Seed Dispersal Patterns by Large Frugivorous Mammals in a Degraded Mosaic Landscape

Seed dispersal by Red fox (Vulpes vulpes), Stone marten (Martes foina), and Wild boar (Sus scrofa) was analyzed in an extensively degraded mosaic landscape in Sierra Nevada (SE Spain). The main objective was to determine whether seed dispersal by mammals was related to habitat degradation within a mosaic of adjacent degraded patches mixed with native forest and thereby to determine the potential role of mammals as seed dispersers in degraded landscape units. For three consecutive years, mammal feces were collected in the fruit production period, extracting all seeds of woody species found therein and analyzing their viability. Feces were collected in three different plots for each of five different landscape units: shrubland, native forest, and dense, cleared, and fenced reforestation stands. Seeds from 16 woody species (which represent more than a half of the total fleshy‐fruited woody species available) were recorded, although some agrarian species are also introduced in a low percentage of the scats. Seeds showed a high viability rate for all dispersed species, irrespective of the mammal disperser. No differences in species composition appeared in the overall landscape units or in the seed density between degraded habitats. Due to the small patch size, the high viability of dispersed seeds, and the large home range of the large mammals, these three animal species act as efficient seed dispersers for a diverse assemblage of woody plant species regardless of the habitat type within this degradation framework. This fact has important consequences for the biodiversity recuperation in these degraded habitats, principally in pine plantations.     

Trophic and spatial relationships of the pine marten (Martes martes) and American mink (Neovison vison) on mountain rivers of the Southern Urals

The American mink (Neovison vison) and pine marten (Martes martes) are the most common mustelid species in mountain forests of the Southern Urals. The bulk of the diet (85.3%) in the American mink consists of small mammals (35.8%), insects (22.7%), gastropods (14.1%), and fish (12.7%). In the pine marten, the main components comprising 79.6% of the diet are vegetable foods (29.8%), small mammals (27.0%), and insects (22.8%). The low diversity of their food spectra is accounted for by landscape and ecological features of the study region. The abundance of rodents is low, their distribution has a mosaic pattern, and other kinds of food are more abundant near rivers and streams, which explains the preference of both mustelid species for riparian biotopes. The breadth of trophic niches in the pine marten and American mink are 1.67 and 1.62, respectively, and the coefficient of their overlap is 0.75.     

Dynamic impacts of feral mink predation on vole metapopulations in the outer archipelago of the Baltic Sea

Predation impacts by introduced predators are predicted to be most intense in island ecosystems, and also variable depending on environmental conditions, but large-scale experimental field testing is rare. In this study we examine the factors that determine the distribution and abundance of vole metapopulations preyed upon by feral American mink Mustela vison in the outer Finnish archipelago of the Baltic Sea. Specifically, we follow the dynamics of field voles Microtus agrestis and bank voles Clethrionomys glareolus on 40 small islands under variable rainfall as part of a large-scale mink removal experiment. For both vole species occupancy rates were negatively influenced by island isolation, as were extinction events for field voles. High summer rainfall in 1998 corresponded to large vole populations where mink were absent, populations that then crashed in 1999 and 2000 when below average rains fell during the summer breeding season. Where mink were present however, vole abundance remained more constant between years with no boom-bust apparent. We conclude that weather and predation may drive vole abundance whereas habitat patchiness and metapopulation processes more strongly drive vole distributions. There may also be potential for interaction between these factors: because feral mink prevent rapid vole population growth after good summer rains, and vole dispersal is influenced by population size, feral mink may be changing vole dispersal patterns to disrupt the natural metapopulation dynamic. Hence this indirect impact of mink could lead to gradual erosion of vole populations in the outer archipelago by reducing recolonisation processes.     

