Site and landscape features ruling the habitat use and occupancy of the polecat (Mustela putorius) in a low density area: a multiscale approach

Spatial and temporal trends in western polecat road mortality in Wales

Roads have considerable ecological effects that threaten the survival of some species, including many terrestrial carnivores. The western polecat is a small-medium sized mustelid native to Asia and Europe, including Britain where its historical stronghold is in Wales. Polecats are frequently killed on roads and road casualties represent the most common source of data on the species in the UK. However, little is known about the factors that increase the risk of collision. We used Generalized Additive Models to explore seasonal patterns in collisions as well as using Principal Component Analysis and regression modelling to identify landscape characteristics associated with polecat road casualties in Wales. Polecat road casualties had a bimodal distribution, occurring most frequently in March and October. Casualties were more frequently associated with road density, traffic volume, presence of rabbits, habitat patchiness and the abundance of proximal improved grassland habitat. Casualties were negatively associated with elevation and the abundance of semi-natural grassland habitat. The results of this study provide a framework for understanding and mitigating the impacts of roads on polecats in their historic stronghold, hence has considerable value to polecat conservation as well as broader applicability to ecologically similar species.

Does the American mink displace the European polecat? A need for more research on interspecific competition between invasive and native species

Introduced alien species can negatively affect native competitors by reducing their populations or eliminating them from ecosystems. However, studies do not always find evidence for anticipated impacts, and changes in native populations can be difficult to estimate. Interactions between the invasive American mink Neovison vison and native European polecat Mustela putorius have been studied in several countries, but the mink’s impact on polecat populations at a large spatiotemporal scale remains unclear. In the years 1995–2018, we live-trapped mink and polecats at 60 study sites in Poland, and we analysed hunting bags of mink and polecats from the years 2009–2018. During 13,766 trap-nights, we captured 905 individuals. Mink comprised 91.2% and polecats 8.8% of trapped animals. The mean mink and polecat trappability was 6 and 0.6 individuals per 100 trap-nights, respectively. At rivers, polecat and mink trappability were negatively correlated, whereas at lakes, they were not correlated. The sex ratio of trapped polecats was more skewed toward males than that of mink. Mink comprised 63.6% and polecats 36.4% of 59,831 animals killed by hunters. Over 10 years, the numbers of mink shot annually increased slightly, whereas the numbers of polecat decreased slightly. There was a positive correlation between numbers of mink and polecats shot annually. We found weak evidence that at a large spatiotemporal scale, the invasion of mink has led to a decline in polecat numbers. Although the datasets we analysed were based on large samples, they were insufficient to show evidence of competitive interactions between these two mustelids.

Helminths of Mustelids with Overlapping Ecological Niches: Eurasian Otter Lutra Lutra (Linnaeus, 1758), American Mink Neovison Vison Schreber, 1777, and European Polecat Mustela Putorius Linnaeus, 1758

This study presents the helminthological data on three mustelid species with overlapping ecological niches in Lithuania. In general, 14 helminth species or higher taxa were reported from all mustelids: Isthmiophora melis, Strigea strigis metacercariae, Pseudamphistomum truncatum, Alaria alata mesocercariae, Phyllodistomum folium, Opisthorchis felineus, Metametorchis skrjabini, Mesocestoides sp., Taenia martis, Aonchotheca putorii, Crenosoma schachmatovae, Eucoleus aerophilus, Molineus patens, and Nematoda g. sp. The largest number of helminths was detected in M. putorius (11) and N. vison (10) from wetlands; 7 helminths were detected in M. putorius from forests, and 8 in N. vison and 4 in L. lutra from water bodies. Habitat-related differences were found in the abundance and prevalence of E. aerophilus in M. putorius. M. putorius has higher indices of infection by I. melis, S. strigis metacercariae, and E. aerophilus compared to N. vison in wetlands. Differences in the abundance and prevalence of P. truncatum among N. vison and L. lutra in water bodies have been observed. Helminths detected in N. vison in the present study are native European parasites.

A review of the status of the Western polecat Mustela putorius: a neglected and declining species?

