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Piżmak Ondatra zibethicus (L. 1766), jest gatunkiem introdukowanym w Europie. Jest rozpowszechniony w całej Polsce, jednak w ostatnich dziesięcioleciach zaobserwowano załamanie jego liczebności. Większość dotychczasowych informacji o występowaniu gatunku opartych było o sprawozdania o stanie zwierzyny Polskiego Związku Łowieckiego. W niniejszej pracy prezentowane są wyniki prac terenowych, w których poszukiwano śladów obecności piżmaka na 1554 stanowiskach badawczych w centralnej i wschodniej Polsce. Ślady obecności piżmaków stwierdzono w 19.5% spośród 1111 stanowisk przebadanych w 1996-1998, i w 5.3% spośród 413 stanowisk przebadanych w 2007 r. Większość stwierdzeń piżmaków znajdowała się w zachodniej części terenu badań. Spadek liczebności gatunku odzwierciedlony jest w istotnym zmniejszeniu się częstości stwierdzeń piżmaków z 44% w 1996-1998 do 7% w 2007 r. na 249 stanowiskach badanych w obu okresach. Spadek liczebności piżmaka spowodowany jest przypuszczalnie drapieżnictwem norki amerykańskiej Neovison vison.

Crosses between different mink lines from 3 Danish mink farms that use different breeding strategies were studied to estimate heterosis and variance components for litter size. The study was designed to analyze crosses between lines of the same color type, between different color types, and between animals originating from different farms. Effect of heterosis, color type, and variance components were estimated using Average information REML (AI-REML) algorithm implemented in the DMU package for analyzing multivariate mixed models. Females from 7 generations that gave birth to at least 1 offspring were analyzed and the effects of parity and production year were included in the analyses. Genetic trend and the proportions of the total variance explained by the effects of additive genetics (h2), common environment (due to repeated litters from the same female; c2), and dam of the female (granddame of the bom litter; d2) were estimated. The results showed that mink of the Black color type potentially produced smaller litters compared to mink of the other studied color types. We found significant general maternal effect of heterosis for litter size. Analyses of specific heterosis showed a significant positive effect of crossing between lines of the same color type. Estimates of variance components revealed h2 levels for farm A, B, and C of 0.15, 0.06, and 0.09, respectively; thus litter size could be selected for in the future. The effect of common environment on litter size was also considerable, with c2 values of 0.005, 0.11, and 0.15 at farms A, B, and C, respectively. In conclusion, we recommend genetic selection as a means of increasing litter size in farmed mink. [ABSTRACT FROM AUTHOR]

A population-genetic comparison between mink populations with tame and aggressive behavior was performed. Six allotypes of the Lpm system, the AIM alpha macroglobulin, and two allotypes of the Ld system, a homologue of APOB low-density lipoprotein, were analyzed. The pairwise compared groups differed in markers Lpml, Lpm3, Lpm5, and Lpm10. Alleles with allotypes Lpml and Lpm3 were significantly associated with aggressive behavior, whereas allele Lpm non-10 was associated tame behavior. No statistically significant differences in the frequencies of Ldl and Ld2 allotypes of the Ld low-density lipoprotein system have been found. [ABSTRACT FROM AUTHOR]

People who have a stake in their environment are more likely to volunteer to assist conservation but they must be empowered to do so. This study explored the possibility of harnessing volunteers in the control of an invasive predator, the American mink Neovison vison, which decimates seabird colonies in coastal west Scotland. A questionnaire was sent to ecotourism boat operators, a group assumed to have an economic interest in wildlife biodiversity and a stake in their environment, to gauge their opinion on lethal control of American mink. The majority (64%) of respondents were concerned about the presence of mink in their area, agreed with control in principle and were willing to become involved in a volunteer capacity. Respondents who would not volunteer but agreed with control (21%) might reconsider if mink had a visible impact on their local wildlife. The minimum level of support people expected was information on where to get, and how to deploy, monitoring and trapping equipment. This study confirms that people with an intrinsic interest in wildlife consider themselves willing to protect their local biodiversity, with only limited resource input, such as an information pack, from external sources. [ABSTRACT FROM AUTHOR]

This study aimed at answering the question whether production of new colour variants of American mink in mink farms using mutations may entail changes in skull morphology and relationships between the bone elements building it. Analyses were made on the skulls of 56 eight-month-old males and females of two American mink colour variants (standard Brown and mutant Sapphire) from the same farm. Mean values, standard deviations and coefficients of variation were determined for carcass weight, cranial and mandibular weights and 7 dorsal surface, 8 lateral surface and 11 basal surface traits of the skull. The values of 24 cranial and mandibular indices and the values of sexual size dimorphism (SSD), i.e. a coefficient describing differences between sexes, were calculated. It was demonstrated that mutant colour variants of American mink may be a significant source of variation (P≤0.05 and P≤0.01) for some traits of skull morphology and relationships between respective bone elements of viscerocranium and neurocranium. [ABSTRACT FROM AUTHOR]

Infectious diseases, in particular canine distemper virus (CDV), are an important threat to the viability of wild carnivore populations. CDV is thought to be transmitted by direct contact between individuals; therefore, the study of species interactions plays a pivotal role in understanding CDV transmission dynamics. However, CDV often appears to move between populations that are ecologically isolated, possibly through bridge hosts that interact with both species. This study investigated how an introduced species could alter multihost interactions and act as a bridge host in a novel carnivore assemblage of domestic dogs ( Canis familiaris), invasive American mink ( Neovison vison), and threatened river otters ( Lontra provocax) in southern Chile. We found that rural dogs interact with mink near farms whereas in riparian habitats, minks and river otters shared the same latrines with both species visiting sites frequently within time intervals well within CDV environmental persistence. No interactions were observed between dogs and otters at either location. Both dog and mink populations were serologically positive for CDV, making the pathogen transfer risk to otters a conservation concern. Altogether, introduced mink in this ecosystem have the potential to act as bridge hosts between domestic dogs and endangered carnivores. [ABSTRACT FROM AUTHOR]

