As the Duck Flies—Estimating the Dispersal of Low-Pathogenic Avian Influenza Viruses by Migrating Mallards

Many pathogens rely on the mobility of their hosts for dispersal. In order to understand and predict how a disease can rapidly sweep across entire continents, illuminating the contributions of host movements to disease spread is pivotal. While elegant proposals have been made to elucidate the spread of human infectious diseases, the direct observation of long-distance dispersal events of animal pathogens is challenging. Pathogens like avian influenza A viruses, causing only short disease in their animal hosts, have proven exceptionally hard to study. Here, we integrate comprehensive data on population and disease dynamics for low-pathogenic avian influenza viruses in one of their main hosts, the mallard, with a novel movement model trained from empirical, high-resolution tracks of mallard migrations. This allowed us to simulate individual mallard migrations from a key stopover site in the Baltic Sea for the entire population and link these movements to infection simulations. Using this novel approach, we were able to estimate the dispersal of low-pathogenic avian influenza viruses by migrating mallards throughout several autumn migratory seasons and predicted areas that are at risk of importing these viruses. We found that mallards are competent vectors and on average dispersed viruses over distances of 160 km in just 3 h. Surprisingly, our simulations suggest that such dispersal events are rare even throughout the entire autumn migratory season. Our approach directly combines simulated population-level movements with local infection dynamics and offers a potential converging point for movement and disease ecology

A Comprehensive Model for the Quantitative Estimation of Seed Dispersal by Migratory Mallards

Long-distance seed dispersal is an important ecosystem service provided by migratory animals. Plants inhabiting discrete habitats, like lakes and wetlands, experience dispersal limitation, and rely heavily on zoochory for their spatial population dynamics. Granivorous waterbirds may disperse viable seeds of wetland plants over long distances during migration. The limited knowledge of waterbird migration has long hampered the evaluation of the importance of waterbirds in seed dispersal, requiring key metrics such as realistic dispersal distances. Using recent GPS tracking of mallards during spring migration, we built a mechanistic seed dispersal model to estimate realistic dispersal distances. Mallards are abundant, partially migratory ducks known to consume seeds of >300 European plant species. Based on the tracking data, we informed a mallard migration simulator to obtain a probabilistic spring migration model for the mallard population wintering at Lake Constance in Southern Germany. We combined the spring migration model with seed retention curves to develop seed dispersal kernels. We also assessed the effects of pre-migratory fasting and the availability of suitable deposition habitats for aquatic and wetland plants. Our results show that mallards at Lake Constance can disperse seeds in the northeastern direction over median distances of 293 and 413 km for seeds with short and long retention times, respectively, assuming a departure immediately after foraging. Pre-migratory fasting strongly affected the dispersal potential, with only 1–7% of ingested seeds left for dispersal after fasting for 12 h. Availability of a suitable deposition habitat was generally <5% along the migratory flyway. The high probability of seed deposition in a freshwater habitat during the first stopover, after the mallards completed the first migratory flight, makes successful dispersal most likely to happen at 204–322 km from Lake Constance. We concluded that the directed long-distance dispersal of plant seeds, realized by mallards on spring migration, may contribute significantly to large scale spatial plant population dynamics, including range expansion in response to shifting temperature and rainfall patterns under global warming. Our dispersal model is the first to incorporate detailed behavior of migratory waterbirds and can be readily adjusted to include other vector species when tracking data are available

Integrating animal movement with habitat suitability for estimating dynamic landscape connectivity

Context: High-resolution animal movement data are becoming increasingly available, yet having a multitude of trajectories alone does not allow us to easily predict animal movement. To answer ecological and evolutionary questions at a population level, quantitative estimates of a species' potential to act as a link between patches, populations, or ecosystems are of importance. Objectives: We introduce an approach that combines movement-informed simulated trajectories with an environment-informed estimate of their ecological likelihood. With this approach, we estimated connectivity at the landscape level throughout the annual cycle of bar-headed geese (Anser indicus) in its native range. Methods: We used a tracking dataset of bar-headed geese to parameterise a multi-state movement model and to estimate temporally explicit habitat suitability within the species' range. We simulated migratory movements between range fragments, and estimated their ecological likelihood. The results are compared to expectations derived from published literature. Results: Simulated migrations matched empirical trajectories in key characteristics such as stopover duration. The estimated likelihood of simulated migrations was similar to that of empirical trajectories. We found that the predicted connectivity was higher within the breeding than in wintering areas, corresponding to previous findings for this species. Conclusions: We show how empirical tracking data and environmental information can be fused to make meaningful predictions about future animal movements. These are temporally explicit and transferable even outside the spatial range of the available data. Our integrative framework will prove useful for modelling ecological processes facilitated by animal movement, such as seed dispersal or disease ecology

Hotspots in the grid: Avian sensitivity and vulnerability to collision risk from energy infrastructure interactions in Europe and North Africa