Seed dispersers help plants to escape global warming

Plants are shifting their ranges towards higher elevations in response to global warming, yet such shifts are occurring at a rate slower than is needed to keep pace with a rapidly changing climate. There is, however, an almost complete lack of knowledge on seed dispersal across altitude, a key process to understand what constrains climate‐driven range shifts. Here, we report the first direct empirical evidence on altitudinal seed dispersal mediated by two common frugivorous mammals: the red fox Vulpes vulpes and the pine marten Martes martes. We conducted a three‐year (bait‐marking) experiment in a mountainous region of Spain. We offered experimental fruits containing colour‐coded seed mimics at feeding stations that simulated source trees. The colour codes allowed us to identify the exact origin of seed mimics found later in mammal scats. Nearly half (47%) of the dispersal events occurred towards higher elevations, despite only ca 25% of the study area being above the average altitude of the feeding stations (1344 m). Seeds dispersed uphill gained an average of 106 m (median = 111 m) and a maximum of 288 m, greatly exceeding the estimated requirements to escape warming (35.4 m per decade). Yet, foxes mediated much more uphill seed dispersal than martens (57% and 26% of dispersal events, respectively), which can be explained by between‐disperser differences in home range size and habitat specificity. Dispersers with larger home ranges move farther and potentially disperse more seeds to higher altitudes, while habitat generalism is necessary to transport seeds above vegetation belts delimiting contrasting habitat types. We discuss how both traits (home range size and habitat specificity) can be used to infer altitudinal seed dispersal across disperser species and mountainous landscapes.     

Habitat selection of European pine marten in Central Italy: from a tree dependent to a generalist species

Studies at small spatial scale are often fundamental to highlight the behavioural plasticity of a species and thus have important implications for conservation planning, in particular for species usually considered as habitat specialists. We investigated second-order habitat selection of the European pine marten in an area dominated by deciduous oak forest and open fields in central Italy, by radio-tracking 16 pine martens (eight males, eight females). Pine martens placed home ranges in areas with more open field than in the study area, whereas woodland (oak and conifer forests) comprised a smaller portion of the home range than predominant forest character of the studied area. Although the presence of the species in the open habitats has been documented, to our knowledge, our results provide the first evidence of home range establishment in this cover type by pine marten at population level. The combination of low predation risk and high availability of resources could allow pine martens to occupy open fields in our study area. We highlighted different individual strategies of habitat selection, with some individuals placing home ranges in areas with high forest coverage while others occupying open areas. We found no effects of sex and body condition on habitat selection, and this could indicate that in the study area, both forested and non-forested cover types, such as open fields, shrub and anthropic areas, can provide adequate food, overhead cover and resting sites for all individuals. Pine marten ability to occupy open fields seems thus more related to the behavioural flexibility of the species, rather than to the need to supplement dens and forage from complementary lower quality habitat. The high quality of the Mediterranean continental area studied could also explain the selection of open areas by the pine marten. Our results offer useful information on pine marten ecology and may be helpful for conservation management of this species in southern Europe.     

Spatial organisation and dynamics of the pine marten Martes martes population in Białowieza Forest (E Poland) compared with other European woodlands

We studied factors affecting density and spacing patterns in the pine marten Martes martes population inhabiting temperate forests of Bia?owieza National Park, eastern Poland. From 1985/1986 to 1995/1996 marten densities ranged from 3.63 to 7.57 individuals 10 km^?2 (mean 5.4) and were positively correlated with abundance of forest rodents in the previous year. The rate of marten population growth was inversely density‐dependent and positively related to rodent density. Annual mortality rate averaged 0.384 and tended to be negatively related to marten densities. Mean annual home range of males (2.58 km², SE=0.24) was larger than that of females (1.41 km², SE=0.20). Seasonal home ranges also differed significantly between males and females. Both sexes held the smallest ranges in December–January. Female ranges increased in April–May, whereas those of males increased in June–September when they were mating. Fidelity of pine martens to their home ranges was very high. The mean shift between arithmetic centres of seasonal ranges was 0.25 km, and the ranges recorded in two consecutive seasons overlapped, on average, by 87–90%. We observed very little home range overlap between neighbouring male (mean 4–6%) or female (mean 6%) marten. Year round the neighbouring individuals of the same sex neither avoided nor attracted each other. Females attracted males only during the spring‐summer mating season. A review of other studies has documented that winter severity and seasonal variation in ecosystem productivity were essential factors shaping the biogeographic variation in pine marten densities between 41^o and 68^oN. The density of marten populations increased in areas with mild winters and lower seasonality. Maximum population densities (indicative of habitat carrying capacity) were correlated with mean winter temperature. In Europe, male home ranges increased with decreasing forest cover in a study area, whereas female ranges varied positively with rodent abundance.     