Understanding changes over time in the distribution of interacting native and invasive species that may be symptomatic of competitive exclusion is critical to identify the need for and effectiveness of management interventions. Occupancy models greatly increase the robustness of inference that can be made from presence/absence data when species are imperfectly detected, and recent novel developments allow for the quantification of the strength of interaction between pairs of species. We used a two-species multi-season occupancy model to quantify the impact of the invasive American mink on the native European mink in Spain through the analysis of their co-occurrence pattern over twelve years (2000-2011) in the entire Spanish range of European mink distribution, where both species were detected by live trapping but American mink were culled. We detected a negative temporal trend in the rate of occupancy of European mink and a simultaneous positive trend in the occupancy of American mink. The species co-occurred less often than expected and the native mink was more likely to become extinct from sites occupied by the invasive species. Removal of American mink resulted in a high probability of local extinction where it co-occurred with the endemic mink, but the overall increase in the probability of occupancy over the last decade indicates that the ongoing management is failing to halt its spread. More intensive culling effort where both species co-exist as well as in adjacent areas where the invasive American mink is found at high densities is required in order to stop the decline of European mink. [ABSTRACT FROM AUTHOR]

Variations in the contaminant burden in feral and ranch mink, resulting from differences in their diet, may permit the identification of farm escapees. However, this is only possible in the case of contaminants that accumulate to significantly different levels in the two groups of animals. The main objective of this study was to identify chemical markers whose concentrations differ between feral and ranch mink, by analyzing the accumulation of 13 chemical elements in liver and kidney samples. Total mercury levels were up to 15-fold higher in kidney, and up to 7-fold higher in liver of feral mink compared with ranch mink. The majority of feral mink samples analyzed for mercury, contained concentrations that ranged from 1 to 5 μg/g in kidney (68 %) and from 1 to 5 μg/g in liver (70 %). In comparison, the organs of ranch mink had significantly lower levels of mercury: 95 % of kidney samples had concentrations below 1 μg/g and 82 % of liver samples had concentrations below 1 μg/g. Small geographical variations in Hg levels were observed in mink from the four studied feral populations. Significant differences in Cu concentrations between ranch and feral mink were also detected, with low variation within the two groups. Less pronounced differences were recorded for other chemical elements. These data suggest that Hg and Cu may be used as chemical markers for the identification of first generation mink farm escapees. [ABSTRACT FROM AUTHOR]

• The mink's dietary composition showed great similarities across study sites. • The basic diet consisted of rodents, amphibians, and fish. • The presence of crayfish in the samples was dependent mostly on insects. • The percentage of crayfish in scats was correlated with crayfish density. • Crayfish density calculations based on mink's diets may differ during droughts. Invasive animal species pose a significant threat to native biocenoses. For the management of invasive species, it is important to know their distribution. We aimed to investigate the potential use of American mink (Neovison vison) scats as a bioindicator of the presence and density of invasive crayfish Faxonius (Orconectes) limosus (Rafinesque, 1817) in the watercourses. The structure and seasonal dynamics of the mink's diet were studied in western Belarus. The dietary composition of the American mink showed great similarities across different types of watercourses (rivers and drainage channels). The basic diet consisted of rodents, amphibians, and fish. The crayfish's presence in the samples during the warm season was negatively dependent on all the other main prey groups, but mostly on aquatic insects. During the cold season the relations were weaker, and crayfish was negatively associated mostly with birds in the samples. The percentage of crayfish in scats collected during the warm season was correlated with crayfish density, which indicated that with higher crayfish densities, the mink more often used this type of prey. However, the regression model was only a moderate fit. Droppings collected during both seasons can indicate the presence of crayfish in the environment. We conclude that the American mink's diet can be a good indicator of invasive crayfish presence and their density in the environment. However, estimating crayfish density based on the mink's diet may deviate from the trend during years of low water level, therefore, it is necessary to first assess precipitation during the season. [ABSTRACT FROM AUTHOR]

The aim of this study was to determine whether farming leads to changes in gastrointestinal function and nitrogen metabolism in farmed mink (FA), as compared with their wild-living counterparts. Three digestibility and balance trials were carried out. Experiment I was performed in May, and experiments II and III were conducted in September 2011. Farmed mink with the standard coat colour were purchased from a production farm in south-eastern Poland. Feral mink were harvested using cages in the hunting grounds of the Polish Hunting Association, Branch in Olsztyn. The experimental materials comprised of the following: trial I - adult males (eight animals per group), trial II - young females (six animals per group), trial III-young animals (five males and five females per group). Food transit time was measured during digestibility trials, on 10 consecutive days. The coefficients of nutrient and energy digestibility and daily nitrogen balance values were compared between groups in each experiment. It was found that farming contributed to changes in gastrointestinal function and nitrogen metabolism in mink. Farmed animals were characterized by a longer bowel transit time, a tendency towards higher nutrient digestibility and higher nitrogen retention, which resulted from selection for higher productivity. [ABSTRACT FROM AUTHOR]

