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The number of highly pathogenic avian influenza (HPAI) H5-related infections and deaths of wild birds in Europe was high during October 1, 2020-September 30, 2022. To quantify deaths among wild species groups with known susceptibility for HPAI H5 during those epidemics, we collected and recorded mortality data of wild birds in the Netherlands. HPAI virus infection was reported in 51 bird species. The species with the highest numbers of reported dead and infected birds varied per epidemic year; in 2020-21, they were within the Anatidae family, in particular barnacle geese (Branta leucopsis) and in 2021-22, they were within the sea bird group, particularly Sandwich terns (Thalasseus sandvicensis) and northern gannet (Morus bassanus). Because of the difficulty of anticipating and modeling the future trends of HPAI among wild birds, we recommend monitoring live and dead wild birds as a tool for surveillance of the changing dynamics of HPAI. [ABSTRACT FROM AUTHOR]

Many plants and invertebrates rely on internal transport by animals for long‐distance dispersal. Their dispersal capacity is greatly influenced by interactions with the animal's digestive tract. Omnivorous birds adjust their digestive tract morphology to seasonally variable diets. We performed feeding trials in waterfowl to unravel how changing organ size, in combination with seed size, affects dispersal potential. We subjected captive mallards to mimics of summer (animal‐based), winter (plant‐based), and intermediate diets, and analyzed gut passage of seeds before and after the treatment (trials 1 and 2). To test the effect of gut morphology on seed digestion, we measured digestive organ size after euthanasia. Three hours before euthanasia, differently sized seeds were fed to test how seed size affects gut passage by determining their relative position in the digestive tract (trial 3). Trials 1 and 2 showed that intact seed passage was lower in the plant‐based than in the animal‐based diet group. Retention time changed only within groups, decreasing in the animal‐based, and increasing in the plant‐based diet group. No post‐diet differences in organ size were detected, probably due to large between‐individual variation within groups. Digestive tract measures did not explain variation in seed survival or retention time. Trial 3 revealed that small seeds pass the digestive tract rapidly, while large seeds are retained longer, particularly in the gizzard. Differential retention in the gizzard, the section where seeds can be destroyed, is likely why larger seeds have a lower probability to pass the digestive tract intact. Our results confirm that rapid, flexible adaptation to diet shifts affects seed digestion in waterfowl, although we could not conclusively relate this to organ size. Large interindividual variation in digestive efficiency between mallards feeding on the same diet may provide opportunities for seed dispersal in the field throughout the annual cycle. Endozoochorous dispersal of many organisms is greatly influenced by seasonally variable morphology of the disperser's digestive tract. We found that seed survival of gut passage was higher and retention time lower in mallards adapted to low‐fibre summer diets versus high‐fibre winter diets, while digestive tract measures did not differ between these groups. However, highly variable digestive efficiency between individual mallards feeding on the same diet likely provides opportunities for seed dispersal throughout the annual cycle. [ABSTRACT FROM AUTHOR]