Marten space use and habitat selection in managed coniferous boreal forests of eastern Canada

Effects of habitat loss and fragmentation on the behavior of individual organisms may have direct consequences on population viability in altered forest ecosystems. The American marten (Martes americana) is a forest specialist considered as one of the most sensitive species to human-induced disturbances. As some studies have shown that martens cannot tolerate >30–40% clear-cuts within their home range, we investigated marten space use (home range size and overlap) and habitat selection in landscapes fragmented by 2 different patterns of timber harvesting in the black spruce boreal forest: dispersed-cut landscapes (10–80 ha cut-blocks) and clustered-cut landscapes (50–200 ha cut-blocks). We installed radio-collars on female martens and determined 20 winter home ranges (100% minimum convex polygons and 60–90% kernels) in dispersed-cut (n = 8) and clustered-cut (n = 12) landscapes. Home range size was not related to the proportion of clear-cuts (i.e., habitat loss), but rather to the proportion of mixedwood stands 70–120 years old. However, female body condition was correlated to habitat condition inside their home ranges (i.e., amount of residual forest and recent clear-cuts). At the home range scale, we determined that mixedwood forests were also among the most used forest stands and the least used were recent clear-cuts and forested bogs, using resource selection functions. At the landscape scale, home ranges included more mixedwood forests than random polygons and marten high activity zones were composed of more residual forest and less human-induced disturbances (clear-cuts, edges, and roads). These results suggest that mixedwood forests, which occupy approximately 10% of the study area, play a critical role for martens in this conifer-dominated boreal landscape. We recommend permanent retention or special management considerations for these isolated stands, as harvesting mixedwood often leads to forest composition conversion that would reduce the availability of this highly used habitat. © The Wildlife Society, 2013     

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.     

The influence of American mink odour on the spatial distribution and behaviour of water voles

The perception and assessment of predation risk often cause changes in the activities of animals and induce behavioural responses that may in turn affect their movements and distribution. To simulate high predation risk in a midfield pond riparian habitat, we used fresh faeces from ranch American mink Neovison vison and recorded behavioural responses of water voles Arvicola amphibius. In areas where mink odour was deployed, the numbers of captured vole individuals and their trappability were significantly lower than in control areas. Several voles migrated from the zones with deployed mink faeces to the areas without faeces, thus proving that increased predation risk affects the distribution of individuals in a population. The response to mink odour was much more pronounced in females than in males; in areas with deployed mink faeces, not a single female was trapped. We conclude that although American mink is a non‐native, invasive predator, water voles respond to mink odour by reducing their activity and/or by avoiding places with higher predation risk.     

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.     

The effects of habitat quality and female size on the productivity of the lesser spotted eagle Aquila pomarina in the light of the alternative prey hypothesis

Habitat quality is an important but insufficiently understood concept in ecology and conservation biology, due to geographic and temporal variation as well as interaction with individual quality. In 1994–2002, we studied the Estonian population of the lesser spotted eagle Aquila pomarina in order to (1) explore the relative contributions of habitat and female size in reproductive success; (2) check for a switch to alternative prey in vole‐poor years and the relevant variation in annual habitat quality as confirmed in the common buzzard Buteo buteo in the same area. We measured five landscape variables, the number of neighbouring conspecifics and the relative size of the female according to large moulted feathers in 77 nesting territories, and related this to the eagles’ productivity in vole‐rich and vole‐poor years. Nesting lesser spotted eagles benefited from heterogeneous landscapes and suffered from the neighbourhood of conspecifics. There was no evidence that different‐sized females used different habitats. In general, female size was positively related to productivity in vole‐poor but not vole‐rich years, but in the presence of competitors, large size appeared to be disadvantageous. The mean annual productivity of the eagle was well correlated with that of the buzzard, both having peaks after every three years. In contrast to the buzzard, the share of voles in the eagle's diet and its habitat quality did not differ significantly between good and poor years. We concluded that despite a superficial ecological similarity to the buzzard, the lesser spotted eagle did not behave as predicted by the alternative prey hypothesis, but the study confirmed that annual variation in prey utilization and relative habitat quality are parts of the same functional response. Non‐switching to alternative prey may be related to a historical foraging strategy, used by the eagles before they spread to agricultural landscapes, since the current effects of body size strongly suggested food shortage in vole‐poor years.     