Wind turbines and power lines can cause bird mortality due to collision or electrocution. The biodiversity impacts of energy infrastructure (EI) can be minimised through effective landscape-scale planning and mitigation. The identification of high-vulnerability areas is urgently needed to assess potential cumulative impacts of EI while supporting the transition to zero carbon energy. We collected GPS location data from 1,454 birds from 27 species susceptible to collision within Europe and North Africa and identified areas where tracked birds are most at risk of colliding with existing EI. Sensitivity to EI development was estimated for wind turbines and power lines by calculating the proportion of GPS flight locations at heights where birds were at risk of collision and accounting for species' specific susceptibility to collision. We mapped the maximum collision sensitivity value obtained across all species, in each 5 × 5 km grid cell, across Europe and North Africa. Vulnerability to collision was obtained by overlaying the sensitivity surfaces with density of wind turbines and transmission power lines. Results: Exposure to risk varied across the 27 species, with some species flying consistently at heights where they risk collision. For areas with sufficient tracking data within Europe and North Africa, 13.6% of the area was classified as high sensitivity to wind turbines and 9.4% was classified as high sensitivity to transmission power lines. Sensitive areas were concentrated within important migratory corridors and along coastlines. Hotspots of vulnerability to collision with wind turbines and transmission power lines (2018 data) were scattered across the study region with highest concentrations occurring in central Europe, near the strait of Gibraltar and the Bosporus in Turkey. Synthesis and applications. We identify the areas of Europe and North Africa that are most sensitive for the specific populations of birds for which sufficient GPS tracking data at high spatial resolution were available. We also map vulnerability hotspots where mitigation at existing EI should be prioritised to reduce collision risks. As tracking data availability improves our method could be applied to more species and areas to help reduce bird-EI conflicts

Biological Earth observation with animal sensors

Space-based tracking technology using low-cost miniature tags is now delivering data on fine-scale animal movement at near-global scale. Linked with remotely sensed environmental data, this offers a biological lens on habitat integrity and connectivity for conservation and human health; a global network of animal sentinels of environmen-tal change

A HITCHHIKER'S GUIDE TO WATERBIRD MIGRATION

The ability to move profits the mobile individual, but also makes it a potential vector for nutrients, pathogens, and propagules. Moving animals thus have the potential to impose effects at an ecological scale that far surpasses the immediate consequences for the single moving individual itself. Long-distance migrants, which are estimated to comprise billions of individuals each year, exert a tremendous potential to link ecosystems, or even continents. In a time that the global phenomenon of long-distance migration is slowly starting to disappear, we are only beginning to understand the drivers and ecological impact of these seasonal mass movements. Technological advances and the miniaturisation of tracking devices allow us to peer ever deeper into the life of individuals, yet these observations remain hard to generalise over large numbers of individuals. Turning to an increasing diversity of movement models, however, offers the possibilities to describe and generalise animal movement by quantitative means. While this provides the opportunity to replicate the underlying movement process, these models often cannot account for the immediate environmental context under which movement occurred. Animals, however, do not move randomly through space, and the incorporation of environmental information into predicting both the causes and effects of massive, long-distance migrations is essential. I develop a framework that integrates movement models with environmental information using movement data collected from several species of Asian waterbirds as a model system. This framework incorporates both the environmental context of simulated trajectories and the habitat use of the species and specifically acknowledges that both environment and habitat use can be subject to seasonal changes. This is mainly achieved by identifying periods of time during which the habitat use of individuals is constant directly from empirical tracking data. Therefore, I introduce a novel segmentation approach for animal movement data in chapter 1. I show that this segmentation approach is able to identify relevant changes in habitat use caused by changes in both the available environment and habitat utilisation using simulations, and apply the method to data collected for the common teal (Anas crecca, Linnaeus 1758). In chapter 2, I explore whether temporally dynamic predictions of habitat suitability that are derived after a segmentation can, in combination with movement simulation, make ecologically sensible predictions of migratory movements. I expand a recently developed movement model to account for the typical migratory strategy of the bar-headed goose (Anser indicus, Latham 1790) and derive a metric to evaluate the ecological likelihood of simulated migratory trajectories. This chapter shows that a combination of predicted habitat suitability at stopover sites and metrics of simulated trajectories can reflect our knowledge of this species’ movements within its native range both in space and time even in areas for which no tracking data were available. Finally, I apply this framework to data from bar-headed geese and the ruddy shelduck (Tadorna ferruginea, Pallas 1764) to estimate their contribution to the dispersal of avian influenza A virus H5N1 under the assumption that both of these species are able to transport the virus between stopover sites. Even though the dispersal patterns of a pathogen with a variety of hosts are likely more complex than assumed in this chapter, I was able to explain a significant portion of the virus diffusion across the Asian continent by incorporating both geographic distance and the environmentally informed movement simulations.In conclusion, this thesis presents one approach how to derive quantitative predictions of how, when, and where animals might move through heterogeneous landscapes from empirical tracking data. I think that the framework established in this thesis is sufficiently flexible to be adapted for a diversity of applications. While this work is only an initial step to understand the complexity of global migration, the results show how movement models can profit from the integration of the environmental context of animal movement.publishe