Highlights • The Flux Collision Model (FCM) enables the use of empirical collision probabilities. • The FCM and the SOSS Band model yield comparable results. • FCM calculations are constrained by limited knowledge of collision probabilities. • SOSS Band model calculations are constrained by limited knowledge of avoidance. • The FCM is less sensitive to variation in avoidance than the SOSS Band model. Abstract Collision of birds with wind turbines is an important negative effect of wind energy generation. Assessments of the potential numbers of bird collisions are required prior to the construction of wind farms. Collision rate models (CRMs) are used as a tool to estimate numbers of collision victims for wind farm initiatives. In the past couple of decades various CRMs have been developed. These models are all based on the theoretical calculation of collision probabilities (theoretical models). In this paper we introduce an empirical model, the Flux Collision Model (FCM), in which actual knowledge of species (group)-specific collision probabilities collected in existing wind farms on land is used to calculate collision rates for planned wind farms. An important quality of the FCM is that it provides a means to use empirical information to assess collision rates in Environmental Impact Assessments (EIAs) for wind farm initiatives. In addition, no detailed information on bird behaviour close to the rotor is needed, as this information is already incorporated in the empirical collision probability. In two case studies, one offshore and one on land, we compare and discuss the use and performance of the empirical FCM and the theoretical SOSS Band model for predicting collision rates of birds at wind farm initiatives. To date, no actual collision rates are known for the offshore situation. Accordingly, in the FCM, collision probabilities derived from wind farms on land were used. Nevertheless, in the offshore case study, the results of the FCM were comparable with those of the SOSS Band model. Basic sensitivity analyses for both the FCM and the SOSS Band model showed that purely theoretically both models are equally sensitive to changes in avoidance rates. However, because lower values for avoidance are applied in the FCM (wind farm avoidance) than in the SOSS Band model (overall avoidance), in practice the effect of realistic variation in avoidance rates on the resulting collision rates is much smaller for the FCM than for the SOSS Band model. Our results show that the FCM provides a valuable addition to the existing suite of (theoretical) CRMs. The predictive value of the theoretical SOSS Band model is constrained by the limited availability of knowledge on species (group)-specific (wind turbine) avoidance rates, which is not the case for the FCM. By contrast, the reliability of the empirical FCM is determined only by variation in the availability and quality of information on species (group)-specific collision probabilities. The choice of which CRM to use (theoretical or empirical) seems not to depend on the location of the wind farm initiative as being offshore or on land, but on the availability and reliability of species (group)-specific information in existing wind farms. The availability of a reliable collision probability supports the use of the FCM, while the availability of information on (overall) avoidance rates in the absence of a species (group)-specific collision probability supports the use of a theoretical CRM like the SOSS Band model. Synthesis and applications. The predictive power of collision rate models relies in the first place on the quality of the input information, and second on the theoretical details of the model calculations. Although the FCM is less dependent on measurements of avoidance rates, an urgent need remains to obtain information on actual collision rates and corresponding collision probabilities as well as avoidance rates in existing wind farms both offshore and on land in order to accurately determine the impact of wind energy on bird populations. [ABSTRACT FROM AUTHOR]

Waterbirds disperse a wide range of plant seeds via their guts, promoting biotic connectivity between isolated habitat patches. However, the intensity of digestive forces encountered by seeds, and therefore their potential to survive digestive tract passage, varies within and between waterbird species. Here, we investigate under controlled conditions how the interaction between seed traits and digestive strategies affect the germinability of seeds following waterbird-mediated dispersal. We exposed seeds of 30 wetland plant species to the main digestive processes in the dabbling duck digestive system: mechanical, chemical and intestinal digestion. These were simulated by 1) a pressure test and scarification treatment, 2) incubation in simulated gastric juice, and 3) incubation in intestinal contents of culled mallards (Anas platyrhynchos). We evaluated their separate and combined effects on seed germination, and identified the role of seed size and seed coat traits in resisting the digestive forces. Seeds were generally resistant to separate digestive processes, but highly sensitive to a combination. Resistance to mechanical break-down was reduced by up to 80% by chemical pre-treatment, especially for seeds with permeable coats. Scarified seeds were 12–17% more vulnerable to chemical and intestinal digestive processes than undamaged seeds. Large seeds and seeds with thin, permeable coats were particularly sensitive to chemical and intestinal digestion. These results indicate that efficient digestion of seeds requires multiple digestive processes. The gizzard, responsible for mechanical digestion, plays a key role in seed survival. Omnivorous birds, which have relatively light gizzards compared to pure herbivores or granivores, are thus most likely to disperse seeds successfully. Regardless of digestive strategy, small seeds with tough seed coats are most resistant to digestion and may be adapted to endozoochorous dispersal by waterbirds. [ABSTRACT FROM AUTHOR]

During autumn-winter 2016-2017, highly pathogenic avian influenza A(H5N8) viruses caused mass die-offs among wild birds in the Netherlands. Among the ≈13,600 birds reported dead, most were tufted ducks (Aythya fuligula) and Eurasian wigeons (Anas penelope). Recurrence of avian influenza outbreaks might alter wild bird population dynamics. [ABSTRACT FROM AUTHOR]

