Small carnivore ecology and conservation

This research line is all about small carnivores, especially within the family of the Mustelidae. I work on several species, from the smallest carnivore in Europe (the least weasel) to the much larger, but still small pine marten. With this work I hope to increase our knowledge of the ecology of these species, enabling better management and conservation strategies. I do part of this research through my association with the Small Mustelid Foundation.

As predators of small rodents, many members of the Mustelidae family play important roles in ecosystems. However, due to the difficulty to study them, they are understudied and we know relatively little about their ecology and conservation status. Currently, I work on two projects specifically aimed at improving the methods to study Mustelids.


I am working on further development of the Mostela, a camera-trapping device that was first designed by Jeroen Mos to capture weasel and stoat. Jeroen and I work on the deployment of Mostelas to study weasels in the Netherlands, where Jeroen does the field work and I do the analyses. In 2020, we published a study from a site near Dieren in the Netherlands. After that, we published a study based on a data set that was collected by Karol Zub from the Mammal Research Institute in eastern Poland, also using the Mostela. Currently, we are working on a multi-year study in another study area in the Netherlands, where we use the Mostela to identify individual weasels based on their spot patterns to see how different individuals move through the study site during the different seasons.

Weasel in a tracking tube. Credit: Jeroen Mos

Swedish Polecat Project

I am involved in the development of a combination of a camera trap and a hair trap to estimate polecat densities. Our aim is to verify if the facial patterns of polecats can be used to identify individuals in a spatial capture-mark-recapture framework. By combining nationwide fur-trapping data with density estimates from a couple of reference areas, we hope to develop a monitoring system for polecats in Sweden.

For those interested, I wrote down a small history of my relationship with Mustelids.

My love for Mustelids

I became interested in Mustelids (carnivore species in the family Mustelidae), their biology, conservation and ecology in 2005, when I just graduated from secondary school and saw a pine marten while on holiday in Poland. Although, I think my fascination really started after seeing a Wolverine in the Borås zoo in 2003. These first encounters led to the membership of the Dutch pine marten working group in 2006, when I started to monitor the pine marten population in a local forest near Wageningen.

Soon afterwards, I started helping with post-mortem examinations of traffic victims at Alterra, Wageningen (now Wageningen Environmental Research), where I learned a lot about the anatomy and biology of all Dutch Mustelids. While getting more involved in the Dutch Mustelid research, I realized that there was very little known about the smaller species – weasel , stoat and polecat – so together with Jasja Dekker, Erwin van Maanen and Jeroen Mos, I resurrected the Dutch small mustelid working group in 2008, the year of the Polecat. With the working group we developed a new monitoring strategy for small Mustelids, which is now used by multiple people in the Netherlands. In 2017, we took the work on small Mustelids one step further and started the Dutch Small Mustelid Foundation.

The experience with Mustelids in my free time resulted in my major MSc thesis project, which looked at the population genetics of the Dutch pine marten population using non-invasive genetics. This project resulted in a peer-reviewed paper (see publications).

Together with Jasja Dekker, I looked at the Dutch population of the invasive American mink (Neovison vison) using stable-isotope analysis or hairs and teeth of traffic victims and animals that were killed in traps used in the control of muskrat. This work also resulted in a peer-reviewed paper.

As part of my hobby, I became a regular participant of the European Mustelid Colloquium (EMC), a biannual conference for researchers interested in Mustelid biology and conservation. In 2021 I joined the scientific committee. Also, I am a member of the global Martes working group since 2014 and will be part of the scientific committee of the Martes Symposium that will be organised in Scotland in 2023.