Raphaël Nussbaumer

Swiss Ornithological Institute

It was recently shown that by matching the measurements of a light-weight pressure sensor with a weather reanalysis dataset, we can derive the position of a device with relatively high precision (10-100km). This method presents several advantages: (1) it does not rely on calibration and its precision does not vary with time of year, (2) it provid...

Background To understand the ecology of long-distance migrant bird species, it is necessary to study their full annual cycle, including migratory routes and stopovers. This is especially important for species in high-elevation habitats that are particularly vulnerable to environmental change. Here, we investigated both local and global movements du...

Tracking technologies have widely expanded our understanding of bird migration routes, destinations and underlying strategies. However, determining the entire trajectory of small birds equipped with lightweight geolocators remains a challenge. We develop a highly optimized hidden Markov model (HMM) for reconstructing bird trajectories. The observat...

Over the past decades, tracking technologies have become more ubiquitous and helped uncover crucial spatiotemporal relationships in nature. In order to apply these technologies to small animals and reduce any potential adverse impact of devices, geopositioning methodologies compatible with lightweight devices are highly sought after. Measured by li...

While many birds are known to be in decline in the northern hemisphere, little is known about long-term trends on the African continent. National atlas data are a main source of information to study changes in species’ distribution range. In Kenya, a precursory national bird atlas survey was conducted between 1970 and 1984 including extensive surve...

The routes, drivers, and strategies of a large number of Afro-tropical migrants are still poorly known today. Light-weight geolocators offer an affordable solution to study the movement of small birds and uncover their migratory journeys. Yet, so far, positioning derived from light-level measurements provides only limited precision along with low a...

Video: https://youtu.be/U7jAK9nZNQU Abstract: The recent development of miniaturized multi-sensor geolocators (<1.3g) offers new opportunities to better understand the movements of small birds. On the spatial scale, light and activity data are most commonly used to determine birds’ location and the inclusion of wind data has shown promise in reduc...

Video: https://youtu.be/Pmeg0_DCv6o Abstract: Quantifying and characterising seasonal bird migration is critical to understand the influence of mass migration on habitats, ecosystems and human societies, especially in light of rapid population declines of common nocturnal migrants. Bird migration is notoriously difficult to measure, occurring conti...

Wind has a significant yet complex effect on bird migration speed. With prevailing south wind, overall migration is generally faster in spring than in autumn. However, studies on the difference in airspeed between seasons have shown contrasting results so far, in part due to their limited geographical or temporal coverage. Using the first full-year...

The phenology and routes of long-distance migrations of European Nightjars are well described for Western European individuals migrating within the East Atlantic and Mediterranean flyways, while little is known about populations from other parts of the Eurasian breeding range. We describe the route choice and timing of European Nightjars breeding i...

Thanks to their light weight and low cost relative to GPS trackers, light-level geolocators are uniquely positioned to uncover bird migration patterns across less well-financed and understudied regions of the world. A main drawback of geolocators is the need to recapture equipped birds to retrieve the data. Maximizing the recapture rate is therefor...

Background In addition to light, the use of pressure and activity data recorded by multi-sensor geolocators has recently been shown to improve the estimation of a bird’s position. At the same time, modelling a bird’s trajectory with an MCMC sampler becomes more challenging when integrating this new information. Method In this work, we propose to m...

1. Tracking technologies have widely expanded our understanding of bird migration routes, destinations, and underlying strategies. However, determining the entire trajectory of small birds equipped with lightweight geolocators remains a challenge. Statistical trajectory models that incorporate both flight behaviour and sensor information provide th...

Do Ospreys prey on coral reef fish? In short, yes. We report for the first time in scientific literature with photographic proof that Ospreys eat coral reef fish and suggest, based on regular sightings of Osprey hunting over the Watamu Marine National Park lagoon and reef, that coral reef fish form a regular part of their diet while in Kenya.

Background Knowing about the temporal and spatial use of habitats by wildlife is crucial to understand ecological relationships in nature. Tracking small birds and bats requires tags of less than 2g, such that light-weight geolocators are currently the most affordable and widespread option. Recent multi-sensor geolocators now capture accelerometer...

Background Understanding the temporal and spatial use of habitats by wildlife is crucial to apprehend ecological relationships in nature. Tracking small birds and bats requires tags of less than 2g, therefore lightweight geolocators are currently the most affordable and widespread option. Recent multi-sensor geolocators now capture accelerometer an...

Background Over the past decades, tracking technologies have become more ubiquitous and helped uncover crucial spatio-temporal relationships in nature. To extend the tracking of small animals and reduce any potential adverse impact of devices, methodologies compatible with light-weight devices are sought after. Measured by light-weight geolocators,...

Weather radar networks have great potential for continuous and long-term monitoring of aerial biodiversity of birds, bats, and insects. Biological data from weather radars can support ecological research, inform conservation policy development and implementation, and increase the public’s interest in natural phenomena such as migration. Weather rad...

Ocean currents have wide-ranging impacts on seabird movement and survival. By extension, the extreme oscillations they are subject to, such as extreme Indian Ocean Dipole (IOD) events, can also be expected to dramatically influence seabird populations. This study links the extreme IOD event that occurred in 2019-2020 to the unusually high number of...

