Range expansion of the pine marten (Martes martes) in an agricultural landscape matrix (NW Italy)

Habitat segregation is considered to favour the coexistence of sympatric pine martens Martes martes and stone martens M. foina, the latter being displaced to agricultural and urbanised areas. Subsequent to the report of pine martens in cultivated areas of the western River Po plain (NW Italy), we reviewed all available information on the presence of this species in plain areas of northern Italy and, for two study areas, applied a non-invasive PCR-RFLP method for the identification of Martes species from faecal mtDNA.A total of 24 pine marten records were collected, grouped in the western part of the River Po plain. The number of records showed an exponential increase from 1988 to 2007, the percentage of woods in a 10 km² wide circular plot surrounding the location of records being inversely correlated to its distance from the 300 m a.s.l. contour line. In the two study areas, 36 out of 119 “marten-like” faeces were assigned to the pine marten, whilst none belonged to the stone marten. In the best monitored area, the pine marten was present almost constantly.Our results suggest that the pine marten is expanding its range to include cultivated areas which were previously considered a prerogative of the more synanthropic stone marten.     

A PCR-RFLP-based method to distinguish sable (<Emphasis Type="Italic">Martes zibellina</Emphasis>) and pine marten (<Emphasis Type="Italic">Martes martes</Emphasis>)

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.     

Nutritional ecology provides insights into competitive interactions between closely related Martes species

1. Closely related predator species often share several prey items, making it hard to differentiate the effects on their feeding habits of variation in food availability and of competition. We hypothesised that we could overcome this obstacle by quantifying and comparing nutritional niches.
2. We reviewed dietary studies that assessed the relative bulk of each food item, as either per cent biomass or per cent mean volume, in the diet of two closely related species, pine marten Martes martes and stone marten Martes foina, and calculated the nutrient profiles (intakes of protein, lipids and carbohydrates) of each diet.
3. Both martens’ diets were tightly clustered (mean values: 47% of energy from protein, 39% from lipid, and 14% from carbohydrate). In allopatry, the nutritional niches of the two species did not differ, but in sympatry, the stone marten ate more carbohydrates and less protein than the pine marten. In allopatry, the protein intake of the stone marten remained high (45–52%) in very different habitats, from cultivated lowland to Alpine forests.
4. Our data suggest that stone marten frugivory may, at least partially, be the result of interspecific competition. By analysing dietary data in the framework of nutritional ecology, we could compare the feeding requirements of pine martens and stone martens more effectively than by using classical estimates of trophic niche overlap at the food item level. This approach may help to shed light on the trophic relationships of other competing species.

     

Remotely plucked hair genotyping: a reliable and non-invasive method for censusing pine marten (Martes martes,L. 1758) populations

We investigated the feasibility of using genetic techniques to census pine marten (Martes martes) populations by genotyping non-invasively collected samples (plucked hair and scats), with particular reference to the genetically depauperate Irish population. Novel real-time polymerase chain reaction methods were developed for species and sex identification, targeting short DNA sequences. Background genetic variation at 17 microsatellite loci was very low in the Irish population, with an average of 2.29 alleles per locus and expected heterozygosity of 0.35. Despite such low polymorphism, a panel of eight loci with a sibling probability of identity of 0.011 reliably identified individual pine marten and their gender, as determined by reference to genotypes of live trapped individuals. With high nuclear DNA amplification success rates (93.8%) and low genotyping error rates (1.8%), plucked hairs may represent a more reliable and cost-effective DNA source than scats for monitoring populations of this elusive carnivore, and similar taxa such as the sympatric stone marten Martes foina.

     

Genetic analysis of sable (<Emphasis Type="Italic">Martes zibellina</Emphasis>) and pine marten (<Emphasis Type="Italic">M. martes</Emphasis>) populations in sympatric part of distribution area in the northern Urals

Analysis of nucleotide sequences of the mitochondrial DNA (mtDNA) control region (495 bp) of sables (Martes zibellina) and pine martens (M. martes) from allopatric parts of the species ranges has shown a considerable interspecific genetic distance (>3%). In sympatric populations of these species in the northern Urals, differences between two species-specific mtDNA lineages are still large; however, classification of each individual nucleotide sequence with one of the two lineages is not correlated with whether the given animal is phenotypically a sable, a pine marten, or a potential hybrid (the so-called “kidas”). This indicates a high degree of reciprocal introgression of the sable and pine marten mtDNA in the northern Urals and suggests that their interspecific hybridization is common in the sympatric zone.     

