dr. Wouter Vansteelant

SPOONBILLS AS “WAAKVOGELS” OF THE WADDEN SEA

In April 2025 I was appointed as coordinator of the Spoonbill research under WAAKVOGELS; a collaborative research project led by BirdEyes in which various research and conservation institutes use scientific and artistic methods to understand the Wadden Sea from the perspective of six migratory shorebirds.

In this project I have the opportunity to build on long-term spoonbill research developed by prof. Theunis Piersma, dr. Petra de Goei, and dr. Tamar Lok, in collaboration with talented Ph.D. candidate Arne van Eerden, research assistant Marycha Franken, B.Sc. and M.Sc. students, and - last but not least - the formidable volunteers of Werkgroep Lepelaar and their international network of spoonbill aficionados.

Together we will investigate how Spoonbills breeding on the barrier islands of the Dutch Wadden Sea use the marine and freshwater habitats of this World Heritage site, how juvenile spoonbills learn and establish individual space use routines, and how survival and breeding succes of Spoonbills has developed since the species reached carrying capacity in the Wadden Sea (Oudman et al. 2017) and started changing migration in response to global change (Lok et al. 2011).

The WAAKVOGELS-Spoonbill research is taking place at a time of mounting human pressures in the Dutch Wadden Sea, including various forms of resource extraction, infrastructural development and recreational pressure. Over the last two years I was already been involved in tracking and observation-based studies of space use by Spoonbills breeding on the island of Schiermonnikoog. These revealed a strong post-breeding congregation of Spoonbills on the mudflats of Lutjewad and the adjacent saltmarsh (Henriques et al. in press), where Spoonbills moult more than half their primary feathers, and fatten up for migration (de Boer et al. 2024). These findings raise concern about the planned (and almost approved) construction of a powerline through the breeding and post-breeding areas of the important Spoonbill population on Schiermonnikoog. In addition, we expect to see major human influences in the Spoonbills’ living areas in the Wadden Sea in coming years, and our research will help monitor the response of this iconic species to habitat loss as well as restoration efforts.

migratory BIRDS AS CULTURED CREATURES: INDIVIDUAL AND SOCIAL LEARNING OF LOCAL AND FLYWAY-SCALE MOVEMENTS

Most of my scientific work to date has focused on long-lived migratory species, and in particular on the complex and flexible migration routines of experienced, adult birds. How individual migrants learn and establish these routines, however, has long been a mystery. Fortunately, continued advancement of tracking and other research techniques have made it possible to study the early-life development of movement routines from local to flyway scales in unprecedented detail. I previously made strides in this direction through my research on Honey Buzzards and Lesser Spotted Eagles. Now, I am working to develop this research line using the long-term studies of migratory shorebirds of BirdEyes and international partners as focal study systems.

The Spoonbill research at BirdEyes offers a particularly exciting system to study the development of multi-scale movements, including social and cultural aspects of foraging and migration behaviour. In this research, I aspire to build on the recent discovery of intense vocal communication among migrating Spoonbills (Lagarde & Piersma 2021) and experimental research into the social learning of differential migration behaviour by dr. Tamar Lok (Lok 2021). At the moment, I am supervising Ph.D. research by Arne van Eerden into the ontogeny of space use patterns in the Wadden Sea and the establishment of non-breeding sites along the East-Atlantic Flyway. A BOU Career Development Bursary is supporting M.Sc. student Leo Akhmeteli to study age differences in endurance flights and response to wind conditions during migration. M.Sc. student Maaike van den Bemt just started a research project into the nature and duration of joint migratory trips by Spoonbills. And I am excited to be part of a study demonstrating that parental care can extend up to several months after fledging, but ends before the onset of migration (Lok et al. in review).

In addition to the Spoonbill system, I am actively seeking funds to support Ph.D. research into the ontogeny of multi-scale movements in other shorebirds, and continue to collaborate with former colleagues to study ontogeny of migration behaviour in long-lived raptors (e.g. Mirski et al. in review; past work - Honey Buzzards). Finally, I am proud to act as external adviser in the postdoctoral research of Lina Lopez-Ricaurte, investigating the ontogeny of annual cycle movements by Greater Flamingos in the Mediterranean basin.

GLOBAL FLYWAY NETWORK: TOWARDS A LIVING MULTI-LAYERED ATLAS OF AVIAN LIFE HISTORIES

Since joining the scientific team of BirdEyes at the University of Groningen, I have been collaborating intensively with graphic designer and web developer Bastiaan Blaauw, providing conceptual input on the bird tracking webpage of Global Flyway Network. This interactive webpage is a brainchild of Theunis Piersma, and we are currently developing it into what may be called a living, interactive and multi-layered atlas of bird life histories.

GFN allows users to interactively colour and animate tracks of migrating birds, which is invaluable to discover behavioural patterns in an ever growing stream of near real-time movement data. We are now working to integrate static as well as dynamic environmental data layers in the system, and a tool to couple field observations and multimedia with tracking data.

All combined, GFN will provide unprecedented capabilities for research, story-telling and stake-holder engagement. In fact, GFN already provides the technical backbone for an interactive Dashboard that will develop monitoring tools on the basis of tracking data for conservation practitioners in the Dutch Wadden Sea, as part of Waakvogels.nl.

Slimmed-down version of the GFN interface with custom selections of data and tailored levels of interactiveness can be provided as an embeddable service to any interested party. Let me know if you want an interactive GFN map on your website!

how shorebirds coped with a historic drought in the doñana biosphere - a vital node in the EAST-ATLANTIC migration flyway

Between 2022 and 2025 I analysed how Black-tailed Godwits Limosa limosa from breeding populations in the Netherlands and Germany coped with a drought of historic proportions in the Doñana World Heritage site and Biosphere reserve; a key node in the migratory network of waterbirds in the the East-Atlantic flyway.

