is Key to Successful Refueling during Staging at Rice Paddy Fields in Midwestern Korea

Successful refueling at staging sites is essential for the survival and reproduction of migratory birds. Understanding their staging ecology is therefore crucial for the conservation of migrant species. Rice fields in the mid-western region of the Korean Peninsula serve as staging habitats for the black-tailed godwit (Limosa limosa). We examined the behavior of staging black-tailed godwits in rice fields located in the East Asian-Australasian Flyway during their northward migration. Specifically, we tested the effect of flock size and water level on the foraging, vigilance, and resting behaviors of black-tailed godwits. Our observations revealed that as flock size increased, stepping rate, pecking rate, and vigilance duration decreased, while probing rate, preening duration, and foraging efficiency increased. Stepping and pecking rates increased at low water levels, compared with high water levels. We determined that the behavior of black-tailed godwits at the staging site is influenced by flock size and water level. These observations suggest that black-tailed godwits form larger flocks to increase foraging efficiency by lowering individual-level vigilance, and to spend more time on preening, which is critical for flight and survival. It can be also inferred, based on the shift in primary foraging mode between probing and pecking depending on the water level, that they obtain higher foraging efficiency by flexibly adapting their foraging mode to the conditions in rice fields that are subject to agricultural activities. Our results are expected to serve as basic data for establishing efficient management strategies for anthropogenic habitats for the conservation of migratory shorebirds such as black-tailed godwit.

Assessing Ecosystem Services Supplied by Agroecosystems in Mediterranean Europe: A Literature Review

Agricultural landscapes in the Mediterranean region may be considered as social-ecological systems that are important for biodiversity conservation whilst contributing to a wide range of ecosystem services. This literature review aims to identify the current state and biases of ecosystem service assessment in agroecosystems within the Mediterranean region, evaluate pressures impacting on agroecosystems and their services, and practices that promote ecosystem service synergies in Mediterranean agroecosystems. A total of 41 papers were selected for analysis from a set of 573 potentially relevant papers. Most of the selected papers focused on supporting, regulating and provisioning services, and mostly assessed ecosystem structure or services in the European Mediterranean context. Literature about benefits and values ascribed to by communities and stakeholders remain limited. Results presented here support the notion of multifunctional Mediterranean agroecosystems and multiple synergies were recorded in this review. Publications dealing with pressures that related to agricultural practices and demographic changes were in the majority and impact on different cropping systems. This review highlights the need to carry out integrated ecosystem service assessments that consider the multiple benefits derived from agroecosystems and which may be used to identify management practices that lead to the improvement of ecosystem services capacities and flows.

Oxidative status and metabolic profile in a long-lived bird preparing for extreme endurance migration

The high metabolic activity associated with endurance flights and intense fuelling of migrant birds may produce large quantities of reactive oxygen species, which cause oxidative damage. Yet it remains unknown how long-lived birds prepare for oxidative challenges prior to extreme flights. We combined blood measurements of oxidative status and enzyme and fat metabolism in Hudsonian godwits (Limosa haemastica, a long-lived shorebird) before they embarked on non-stop flights longer than 10,000 km during their northbound migrations. We found that godwits increased total antioxidant capacity (TAC) and reduced oxidative damage (TBARS) as the pre-migratory season progressed, despite higher basal metabolic rates before departure. Elevations in plasma β-hydroxybutyrate and uric acid suggest that lipid and protein breakdown supports energetic requirements prior to migration. Significant associations between blood mitochondrial cytochrome-c oxidase and plasma TAC (negative) and TBARS (positive) during winter indicate that greater enzyme activity can result in greater oxidative damage and antioxidant responses. However enzyme activity remained unchanged between winter and premigratory stages, so birds may be unable to adjust metabolic enzyme activity in anticipation of future demands. These results indicate that godwits enhance their oxidative status during migratory preparation, which might represent an adaptation to diminish the physiological costs of long-distance migration.