Far from the madding crowd: Tolerance toward human disturbance shapes distribution and connectivity patterns of closely related Martes spp.

To assess niche overlap between the most similar European sympatric carnivores, the pine marten Martes martes and stone marten Martes foina, and outline their potential distributions and connectivity corridors in Central Italy, we applied a multivariate kernel density procedure which allowed to assess both species' ecological hypervolumes based on a set of 16 environmental predictors and used the resulting probability of occurrence map as a resistance surface in electrical circuit theory-based models. Distance to watercourses and percent cover of deciduous forest and shrubland were the most relevant factors shaping pine marten ecological niche, while stone marten distribution was mainly shaped by human population density and cover of both human settlements and deciduous forest. Overlap between the hypervolumes of the two martens was low-to-moderate, while, on average, landscape connectivity was higher for the stone marten. The inclusion in the models of human disturbance-related variables enabled to define a possible mechanism driving habitat partitioning in human-altered landscapes. Based on our results, increasing human density and urbanization of European lowland and hilly landscapes are expected to represent a greater threat to the pine marten than the stone marten.     

Spatial Niche Segregation of Sympatric Stone Marten and Pine Marten – Avoidance of Competition or Selection of Optimal Habitat?

Coexistence of ecologically similar species relies on differences in one or more dimensions of their ecological niches, such as space, time and resources in diel and/or seasonal scales. However, niche differentiation may result from other mechanisms such as avoidance of high predation pressure, different adaptations or requirements of ecologically similar species. Stone marten (Martes foina) and pine marten (Martes martes) occur sympatrically over a large area in Central Europe and utilize similar habitats and food, therefore it is expected that their coexistence requires differentiation in at least one of their niche dimensions or the mechanisms through which these dimensions are used. To test this hypothesis, we used differences in the species activity patterns and habitat selection, estimated with a resource selection function (RSF), to predict the relative probability of occurrence of the two species within a large forest complex in the northern geographic range of the stone marten. Stone martens were significantly heavier, have a longer body and a better body condition than pine martens. We found weak evidence for temporal niche segregation between the species. Stone and pine martens were both primarily nocturnal, but pine martens were active more frequently during the day and significantly reduced the duration of activity during autumn-winter. Stone and pine martens utilized different habitats and almost completely separated their habitat niches. Stone marten strongly preferred developed areas and avoided meadows and coniferous or deciduous forests. Pine marten preferred deciduous forest and small patches covered by trees, and avoided developed areas and meadows. We conclude that complete habitat segregation of the two marten species facilitates sympatric coexistence in this area. However, spatial niche segregation between these species was more likely due to differences in adaptation to cold climate, avoidance of high predator pressure and/or food preferences by both species than competitive interaction between them.     

Fur snagging as a method of evaluating the presence and abundance of a small carnivore, the pine marten (Martes martes)

The pine marten Martes martes was once considered one of Ireland's rarest carnivores, but is now recolonizing many of the areas where it was once extirpated. It is important to monitor its population expansion so that conservation management decisions can be made regarding the status of this species. In this study, we investigate the use of fur snagging devices as a method of estimating pine marten presence and abundance in lowland and upland broadleaf woodland. We investigated whether these devices reliably detected presence, and how quickly. It was found that hair traps functioned very well in detecting pine martens on all survey transects and was essential in their detection in the most isolated site. A survey length of 6 days was sufficient to detect pine marten in all survey sites, with most detections occurring within the first 4 days. The hair traps functioned equally well as scat location for detecting pine marten and had the added advantage of there being no confusion as to the origin of the sample. Live trapping was used to verify the estimates of relative abundance from hair traps. There was a trend for the number of hair samples per site and the number of times animals were trapped per site to be positively correlated, although this was not significant. Hair traps do provide a real alternative for the monitoring of pine martens in both lowland and upland broadleaf woodlands, overcoming many of the disadvantages associated with scat location.     

