Morten Elmeros

Concentrations of anticoagulant rodenticides in stoats Mustela erminea and weasels Mustela nivalis from Denmark.

Anticoagulant rodenticides are widely used to control rodent populations but they also pose a risk of secondary poisoning in non-target predators. Studies on anticoagulant rodenticide exposure of non-target species have mainly reported on frequency of occurrence. They have rarely analyzed variations in residue concentrations. We examine the occurrence and concentrations of five anticoagulant rodenticides in liver tissue from 61 stoats (Mustela erminea) and 69 weasels (Mustela nivalis) from Denmark. Anticoagulant rodenticides were detected in 97% of stoats and 95% of weasels. 79% of the animals had detectable levels of more than one substance. Difenacoum had the highest prevalence (82% in stoats and 88% in weasels) but bromadiolone was detected in the highest concentrations in both stoat (1.290 μg/g ww) and weasel (1.610 μg/g ww). Anticoagulant rodenticide concentrations were highest during autumn and winter and varied with sampling method. Anticoagulant rodenticide concentrations were higher in stoats and weasels with unknown cause of death than in specimens killed by physical trauma. There was a negative correlation between anticoagulant rodenticide concentrations and body condition. Our results suggest that chemical rodent control in Denmark results in an extensive exposure of non-target species and may adversely affect the fitness of some stoats and weasels.

Revisiting the phylogeography and demography of European badgers (Meles meles) based on broad sampling, multiple markers and simulations

Although the phylogeography of European mammals has been extensively investigated since the 1990s, many studies were limited in terms of sampling distribution, the number of molecular markers used and the analytical techniques employed, frequently leading to incomplete postglacial recolonisation scenarios. The broad-scale genetic structure of the European badger (Meles meles) is of interest as it may result from historic restriction to glacial refugia and/or recent anthropogenic impact. However, previous studies were based mostly on samples from western Europe, making it difficult to draw robust conclusions about the location of refugia, patterns of postglacial expansion and recent demography. In the present study, continent-wide sampling and analyses with multiple markers provided evidence for two glacial refugia (Iberia and southeast Europe) that contributed to the genetic variation observed in badgers in Europe today. Approximate Bayesian computation provided support for a colonisation of Scandinavia from both Iberian and southeastern refugia. In the whole of Europe, we observed a decline in genetic diversity with increasing latitude, suggesting that the reduced diversity in the peripheral populations resulted from a postglacial expansion processes. Although MSVAR v.1.3 also provided evidence for recent genetic bottlenecks in some of these peripheral populations, the simulations performed to estimate the method’s power to correctly infer the past demography of our empirical populations suggested that the timing and severity of bottlenecks could not be established with certainty. We urge caution against trying to relate demographic declines inferred using MSVAR with particular historic or climatological events.

Food habits of stoatsMustela erminea and weaselsMustela nivalis in Denmark

StoatsMustela erminea Linnaeus, 1758 and weaselsMustela nivalis Linnaeus, 1766 exploit the same array of prey species at different frequencies according to body size. The rabbitOryctolagus cuniculus, which typically is the dominant prey for stoats in temperate parts of Europe, is absent in Denmark. The present study based on gastrointestinal tract contents examines the food habits of sympatric stoats (n=112) and weasels (n=132) from Denmark. Rodents were the most important prey group for both stoats and weasels, constituting 77% and 84% of their diet respectively, expressed as frequency of occurrence. No differences were detected in the proportions of major prey groups between sexes within species, but between species the diets differed. Stoats ate birds and birds’ eggs more often than weasels did, while weasels ate more insectivores. Stoats ate more oftenMicrotus voles and water voleArvicola terrestris than weasels did, while weasels ate more bank voleClethrionomys glareolus and moleTalpa europaea. There was a larger dietary overlap between sympatric stoats and weasels in Denmark than in other dietary studies in areas where rabbits were available.

Effectiveness of odour repellents on red deer (Cervus elaphus) and roe deer (Capreolus capreolus): a field test

Chemical repellents are promoted as a method to reduce ungulate–vehicle collisions and ungulate browsing damages to agricultural and forestry resources. We tested the effectiveness of two odour repellents (Mota FL and Wolf Urine) on the foraging behaviour and area avoidance of free-ranging roe deer (Capreolus capreolus) and red deer (Cervus elaphus). The effects of the repellents were assessed by comparing deer visitation rates to sand arenas before and after application of repellents and visitation rates to control arenas. Neither of the tested products reduced deer visitation rates. Rapid habituation to olfactory stimuli and lack of sensitivity to predator odours may explain the ineffectiveness of the repellents to alter the behaviour of the deer. The results indicate that the tested products have no effects on roe deer and red deer behaviour and suggest that the effectiveness of the chemical area repellents as a measure to reduce deer–vehicle collision risk and browsing damages is questionable.

