mefupa's Journal

Species identification of the two sympatric Central European Water Shrews Neomys fodiens and N. milleri based on external features is tricky due to a relatively high variability of the traditionally used features (e.g., hair fringe on the hind feet and the tail), which in addition are often not readily visible on camera trap footage. For the Italian populations of these two species, it has relatively recently been suggested that the shape of the facial line of demarcation (line between the dark fur on the dorsal side and the lighter fur on the ventral side) can be used as an additional feature for species identification. In the current study, we evaluated this feature also in populations North of the Alps, focusing on Switzerland and – on a smaller scale – other parts of Europe. The examined, in part genetically identified specimens confirm that the facial line of demarcation shows a characteristic and mostly well discernible dichotomy between N. fodiens and N. milleri: in most of the examined N. milleri the dark facial mask involves the corners of the mouth and/or other parts of the mouth. In N. fodiens, however, there is usually an evenly spaced and relatively broad line of light fur between the mouth and the line of demarcation. This study corroborates that the shape of the facial line of demarcation is a helpful tool for the identification of these two Neomys-species and that this feature can be particularly relevant for studies using non-invasive monitoring methods such as camera traps.

Full publication (open access: http://www.italian-journal-of-mammalogy.it/Evaluation-of-a-facial-feature-to-distinguish-two-sympatric-Water-Shrew-species,176139,0,2.html

Cite as: Geiger, M., & Vinciguerra, L. (2023). Evaluation of a facial feature to distinguish two sympatric Water Shrew species. Hystrix, the Italian Journal of Mammalogy.

The monitoring of small mammals has been greatly facilitated by the recently developed
camera trap-boxes (e.g., McCleery et al. 2014, Soinien et al. 2015, Aegerter 2019, Croose &
Carter 2019, Mos & Hofmeester 2020, Littlewood et al. 2021).

For a research project at the Natural History Museum St.Gallen, in the course of which the
altitudinal distribution of various small mammals and invertebrates in north-eastern Switzer-
land is being monitored, a novel camera trap-box was developed and optimised for usage in
mountainous areas based on previous designs. Important for the development of this new
“MiniMammalCamBox” was that (1) it is kept as light and robust as possible; (2) it records as
many diagnostic features of the photographed animal as possible; and (3) the resulting photo-
graphs appear as close to reality as possible, so that they can also be used for other purposes
(e.g. illustrations, museum exhibitions).

The MiniMammalCamBox is based on commercially available, inexpensive plastic-boxes mea-
suring 30 cm x 40 cm x 17 cm. A camera trap (Reconyx HP2X S) was fixed to the inside of one
wall and a large opening was cut into the opposite wall (Figure 6). A scale can be mounted
above the opening for size comparisons. Camouflage painting was applied to protect against
theft (Figure 7). Additional side walls in the corners to the left and right of the camera trap also
prevent small mammals triggering the trap without being imaged (Figure 13). Several Mini-
MammalCamBoxes in different stages of development have been used in different test runs,
including the aforementioned research project, and the first results are promising (e.g., Figures
14, 15, and 17) .

Full report in German: https://naturinfo.ch/wp-content/uploads/2023/02/Naturinfo-Methodenreport_MiniMammalCamBox.pdf