Widespread distribution of Pine martens (<Emphasis Type="Italic">Martes martes</Emphasis>) in a fragmented suburban landscape

Pine martens (Martes martes) are forest specialists that depend either on large patches of forest or on the absence of barriers between smaller forest patches. It thus seems likely that they would disappear from landscapes with heavily fragmented forests and a high density of presumptive barriers that are typical of Central Europe. We studied the distribution of pine martens in a suburban landscape characterised by fragmented forests and a high density of presumptive barriers (e.g. housing areas, roads). We assessed the presence of pine martens using camera traps in a sample of 170 1?×?1-km quadrats and used occupancy modelling to account for imperfect detection. We found an almost complete and countrywide distribution of the pine marten. Larger roads and housing areas were not negatively related to its current distribution as we predicted. We conclude that pine martens are capable to survive in some heavily fragmented landscapes.     

Anomalous coloration in European pine marten Martes martes in Elba Island,Central Italy

Evidence of abnormal coloration in wild animals provides useful information to better understand its adaptive function and its impact on survival. For this reason, we need to know the frequency and distribution of these abnormal phenotypes in wild populations. Here, we report two records of hypopigmentation in European pine marten Martes martes, obtained during a camera‐trapping survey on Elba Island, Central Italy. We do not know what has caused anomalous coloration of pine marten on Elba Island, but it is possible that the inbreeding may have played a role in this isolated population. Although the light coloration certainly entails an increased visibility of pine martens, it is possible that the low predator pressure and the absence of other wild carnivore populations in our study could mitigate the mortality risk due to the light phenotype. The increased use of camera traps across the world can potentially facilitate the discovery of cases of anomalous colorations in wild populations, providing an unprecedented insight into the occurrence of this phenomenon in wild mammal species.     

Accuracy in molecular sexing of martens (Martes americana and Martes caurina) varies among sample types

We evaluated the accuracy of sex identification using the SRY marker for American marten (Martes americana) and Pacific marten (Martes caurina) using samples collected from commercial trappers and those obtained via noninvasive sampling. We determined that sex identification from Lut-SRY primers is accurate at >90% for muscle and hair samples collected noninvasively. We found much lower accuracy when using hair samples plucked from trapper-killed carcasses, errors presumably incurred from contamination from the DNA of trappers, who were entirely male. We also found that the sequence generated from Lut-SRY primers, originally developed for Eurasian otters (Lutra lutra), differed slightly for martens, and recommend that new primers be developed from the sequences we provide. The SRY marker can be reliably used for sex identification in both species of marten, provided that samples have low probabilities of contamination. Researchers should avoid samples collected from external locations on trapper-killed carcasses for DNA-based analyses.     

Efficient species identification of pine marten (<Emphasis Type="Italic">Martes martes</Emphasis>) and red fox (<Emphasis Type="Italic">Vulpes vulpes</Emphasis>) scats using a 5′ nuclease real-time PCR assay

Monitoring wildlife species by DNA identification of samples collected non-invasively is an important tool in conservation management. DNA identification of species from faecal (scat) samples is problematic due to the small quantities and poor quality of the DNA isolated from such samples. This study demonstrates the use of real-time PCR technology in the identification of red fox (Vulpes vulpes) and pine marten (Martes martes). It is shown that real-time PCR can be used to identify fox and pine marten by either melting curve analysis (Tm determination) with SYBR Green 1 detection or by the use of species specific fluorogenic probes. The technique is shown to work efficiently with scat DNA.     

Effect of felling on red fox (Vulpes vulpes) and pine marten (Martes martes) diets in transitional mixed forest in Belarus

In transitional mixed forests in northern and central Belarus the influence of intensified felling on the diets of red foxes Vulpes vulpes L. and pine martens Martes martes L. was investigated in two model forested terrains with sandy and clay top-grounds. A total of 1904 scats of red foxes and 1624 scats of pine martens were analysed over two periods differed by logging rate. When logging rate was conservative, red fox and pine marten diets were found to be similar, but under heavy logging feeding of the predator species shifted. In both model woodlands we found the same pronounced dietary trend of higher consumption of rodents, first of all, Microtus voles. The dietary changes were well related to the registered increase in Microtus vole numbers and total number of rodents in felling areas. The increased preying on rodents caused lower consumption of other food items, particularly medium-sized mammals (year-round) or/and birds or/and fruits (in the warm season) or/and mammalian carrion (in the cold season). In the conditions of intensified felling the food niches of the red fox and pine marten diverged mostly because of the great difference in the species structure of rodents consumed. Red foxes turned to preying on Microtus voles more frequently, but less on bank voles Myodes glareolus; while pine martens increased their taking of Microtus voles, continued foraging for bank voles and began taking slightly more of Apodemus mice. Before heavy logging dietary similarity between the red fox and pine marten was high and did not vary considerably through seasons and study areas, whereas after felling was intensified their diet overlap became lower.     

