Felix Liechti

• Doctor of Philosophy
• Guest Researcher at University of Basel

The main features of long-distance migration are derived from landbirds breeding in the Northern Hemisphere. Little is known about migration within the tropics, presumably because tropical species typically move opportunistically and over shorter distances. However, such generalizations are weakened by a lack of solid data on spatial, temporal and...

Birds breeding in high-Alpine habitats must select a suitable breeding site and achieve successful reproduction within a restricted time. During four breeding seasons, we monitored nest sites of the Northern Wheatear ( Oenanthe oenanthe ), a high-Alpine long-distance migrant. We investigated how ecological factors predicted the selection of a site...

Birds and bats are prone to collisions with wind turbines. To reduce the number of bat collisions, weather variables are commonly used to shut down wind turbines when a certain constellation of weather variables occurs. Such a general approach might also be interesting to mitigate raptor collisions. Studies on the relationship between flight behavi...

Background Migrating birds fly non-stop for hours or even for days. They rely mainly on fat as fuel complemented by a certain amount of protein. Studies on homing pigeons and birds flying in a wind-tunnel suggest that the shares of fat and protein on total energy expenditure vary with flight duration and body fat stores. Also, flight behaviour, suc...

Many insects depend on high-altitude, migratory movements during part of their life cycle. The daily timing of these migratory movements is not random, e.g. many insect species show peak migratory flight activity at dawn, noon or dusk. These insects provide essential ecosystem services such as pollination but also contribute to crop damage. Quantif...

The Alps are a natural barrier for avian broad‐front migration in Central Europe. While most birds that approach the Alps are deflected and circumvent the mountains, some choose to make the crossing. Here, they are funnelled and channelled in valleys, leading to high bird densities. Many Alpine valleys are suitable locations for wind farms, potenti...

Insects are of increasing conservation concern as a severe decline of both biomass and biodiversity have been reported. At the same time, data on where and when they occur in the airspace is still sparse, and we currently do not know whether their density is linked to the type of landscape above which they occur. Here, we combined data of high-flyi...

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...

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...

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...

The northern wheatear Oenanthe oenanthe has an almost circumpolar breeding distribution in the Northern Hemisphere, but all populations migrate to sub‐Saharan Africa in winter. Currently, tracking data suggest two main access routes to the northern continents via the Middle East and the Iberian Peninsula. These routes would require detours for bird...

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...

Light‐level geolocators have revolutionised the study of animal behaviour. However, lacking spatial precision, their usage has been primary targeted towards the analysis of large‐scale movements. Recent technological developments have allowed the integration of magnetometers and accelerometers into geolocator tags in addition to barometers and ther...

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 environmental change.

During their annual migration, avian migrants alternate stopover periods, for refuelling, with migratory flight bouts. We hypothesise that European Nightjars (Caprimulgus europaeus) adapt their daily migration tactics in association with biomes. We tracked the autumn migration of 24 European Nightjars, from breeding populations in Mongolia, Belgium...

To investigate the complex phenomenon of bird migration, researchers rely on sophisticated methods for tracking long‐distant migrants. While large birds can be equipped with satellite tags, these are too heavy for many species. Instead, researchers often use light‐level geolocation for tracking individual small migratory birds. Unfortunately, light...

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...

This repository contains the reference dataset of labelled (or otherwise useful) echo samples acquired with a BirdScan MR1 radar. This dataset enables classification of the radar echoes acquired with a BirdScan MR1 into a number of biological groups of interests (as well as the removal of non-biological targets). Follow the DOI link for more info...

Mountains naturally offer variable habitat conditions, but their biodiversity is currently facing the extra challenge of adapting to rapid environmental shifts that are much more pronounced than in the lowlands. Among adaptive responses, intra- and inter-seasonal movements represent potentially important coping strategies for wildlife that remain l...

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...

Light-level geolocators have revolutionised the study of animal behaviour. However, lacking precision, they cannot be used to infer behaviour beyond large-scale movements. Recent technological developments have allowed the integration of barometers, magnetometers, accelerometers and thermometers into geolocator tags, offering new insights into the...

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...

Airspace is a key but not well-understood habitat for many animal species. Enormous amounts of insects and birds use the airspace to forage, disperse, and migrate. Despite numerous studies on migration, the year-round flight activities of both birds and insects are still poorly studied. We used a 2 year dataset from a vertical-looking radar in Cent...

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...

Mountains naturally offer very contrasted habitat conditions, but their biodiversity is nowadays facing the extra challenge of adapting to rapid environmental shifts that are much more pronounced than in the lowlands. Among the possible adaptive responses of wildlife, intra- and inter-seasonal movements represent an important coping strategy that r...

Mountains naturally offer very contrasting habitat conditions, but their biodiversity is nowadays facing the extra challenge of adapting to rapid environmental shifts that are much more pronounced than in the lowlands. Among the possible adaptive responses of wildlife, intra- and inter-seasonal movements represent an important coping strategy that...