Homogenous Population Genetic Structure of the Non-Native Raccoon Dog (Nyctereutes procyonoides) in Europe as a Result of Rapid Population Expansion

The extent of gene flow during the range expansion of non-native species influences the amount of genetic diversity retained in expanding populations. Here, we analyse the population genetic structure of the raccoon dog (Nyctereutes procyonoides) in north-eastern and central Europe. This invasive species is of management concern because it is highly susceptible to fox rabies and an important secondary host of the virus. We hypothesized that the large number of introduced animals and the species’ dispersal capabilities led to high population connectivity and maintenance of genetic diversity throughout the invaded range. We genotyped 332 tissue samples from seven European countries using 16 microsatellite loci. Different algorithms identified three genetic clusters corresponding to Finland, Denmark and a large ‘central’ population that reached from introduction areas in western Russia to northern Germany. Cluster assignments provided evidence of long-distance dispersal. The results of an Approximate Bayesian Computation analysis supported a scenario of equal effective population sizes among different pre-defined populations in the large central cluster. Our results are in line with strong gene flow and secondary admixture between neighbouring demes leading to reduced genetic structuring, probably a result of its fairly rapid population expansion after introduction. The results presented here are remarkable in the sense that we identified a homogenous genetic cluster inhabiting an area stretching over more than 1500km. They are also relevant for disease management, as in the event of a significant rabies outbreak, there is a great risk of a rapid virus spread among raccoon dog populations.

Microsatellite markers for genetic studies in the weasel (Mustela nivalis)

This study reports the first set of microsatellite markers for the weasel (Mustela nivalis). We chose to isolate loci with tetranucleotide repeat motifs because they can be scored less ambiguously than the more commonly used dinucleotide loci. All 11 loci showed considerable variation within a population sample of 28 individuals from Portugal, with number of alleles ranging from four to nine per locus and observed and expected heterozygosities ranging from 0.21 to 0.86 and from 0.40 to 0.84, respectively. No linkage disequilibrium was detected between pairs of loci, and only one locus (Mn 1.30) deviated from Hardy–Weinberg equilibrium expectations in the analyzed population sample. Among the 11 loci, Mn 1.30 was the only one for which all known males were homozygous. Analysis of an additional population sample of 23 individuals (14 males and 9 females) from Denmark revealed that all males, but only four females, were homozygous for Mn 1.30, supporting the idea that the locus is X-linked. These novel polymorphic microsatellite markers should be useful in studies of population genetics and molecular ecology of the weasel.

Prevalence of embedded shotgun pellets in protected and in legally hunted medium-sized carnivores in Denmark

Illegal killings of protected species may significantly affect their population status or lower recovery rates after protection. Poaching is difficult to monitor directly, hence indirect methods are required to document poaching incidences and levels. The use of shotguns inevitably results in wounding some animals that are not killed. Inefficient hunting methods may result in high annual infliction rates in game species. To reduce wounding of game species, an action plan was implemented in Denmark. Using X-ray analysis, we monitor trends in prevalence of embedded shotgun pellets in the legally hunted red fox (Vulpes vulpes) after the implementation of the action plan, and assess poaching levels of two protected species, the otter (Lutra lutra) and the badger (Meles meles) in Denmark. Overall, 13.8% of the red foxes and 6.9% of the otters carried embedded shotgun pellets, while none were recorded in badgers. The prevalence of embedded shotgun pellets in red foxes declined from 24.9% to 8.5% from the late 1990s to the late 2000s, while no change was recorded in otters. Prevalence of embedded shotgun pellets was similar in otters and red foxes collected in the late 2000s. The decline in wounded red foxes suggests that the hunting methods have changed after the action plan was implemented in Denmark. The high proportion of otters carrying embedded shotgun pellets shows that there is a significant poaching of this protected species in Denmark, possibly by hunters and fish farmers that cannot distinguish between otter and non-native American mink (Neovison vison).