Link to video: https://www.youtube.com/watch?v=0JsYU_xfKN8 Abstract: The recent development of miniaturized multi-sensor geolocators (1.3g) offers new potential to refine our understanding of birds’ movement at a very fine temporal scale. On the spatial scale, light measurement is the most common variable used to determine birds’ location. Yet at...

Several populations of Pied Avocet are understood to overlap in East Africa, yet the specific movements and size of each of them remains largely unclear. A review of current literature, combined with waterbird counts and recent citizen science data, suggests that potentially three populations occur in the region (Palaearctic, southern origin, and r...

To understand the influence of biomass flows on ecosystems, we need to characterize and quantify migrations at various spatial and temporal scales. Representing the movements of migrating birds as a fluid, we applied a flow model to bird density and velocity maps retrieved from the European weather radar network, covering almost a year. We quantifi...

Recent and archived data from weather radar networks are extensively used for the quantification of continent-wide bird migration patterns. While the process of discriminating birds from weather signals is well established, insect contamination is still a problem. We present a simple method combining two Doppler radar products within a Gaussian mix...

Recent and archived data from weather radar networks are extensively used for quantification of continent-wide bird migration pattern. While discriminating birds from weather signals is well established, insect contamination is still a problem. We present a simple method combining two doppler radar products within a single Gaussian-mixture model to...

The movements of migratory birds constitute huge biomass flows that influence ecosystems and human economy, agriculture and health through the transport of energy, nutrients, seeds, and parasites. To better understand the influence on ecosystems and the corresponding services and disservices, we need to characterize and quantify the migratory movem...

Bayesian sequential simulation (BSS) is a geostastistical technique, which uses a secondary variable to guide the stochastic simulation of a primary variable. As such, BSS has proven significant promise for the integration of disparate hydrogeophysical data sets characterized by vastly differing spatial coverage and resolution of the primary and se...

Within the current context of climate change particularly affecting Africa, it has become all the more urgent to study intra-African migratory birds, whose even general migration routes and timing are in most cases as yet largely unknown. In one of the first studies leveraging geolocators to uncover intra-African bird migration, we propose to inves...

Quantifying nocturnal bird migration at high resolution is essential for (1) understanding the phenology of migration and its drivers, (2) identifying critical spatio-temporal protection zones for migratory birds, and (3) assessing the risk of collision with artificial structures. We propose a tailored geostatistical model to interpolate migration...

Quantifying nocturnal bird migration at high resolution is essential for (1) understanding the phenology of migration and its drivers, (2) identifying critical spatio-temporal protection zones for migratory birds, and (3) assessing the risk of collision with man-made structures. We propose a tailored geostatistical model to interpolate migration in...

Deterministic geophysical inversion approaches yield tomographic images with strong imprints of the regularization terms required to solve otherwise ill-posed inverse problems. While such tomograms enable an adequate assessment of the larger-scale features of the probed subsurface, the finer-scale details tend to be unresolved. Yet, representing th...

Video of the full presentation (1h26): youtu.be/sQD3sspBewM. Video of the introduction (2min20): youtu.be/u7dYTx2e8Ug

Around the world, groundwater is vital for humankind, yet threatened by anthropogenicdeterioration. Sustainable groundwater management is thus crucial and relies on numericalmodels for adequately forecasting groundwater conditions. A key step in the construction ofsuchmodels is to determine hydrogeological parameters that describe the behaviour of...

See the final paper: https://www.researchgate.net/publication/333825476_Simulation_of_fine-scale_electrical_conductivity_fields_using_resolution-limited_tomograms_and_area-to-point_kriging

Sequential Gaussian Simulation (SGS) is a stochastic simulation technique commonly employed for generating realizations of Gaussian random fields. Arguably, the main limitation of this technique is the high computational cost associated with determining the kriging weights. This problem is compounded by the fact that often many realizations are req...

Sequential Gaussian Simulation is a commonly used geostatistical method for populating a grid with a Gaussian random field. The theoretical foundation of this method implies that all previously simulated nodes, referred to as neighbors, should be included in the kriging system of each newly simulated node. This would, however, require solving a lar...

Improving Bayesian Sequential Simulation with an Adaptative Log-linear Pooling

Constant path in SGS: Consequences and benefits

Sequential Simulation Path Biases and how to live with them?

Bayesian sequential simulation (BSS) is a powerful geostatistical technique, which notably has shown significant potential for the assimilation of datasets that are diverse with regard to the spatial resolution and their relationship. However, these types of applications of BSS require a large number of realizations to adequately explore the soluti...

Bayesian sequential simulation (BSS) is a powerful geostatistical technique, which notably has shown significant potential for the assimilation of datasets that are diverse with regard to the spatial resolution and their relationship. However, these types of applications of BSS require a large number of realizations to adequately explore the soluti...

The geostatistical integration of geophysical and hydrological data has significant potential for adequately characterizing heterogeneous aquifers. Although progress has been made in this regard, the proposed methods were so far mostly limited to the local scale. Recently, Ruggeri et al. (2013) proposed a two-step Bayesian sequential simulation (BS...

The Prairie Pothole Region (PPR) is a critical region in Canada because of its crucial role in agricultural production. The area is highly vulnerable to costly floods and droughts, and climate change impacts are likely to be highly damaging. The prairies are relatively flat, seasonally frozen, and semi-arid. The landscape is covered with ponds of v...