Droevendaalsesteeg 10
6708 PB Wageningen
The Netherlands
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About
My research focusses on vector borne diseases in bird populations to investigate which birds are impacted by these diseases and detect the underlying mechanism of these effects. My project includes an in-depth study on Common blackbirds.
Biography
I started in 2016 with the study Applied Biology at the HAS Hogeschool, which was followed by the Master Biology at the Radboud University in Nijmegen. During my masters I worked on modelling population dynamics and effects of environmental conditions on the populations of Oystercatchers, Kentish and Ringed plovers.
Publications
Peer-reviewed publications
One Health approach uncovers emergence and dynamics of Usutu and West Nile viruses in the Netherlands
https://doi.org/10.1038/s41467-025-63122-wMosquito-borne arboviruses, including Usutu virus (USUV) and West Nile virus (WNV), are emerging threats in Europe, with changes in climate, land use shifts, and increasing global connectivity influencing their dynamics. Understanding how these viruses emerge and establish in new regions is critical for mitigating risks and improving public and wildlife health preparedness. Here, we present a seven-year study (2016–2022, inclusive) documenting the emergence and spread of USUV and WNV in the Netherlands. We established a nationwide sampling framework integrating live birds sampling by volunteer ringers, dead birds referrals by citizen scientists and zoos, and mosquito trapping. Samples were analyzed using molecular, genomic, and serological methods. USUV was first detected in the Netherlands in 2016, caused major outbreaks in birds until 2018 and resurged in 2022. The dominant, enzootic lineage, Africa 3, co-circulated with sporadic introductions of lineage Europe 3. The first localized WNV lineage 2 outbreak occurred in live birds and mosquitoes in 2020, followed by a detection in a bird in 2022 and serological evidence of continued circulation, suggesting WNV is in an early stage of establishment. Our findings were crucial in detecting a human WNV outbreak, underscoring the value of integrated wildlife studies in detecting emerging threats to public health.
Usutu Virus Antibody Dynamics in Naturally Infected Blackbirds, the Netherlands, 2016-2018
https://doi.org/10.3201/eid3106.241744Usutu virus is a zoonotic arbovirus that causes massive mortality in blackbirds. Using a unique longitudinal dataset on the kinetics of virus-specific antibodies in naturally infected wild blackbirds (Turdus merula), we found that individual birds may remain seropositive for >1 year and that reinfection can occur despite low-level virus neutralizing antibodies.
Spatio‐temporal Usutu virus model explains Eurasian blackbird Turdus merula population trends
Emerging vector-borne pathogens (VBPs) pose significant global health threats, occasionally causing widespread outbreaks with high wildlife mortality. Understanding climatic and anthropogenic drivers behind transmission dynamics in wildlife populations is key to mitigate health risks. Citizen science data may allow us to investigate the spread of pathogen outbreaks as it can be collected over a wide range within short time periods. In this study, we explored the use of wildlife mortality data to model the annual occurrence of VBPs. Making use of retrospective Eurasian blackbird Turdus merula mortality data collected within a citizen science program, we employed an ecological niche modelling framework to model the annual distribution of Usutu virus (USUV) in the Netherlands. Based on these modelled USUV occurrence probabilities, we assessed the impact of the USUV occurrence on blackbird populations. Our results reveal a rapid south–north spread of USUV across the Netherlands within three years with an average expansion rate of 91 km year-1. This spread led to significant population declines in blackbirds, reducing population numbers by 30% compared to pre-USUV levels. Our study demonstrated that citizen science bird mortality surveillance can generate useful data to model the spatial transmission intensity of VBP over time that follows the declines in wildlife populations. Higher winter and spring temperatures, which may have facilitated early development of mosquito populations and resulted in greater mosquito abundance later in the year, had a positive impact on the USUV occurrence estimates. While our approach proved successful in modelling pathogen distribution using a well-monitored species like the blackbird, it may be less effective for pathogens that cause minimal wildlife mortality or affect species that are harder to detect. This study provides a first example of a spatio-temporal estimation of USUV transmission intensity in Europe, offering a framework for investigating the annual impact of USUV outbreaks on wildlife populations.https://doi.org/10.1111/ecog.07759State-dependent environmental sensitivity of reproductive success and survival in a shorebird
https://doi.org/10.1111/ibi.13038To understand the consequences of anthropogenic and environmental changes for wildlife populations, it is important to study how individuals differ in their sensitivity to environmental change and whether this depends on individual characteristics. An individual's reproductive performance may provide an integrative, unidimensional proxy of an individual's characteristics. In this study, we define an individual's characteristics by three such reproductive states, namely successful, failed and non-breeders in the previous year. We used a 16-year dataset of individually marked breeding Eurasian Oystercatchers Haematopus ostralegus to examine the interannual fluctuations in reproductive success and survival among breeding states, and their state-dependent sensitivity to environmental conditions. Environmental conditions included available biomass of the main prey species of breeding Oystercatchers (Ragworm, Baltic Tellin and Lugworm), tidal height, which reflects one of the main causes of nest loss (flooding), and conditions that may impact the energetic requirements during incubation, such as temperature. We also included environmental variables measured in winter, including available biomass of the main winter prey species (Blue Mussel and Common Cockle) along with factors that may affect food availability and energetic requirements for homeostasis, namely bivalve weight loss, windchill, winter severity and precipitation. Breeding birds that were successful the previous year had higher survival and were more likely to remain successful, in comparison with failed or non-breeders. The effects of environmental conditions acted in the same direction on reproductive success but had opposite effects on survival among the three breeding states, especially for windchill and Blue Mussel biomass. The contrasting state-dependent effects of the environment on survival thus averaged out when examining consequences for lifetime reproductive nest success (LRnS); instead, LRnS was largely influenced by environmental conditions acting upon reproduction. Our study indicates that an individual's previous breeding state provides an integrative measure of heterogeneity in individuals' sensitivity of reproduction and survival to environmental change. Incorporating previous breeding state as a source of individual heterogeneity in population modelling may improve predictions of future population dynamics in a rapidly changing world.