The paper describes the phenomenon of substitution of the reduced M 2 with a tooth of a complex structure in the American mink Neovison vison Schreber. The anomaly is observed on three skulls out of the 574 examined (0.52%) and is characterized by a clear localization, identical structure, and symmetrical manifestation. Atypical molars have two roots, equally well-developed paraconid, eokonid, hypoconid, and a less pronounced metaconid. Some possible hypotheses for the anomaly that are considered include disruption in the development of the dental germ, mutation, and phenotypic expression of genes that are characteristic of plesiomorphic species of mustelids. The substantiated viewpoint is that the cause of this phenomenon may be the “awakening of dormant genes” as a result of destabilizing selection and hybrid dysgenesis in the area of contact of farm and feral American minks. [ABSTRACT FROM AUTHOR]

A spatial gradient in the interactions between American minks (Neovison vison) and muskrats (Ondatra zibethicus) occurs in the Hudson's Bay Company fur harvest returns of Canada. Evidence for strong dependence of minks on muskrats exists in northwestern Canada, whereas evidence for weaker interactions exists in central and eastern Canada. We tested the hypothesis that minks consume fewer muskrats and more alternative prey in some areas, using fur records from 56 Hudson's Bay posts. Both muskrats and small microtines were found to explain mink dynamics, with small microtines and other alternative prey gaining importance in the eastern portion of our study area. Mink fur returns exhibited a range of cycle lengths from 2.6 to 13 years encompassing typical small microtine periodicities of 3-5 years and typical muskrat periodicities of 8-13 years. A time lag of 0 years occurred between mink and muskrat harvest data frequently in the eastern portion of our study area, hypothesized to be a result of minks consuming alternative prey. To biologically verify small microtines as a potential prey source, we modeled mink and muskrat population dynamics assuming small microtines were an alternative prey by modifying the Turchin and Hanski (1997) model. Simulated mink and muskrat time series replicated observed periodicity and time-lag range, suggesting that minks can be generalist predators and consume alternative prey. Finally, we examined species richness and land cover as potential drivers of mink prey-switching, but were unable to find support for either hypothesis, suggesting that additional environmental-or competition-related interactions influence mink population dynamics. [ABSTRACT FROM AUTHOR]

Abstract: The mutation causing the Silverblue color type (pp) is one of the most used recessive mutations within American mink (Neovison vison) fur farming, since it is involved in some of the popular color types such as Violet and Saphire which originate from a combination of recessive mutations. In the present study, the genomic and mRNA sequences of the melanophilin (MLPH) gene were studied in Violet, Silverblue and wild-type (wt) mink animals. Although breeding schemes and previous literature indicates that the Violet (aammpp) phenotype is a triple recessive color type involving the same locus as the Silverblue (pp) color type, our findings indicate different genotypes at the MLPH locus. Upon comparison at genomic level, we identified two deletions of the entire intron 7 and of the 5′ end of intron 8 in the sequence of the Silverblue MLPH gene. When investigating the mRNA, the Silverblue animals completely lack exon 8, which encodes 65 residues, of which 47 define the Myosin Va (MYO5A) binding domain. This may cause the incorrect anchoring of the MLPH protein to MYO5A in Silverblue animals, resulting in an improper pigmentation as seen in diluted phenotypes. Additionally, in the MLPH mRNA of wt, Violet and Silverblue phenotypes, part of intron 8 is retained resulting in a truncated MLPH protein, which is 359 residues long in wt and Violet and 284 residues long in Silverblue. Subsequently, our findings point out that the missing actin-binding domain, in neither of the 3 analyzed phenotypes affects the transport of melanosomes or the consequent final pigmentation. Moreover, the loss of the major part of the MYO5A domain in the Silverblue MLPH protein seems to be the responsible for the dilute phenotype. Based on our genomic DNA data, genetic tests for selecting Silverblue and Violet carrier animals can be performed in American mink. [Copyright &y& Elsevier]

An experimental release of the European mink ( Mustela lutreola) was carried out in the Salburua wetland in North Spain between 2008 and 2010. A partial removal of feral American mink ( Neovison vison) was done preceding the release. The survival and the cause of death of each of 27 captive-bred minks were studied during five months after release. Only 22 % of the minks ( N = 6) survived during whole radio-tracking period. Predation was the most significant cause of mortality (76 %, N = 16). Seven European minks (33 % of mortality) were killed by another 'mink-size' carnivore-the causes of death of these individuals were of particular interest to clarify possible impact of a few remained American mink to released European mink. We used three criteria to identify the exact causes of death of these seven minks: 1. Comparison of the distances of bite marks with the inter-canine distances of small carnivores, 2. Site descriptions and signs of predators and 3. Density of carnivores within the study area. None of the criteria taken separately allowed the complete identification of the predator species. Summing up the results of all three criteria, a male American mink was found to be the most likely predator of at least six released European minks (29 % of overall mortality and 38 % of predated minks). Our results show that the presence of American mink, even if the number is estimated to be low, may seriously limit the success of reinforcement or reintroduction of the European mink. [ABSTRACT FROM AUTHOR]