Day and night use of habitats by northern pintails during winter in a primary rice-growing region of Iberia

Loss of natural wetlands is a global phenomenon that has severe consequences for waterbird populations and their associated ecosystem services. Although agroecosystems can reduce the impact of natural habitat loss, drivers of use of such artificial habitats by waterbirds remain poorly understood. Using the cosmopolitan northern pintail Anas acuta as a model species, we monitored home-range and fine-scale resource selection across the agricultural landscape. Individuals were tracked using GPS-GSM transmitters, and a suite of environmental and landscape features were measured throughout the winter seasons. Spatial patterns of habitat use were analysed using generalized linear mixed effect models by integrating field-observations with GPS telemetry. All birds used rice fields as foraging grounds at night and commuted to an adjacent reservoir to roost during daylight. Home-ranges and maximum foraging distances of nocturnally foraging birds increased with decreasing availability of flooded fields, and were positively correlated with moonlight levels. Birds selected flooded rice paddies (water depth range: 9–21 cm) with standing stubble and substrate with pebbles smaller than 0.5 cm in diameter. Density of rice seeds, rice paddy size, and other environmental and landscape features did not emerge as significant predictors. Our findings indicate that nocturnal foraging of northern pintails within rice fields is driven primarily by straw manipulation, water level and substrate pebble size. Thus, the presence of standing stubble in flooded paddies with soft bottoms should be prioritized to improve foraging areas for dabbling ducks. These management procedures in themselves would not increase economic costs or affect rice production and could be applied for dabbling-duck conservation throughout the world.

Understanding how birds rebuild fat stores during migration: insights from an experimental study

Mechanisms underlying fat accumulation for long-distance migration are not fully understood. This is especially relevant in the context of global change, as many migrants are dealing with changes in natural habitats and associated food sources and energy stores. The continental Black-tailed godwit Limosa limosa limosa is a long-distance migratory bird that has undergone a considerable dietary shift over the past few decades. Historically, godwits fed on an animal-based diet, but currently, during the non-breeding period godwits feed almost exclusively on rice seeds. The latter diet may allow building up of their fuel stores for migration by significantly increasing de novo lipogenesis (DNL) activity. Here, we performed an experiment to investigate lipid flux and the abundance of key enzymes involved in DNL in godwits, during fasting and refueling periods at the staging site, while feeding on rice seeds or fly larvae. Despite no significant differences found in enzymatic abundance (FASN, ME1, ACC and LPL) in stored fat, experimental godwits feeding on rice seeds presented high rates of DNL when compared to fly-larvae fed birds (~35 times more) and fasted godwits (no DNL activity). The increase of fractional DNL in godwits feeding on a carbohydrate-rich diet can potentially be enhanced by the fasting period that stimulates lipogenesis. Although requiring further testing, these recent findings provide new insights into the mechanisms of avian fat accumulation during a fasting and refueling cycle and associated responses to habitat and dietary changes in a migratory species.

Cross-ecosystem carbon flows connecting ecosystems worldwide

Ecosystems are widely interconnected by spatial flows of material, but the overall importance of these flows relative to local ecosystem functioning remains unclear. Here we provide a quantitative synthesis on spatial flows of carbon connecting ecosystems worldwide. Cross-ecosystem flows range over eight orders of magnitude, bringing between 10⁻³ and 10⁵ gC m⁻² year⁻¹ to recipient ecosystems. Magnitudes are similar to local fluxes in freshwater and benthic ecosystems, but two to three orders of magnitude lower in terrestrial systems, demonstrating different dependencies on spatial flows among ecosystem types. The strong spatial couplings also indicate that ecosystems are vulnerable to alterations of cross-ecosystem flows. Thus, a reconsideration of ecosystem functioning, including a spatial perspective, is urgently needed.

Material flows between ecosystems, though the degree to which ecosystems are coupled is under investigation. Here Gounand et al. analyze cross-ecosystem carbon flows and relate them to in situ functions, and report different dependencies on spatial flows across numerous ecosystems.

Wetland salinity induces sex-dependent carry-over effects on the individual performance of a long-distance migrant

Salinization is having a major impact on wetlands and its biota worldwide. Specifically, many migratory animals that rely on wetlands are increasingly exposed to elevated salinity on their nonbreeding grounds. Experimental evidence suggests that physiological challenges associated with increasing salinity may disrupt self-maintenance processes in these species. Nonetheless, the potential role of salinity as a driver of ecological carry-over effects remains unstudied. Here, we investigated the extent to which the use of saline wetlands during winter - inferred from feather stable isotope values - induces residual effects that carry over and influence physiological traits relevant to fitness in black-tailed godwits Limosa limosa limosa on their northward migration. Overwintering males and females were segregated by wetland salinity in West Africa, with females mostly occupying freshwater wetlands. The use of these wetlands along a gradient of salinities was associated with differences in immune responsiveness to phytohaemagglutinin and sized-corrected body mass in godwits staging in southern Europe during northward migration - 3,000 km from the nonbreeding grounds - but in males only. These findings provide a window onto the processes by which wetland salinity can induce carry-over effects and can help predict how migratory species should respond to future climate-induced increases in salinity.

Metabolic plasticity for subcutaneous fat accumulation in a long distance migratory bird traced by 2H2O

The migrant black-tailed godwit (Limosa limosa) traditionally used natural wetlands in the Iberian Peninsula preparing for migratory flights by feeding mainly in estuaries. In recent decades this species has become increasingly dependent on rice fields, thereby relying on a plant-based diet for fueling. Dietary fatty acids (FA) seem to be determinant to the composition of accumulated subcutaneous fat in migratory birds. It is still unclear whether metabolic plasticity allows for modification and/or synthesis of FA, contributing for a lipid profile that enables a successful migratory performance.

Deuterated water was administered to captive black-tailed godwits submitted to two diets (fly larvae vs. rice) and the incorporation of deuterium (2H) into subcutaneous triglycerides was analysed by NMR. A recently developed localized biopsy method for sampling subcutaneous fat was employed with ulterior successful release of all birds into the wild. The average chemical structure reflected mostly a mixture of saturated and monounsaturated 16- and 18-carbon FA, a profile frequently found in migrant birds. Significantly higher levels of polyunsaturated FA, as well as detectable levels of n-3 FA were observed in fly larvae-fed birds. Excess 2H-enrichments in FA revealed significantly higher rates of fractional de novo lipogenesis and FA desaturation capacity in rice-fed birds.

This novel and non-lethal tracer method revealed the capacity of this species to alter its lipid metabolism to compensate for a poorer dietary lipid contribution. Due to its versatility, adapting this method to other scenarios and/or other migratory species is considered feasible and cost-effective.

Latitudinal-Related Variation in Wintering Population Trends of Greylag Geese (Anser Anser) along the Atlantic Flyway: A Response to Climate Change?

The unusually high quality of census data for large waterbirds in Europe facilitates the study of how population change varies across a broad geographical range and relates to global change. The wintering population of the greylag goose Anser anser in the Atlantic flyway spanning between Sweden and Spain has increased from 120 000 to 610 000 individuals over the past three decades, and expanded its wintering range northwards. Although population sizes recorded in January have increased in all seven countries in the wintering range, we found a pronounced northwards latitudinal effect in which the rate of increase is higher at greater latitudes, causing a constant shift in the centre of gravity for the spatial distribution of wintering geese. Local winter temperatures have a strong influence on goose numbers but in a manner that is also dependent on latitude, with the partial effect of temperature (while controlling for the increasing population trend between years) being negative at the south end and positive at the north end of the flyway. Contrary to assumptions in the literature, the expansion of crops exploited by greylag geese has made little contribution to the increases in population size. Only in one case (expansion of winter cereals in Denmark) did we find evidence of an effect of changing land use. The expanding and shifting greylag population is likely to have increasing impacts on habitats in northern Europe during the course of this century.