Since the first studies in the mid-twentieth century, lightweight electronic tracking devices have been increasingly used to study waterfowl movements. With half a century of experience and growing sample sizes, it has become clear that the attachment of a tracking device can affect a bird's behaviour and fitness. This becomes problematic when it introduces uncertainty about whether the recorded data represent natural behaviour. Waterfowl may be particularly prone to tag effects, since many species are migratory and tracking devices can disrupt their waterproof plumage. The primary aim of this paper is to identify how tracking devices may affect waterfowl survival, migration and reproduction, and how better measuring and reporting of such effects can improve our understanding of the risks, providing a first step towards reducing their impact in future studies. We reviewed literature on electronic tracking of waterfowl to create an overview of currently recognized effects of harness-attached backpacks, implants, subcutaneous attachments and neck collars. Additionally, we analysed developments in the use of attachment methods, the weight of tracking devices relative to bird body mass, and the reporting rate of effects of tracking devices in 202 original tracking studies. We found that although the number of waterfowl tracking studies described in peer-reviewed literature has steeply increased over the past decades, reporting rates of potential effects have decreased from 65.0 to 26.5%. Meanwhile, the mean weight of the tracking devices relative to the bird's body mass remained stable around 2.0%. Major negative effects were reported in 17% of all studies and were found for all attachment methods. Overall, large differences exist in the occurrence and type of negative effects between species and studies, even if the same tracking methods were used. Inconsistent reporting of effects, lack of control groups to measure effects and incomplete descriptions of the methodology hamper the identification of factors contributing to these effects. To accomplish a reduction in adverse effects of tracking, it is necessary to improve the measuring and reporting of effects. We propose a framework for standardized reporting of methods in primary tracking studies and standardized protocols to measure effects of tracking devices on waterfowl. [ABSTRACT FROM AUTHOR]

Dispersal via animals (zoochory) is a primary mechanism for seed exchange between habitat patches. Recent studies have established that many plant species can survive waterbird gut passage. To quantify the patterns and consequences of waterbird-mediated dispersal, information on ingestion and gut passage must be combined with bird movement data. Such analysis has recently revealed seed dispersal kernels by migrating waterbirds. However, since many waterbird populations are largely resident, and migrating populations spend only a minor part of the main dispersal season (autumn-winter) on active migration, daily regional-scale movements probably cause more frequent dispersal., We synthesized high-resolution empirical data on landscape-scale movements and seed gut passage times in a key disperser species, the mallard ( Anas platyrhynchos), using a spatially explicit, mechanistic model to quantify dispersal distributions resulting from daily autumn-winter movements. We evaluated how landscape composition and seed traits affect these dispersal patterns., The model indicates that mallards generate highly clumped seed deposition patterns, dispersing seeds primarily between core areas used for foraging and resting. Approximately 34% of all dispersed seeds are transported to communal roost areas, which may function as reservoirs for mallard-dispersed species, and 7% are transported between foraging areas. Landscape-dependent movement patterns strongly affect the dispersal distributions, resulting in multi-modal dispersal kernels, with dispersal distances increasing with fragmentation of freshwater foraging habitat. Seed size-related gut retention times determine the proportion of seeds being dispersed away from the ingestion area, with larger seeds (20 mm3) having a 8-10% higher potential for long-distance dispersal than smaller seeds (0·2 mm3), if surviving gut passage. However, twice as many small seeds will finally accomplish long-distance dispersal due to their higher gut passage survival., Synthesis. Firstly, this study reveals how seed dispersal patterns resulting from daily waterfowl movements are shaped by landscape-dependent differences in movement patterns. Secondly, seed survival appears more important than retention time in determining the scale of long-distance dispersal by non-migrating mallards. We conclude that the frequent flights of staging waterbirds result in directed dispersal over distances inversely related to wetland availability, indicating that they maintain landscape connectivity across a range from wet to increasingly dry landscapes. [ABSTRACT FROM AUTHOR]