The introduction of American mink ( Neovison vison; hereafter mink) into Europe has had severe impacts on many native wildlife species, including the water vole ( Arvicola amphibius) in mainland Britain. Although trapping has been widely used to attempt to control mink, managers have little direct evidence of its effect on mink density or distribution, particularly where immigration of mink from nearby areas is inevitable. Such evidence is needed to justify the use of lethal methods in conservation policy. During 2006-2010 we removed mink from the River Monnow Catchment in western Britain, using track-recording rafts to monitor continuously for mink presence, guiding a strategic trapping effort. The area monitored and trapped was increased in stages, from a core sub-catchment with 109 km of water-course in 2006, to a 421-km2 catchment with 203 km of water-course in 2009. In each successive sub-catchment, mink detection and capture rates declined rapidly to near-zero levels after trapping began. Detections and captures showed seasonal peaks in every year corresponding to known dispersal periods, but also declined steadily from year to year, with increasing periods in which we did not detect mink. These results suggested that each sub-catchment was cleared of mink within a few months, with subsequent captures attributable to immigration. On average, we detected each mink 5.1 times before capture (daily probability of detection = 0.059 per mink and raft), and trapped them 3.4 days after deploying traps in response. On average, mink entering the area were likely to have been present for less than 13 days before capture. Water voles had been extinct in the Monnow Catchment since the 1980s. During 2006-2008 (starting 6 months after mink trapping commenced), we released 700 captive-bred water voles into the treatment area to re-establish a wild population. Persistence of this population through the 4 years of the project was considered indicative of effective mink control. This study demonstrates that, even in a mainland context, a systematic trapping strategy can have a substantial impact on the density and distribution of a damaging species, in this case allowing the restoration of a native prey species. © 2013 The Wildlife Society [ABSTRACT FROM AUTHOR]

Abstract: Effects of sub-optimal housing on inactivity vary across species and experiments, probably because inactivity is heterogeneous, reflecting both positive states (e.g. relaxation) and negative ones (e.g. fear). We therefore aimed to identify specific subtypes of inactivity that could indicate poor welfare in mink, by comparing their behaviour in enriched and non-enriched conditions (the former having been previously demonstrated to be highly preferred by mink and to enhance their welfare). We assessed this in three groups of subjects, as well as after housing conditions were reversed for the last group. During live scans, inactive animals were scored for posture, location, and whether awake or apparently asleep. Data on temperament and physiological stress indicators were also collected for one group; these confirmed that non-enriched housing increased faecal cortisol metabolites (FCM; P =0.040). Non-enriched housing also increased locomotor stereotypy in females (sex×housing: P =0.004). Inactivity in the nest-box (vs. in the open cage) was higher among females in non-enriched housing (housing×sex: P <0.001), and increased by 20% of observations after enrichment removal (P =0.018) for both sexes. Furthermore, males with fearful temperaments spent the most time inactive in the nest-box (sex×temperament: P =0.054), while females whose FCM decreased most when given enrichment also showed the largest decreases in this behaviour (sex×FCM change: P =0.019). Together, this suggests that inactivity in the nest-box may reflect anxiety-induced hiding. Lying awake (i.e. prone with eyes open) was also higher in non-enriched housing (3.1% of observations vs. 1.7%; P =0.002); furthermore, this subtype of inactivity increased after enrichment removal (by 1.0% of observations; P =0.021), and decreased when non-enriched mink were given enrichment (by 2.4% of observations; P =0.004). This behaviour did not co-vary with fearfulness, however, nor with FCM (both P >0.05). This suggests that lying awake is not fear-related (e.g. not reflecting enhanced vigilance) but instead reflects some other negative state. Effects on inactivity subtypes as defined by posture were less consistent. For example, time spent lying belly down tended to decrease in mink moved from non-enriched to enriched cages (P =0.054), but enriched mink spent significantly less time belly down (in one of the three groups; P =0.002). Overall, two subtypes of inactivity, lying in the nest-box and lying awake seem likely to be valid indicators of housing-induced poor welfare in this species, being consistently increased by non-enriched cages. Lying in the nest-box may indicate fear or anxiety, and lying awake, a boredom-like state. [Copyright &y& Elsevier]

Knowledge about interactions between endangered native southern river otters ( Lontra provocax) and introduced American mink ( Neovison vison) is essential for effective management of both species. We evaluated competition for spatial and trophic niches between otter and mink in overlapping and non-overlapping areas, comparing distribution, habitat preference, diet and mink marking behavior. We surveyed otter and mink signs along 250 km of Beagle Channel coastline. Habitat suitability models were constructed based on species presence/absence and habitat characteristics, using generalized linear models. Feces were collected for diet analyses. Otters used forested coasts with 12°-32° shoreline slope and without human influence, and our evidence suggests they were not affected by mink presence. Mink preferred forested and shrubland coasts with 10°-28° shoreline slope. Neither human influence nor otter presence affected mink habitat occupation, but in the presence of otters, mink left fewer signs. Otters consumed more aquatic prey than mink, and mink modified their diet in the presence of otters, consuming more exotic small terrestrial mammals and less fish as well as shifting to smaller and shallower fish species that are less consumed by otters. Mink showed more plastic, generalist behavior than otters, being more tolerant of human presence, using more habitat types and having greater diet breadth. At the same time, otters apparently affect mink adversely and could help limit their invasion in sympatric areas. Conservation and recovery of otters, therefore, may produce a secondary benefit of simultaneously reducing the effect of mink, thereby providing an additional way to control this exotic predator's population. [ABSTRACT FROM AUTHOR]

The morphological variability of 367 skulls of the American mink from Tver, Pskov, and Novgorod oblasts (Caspian-Baltic watershed) are investigated using quantitative and qualitative traits. Out of the six investigated samplings, five represent feral populations and one represents ranch minks. It is shown that significant morphological differences between feral mink populations exist within a relatively small area (about 250 × 350 km). Differences in the phenotype are determined by different history of the populations and by the degree of affection of escaped ranch animals. The possible consequences of interactions between the feral and ranch mink populations, which may influence the phenotype, are discussed. The morphological differences observed between the feral mink populations are lower than those theoretically expected when taking into account the considerable influence of domesticated animals. Among the possible reasons of morphological stability of skulls of feral populations of the American mink, we specify naturalization of sizes of ranch escapees under pressure of environmental conditions, as well as possible elimination of the first-generation hybrids between feral and domesticated minks owing to outbreeding depression. [ABSTRACT FROM AUTHOR]