Climate change is drastically changing the timing of biological events across the globe. Changes in the phenology of seasonal migrations between the breeding and wintering grounds have been observed across biological taxa, including birds, mammals, and insects. For birds, strong links have been shown between changes in migration phenology and chang...

This dataset contains the spring and autumn migration phenology dataset used in Haest et al. (2020) to determine the drivers of migration phenology of Brazilian free-tailed bats at Bracken Cave (USA) over the period 1995-2017. The phenology dataset was derived from nightly colony population sizes estimated using weather radar data (Stepanian et al....

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...

For migratory birds optimal timing of the onset of reproduction is vital, especially when suitable conditions for reproduction occur only for a short while during the year. With increasing latitude the suitable period becomes shorter and we expect the organization of annual cycle to be more synchronized to the local conditions across individuals of...

Biological rhythms of nearly all animals on earth are synchronized with natural light and are aligned to day‐and‐night transitions. Here, we test the hypothesis that the lunar cycle affects the nocturnal flight activity of European Nightjars (Caprimulgus europaeus). We describe daily activity patterns of individuals from three different countries a...

The airspace of the lower troposphere is an important habitat for many animals, including open-space foraging bats. Yet, we are missing a detailed understanding of how bats forage in the seemingly unstructured open space. As part of an exploratory study, we present data on flight activity for Taphozous theobaldi (Dobson 1872), an aerial insectivore...

Aim Knowledge of broad‐scale biogeographical patterns of animal migration is important for understanding ecological drivers of migratory behaviours. Here, we present a flyway‐scale assessment of the spatial structure and seasonal dynamics of the Afro‐Palaearctic bird migration system and explore how phenology of the environment guides long‐distance...

The spatial and temporal patterns of broad front bird migration are governed by the geospatial distributions of landmasses, mountain ranges, and weather conditions. These distributions interact with the birds' innate program during migration and are critical to successful migration. Hence, favourable environmental conditions for migration consequen...

Each year, billions of birds migrate across the continents by day and night through airspaces increasingly altered by human activity, resulting in the deaths of millions of birds every year through collisions with man‐made structures. To reduce these negative impacts on wildlife, forecasts of high migration intensities are needed to apply mitigatio...

In SE Europe, the spatial and temporal distribution of nocturnal migration is hardly known. With the moon-watching technique the passage of 5603 nocturnal migrants was recorded during 419 observation hours at 28 sites spread over Bulgaria, SE Romania and northern Greece. Mean migratory traffic rate was 1400 birds.km-1.h-1 in autumn and 900 birds.km...

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...

The influence of mountain ranges on broad-front bird migration has been investigated for several decades. However, almost all the studies have focused on flight behaviour, and have rarely considered the quantitative effect of mountain ranges as a barrier. The present study investigates the spatial and temporal pattern of autumnal bird migration acr...

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...

In many taxa, the most common form of sex-biased migration timing is protandry-the earlier arrival of males at breeding areas. Here we test this concept across the annual cycle of long-distance migratory birds. Using more than 350 migration tracks of small-bodied trans-Saharan migrants, we quantify differences in male and female migration schedules...

Quantitative radar studies are an important component of studying the movements of birds. Whether a bird, at a certain distance from the radar, is detected or not depends on its size. The volume monitored by the radar is therefore different for birds of different sizes. Consequently, an accurate quantification of bird movements recorded by small‐sc...

From 1 November 2013 to 30 April 2014 an avian radar system was operated in Tsavo West National Park, Kenya. The aim of this research was to study the temporal and spatial distribution of migrating birds over Ngulia Safari Lodge and to compare radar data with catching results of grounded birds. Additionally, the general pattern of flight directions...

Large parts of the continents are continuously scanned by terrestrial weather radars to monitor precipitation and wind conditions. These systems also monitor the mass movements of bird, bat, and insect migration, but it is still unknown how many of these systems perform with regard to detection and quantification of migration intensities of the dif...

Nocturnal avian migration flyways remain an elusive concept, as we have largely lacked methods to map their full extent. We used the network of European weather radars to investigate nocturnal bird movements at the scale of the European flyway. We mapped the main migration directions and showed the intensity of movement across part of Europe by ext...

Background Over the past decade, the miniaturisation of animal borne tags such as geolocators and GPS-transmitters has revolutionized our knowledge of the whereabouts of migratory species. Novel light-weight multi-sensor loggers (1.4 g), which harbour sensors for measuring ambient light intensity, atmospheric pressure, temperature and acceleration,...

With timely allocated movement phases, mobile organisms can match their space‐use with the seasonality of the environment and thereby optimise their resource utilisation over time. Long‐distance avian migrants are known to move with the seasonal dynamics on an annual basis, but how individuals respond to seasonality within their tropical non‐breedi...