Agri-environmental measures (AEMs) are the main instrument of the Common Agricultural Policy to protect farmland biodiversity, but their effectiveness is questioned. In the Netherlands, AEMs have been implemented by farmers' collectives since 2016, with the goal to improve the spatial targeting and coordination of measures, and thereby increase their effectiveness. The objective of this paper is to assess the effects of two AEMs, bird plots and field margins, on the abundance of seven cropland bird species targeted by the Dutch agri-environmental policy, and on their total abundance and species richness. The study was carried out in four farmers' collectives in the provinces of Groningen, Drenthe and Flevoland in the Netherlands. We assessed how bird abundance and species richness measured on AEM plots and control plots were related to management and landscape factors. Furthermore, we assessed whether bird abundance and species richness measured on AEM plots were related to the spatial concentration of other AEM plots in landscapes surrounding AEM plots. With regard to plot management, we found a significant positive effect of field margins on skylarks, yellowhammers, common linnets, common kestrels, total bird abundance and species richness. Bird plots had a significant positive effect on skylarks and total bird abundance. However, western yellow wagtails, northern lapwings and Eurasian oystercatchers did not benefit from the two studied measures, likely because the vegetation in the bird plots and field margins is too high and dense for these species. Landscape factors, such as landscape openness, had contrasting effects on the analysed species, due to their different habitat requirements. Hence, there are no optimal landscapes for all target species, which underlines the need for a fine scale spatial targeting of measures based on species habitat requirements. Furthermore, the spatial concentration of other AEM plots in the landscape surrounding AEM plots had a significant effect for only two species (yellowhammer and western yellow wagtail), and this effect was negative. Thus, our results suggest that - for the studied species and landscapes - the type of measures and landscape in which they are taken are more important than their spatial concentration. • Measures benefit four of seven species, total abundance and species richness. • Field margins benefit a larger number of species than bird plots. • Alternative measures are needed for species breeding and foraging on bare soil. • Contrasted habitat requirements of species impose choices on policy targets. • The type and location of measures seem more important than their concentration. [ABSTRACT FROM AUTHOR]

Dispersal of plant seeds by ducks and other waterbirds is of great importance to the ecology of freshwater habitats. To unravel the mechanisms of waterbird-mediated seed dispersal, numerous laboratory experiments have been conducted, but effects of seed and waterbird traits on dispersal potential have rarely been investigated under field conditions., Through analysis of the digestive tracts of 100 wild mallards ( Anas platyrhynchos) across a winter season in the Netherlands, we assessed (i) the inter-individual and seasonal variability of seeds in the digestive tract, (ii) the variability of digestive tract organ size and gizzard grit mass, and (iii) the potential effects of seed species traits and gut traits on the survival potential of ingested seeds., We found 4548 ingested seeds of at least 66 plant species from a wide range of habitats, most of which were retained in the gizzard. Nineteen species had not previously been reported from mallard diets. Individual tracts contained anywhere between 0 and 1048 seeds, of up to 14 species (median of three species). Diet composition and digestive tract size varied substantially between individuals and over the course of the winter season. As predicted from controlled feeding studies, we found that also in wild mallards, size-dependent gut passage survival favours the dispersal of small-seeded species. Despite the large variation in gizzard and small intestine size in this study, their effect on the dispersal potential of ingested seeds in the field remains unclear. We found no difference in dispersal potential between plants species growing in wet or dry habitats., This study demonstrates that wild mallards are opportunistic seed consumers with a very diverse diet as reflected by seed species composition in both the foregut and hindgut. However, we also show that serious limitations of field-based analyses compared to controlled experiments can impede drawing conclusions about gut passage survival of seeds. The large variability in diet composition among individuals and over time indicates high endozoochorous dispersal potential for a wide range of plant species by wild mallard in aquatic and wetland, as well as surrounding terrestrial habitats. [ABSTRACT FROM AUTHOR]