Abstract: Eradication of Aleutian disease was initiated in Denmark in 1976. The prevalence of positive farms has since then been reduced from 100% to only being continuously present in the region of Vendsyssel, Northern Denmark since 2004. In this study, we attempted to identify risk factors for the infection in this region based on logistic regression of spatial (environmental, neighbourhood) variables and biosecurity measures. Information on potential biosecurity (management) risk factors in the region was obtained from interviews in 342 registered farms in the region using a structured questionnaire. A total of 279 questionnaires were completed (response rate 82%). Additional spatial variables were included in the analysis. The study shows that farm size (the number of animals in the farm) and proportion of infected neighbouring farms were significant risk factors for infection with Aleutian Mink Disease Virus. These factors account for 35% of the variation of the infection status of mink farms located in Vendsyssel during 2009. These results indicate that only a coordinated effort from the farmers in the area will succeed in eradicating the disease from Denmark, because individual farms that have eradicated the disease will be at risk of re-infection from test-positive neighbours. [Copyright &y& Elsevier]

Regular counts from 2005 to 2009 were made of the waterbirds inhabiting lakes and ponds in Lanín National Park in the southwestern part of Neuquén Province, Argentina, a landscape dominated by Andean-Patagonian wetlands and forests. Bird surveys conducted on 21 wetland areas detected 8,311 individuals belonging to 27 species from 9 families. The most abundant and frequent species were Ashy-headed Goose ( Chloephaga poliocephala), Speckled Teal ( Anas flavirostris), Red-gartered Coot ( Fulica armillata) and White-winged Coot ( Fulica leucoptera). The presence and abundance of bird species with respect to wetland surface area was examined. Small lakes (<100 ha) had higher numbers of individuals, but some species such as the Neotropic Cormorant ( Phalacrocorax olivaceus), Great Grebe ( Podiceps major), Flying Steamer Duck ( Tachyeres patachonicus) and Spectacled Duck ( Anas specularis) were more abundant at larger lakes. Speckled Teal, Red Shoveler ( Anas platalea) and Chiloe Wigeon ( A. sibilatrix) were more common in small- and medium-sized lakes. Most waterbird species were found at a smaller percentage of the lakes where mink were present than at mink-free lakes. Although the ponds and lakes studied are protected within the network of this Argentine National Park, such protection is not implemented effectively. Hence, their future conservation faces several potential threats such as American mink expansion, tourism, fishing and hunting. This information could contribute to the development of management guidelines for the effective conservation of Patagonian wetlands. [ABSTRACT FROM AUTHOR]

Abstract: We studied the morphology of American mink Neovison vison in five out of the six introduced populations in Spain. The spatial and temporal variation of body weight (BW), body length (BL), tail length, hind-foot length and ear length were analysed. Temporal trends in BW and BL in relation to years since mink introduction were also analyzed. In addition, we tested the effect of sex, age (juvenile, subadult and adult) and age–sex interaction, on each parameter. Morphological parameters differed between populations, illustrating the high variability of body size of American mink in different environments, and the phenotypic plasticity of the species. Annual variations were synchronized between populations, suggesting a large-scale effect on all of them. BW and BL showed a decreasing trend in both males and females in relation to years since introduction. This decrease may be related to mink''s diet. Differences in sex and age were found, pointing to sexual dimorphism in adults, subadults and juveniles. The dimorphism in non-adult individuals suggests that subadult males may have a competitive advantage from subadult females in feeding and/or hunting on bigger prey from an early age (resource partitioning hypothesis). [Copyright &y& Elsevier]

The article discusses the decrease in litter size pf inactive female minks. The minks which are inactive with excess fat, chronic stress and health problems produce decreased litter size as compared to the minks which perform stereotypic behavior. The inactive minks are neither stressed nor ill, so to increase their productivity, it is better to alter their husbandry rather than focusing on decreasing their body weight.

American mink ( Neovison vison) are secretive, semi-aquatic carnivores that often require noninvasive methods based on field signs such as tracks and scat for determining their spatial distribution. Most previous assessments of survey methods for American mink have been conducted in the United Kingdom where mink are an invasive species. We evaluated survey techniques for American mink in riparian habitat in its native range in the midwestern United States. We used occupancy modeling to compare detection rates between walking surveys and mink raft surveys, and we evaluated the potential for environmental covariates and observer bias to influence detectability from walking surveys. Per-survey detection probabilities were greater for walking surveys (0.72) than for mink rafts (0.39). Walking surveys also were cheaper and easier to conduct in small streams prone to flooding when compared to mink raft surveys. However, detection probabilities from walking surveys were affected by observer bias, recent rainfall, substrate, and date. We recommend walking surveys for determining the distribution of American mink in riparian habitat in the Midwest if occupancy modeling is applied to adjust for environmental and observer effects on detectability. We used such an approach to demonstrate occupancy dynamics of mink were related to variable water depths, which has implications for how this carnivore might be influenced by climate change. Mink rafts standardize the substrate for recording mink tracks and reduce the likelihood of observer effects. For studies using many volunteers, we recommend mink rafts for determining site occupancy by American mink. © 2011 The Wildlife Society. [ABSTRACT FROM AUTHOR]

The article presents information on a study which examined the high prevalence of Aleutian mink disease virus (AMDV) in free-ranging mink on the island of Bornholm, Denmark. Polymerase chain reaction detected AMDV in 32 of 49 antibody-positive free-ranging mink on Bornholm but not in mink collected from other parts of Denmark. The most likely origin of AMDV in free-ranging mink is farmed mink on the island at a time when AMDV was still circulating in the farmed mink.

