A nine month small mustelid survey across four research sites in the Netherlands

Abstract: There is a general concern amongst ecologists about the apparent decline of small mustelids in The Netherlands over the past decades. However, little is known about their actual historic and present numbers. To better understand their ecology and the cause of the decline more research into these small predators is a necessity. Between October 2016 and August 2017 four different research sites in the vicinity of Deventer, the Netherlands, were investigated by surveying 64 locations with camera trap boxes and nest boxes fitted with tracking tunnels with the intention to gather distributional data of small mustelids common weasel (Mustela nivalis vulgaris) and stoat (Mustela erminea). Three locations were chosen for their small-scale agricultural landscapes, regarded as prime habitat for the target species. One location concerned an open large-scale intensively managed agricultural landscape, regarded as degraded habitat. Weasels were found with both camera-trap boxes and nest boxes but the footprints of weasel and stoat from tracking tunnels could not always be identified to species. Zero stoats were found during this study. Stoats are either very rare or not present at the time of research. Research materials proved not to be suitable for Western polecat (Mustela putorius) and other larger mustelids as the limited diameter of the entrance tubes used in the research materials averts entry. There was no clear difference in number of weasel recordings between large-scale agricultural landscape (two recordings) and small-scale agricultural landscapes (one, five and zero recordings) that were included in this study. Striking is the fact that most observations occurred between March and October. The outcome of this study concludes that small mustelid studies require innovative research materials, time consuming methods and harvest meagre results. Based on historical data and recent research results, including this study, it is not possible to provide a better foundation for the status and trend of weasel and stoat. The available data is too minimal. In order to get a better understanding of current status and population trends largescale, long-term monitoring studies with camera-trap boxes are recommended.