Species’ surrogacy for conservation planning: caveats from comparing the response of three arboreal rodents to habitat loss and fragmentation

The use of surrogate species in conservation planning has been applied with disappointing results on relatively large sets of species. It could still prove useful for optimizing conservation efforts when considering a small set of species with similar ecological requirements, however few field tests of this nature have been carried out. The aim of this research is to compare the response of three arboreal rodent species—the fat dormouse (Glis glis), the hazel dormouse (Muscardinus avellanarius) and the red squirrel (Sciurus vulgaris)—to habitat loss and fragmentation, with the aim of identifying priorities for conservation and evaluating possible optimization of conservation efforts under different scenarios: habitat restoration and selection of focal patches. We studied the distribution of the three species in a sample of patches in a highly fragmented landscape in central Italy, using a patch-landscape scale approach. The distribution was studied by using hair tubes, nestboxes and nocturnal surveys. The three species showed analogous responses to increasing isolation and decreasing size of habitat patches; what differed however, was the magnitude of responses. Our results show possible application of surrogacy within this restricted group of species, however several caveats arise depending on the conservation strategy and available funding. If habitat restoration is the objective, then the fat dormouse should be the target species for guiding size and isolation of patches. On the other hand, the magnitude of the differences and patch requirements for this species, question the feasibility of these conservation actions. If selection of focal patches for conservation is the objective then selecting the fat dormouse as a focal/umbrella species would overlook areas suitable for the other two species. Feasible optimisation of conservation efforts may be possible only between the red squirrel and the hazel dormouse.     

Population genetic structure and distribution of introduced American mink (<Emphasis Type="Italic">Mustela vison</Emphasis>) in Spain,based on microsatellite variation

The population genetic structure of an invasive species in Spain, the American mink (Mustela vison), was investigated using microsatellite DNA markers. This semi-aquatic carnivore, originating from North America, was imported into Europe for fur farming since the beginning of the 20th century. Due to massive escapes, farm damages, deliberate releases and/or accidents, feral mink populations were established in the aquatic ecosystems of many European countries, including Spain. We genotyped 155 American mink originating from the Spanish regions Basque Country, Catalonia, Castilla-Leon, Aragon, Valencia and Galicia using 10 polymorphic microsatellite loci to highlight population genetic structure, distribution and dispersal. M. vison populations in Spain appear differentiated and not yet connected by gene flow. Bayesian clustering analyses and spatial analyses of molecular variance detected four inferred clusters, overall coinciding with the sampled geographical localities. Preliminary testing shows moderate to large estimated effective population sizes. Molecular analyses result useful to provide baseline data for further research on the evolution of invasive mink populations, as well as support local management strategies and indirectly benefit the conservation of threatened species in Spain, such as the endangered European mink (Mustela lutreola), and the polecat (Mustela putorius), which share the habitat with the American mink. This paper is dedicated to the memory of Xavier Domingo-Roura.     

Climate,landscape, habitat,and woodland management associations with hazel dormouse Muscardinus avellanarius population status

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Serologic survey for selected viral pathogens in free-ranging endangered European mink (Mustela lutreola) and other mustelids from south-western France

To investigate the possible role of selected pathogens in the decline of endangered European mink (Mustela lutreola) populations and the potential for these pathogens to affect mink survival, a serologic survey was conducted using serum samples collected from March 1996 to March 2003 in eight departments of south-western France. In total, 481 free-ranging individuals of five mustelid species (including the European mink) were tested. Sympatric mustelids can serve as sentinels to determine the presence of antibodies to viruses in the study area that could potentially infect mink. Antibodies to Canine distemper virus (CDV) were detected in all species; 9% of 127 European mink, 20% of 210 polecats (Mustela putorius), 5% of 112 American mink (Mustela vison), 33% of 21 stone marten (Martes foina) and 5% of 20 pine marten (Martes martes). Antibody prevalence was significantly higher in stone marten and polecats, possibly because their ranges overlap more closely with that of domestic species than that of the other species tested. Antibodies to Canine adenovirus were detected in all species but the pine marten; antibody prevalence estimates ranging from 2% to 10%. