Abstract
In spite of their potential important role in shaping small mammal population dynamics, weasel (Mustela nivalis) and stoat (Mustela erminea) are understudied due to the difficulty of detecting these species. Furthermore, their conservation status in many countries is unknown due to lack of monitoring techniques. There is thus an important need for a method to detect these small mustelids. In this study, we tested the efficiency of a recently developed camera trapping device, the Mostela, as a new technique to detect mustelids in a study area near Dieren, the Netherlands. We placed Mostelas in linear landscape features, and other microhabitats thought to be frequently visited by weasels, from March to October 2017 and February to October 2018. We tested for yearly and monthly differences in site use and detectability, as well as the effect of entrance tube size, using an occupancy modelling framework. We found large seasonal differences in site use and detectability of weasels with the highest site use in June to October and highest detection probability in August and September. Detection probability was approximately two times higher for Mostelas with a 10-cm entrance tube compared with 8-cm. Furthermore, we were able to estimate activity patterns based on the time of detection, identify the sex in most detections (69.5%), and distinguish several individuals. Concluding, the Mostela seems promising as a non-invasive monitoring tool to study the occurrence and ecology of small mustelids. Further development of individual recognition from images would enable using the Mostela for density estimates applying capture-recapture models.
Highlights
Small mustelids like weasel (Mustela nivalis) and stoat (M. erminea) play a complex role within natural systems as the most common specialist predators involved in rodentCommunicated by: Karol Zub Electronic supplementary material The online version of this article contains supplementary material, which is available to authorized users.Weasels and stoats are rarely seen and do not leave visible field signs (King and Edgar 1977; King and Powell 2010)
We identified six other small mammal species: common or field vole (Microtus agrestis or arvalis), wood mouse (Apodemus sylvaticus), bank vole (Myodes glareolus), harvest mouse (Micromys minutus), common shrew (Sorex araneus), and pygmy shrew (Sorex minutus)
We present a novel camera trapping device, the Mostela, developed to detect small mustelids, and tested it during two field seasons in a study site in the Netherlands to quantify its functioning as a monitoring tool
Summary
Live trapping has been used successfully in the past (e.g., King 1980; Zub et al 2008), but non-invasive methods are preferred, especially for long-term and large-scale monitoring, and with respect to animal welfare. Mamm Res. Snow tracking and tracking tunnels have been extensively used to monitor small mustelids (e.g., Graham 2002; Korpela et al 2014), but these methods suffer from the fact that it is often difficult to distinguish tracks from male weasels and female stoats, which overlap in footprint size (King and Powell 2010). In contrast to live trapping or genetics-based methods, the use of cameras to monitor terrestrial small mammals can be more cost-effective (Bondi et al 2010)
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