Knowledge on whereabouts within the annual cycle of migratory species is prerequisite for many aspects in ecology and biological conservation. Spatial assignments of stable isotopes archived in tissues allows for later inference on sites where the specific tissue had been grown. It has been rarely tested whether spatial assignments match directly t...

Predicted moult origin/overwintering regions for two individual barn swallows based on isotope assignment for three isotopes δ2H, δ13C and δ15N and geolocation. 75% Kernel density estimates are shown in red. a) Example of best geographical overlap. b) Example of least overlap. (TIFF)

Thousands of species migrate [1]. Though we have some understanding of where and when they travel, we still have very little insight into who migrates with whom and for how long. Group formation is pivotal in allowing individuals to interact, transfer information, and adapt to changing conditions [2]. Yet it is remarkably difficult to infer group m...

Crossing of large ecological barriers, such as mountains, is in terms of energy considered to be a demanding and critical step during bird migration. Besides forming a geographical barrier, mountains have a profound impact on the resulting wind flow. We use a novel framework of mathematical models to investigate the influences of wind and topograph...

Advances in information technology are increasing the use of radar as a tool to investigate and monitor bird migration movements. We set up a field campaign to compare and validate outputs from different radar systems. Here we compare the pattern of nocturnal bird migration movements recorded by four different radar systems at a site in southern Sw...

Chapman, J., Shamoun-Baranes, J., Dokter, A., Leijnse, H., Liechti, F., Koistinen, J., Nilsson, C., van Gasteren, H., Alves, J., Sapir, N., Hüppop, O., Reynolds, D. & Bauer, S. (2018) The European Network for the Radar surveillance of Animal Movement (ENRAM). Presentation EGU2018-12875 at European Geosciences Union General Assembly 2018, Vienna, A...

Bird collisions at wind turbines are perceived to be an important conservation issue. To determine mitigation actions such as temporary shutdown of wind turbines when bird movement intensities are high, knowledge of the relationship between the number of birds crossing an area and the number of collisions is essential. Our aim was to combine radar...

One of the methods of estimating the large-scale spatial distribution of birds is to compare the numbers of birds in flight, estimated by a single method at several sites lying across the main path of migration (Dolnik & Bolshakov 1985, Dolnik 1990). This method is particularly suitable for estimating the spatial distribution of nocturnal passerine...

Studying individual flight behaviour throughout the year is indispensable to understand the ecology of a bird species. Recent development in technology allows now to track flight behaviour of small long-distance bird migrants throughout its annual cycle. The specific flight behaviour of twilight ascents in birds has been documented in a few studies...

In their 2015 Current Biology paper, Streby et al. [1] reported that Golden-winged Warblers (Vermivora chrysoptera), which had just migrated to their breeding location in eastern Tennessee, performed a facultative and up to “>1,500 km roundtrip” to the Gulf of Mexico to avoid a severe tornadic storm. From light-level geolocator data, wherein geogra...

Introduction: Impact assessment studies are required prior and sometimes after construction of wind farms and such studies typically involve the quantitative monitoring of bird movements. Radar is an approved tool to detect flying birds and it operates under almost all conditions. However, a proper quantitative monitoring of bird movements by radar...

Light-level geolocators are currently widely used to track the migration of small-sized birds, but their potentially detrimental effects on survival of highly aerial species have been poorly investigated so far. We recorded capture-recapture histories of 283 common swifts Apus apus and 107 pallid swifts Apus pallidus breeding in 14 colonies in Ital...

Variation in wing morphology results from the combination of diverse selection pressures. Wing feather morphology within species varies with sex and ontogenetic effects, and also with ecological factors. Yet, the direction of causation for the wing morphology–ecology association remains to be elucidated. Under the ‘ecology-dependence’ hypothesis, w...

The extraordinary adaptations of birds to contend with atmospheric conditions during their migratory flights have captivated ecologists for decades. During the 21st century technological advances have sparked a revival of research into the influence of weather on migrating birds. Using biologging technology, flight behaviour is measured across enti...

Between August 27th and September 30th 2014 the intensity of nocturnal bird migration was measured in the Dobrudzha Region (NE Bulgaria) using a specific bird radar. During the same time period and in the same area (part of Natura 2000 net BGSPA0002051 Kaliakra and adjacent areas), road-kills as well as collisions of birds with wind turbines were r...

Individuals often considerably differ in the timing of their life-cycle events, with major consequences for individual fitness, and, ultimately, for population dynamics. Phenological variation can arise from genetic effects but also from epigenetic modifications in DNA expression and translation. Here, we tested if CpG methylation at the poly-Q and...

In the context of an extensive study on bird migration in the Austrian Alps, we compared data from a fixed-beam radar with data collected by visual observation to estimate the intensity of migrating birds up to a height of 150 m above the ground. Migration traffic rates calculated from visual bird counts and radar measurements were strongly correla...