American mink (Neovison vison) are an ecologically damaging invasive species in Europe and Iceland where attempts to control them typically rely on trapping. The focus and efficiency of trapping can be improved by using track-recording mink rafts to identify where mink are present before traps are deployed. This paper describes development of operating strategy for the use of mink rafts with traps, to optimise capture efficiency against costs. We worked sequentially on two unconnected chalk streams in central southern England. On 17 km of the River Itchen, we operated a very high density of rafts (5.9 per km) through spring and summer to generate multiple detections of each mink present. All rafts recording mink tracks were armed with traps, and captured mink were euthanased. After removal of mink until no further detections were made, we calculated that each mink was detected 5.3 times at 5.1 raft sites, and on this basis, rationalised raft density to a standard one per kilometer of river. We set a trap deployment time (10 days) that encompassed the longest observed lapse from detection to capture (7 days), and extended the check interval for rafts in monitoring mode from 1 week to 2 weeks to further reduce costs. These operating rules were then deployed for 12 months on the 44-km River Wylye beginning in autumn. Rafts indicated that the river was cleared of mink through the capture of seven individuals, each of which was detected 3.6 times at 2.7 raft sites, on average, and was trapped within 6 days of detection giving a response time of less than 20 days. Although these operating rules may need refinement for other environments, we believe this is a sound basis for effective mink control. [ABSTRACT FROM AUTHOR]

Abstract: A behavioral response is usually the first adaptation of animals to environmental changes such as the introduction of an alien invasive species, and it seems to be the most important factor in reducing the negative impact of new predators on naive prey. This study examined changes in the abundance and behavior of breeding coots (Fulica atra) and great crested grebes (Podiceps cristatus) in response to invasion of the Mazurian Lakeland (NE Poland) by American mink (Neovison vison), first recorded here in 1984. Feral mink densities varied from 1.0 to 14.6 individuals per 10km of shoreline. Mink were responsible for the losses of 17–58% of experimental clutches (artificial nests containing chicken eggs) that were deployed. Mink destroyed more experimental clutches than other predators; the effects of mink predation were similar in reeds and on the bank. Radio-tracking showed that mink avoided lake banks near human settlements. Mink have markedly affected the breeding distribution of both species and caused a greater than 20-fold decline in coot numbers. For coots and grebes breeding distribution and nesting success were positively associated with built-up areas along lake shores and also with whether the birds were breeding in colonies. Increased brood survival of coots and grebes near human settlements is a paradox in the sense that a man-made habitat change has provided refuge from an alien predator. [Copyright &y& Elsevier]

Following the establishment of American mink farms outside North America, the species has successfully invaded Europe and South America, and in some places, their presence demonstrably threatens native biodiversity. We surveyed for mink signs along the Andean Patagonian forest in Argentina from 38°52′ S to 54°52′ S, revealing that their range has now expanded to span 800 km of contiguous occupation on the continent including several types of wetlands and has also colonised Tierra del Fuego Island. Rate of expansion was estimated using two methodologies and varied between 5.53 and 9.00 km/year (linear method, large-scale spread) and 4.86 km/year (within a more restricted area, grid method). Diet throughout the region fitted the generalist pattern described for mink elsewhere. Native small mammals were the most frequently consumed category. Crustaceans (patchily distributed in the region) occurred in the diet in proportion to their availability ( r=0.961, p<0.001), but that of waterfowl did not ( r=0.178, p=0.713). Diet was evaluated at one lake throughout a year, revealing that consumption of crustaceans fell in the cold months when bird abundance increased. Based on published work on the impact of American mink as an introduced species in Patagonia and elsewhere, together with our own survey, we discuss the implications of this invasion for biodiversity conservation in Argentinean Patagonia and the associated dilemmas for management policy. [ABSTRACT FROM AUTHOR]

Abstract: American mink (Neovison vison) is a widely distributed invasive species in southern Chile. Thirty four feral minks were trapped at two distinct sites (rural and peri-urban), diet analyzed and Toxoplasma gondii exposure compared using PCR and specific antibodies. Serum samples were evaluated using a commercial latex agglutination test where a titer ≥1:32 was considered positive. Of 30 mink analyzed, 21 (70%) were positive to T. gondii antibodies, with titers ranging from 1:32 to 1:2048. As expected, adult mink showed higher seroprevalence of exposure to T. gondii (18/21) than young mink (3/9) (P =0.008). There was not statistically significant difference between sex groups (P =0.687). Differences in seroprevalence were observed between the two sample sites with a higher proportion of positive individuals in the peri-urban area, and therefore, closer to human settlements (35.7% vs. 100%, P =0.0001). Individuals positive to T. gondii using PCR and/or serology showed similar differences by site with higher infected individuals in peri-urban areas (58.8% vs. 100%, P =0.007). Diet of American mink based in fecal composition analyses was mainly based on crustaceans (frequency of occurrence: crustaceans=100%, birds and rodents<7%), suggesting that the high observed prevalence of T. gondii infection might be more associated with its aquatic behavior (e.g. ingestion of oocysts in contaminated fresh water) than with their trophic behavior (e.g. preying over species that can have T. gondii cysts in their tissues). As an invasive species potentially subject to routine culling to maintain population sizes under control, minks could be used as a sentinel species to monitor pathogens of public and wildlife health importance, such as T. gondii, in aquatic environments. [ABSTRACT FROM AUTHOR]