The Western polecat Mustela putorius has a widespread European distribution and is currently listed as Least Concern by the IUCN Red List of Threatened Species. Reports are increasing of polecat population declines in several countries, although a paucity of data means population trends are poorly understood. This paper reviews and summarises information on the polecat’s status and range-wide population trends. Information and opinion were gathered for 34 countries, from individuals and organisations studying polecats and from reviewing the literature and national Red Lists. Where trends were identified, the polecat population is known or suspected to be declining in 20 countries, reported to be stable in five countries, stable or increasing in one country, and increasing in two countries. For many countries, data are so limited in quantity or spatial scale, or at risk of bias, that trends could not be identified or confidence in trend assessments is low. The main drivers of polecat decline are poorly understood, but might include habitat degradation; changes in prey availability; competition with invasive carnivores; poisoning; conflict with human interests; harvesting and killing of polecats; and hybridisation. Robust survey methods and systematic monitoring programmes are urgently needed to gather up-to-date data on polecat population trends across the species’ range.

Garbage in the diet of carnivores in an agricultural area

Human food waste is considered to be richer in carbohydrates, lipids and proteins than most natural food supplies; however, it is very well digested in scats. So, as an indication of this kind of food in the diet, we have used each indigestible, anthropogenic origin element found in faeces (e.g., glass, plastic, rubber, etc.). There are few studies discussing the importance of garbage in the diet of mammalian predators living in farmland; definitely, most focus on this issue in urban areas. We studied the contribution of garbage in the diet of raccoon dog (Nyctereutes procyonoides), red fox (Vulpes vulpes), marten (Martessp.), polecat (Mustela putorius), stoat (Mustela erminea), American mink (Neovison vison) and Eurasian otter (Lutra lutra) in the agricultural areas of western Poland in 2006-2010. In addition, we examined the spatial changes in the diet of red fox and polecat. The largest contribution of garbage was found in scats of raccoon dog (8.8%), red fox (4.8%) and marten (4.3%). The diet of polecat, stoat and Eurasian otter contained 2.5%, 1.7% and 0.2% garbage items respectively. The most frequent item was plastic. Our analysis showed that garbage consumption by red fox and polecat was greater closer to human settlements. The results reveal a continuous gradient in the garbage consumption that corresponds with the degree of synanthropization of particular species.

Silvicolous on a small scale: possibilities and limitations of habitat suitability models for small, elusive mammals in conservation management and landscape planning

Species distribution and endangerment can be assessed by habitat-suitability modelling. This study addresses methodical aspects of habitat suitability modelling and includes an application example in actual species conservation and landscape planning. Models using species presence-absence data are preferable to presence-only models. In contrast to species presence data, absences are rarely recorded. Therefore, many studies generate pseudo-absence data for modelling. However, in this study model quality was higher with null samples collected in the field. Next to species data the choice of landscape data is crucial for suitability modelling. Landscape data with high resolution and ecological relevance for the study species improve model reliability and quality for small elusive mammals like Muscardinus avellanarius. For large scale assessment of species distribution, models with low-detailed data are sufficient. For regional site-specific conservation issues like a conflict-free site for new wind turbines, high-detailed regional models are needed. Even though the overlap with optimally suitable habitat for M. avellanarius was low, the installation of wind plants can pose a threat due to habitat loss and fragmentation. To conclude, modellers should clearly state the purpose of their models and choose the according level of detail for species and environmental data.

Seasonal blowfly distribution and abundance in fragmented landscapes. Is it useful in forensic inference about where a corpse has been decaying?

Blowflies are insects of forensic interest as they may indicate characteristics of the environment where a body has been laying prior to the discovery. In order to estimate changes in community related to landscape and to assess if blowfly species can be used as indicators of the landscape where a corpse has been decaying, we studied the blowfly community and how it is affected by landscape in a 7,000 km2 region during a whole year. Using baited traps deployed monthly we collected 28,507 individuals of 10 calliphorid species, 7 of them well represented and distributed in the study area. Multiple Analysis of Variance found changes in abundance between seasons in the 7 analyzed species, and changes related to land use in 4 of them (Calliphora vomitoria, Lucilia ampullacea, L. caesar and L. illustris). Generalised Linear Model analyses of abundance of these species compared with landscape descriptors at different scales found only a clear significant relationship between summer abundance of C. vomitoria and distance to urban areas and degree of urbanisation. This relationship explained more deviance when considering the landscape composition at larger geographical scales (up to 2,500 m around sampling site). For the other species, no clear relationship between land uses and abundance was found, and therefore observed changes in their abundance patterns could be the result of other variables, probably small changes in temperature. Our results suggest that blowfly community composition cannot be used to infer in what kind of landscape a corpse has decayed, at least in highly fragmented habitats, the only exception being the summer abundance of C. vomitoria.