Popular-scientific publications
Trekvogels geven inzicht in verspreiding infectieziekten
Wilde trekvogels spelen een belangrijke rol bij de introductie en verspreiding van infectieziekten die van dier op mens worden overgedragen, Los van de oorsprong van infectieziekten, kan onderzoek aan trekvogels dan ook belangrijke lessen leren over de verspreiding van die infectieziekten.Broedresultaten van Merels in het bos en in stedelijk gebied - leefgebieden met afwijkende populatietrends
After a long period of increase, the Dutch breedingpopulation of the Blackbird stabilized from the 1990s onwards, with large variation between habitats. Particularly in urban areas, and in woodlands in the northern part of the country, the numbers have declined markedly. Since reproductive data are scarce, we collected data on breeding performance in 2021 and 2022 as part of the ‘Year of the Blackbird’. In these years 361 respectively 535 nest records were submitted by dedicated volunteers, far more than the average of 83 per year in 1995-2020. Blackbirds started egg-laying in urban areas earlier than in woodland habitat (Fig. 2), and seem to have advanced egg-laying by a week since 1990. On average 3.4 young fledged per successful nest, without clear differences between habitats or time periods. On average 26.1% of Blackbird nests were successful. Nest success was higher in urban areas than in woodlands, but also declined stronger over time (Fig. 3). Within urban areas, the number of fledged young per successful nest decreased with increasing urbanisation (Fig. 4), but not nest success. Within woodlands, nest success was lower in the northern part of the country, where population abundance decreased, as compared to other parts. Gathering data on reproduction and survival from other nationwide surveys is necessary to assess the relative importance of these demographic drivers for the recent Blackbird decline.Vis als voedsel voor nestjongen bij Merels
On May 20th in 2022 we observed that a breeding pair of the Common Blackbird fed Three-spined Sticklebacks Gasterosteus aculeatus to their 5-days-old chicks twice. In 2016 an online video showed another Blackbird feeding its 9-day-old chicks with Sticklebacks in the Netherlands. To understand whether catching fish (and possibly feeding fish to nestlings) is perhaps more common among passerines, we sent out a nationwide call to report observations of fishing passerines and searched the scientific literature and online media for reports of this phenomenon. We received nine observations of fishing Common Blackbirds, and five observations of fishing by three other non-corvid passerine bird species. This suggests that capturing and feeding fish seems a rare but widespread behaviour among passerines. Blackbirds normally rely on earthworms and caterpillars to feed their chicks, however, 2022 was one of the driest years in the Netherlands. Drought and heat may have resulted in lower availability of earthworms and caterpillars, while chances of finding fish in shallow or dried-up streams would be relatively high. As a result, some Blackbirds may have substituted the low availability of earthworms and caterpillars with fish to feed their nestlings. Fish has a lower calorific value in gram dry mass than earthworms and caterpillars, but it has a higher content of lipids and consists of 10% less water compared to earthworms. Fish feeding may thus be profitable when other food sources become scarce, such as during severe droughts. However, more observations are needed to understand whether fish feeding is a novel behaviour driven by the more frequent occurrence of droughts or a common behaviour among passerines breeding near water.
Projects & collaborations
Projects
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One Health PACT - Predicting Arboviruses Climate Tipping points
Our water-dominated landscape, combined with a dense human- and livestock population make the Netherlands particularly vulnerable to outbreaks of zoonotic viral diseases that are transmitted by mosquitoes among avian and mammalian host species.