Establishing relationships of species occurrence with environmental variables is important to define and develop species conservation schemes. The character of the riparian environment which supports populations of otter ( Lutra lutra) and mink ( Neovison vison) was investigated across spatial scales. Both species were positively associated with increased habitat diversity, the provision of natural land cover and a reduced level of urbanisation. However, mink were most closely associated with immediate riparian conditions whereas otters were associated more strongly with broad scale environmental characteristics. We argue that the benefits of habitat improvements may be seen more quickly in the occurrence of mink, a non-native pest species, than in the occurrence of the native otter. This has implications for the perceived benefits of conservation schemes which are applied at a fine scale, with particular relevance to farm-based conservation prescriptions such as agri-environment schemes. We show that mink presence is associated with higher levels of riparian bird diversity, a pattern which was not observed with occurrence of otter. It may be inevitable that conservation schemes benefit populations of both desirable and undesirable species. The present study demonstrates the importance of considering scale in animal ecology when developing conservation strategies. The use of specialist species with large home ranges to reflect the success of conservation schemes which are applied on a farm scale should be avoided. Effective conservation schemes may require specific pest species monitoring and management. [ABSTRACT FROM AUTHOR]

No abstract available [ABSTRACT FROM AUTHOR]

In a number of countries around the world, introduced American mink are acknowledged to have had a negative effect on a number of native species, many of which are of particular conservation concern. In the UK, there has been an observed correlation between the spread of mink and the decline of the, once common and widespread, water vole. Large wetlands, such as extensive reed bed, appear to mitigate the impact of mink predation on water voles and some bird species. The present study was carried out to test the hypothesis that the observed refuge effect of reed beds arises from the way mink forage in this type of wetland. The results suggest that the interior of reed bed offers a spatial refuge for water voles, and other species, from predation by mink, because more than 60% of mink foraging activity occurred within 10 m of a main (>10 m wide) channel. Where mink ventured within the reed bed itself, they associated closely with scrub. The implication is that easily navigable channels and areas of scrub probably compromise the refuge effect of reed beds. This can be used to inform management recommendations at these sites. [ABSTRACT FROM AUTHOR]

Abstract: Adiponectin is a novel adipocyte-derived hormone with low circulating concentrations and/or mRNA expression in obesity and non-alcoholic fatty liver disease (NAFLD). The adiponectin mRNA of several Carnivora species was sequenced to enable further gene expression studies in this clade with potential experimental species to examine the connections of hypoadiponectinemia to hepatic lipidosis. In addition, adiponectin mRNA expression was studied in the retroperitoneal fat of the American mink (Neovison vison), as hepatic lipidosis with close similarities to NAFLD can be rapidly induced to the species by fasting. The mRNA expression was determined after overnight–7d of food deprivation and 28d of re-feeding and correlated to the liver fat %. The homologies between the determined carnivoran mRNA sequences and that of the domestic dog were 92.2–99.1%. As the mRNA expression was not affected by short-term fasting and did not correlate with the liver fat %, there seems to be no clear connection between adiponectin and the development of lipidosis in the American mink. In the future, the obtained sequences can be utilized in further studies of adiponectin expression in comparative endocrinology. [ABSTRACT FROM AUTHOR]

American mink (Neovison vison) are an ecologically damaging invasive species where they have been introduced in Europe. Effectiveness of mink population control by trapping has been difficult to assess, without knowing how efficiently mink are caught by traps or detected by other methods. Use of track-recording rafts to detect mink and guide trapping effort has proved efficient and leads to a supposition that no detection indicates absence of mink. To draw this conclusion with any confidence requires a measure of detectability. We applied occupancy models to data from an earlier study to estimate detectability of individual American mink on track-recording rafts. Estimated detectability of individual mink, per raft, and 2-week check period varied between 0.4 in late summer and 0.6 in late autumn. By inference, risk of failing to detect a mink that was present would be ,5% given 4-6 independent opportunities to detect it. These opportunities could be created either by using a raft spacing that ensured multiple detections of each mink or by monitoring rafts through a succession of check intervals. Within certain simple constraints, raft location did not contribute substantially to detection probability. These findings will allow field operators, strategists, and funders to assess with confidence the success of efforts to control mink density. We expect the estimation of individual detectability to be similarly valuable in population control or eradication of other species. [ABSTRACT FROM AUTHOR]

The American mink Neovison vison is a widely distributed species in Spain, for which important basic ecological data are lacking. We studied mink den site selection in a location in central Spain during the winter of 2008/09 using snowtracking and direct observation. Dens were located more frequently in tree roots (51.9%; N ¼ 79) inside emergent vegetation (15.2%) and on human-created enbankments (15.2%). Human buildings and burrows were scarcely used(,10%). The logistic regressions we carried out supported that minks used secondary river beds for shelter more often than their availability in the environment should predict. These secondary areas are characterised by their low width and the frequent presence of small streams (of , 1m width). In rough terms, this pattern could be a way of avoiding potential interactions with other animals sharing the same habitat, and also for thermoregulation while resting. On the basis of the wide habitat niche, ecosystem management as a measure of mink control appears to be ineffective. [ABSTRACT FROM AUTHOR]