Pine marten (Martes martes) distribution and abundance in Ireland: A cross-jurisdictional analysis using non-invasive genetic survey techniques

On the Island of Ireland, pine martens (Martes martes) exist at the western edge of their global geographic range in the least forested region of Europe. The species has undergone substantial declines in abundance and distribution during the 20th century. Here, we report on the first cross-jurisdictional (Republic of Ireland and Northern Ireland) survey that aimed to investigate current pine marten distribution, assess any recent historical change and provide preliminary estimates of population abundance.A standardised non-invasive survey technique that used scat-based transect surveys and DNA analysis to confirm scat identity was deployed in 258 10 km national grid squares during 2005–2007. In the Republic of Ireland, an occupancy rate of 59.6% was found. Comparisons with historical data indicated that a range expansion of pine marten had occurred over the last 30 years. Indicative core population range extended to over 50% of the land area with population abundance estimates of 2740 individuals.In Northern Ireland, an occupancy rate of 56.7% was determined with the population largely concentrated in western areas. There was little or no evidence of any recent expansion from core population areas (18% of land area) despite recent increases in forest cover and full legal protection. Population abundance estimates of 320 emphasise the critical requirement for action to conserve this species.The pine marten is one of the rarest wildlife species in Ireland and, based on our studies, an evidenced based conservation strategy that promotes a sustainable future for the species needs to be developed.     

A non-invasive genetic method to identify the sympatric mustelids pine marten (<Emphasis Type="Italic">Martes martes</Emphasis>) and stone marten (<Emphasis Type="Italic">Martes foina</Emphasis>): preliminary distribution survey on the northern Iberian Peninsula

The closely related mustelids European pine marten (Martes martes) and stone marten (Martes foina) sympatrically inhabit a large area of Europe. However, given our limited knowledge of their bioecological relationships, their extremely elusive behaviour and the fact that their faeces cannot be distinguished on the basis of morphology alone, it is very difficult to monitor their populations. In this study, we describe a reliable non-invasive polymerase chain reaction (PCR)–restriction fragment length polymorphism (PCR-RFLP) method for distinguishing between M. martes and M. foina based on the analysis of deoxyribonucleic acid extracted from faeces samples. The method was specifically designed to avoid possible interference from potential prey mammals and other sympatric carnivores. The procedure consists of PCR amplifying a mitochondrial D-loop region followed by digesting the resulting 276-bp-long amplicons with the restriction enzymes HaeIII and RsaI. To assess the efficiency of this technique, we conducted a preliminary field study across the potential sympatric distribution areas of both marten species in the northern Iberian Peninsula. Out of 359 faeces samples collected, we identified 80 as specimens from the stone marten and 235 from the pine marten. Unequivocal species identification was thus possible in 88% of the faeces samples collected. These findings reveal the combined use of non-invasive genetic sampling and GIS technology to be a reliable and cost-effective procedure for improving our knowledge of the spatial distributions of sympatric marten species. This protocol could also be used to identify and improve information gaps, to develop effective research and management programmes and in population and landscape genetics studies of marten species. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

The NATURA 2000 database as a tool in the analysis of habitat selection at large scales: factors affecting the occurrence of pine and stone martens in Southern Europe

Most studies on habitat selection among animals are conducted at local scales, whereas reliable determination of species requirements at larger spatial scales can be problematic. We used data available for NATURA 2000 sites to determine the habitat requirements of two relatively widespread and common species—pine marten Martes martes and stone marten Martes foina—in Southern Europe. Using presence-absence data, we applied statistical models at two spatial scales. At the local scale (within the dispersal distances of the species), sites occupied by martens were compared with unoccupied sites using buffers of different sizes, whereas at the regional scale, unoccupied sites were selected randomly. To adjust for spatial autocorrelation of data, penalised quasi-likelihood approximations were used. Both species of martens demonstrated preferences for areas with higher proportions of forest cover and steeper terrain. At the local, but not at the regional, scale, pine martens occurred at lower elevations, whilst stone martens occurred at higher elevations. We found that climatic variables (mean temperature, precipitation) had no significant effect on the presence of the martens. The results of our analyses generally confirmed findings of previous studies on habitat selection of both marten species in Southern Europe. This demonstrates the utility of data collected for NATURA 2000 sites for use in various analyses such as conservation planning and evaluating the impact of climate change on the distribution of animal species.     