Birds commonly regurgitate indigested particles after foraging. Many frugivorous birds regurgitate seeds ingested with the flesh of fruits, which importantly contributes to plant dispersal in terrestrial ecosystems. In freshwater ecosystems, waterbirds are known to defecate viable seeds in their faeces, but little is known about regurgitation as a potential additional seed dispersal mechanism. We experimentally fed eight mallards ( Anas platyrhynchos ) with a high and low volume of seeds of ten wetland plant species, and monitored regurgitation and defecation of intact seeds over 24 h. Regurgitation occurred at least once in all individual mallards and was induced by two different mechanisms: (i) feeding of high food volumes was significantly associated with regurgitation of all seed species from the crop after retention times of 1–3 h, and (ii) large indigestible seeds were expelled from the gizzard 11 or more hours after feeding. Seed regurgitation was much less plant species-specific than survival of seeds passing digestion, which suggests it is a particularly suitable dispersal mechanism for plant species unable to disperse by endozoochory (such as plant species with large, soft-bodied seeds). Observations of regurgitation by wild waterbirds are needed to improve our knowledge on this additional role of waterbirds in ecosystem functioning. [ABSTRACT FROM AUTHOR]

Animal movements may contribute to the spread of pathogens. In the case of avian influenza virus, [migratory] birds have been suggested to play a role in the spread of some highly pathogenic strains (e.g. H5N1, H5N8), as well as their low pathogenic precursors which circulate naturally in wild birds. For a better understanding of the emergence and spread of both highly pathogenic (HPAIV) and low pathogenic avian influenza virus (LPAIV), the potential effects of LPAIVs on bird movement need to be evaluated. In a key host species, the mallard Anas platyrhynchos, we tested whether LPAIV infection status affected daily local (< 100 m) and regional (> 100 m) movements by comparing movement behaviour 1) within individuals (captured and sampled at two time points) and 2) between individuals (captured and sampled at one time point). We fitted free-living adult males with GPS loggers throughout the autumn LPAIV infection peak, and sampled them for LPAIV infection at logger deployment and at logger removal on recapture. Within individuals, we found no association between LPAIV infection and daily local and regional movements. Among individuals, daily regional movements of LPAIV infected mallards in the last days of tracking were lower than those of non-infected birds. Moreover, these regional movements of LPAIV infected birds were additionally reduced by poor weather conditions (i.e. increased wind and/or precipitation and lower temperatures). Local movements of LPAIV infected birds in the first days of tracking were higher when temperature decreased. Our study thus demonstrates that bird-assisted dispersal rate of LPAIV may be lower on a regional scale than expected on the basis of the movement behaviour of non-infected birds. Our study underlines the importance of understanding the impact of pathogen infection on host movement in order to assess its potential role in the emergence and spread of infectious diseases. [ABSTRACT FROM AUTHOR]

Plant populations in fragmented ecosystems rely largely on internal dispersal by animals. To unravel the mechanisms underlying this mode of dispersal, an increasing number of experimental feeding studies is carried out. However, while physical activity is known to affect vertebrate digestive processes, almost all current knowledge on mechanisms of internal seed dispersal has been obtained from experiments with resting animals. We investigated how physical activity of the mallard Anas platyrhynchos, probably the quantitatively most important biotic dispersal agent in aquatic habitats in the entire Northern Hemisphere, affects gut passage survival and retention time of ingested plant seeds. We fed seeds of nine common wetland plants to mallards trained to subsequently swim for six hours in a flume tank at different swimming speeds (activity levels). We compared gut passage survival and retention times of seeds against a control treatment with mallards resting in a conventional dry cage. Intact gut passage of seeds increased significantly with mallard activity (up to 80% in the fastest swimming treatment compared to the control), identifying reduced digestive efficiency due to increased metabolic rates as a mechanism enhancing the dispersal potential of ingested seeds. Gut passage speed was modestly accelerated (13% on average) by increased mallard activity, an effect partly obscured by the interaction between seed retention time and probability of digestion. Gut passage acceleration will be more pronounced in digestion-resilient seed species, thereby modulating their dispersal distances. Our findings imply that seed dispersal potential by mallards calculated from previous experiments with resting birds is highly underestimated, while dispersal distances may be overestimated for some plant species. Similar effects of physical activity on digestive efficiency of mammals suggests that endozoochorous dispersal of plant seeds by vertebrates is more effective and plays a quantitatively more important ecological role in both terrestrial and aquatic ecosystems than previously thought. [ABSTRACT FROM AUTHOR]