Introduced predators are a major threat to biodiversity. While in island ecosystems the favoured management option is species eradication, in continental areas most managers tend to control-orientated options, assuming that eradication is an impossible goal. However, many management actions are conducted without precise or quantifiable goals, and their output is difficult to assess due to the lack of experimental approaches and scientific evidence. Here, we analyse the results of a typical small-scale short-term management action consisting of live-trapping and culling invasive American mink. We estimate the American mink population size at the beginning of the study assuming three different scenarios, assess the output of the management action in each scenario and model the results of further trapping efforts. Based on the results we estimate the effort and economic costs required for culling different population percentages per unit area, as well as the costs and feasibility of eradication. Our results provide a basis for planning invasive predator management, setting realistic management goals and estimating funding required, as well as a framework for managers to evaluate on-going management actions. In addition, our results suggest that American mink eradication from some continental areas would be feasible with current techniques at a moderate-low cost. We suggest that invasive predator management in continental areas should move towards eradication when feasible, regarding control as a second option. [ABSTRACT FROM AUTHOR]

Despite the numerous studies carried out on the endangered European mink (Mustela lutreola) for conservation purposes, the reproductive biology of this species is largely unknown. In the wild reproductive parameters such as litter size are difficult to observe, particularly for cryptic species such as mustelids. We compared the reliability of nonstained and stained placental scar counts in farmed American mink (Neovison vison) with known litter sizes and then applied the best methodology to free-ranging related species--European mink, European polecat (Mustela putorius), and feral invasive American mink--for a comparative study of embryonic litter size in western Europe populations. The staining method allowed us to improve the detection of placental scars and to increase the reliability of the method by reducing the observer effect. Nevertheless, this analysis must be performed by 7 months postpartum, before the regeneration of uterine tissues. In free-ranging animals the mean embryonic litter size, estimated by stained placental scar counts and embryo counts, was significantly lower in European mink compared with polecats and American mink, and in polecats compared with American mink. Small litter sizes in European mink could be a factor limiting population growth rates in the species. Our results constitute a first step toward demographic analyses aimed at modeling the population dynamics of these species. [ABSTRACT FROM AUTHOR]

Understanding processes allowing the co-existence of ecologically similar species is important but difficult to study in community ecology. Introductions of alien species are unplanned experiments allowing investigation of co-adaptation of both native and invasive species over a short period. We analysed food niche differentiation between native European mink and alien American mink after invasion of the latter species in Belarus. European mink feed mainly on crayfish, frogs and fish whereas American mink prefer small mammals, fish and frogs. The diet of both species varied between seasons and during the period of alien mink invasion. Concurrent with the progress of American mink invasion, the European mink food niche has narrowed to feeding mainly on frogs, with the proportion of aquatic prey (fish and crayfish) in their diet drastically reduced. In contrast, the American mink food niche became wider during invasion. The breadth was stable but included a varied proportion of different prey categories: namely an increased proportion of aquatic prey and a decreased proportion of water vole and waterfowl. The increase in abundance of American mink saw a decrease in the proportion of larger prey in their diet. When American mink preyed more often on frogs, food niche overlap of both predators increased. This result suggests that arrival of an alien competitor reduced food abundance (exploitative competition) and caused a change in native mink diet. [ABSTRACT FROM AUTHOR]

Abstract: β-Sitosterol is a weakly estrogenic phytosterol used in functional foods to lower elevated serum cholesterol concentrations. It has been reported to cause reproductive disturbances in fish and lower the sperm count of rodents but, in contrast, there were indications of enhanced reproduction in a preliminary study on the brown American mink (Neovison vison). In the present experiment the effects of chronic dietary β-sitosterol exposure on the reproduction of the American mink were evaluated with a large number of experimental animals. Male and female finnwhite mink (n =200) – a previously uninvestigated color type with lower reproductive success compared to brown mink – were exposed to 50mgβ-sitosterolkg−1 d−1 for 10 months and compared with 200 control animals. After 3 months in November, 15 males per group were sacrificed and their biochemical variables determined. The serum glucose and high-density lipoprotein cholesterol concentrations were lower in the β-sitosterol-exposed group, while other effects were minor. The females were mated with the top-rated males (4–5:1) in March and their reproductive performance was determined. The reproductive success increased in the β-sitosterol group with significantly fewer barren females and a higher number of successfully reproducing females than in the control group, which supports previous studies on brown mink and voles indicating that β-sitosterol could be used to enhance the reproductive performance of these mammals. [Copyright &y& Elsevier]

Since 2001 invasive American mink has been known to populate Navarino Island, an island located in the pristine wilderness of the Cape Horn Biosphere Reserve, Chile, lacking native carnivorous mammals. As requested by scientists and managers, our study aims at understanding the population ecology of mink in order to respond to conservation concerns. We studied the abundance of mink in different semi-aquatic habitats using live trapping (n = 1,320 trap nights) and sign surveys (n = 68 sites). With generalized linear models we evaluated mink abundance in relation to small-scale habitat features including habitats engineered by invasive beavers (Castor canadensis). Mink have colonized the entire island and signs were found in 79% of the surveys in all types of semiaquatic habitats. Yet, relative population abundance (0.75 mink/km of coastline) was still below densities measured in other invaded or native areas. The habitat model accuracies indicated that mink were generally less specific in habitat use, probably due to the missing limitations normally imposed by predators or competitors. The selected models predicted that mink prefer to use shrubland instead of open habitat, coastal areas with heterogeneous shores instead of flat beaches, and interestingly, that mink avoid habitats strongly modified by beavers. Our results indicate need for immediate mink control on Navarino Island. For this future management we suggest that rocky coastal shores should be considered as priority sites deserving special conservation efforts. Further research is needed with respect to the immigration of mink from adjacent islands and to examine facilitating or hampering relationships between the different invasive species present, especially if integrative management is sought. [ABSTRACT FROM AUTHOR]