Where to sleep in a rural landscape? A comparative study of resting sites pattern in two syntopic Martes species

The niche‐complementarity hypothesis predicts that two sympatric species must differ in their requirements for one of the three main ecological dimensions (i.e. habitat use, diet, and activity time) to coexist. European pine marten Martes martes and stone marten M. foina are syntopic medium‐sized mustelids with very similar morphology and ecology for which resting sites are a key resource. To better understand how these species coexist, we investigated whether key features of their resting site pattern (number of resting sites, area over which they are distributed, main habitat type used for resting) differed. We used diurnal telemetry to identify resident individuals (e.g. spatially stable individuals over time) and to locate them during resting periods in a fragmented forested area in France. Stone marten used fewer resting sites distributed over a smaller surface area than pine marten. Most stone marten resting sites were located in open habitat (83%) in the proximity of human habitations, whereas pine martens rested almost exclusively in forest (98%). Sex, age, and season explained some variability in both the number of resting sites and the probability of resting within forested habitat for stone marten but not pine marten. The area covered by resting sites was larger in males than in females, but age modulated this difference in an opposite way for the two species. Such a pattern was expected given the intra‐sexual territoriality and the reproductive phenology of these species. Overall, stone marten showed higher inter‐individual variability in resting site pattern than pine marten. The particular pattern observed in subadult male stone martens during summer (increase in resting site surface area and in the probability to rest in forest) may reflect an attempt to settle in forests, and we discuss these implications in the context of interspecific competition.     

Non-invasively determined multi-site variation in pine marten <Emphasis Type="Italic">Martes martes</Emphasis> density,a recovering carnivore in Europe

Pine martens (Martes martes) are subject to national and international conservation legislation throughout most of their European range. Yet population density and abundance estimates, which are a key component of effective conservation management, are lacking in many countries. In this study, a large-scale non-invasive survey was undertaken in 14 forested study sites throughout Ireland to assess variation in pine marten density and abundance. Pine marten hair samples were collected in each study site and analysed using genetic techniques to determine individual identity data. Density and abundance estimates were obtained using spatially explicit capture-recapture models and CAPWIRE. Across all study sites, a total of 93 individual pine marten were identified and captured 217 times. Estimated pine marten density varied from 0 to 2.60 individuals per km² of forested habitat, with all but a single site having estimated densities of ≤1 pine marten per km² of forest habitat. Mean population abundance estimates across all study sites ranged from 0 to 27 individuals. Spatially explicit capture-recapture models on combined data across all 14 study sites provided a mean density estimate of 0.64 (95% CI 0.49–0.81). Combining this with data on the current distribution and estimated area of forest habitat occupied by the species in Ireland, the total pine marten population abundance of pine marten in Ireland was estimated at 3043 (95% CI 2330–3852) individuals. This research has conducted the largest scale investigation of pine marten density and abundance in any part of its global distribution and provided an improved basis for future population assessment and monitoring of this species.     

Linking habitat characteristics with genetic diversity of the European pine marten (Martes martes) in France

Although typically considered as a forest specialist species, the European pine marten (Martes martes) is an example of a number of species that have recently been found to also live in fragmented landscapes. Considering that habitat fragmentation and loss is a major threat to the persistence of mammal species in such landscapes, we investigated the association between habitat characteristics and genetic diversity across four pine marten populations occupying contrasting landscapes in France with different degrees of forest availability and fragmentation. Bayesian and multivariate clustering methods evidenced the presence of three genetic clusters and isolation by distance between populations was found at the national scale. We found an overall moderate level of genetic variability, but no evidence of a bottleneck or deficit in heterozygosity in any of the populations. No pattern of isolation by distance was found within the populations, except in the one located in the Pyrenean Mountains which appeared partly isolated from other continental populations and also showed a lower level of genetic diversity. No obvious association between the pattern of genetic variability and the pattern of forested habitat characteristics was found. We discuss the possibility that pine martens show greater behavioural plasticity than typically expected allowing them to adapt to different habitat types.