This work, funded by a MAVA fellowship, was prompted by the rapid loss of almost 40.000ha of artificial wetland habitat during an intense 5-year drought that resulted in severe surface water shortages, and the cessation of rice cultivation in the region. This was a cause of great concern among migratory bird specialists given that rice fields have supplanted much of the natural wetlands in the Mediterranean, and especially because the quality and resilience of the Doñana’s remaining natural wetlands have been declining due to decades of unsustainable water management. The drought finally ended in the winter of 2024-2025, but offers a dire warning for the future of the Doñana and the waterbirds that depend on it. After all, the Iberian peninsula faces a growing threat of desertification due to rapid climate breakdown.

At the time I started this research, there was much populist discourse around the historic mismanagement of the Doñana World Heritage site. Therefore, I co-wrote a Letter to Science (Navedo et al. 2022) alerting to these issues. In the following year I wrote a perspective article in Wader Study (Vansteelant et al. 2023) addressing common misconceptions about the conservation challenges in Doñana’s World Heritage, and discussing the severity of the 2019-2024 drought from a Godwit’s perspective. With the support of prominent waterbird experts from the Netherlands, France and Spain I then led an open letter co-signed by 30+ major international expert groups that was published in 5 languages. The open letter was picked up by major media outlets in Spain and Portugal, and was used by conservation organisations such as WWF to lobby for evidence-based conservation action in the Doñana World Heritage site.

Currently, I am wrapping up this project and working towards submission of two scientific articles. A first article will focus on regional differences in the extent to which Black-tailed Godwits use rice fields across all of the major Mediterranean rice-growing regions in the East-Atlantic flyway. Tracking data reveals that where natural freshwater habitats are available alongside rice fields, Godwits use the former as least as much as the latter, which indicates that current action plans for Godwit conservation give too little priority too wetland restoration, alongside bird-friendly management of rice fields. A second article leverages the long-term tracking data from the Netherlands and Germany to show how Godwits adjust their space use to persist through the 5-year drought in the Doñana Biosphere.

Batumi Raptor Count: participatory science in one of the worlds’ prominent raptor flyways

My journey as a bird migration researcher started in 2008, when I volunteered in the full-season autumn raptor migration count at Batumi, Georgia, then organised by fellow biology students Brecht Verhelst and Johannes Jansen. During my stay I quickly became involved in day-to-day management of the count. In the years that followed I helped to develop a rich research and conservation program that became known as the Batumi Raptor Count. For over 15 years we have monitored the autumn passage of ca. 1 million raptors with the help of dozens of volunteers from over 30 countries and 6 continents, and from increasingly diverse backgrounds. Batumi Raptor Count is now widely recognised as a model for volunteer-based monitoring of raptor migration in the East African-Eurasian Flyway (Jobson et al. 2021).

During the first 5 year so the project I was involved in all aspects of the project, ranging from the recruitment and coordination of volunteers, co-developing the now fully digitised count protocol (Wehrmann et al. 2019), organising international exchanges for dozens of students in nature conservation and environmental education from six countries, and (co-)authoring the first BRC publications describing the magnitude and phenology of autumn raptor migration (Verhelst et al. 2011) and species-specific flight behaviour through the Batumi bottleneck (Vansteelant et al. 2014).

Since approx. 2015 most of my attention has been focused on coordinating the participatory research program at BRC, including research into the causes and impact of illegal hunting along Georgia’s Black Sea coast (Sandor et al. 2017). Following the 10th anniversary of the project in 2017, BRC and the Dutch-Georgian Ornithological Foundation (DuGOF) secured an NLBIF grant to fund the open access publication of the BRC dataset through the Global Biodiversity Information Facility (GBIF). The NLBIF grant also funded a first analysis of demographic and phenological trends in 8 raptor species, published in Ibis (Vansteelant et al. 2020). This paper demonstrated that we could detect significant population and demographic trends in the raptor populations moving through the Batumi bottleneck after just 10 years of counting, and established a solid benchmark for volunteer-based monitoring of raptor migration at Batumi in the 21st century.

As BRC research coordinator I have been privileged to supervise talented B.Sc. and M.Sc. students, and collaborate with other BRC team members on several active research lines. Most recently, I supported the publication of the first comprehensive study of spring raptor migration through the eastern Black Sea flyway, led by the talented young ornithologist, and current BRC chairman, Tohar Tal (Tal et al. in press). Several more research projects are underway, including a photography-based study of primary moult in migrating raptors (led by Elien Hoekstra), a description of flocking migration of European Rollers (led by Dries Engelen), a tracking study of Levant Sparrowhawk migration in collaboration with Georgian falconers (led by Dries Engelen), and a study on seasonal differences and long-term changes in the occurrence of light and dark morph Booted Eagles (building on B.Sc. project by Joachim Pintens).

There are numerous opportunities for students to work on various aspects of raptor migration at Batumi, including (i) age- and sex-specific migration behaviour of raptors, (ii) weather influences on the diel and seasonal timing and flight paths at Batumi, (iii) flyway differences and (iv) historical changes in the timing of raptor migration, and so much more. Several students have already worked on some of these topics in recent years, revealing interesting results that would merit publication upon reanalysis with additional data. So don’t hesitate to get in touch if you think a BRC-project would be a good fit for your B.Sc. or M.Sc. dissertation project!