Field studies have shown that waterbirds, especially members of the Anatidae family, are major vectors of dispersal by endozoochory for a broad range of plants lacking a fleshy fruit, yet whose propagules can survive gut passage. Widely adopted dispersal syndromes ignore this dispersal mechanism, and we currently have little understanding of what traits determine the potential of angiosperms for endozoochory by waterbirds. Results from previous experimental studies have been inconsistent as to how seed traits affect seed survival and retention time in the gut and have failed to control for the influence of plant phylogeny. Using 13 angiosperm species from aquatic and terrestrial habitats representing nine families, we examined the effects of seed size, shape, and hardness on the proportion of seeds surviving gut passage through mallards (Anas platyrhynchos) and their retention time within the gut. We compiled a molecular phylogeny for these species and controlled for the nonindependence of taxa due to common descent in our analyses. Intact seeds from all 13 species were egested, but seed survival was strongly determined by phylogeny and by partial effects of seed mass and hardness (wet load): species with seeds harder than expected from their size, and smaller than expected from their loading, had greater survival. Once phylogeny was controlled for, a positive partial effect of seed roundness on seed survival was also revealed. Species with seeds harder than expected from their size had a longer mean retention time, a result retained after controlling for phylogeny. Our study is the first to demonstrate that seed shape and phylogeny are important predictors of seed survival in the avian gut. Our results demonstrate that the importance of controlling simultaneously for multiple traits and relating single traits (e.g., seed size) alone to seed survival or retention time is not a reliable way to detect important patterns, especially when phylogenetic effects are ignored. [ABSTRACT FROM AUTHOR]

Variation in the home-range size of nesting animals is thought to be driven by nutritional requirements, food availability, and predation risk of the animals during foraging. Only few studies have considered that the risk of nest predation may also affect home-range size because nests become more difficult to defend as animals move further away. We used a theoretical model to explore the combined effects of nest defensibility, nest predation risk, and food availability on foraging distance from the nest, and hence home-range size. In our model, foragers adjust the foraging distance around the central place such that the required amount of food is collected within the available time with the lowest predation risk for the nest. We found that foraging distance decreased with food availability and the risk of nest predation during absence, but also with nest defensibility. When food was abundant, both nest predation risk and defensibility hardly influenced foraging distance. When food was scarce, animals able to deter predators foraged close-by, whereas animals less able to deter predators foraged further away. Likewise, animals that were themselves vulnerable to predation stayed closer to their nest if the nest provided safety, as is typical for central place foragers. This study is the first to assess the importance of nest defense and nest predation risk for foraging distance of central place foragers and provides a better understanding of the drivers of home-range size. [ABSTRACT FROM AUTHOR]

Dabbling ducks (Anatinae) are omnivorous birds that are widespread, numerous, highly mobile and often migratory, and therefore have great potential for (long distance) dispersal of other organisms, including plants. However, their ability to act as plant dispersal vectors has received little attention compared to frugivores and is often assumed to be relevant only for wetland species., To evaluate the potential for plant dispersal by dabbling ducks, we collated and analysed existing data. We identified all plant species whose seeds have been recorded in the diets of the seven dabbling duck ( Anas) species in the Western Palaearctic, as reported from gut content analyses. We then analysed the habitats and traits of these plant species to identify general patterns, and related these to data on gut passage survival and duck movements., A large number of plant species (> 445 species of 189 genera and 57 families) have been recorded in the diet of dabbling ducks. These plant species represent a very wide range of habitats, including almost the full range of site fertility, moisture and light conditions, excluding only very dry and deeply shaded habitats. The ducks prefer seeds of intermediate sizes (1-10 mm3), which have good chances to survive gut passage, but also ingest smaller and larger seeds. Ingested seeds represent a wide range of dispersal syndromes, including fleshy fruits. Many species (62%) were not previously considered animal-dispersed in plant data bases, and 66% were not identified as bird-dispersed. Rarefaction analyses suggest that our analysis still greatly underestimates the total number of plant species ingested., Synthesis. Dabbling ducks do not exclusively ingest seeds of wetland plants, which make up only 40% of the ingested species. Rather, they feed opportunistically on a wide cross-section of plant species available across the landscapes they inhabit. Given the millions of ducks, the hundreds to thousands of seeds ingested per individual on a daily basis, and known gut passage survival rates, this results in vast numbers of seeds dispersed by ducks per day. Internal seed dispersal by dabbling ducks appears to be a major dispersal pathway for a far broader spectrum of plant species than previously considered. [ABSTRACT FROM AUTHOR]