A PCR-RFLP-based method to distinguish sable ( Martes zibellina ) and pine marten ( Martes martes )

Species identification is an important issue in conservation and a particular focus for wildlife forensics. Molecular biological methods retain a unique power to differentiate between difficult samples that lack other identifiable characteristics. The pine marten (Martes martes) and sable (Martes zibellina) are closely related species with very similar pelage characteristics and are often difficult to distinguish from each other. The sable, however, in contrast to the pine marten, remains an endangered and protected animal in China with both hunting and fur trade strictly prohibited for this species. Here, we present a polymerase chain reaction-based restriction fragment length polymorphism method for distinguishing the two species. We sequenced a 638-bp fragment of cytochrome b gene in 39 sables, 68 pine martens, and 10 stone martens and identified all variable nucleotides. A new primer pair was subsequently designed to amplify a 316-bp fragment containing restriction sites of enzyme BseG I and BamH I that are different among martens. When the fragment was cut using BseG I, the resulting restriction pattern was identical in the sable and pine marten, but differed from all other martens. When cut using BamH I, the fragment generated two diagnostic fragments in the sable which could distinguish them from pine martens. This method was valid for all haplotypes of sable and pine marten thus far identified and has high potentially applicability for the identification of the two species.

Distribution and molecular phylogeny of biliary trematodes (Opisthorchiidae) infecting native Lutra lutra and alien Neovison vison across Europe

The recent identification of Pseudamphistomum truncatum, (Rudolphi, 1819) (Trematoda: Opisthorchiidae) and Metorchis bilis (Braun, 1790) Odening, 1962 (synonymous with Metorchis albidus (Braun, 1893) Loos, 1899 and Metorchis crassiusculus (Rudolphi, 1809) Looss, 1899 (Trematoda: Opisthorchiidae)) in otters from Britain caused concern because of associated biliary damage, coupled with speculation over their alien status. Here, we investigate the presence, intensity and phylogeny of these trematodes in mustelids (principally otters) across Europe (Czech Republic, Denmark, France, Germany, Norway, Poland and Sweden and Britain). The trematodes were identified to species using the internal transcribed spacer II (ITS2) locus. Both parasites were found across Europe but at unequal frequency. In the German state of Saxony, eight out of eleven (73%) otters examined were infected with P. truncatum whilst this parasite was not found in either mink from Scotland (n=40) or otters from Norway (n=21). Differences in the phylogenies between the two species suggest divergent demographic histories possibly reflecting contrasting host diet or competitive exclusion, with M. bilis exhibiting greater mitochondrial diversity than P. truncatum. Shared haplotypes within the ranges of both parasite species probably reflect relatively unrestricted movements (both natural and anthropogenic) of intermediate and definitive hosts across Europe.

Modeling Exposure of Mammalian Predators to Anticoagulant Rodenticides

Anticoagulant rodenticides (AR) are a widespread and effective method of rodent control but there is concern about the impact these may have on non-target organisms, in particular secondary poisoning of rodent predators. Incidence and concentration of AR in free-living predators in Denmark is very high. We postulate that this is caused by widespread exposure due to widespread use of AR in Denmark in and around buildings. To investigate this theory a spatio-temporal model of AR use and mammalian predator distribution was created. This model was supported by data from an experimental study of mice as vectors of AR, and was used to evaluate likely impacts of restrictions imposed on AR use in Denmark banning the use of rodenticides for plant protection in woodlands and tree-crops. The model uses input based on frequencies and timings of baiting for rodent control for urban, rural and woodland locations and creates an exposure map based on spatio-temporal modelling of movement of mice-vectored AR (based on Apodemus flavicollis). Simulated predator territories are super-imposed over this exposure map to create an exposure index. Predictions from the model concur with field studies of AR prevalence both before and after the change in AR use. In most cases incidence of exposure to AR is predicted to be greater than 90%, although cessation of use in woodlots and Christmas tree plantations should reduce mean exposure concentrations. Model results suggest that the driver of high AR incidence in non-target small mammal predators is likely to be the pattern of use and not the distance AR is vectored. Reducing baiting frequency by 75% had different effects depending on the landscape simulated, but having a maximum of 12% reduction in exposure incidence, and in one landscape a maximum reduction of <2%. We discuss sources of uncertainty in the model and directions for future development of predictive models for environmental impact assessment of rodenticides. The majority of model assumptions and uncertainties err on the side of reducing the exposure index, hence we believe the predictions to be robust and to indicate that the scale of the problem may be large.