Långsiktiga trender i förekomst, fenologi och morfometri för småsnäppor Calidris minuta på höstflyttning vid Ottenby 1946–2020

THE LITTLE STINT Calidris minuta is an Arctic wader species that migrates through the Baltic Sea region towards wintering areas in North and West Africa and the Mediterranean region. We use a 75-year trapping series, comprising 4,791 Little Stints on autumn migration, from Ottenby Bird Observatory in Sweden to illustrate long-term trends in abundance, phenology, and morphometrics. Numbers of trapped juveniles dropped from median 31 (mean 74) in 1946–1999 to median 1.5 (mean 3.5) birds in 2000–2020, while the number of adults was generally low and without trends. Rolling window analyses showed that the drop in juveniles started around 1984, and from 1993 onward the median never exceeded seven juveniles/year (25%-quantile: 0–1; 75%-quantile: 4–55). Moreover, adult birds advanced their passage on average 0.48 days per year, passing 26 days earlier in 2020 than in 1946. Earlier migration of adults and decreased numbers of juveniles suggest low reproductive output in recent decades. Morphometric data of recaptured birds show that Little Stints on stopover at Ottenby gain fuel at a speed close to the theoretical maximum, strongly indicating that the conditions at the trapping site remain favourable for foraging waders

Linking colony size with quantitative estimates of ecosystem services of African fruit bats

Animal-mediated seed dispersal is a pivotal component of functioning forest ecosystems all over the globe. Animals that disperse seeds away from their parental plants increase the seeds' chances of survival by releasing them from competition and specialised predators and so contribute to maintain the biodiversity of forests. Furthermore, seeds dispersed into deforested areas provide the opportunity for reforestation. Forest regeneration especially depends on animals that cover large distances easily and cross forest gaps, in particular large-bodied frugivores or mobile species such as birds and bats. Yet, frugivores have started to disappear from forests everywhere, with potentially dramatic consequences for forest composition, regeneration and overall forest biomass. Identifying which species contribute substantially to the dispersal of viable seeds, and how these services are affected by fluctuations in population size, is thus pivotal to the understanding and conservation of forest ecosystems.publishe

Migration distance affects how closely Eurasian wigeons follow spring phenology during migration

Background: The timing of migration for herbivorous migratory birds is thought to coincide with spring phenologyas emerging vegetation supplies them with the resources to fuel migration, and, in species with a capital breedingstrategy also provides individuals with energy for use on the breeding grounds. Individuals with very long migrationdistances might however have to trade of between utilising optimal conditions en route and reaching the breeding grounds early, potentially leading to them overtaking spring on the way. Here, we investigate whether migrationdistance afects how closely individually tracked Eurasian wigeons follow spring phenology during spring migration. Methods: We captured wigeons in the Netherlands and Lithuania and tracked them throughout spring migration toidentify staging sites and timing of arrival. Using temperature-derived indicators of spring phenology, we investigatedhow maximum longitude reached and migration distance afected how closely wigeons followed spring. We furtherestimated the impact of tagging on wigeon migration by comparing spring migratory timing between tracked individuals and ring recovery data sets. Results: Wigeons migrated to locations between 300 and 4000 km from the capture site, and migrated up to1000 km in a single day. We found that wigeons migrating to more north-easterly locations followed spring phenology more closely, and increasingly so the greater distance they had covered during migration. Yet we also found thatdespite tags equalling only around 2% of individual’s body mass, individuals were on average 11–12 days slower thanring-marked individuals from the same general population. Discussion: Overall, our results suggest that migratory strategy can vary dependent on migration distance withinspecies, and even within the same migratory corridor. Individual decisions thus depend not only on environmentalcues, but potentially also trade-ofs made during later life-history stages

Evidence for continental-scale dispersal of antimicrobial resistant bacteria by landfill-foraging gulls

Anthropogenic inputs into the environment may serve as sources of antimicrobial resistant bacteria and alter the ecology and population dynamics of synanthropic wild animals by providing supplemental forage. In this study, we used a combination of phenotypic and genomic approaches to characterize antimicrobial resistant indicator bacteria, animal telemetry to describe host movement patterns, and a novel modeling approach to combine information fromthese diverse data streams to investigate the acquisition and long-distance dispersal of antimicrobial resistant bacteria by landfill-foraging gulls. Our results provide evidence that gulls acquire antimicrobial resistant bacteria from anthropogenic sources, which they may subsequently disperse across and between continents via migratory movements. Furthermore,we introduce a flexible modeling framework to estimate the relative dispersal risk of antimicrobial resistant bacteria in western North America and adjacent areas within East Asia, which may be adapted to provide information on the risk of dissemination of other organisms and pathogens maintained by wildlife through space and time