We collected data on mass mortality in Sandwich terns (Thalasseus sandvicensis) during the 2022 breeding season in the Netherlands. Mortality was associated with at least 2 variants of highly pathogenic avian influenza A(H5N1) virus clade 2.3.4.4b. We report on carcass removal efforts relative to survival in colonies. Mitigation strategies urgently require structured research. [ABSTRACT FROM AUTHOR]

Europe's highest densities of breeding Mallards (Anas platyrhynchos) are found in the Netherlands, but the breeding population there has declined by ~30% since the 1990s. The exact cause of this decline has remained unclear. Here, we used an integrated population model to jointly analyze Mallard population survey, nest survey, duckling survival, and bandrecovery data. We used this approach to holistically estimate all relevant vital rates, including duckling survival rates for years for which no explicit data were available. Mean vital rate estimates were high for nest success (0.38 ± 0.01) and egg hatch rate (0.96 ± 0.001), but relatively low for clutch size (8.2 ± 0.05) compared to populations in other regions. Estimates for duckling survival rate for the three years for which explicit data were available were low (0.16-0.27) compared to historical observations, but were comparable to rates reported for other regions with declining populations. Finally, the mean survival rate was low for ducklings (0.18 ± 0.02), but high and stable for adults (0.71 ± 0.03). Population growth rate was only affected by variation in duckling survival, but since this is a predominantly latent state variable, this result should be interpreted with caution. However, it does strongly indicate that none of the other vital rates, all of which were supported by data, was able to sufficiently explain the population decline. Together with a comparison with historic vital rates, these findings point to a reduced duckling survival rate as the likely cause of the decline. Candidate drivers of reduced duckling survival are increased predation pressure and reduced food availability, but this requires future study. Integrated population modeling can provide valuable insights into population dynamics even when empirical data for a key parameter are partly missing. [ABSTRACT FROM AUTHOR]

Aim: In many species, density‐dependent effects on reproduction are an important driver of population dynamics. However, it is rarely considered that the direction of density dependence is expected to vary over space and time depending on anti‐predator behaviour and predator community. Aggregation may allow for effective group mobbing against avian nest predators while aggregation may also attract mammalian predators, causing negative density dependence. We aim to quantify spatial variation in the effect of conspecific breeding density on nest survival in a mobbing bird species (Eurasian oystercatcher; Haematopus ostralegus) and identify whether this variation in density dependence can be explained by the predator community. Location: Country‐wide (The Netherlands). Methods: We integrated reproductive data with breeding territory maps of Eurasian oystercatchers and occupancy maps of avian and mammalian predator species across the Netherlands for a 10‐year period. Results: Spatial variation in the composition of the predator community explained the effects of neighbour density, showing decreasing nest survival when both conspecific density and mammalian dominance increased. Also, heterospecific density (from breeding godwits and lapwing) has an additional effect on the oystercatcher nest survival. Strikingly, this pattern did not extend to mammal‐free island populations. Main conclusions: Our study provides evidence that both the strength and sign of density dependence can vary spatially within species, implying that it is dangerous to generalize results from a single local population to large‐scale management implications and modelling exercises. The study also suggests that conservation actions that aim to attract breeding birds should be prioritized in areas with fewer mammalian predators, but this idea requires further testing on island populations. [ABSTRACT FROM AUTHOR]

Dispersal and colonisation are key processes determining species survival, and their importance is increasing as a consequence of ongoing habitat fragmentation, land-use change and climate change. Identification of long-distance dispersal events, including upstream dispersal, and of the dispersal mechanisms and resulting spatial dispersal patterns involved provides much-needed information for conservation in an era of rapid environmental change., However, quantifying contemporary dispersal among populations is far from straightforward. We used the relatively well-defined, typically linear, spatial structure of streams, rivers and their associated riparian and aquatic plant populations to illustrate this. We performed a literature review on studies where dispersal and its directionality (upstream versus downstream) were explicitly quantified., Upstream dispersal was detected in the majority (75%) of examined stream and riparian plant species and mediated mainly by waterfowl, but also by other animals and wind. However, upstream movements are generally less frequent than downstream. Upstream dispersal can occur in excess of tens and sometimes even hundreds of kilometres., Most of the reviewed studies suffer from important methodological limitations that generate difficulties in detecting uncommon dispersal events. Major limitations include use of molecular ecological analyses based on unrealistic assumptions, and the inability to separate seed from pollen flow. On the basis of these findings, we outline a flexible research design using DNA-based assignment methods that allows quantification of contemporary dispersal in future studies. We suggest four key improvements: (i) assignment of propagules and/or seedlings; (ii) use of spatial models to inform sampling design; (iii) reducing the influence of unsampled populations and (iv) combined use of nuclear and uniparentally inherited DNA markers to separate gene flow (including pollen and sperm) in general from propagule-mediated dispersal. In combination with direct measurements of seed dispersal these facilitate empirical quantification of dispersal and the detection of uncommon dispersal events, allowing more realistic assessment of spatial population dynamics, relevant for sedentary and relatively immobile organisms. [ABSTRACT FROM AUTHOR]

We report the results of an experimental search for ultralight axionlike dark matter in the mass range 162-166 neV. The detection scheme of our Cosmic Axion Spin Precession Experiment is based on a precision measurement of 207Pb solid-state nuclear magnetic resonance in a polarized ferroelectric crystal. Axionlike dark matter can exert an oscillating torque on 207Pb nuclear spins via the electric dipole moment coupling gd or via the gradient coupling gaNN. We calibrate the detector and characterize the excitation spectrum and relaxation parameters of the nuclear spin ensemble with pulsed magnetic resonance measurements in a 4.4 T magnetic field. We sweep the magnetic field near this value and search for axionlike dark matter with Compton frequency within a 1 MHz band centered at 39.65 MHz. Our measurements place the upper bounds |gd|<9.5×10-4  GeV-2 and |gaNN|<2.8×10-1  GeV-1 (95% confidence level) in this frequency range. The constraint on gd corresponds to an upper bound of 1.0×10-21  e cm on the amplitude of oscillations of the neutron electric dipole moment and 4.3×10-6 on the amplitude of oscillations of CP-violating θ parameter of quantum chromodynamics. Our results demonstrate the feasibility of using solid-state nuclear magnetic resonance to search for axionlike dark matter in the neV mass range. [ABSTRACT FROM AUTHOR]

We report the results of an experimental search for ultralight axionlike dark matter in the mass range 162-166 neV. The detection scheme of our Cosmic Axion Spin Precession Experiment is based on a precision measurement of 207Pb solid-state nuclear magnetic resonance in a polarized ferroelectric crystal. Axionlike dark matter can exert an oscillating torque on 207Pb nuclear spins via the electric dipole moment coupling gd or via the gradient coupling gaNN. We calibrate the detector and characterize the excitation spectrum and relaxation parameters of the nuclear spin ensemble with pulsed magnetic resonance measurements in a 4.4 T magnetic field. We sweep the magnetic field near this value and search for axionlike dark matter with Compton frequency within a 1 MHz band centered at 39.65 MHz. Our measurements place the upper bounds |gd|<9.5×10-4  GeV-2 and |gaNN|<2.8×10-1  GeV-1 (95% confidence level) in this frequency range. The constraint on gd corresponds to an upper bound of 1.0×10-21  e cm on the amplitude of oscillations of the neutron electric dipole moment and 4.3×10-6 on the amplitude of oscillations of CP-violating θ parameter of quantum chromodynamics. Our results demonstrate the feasibility of using solid-state nuclear magnetic resonance to search for axionlike dark matter in the neV mass range. [ABSTRACT FROM AUTHOR]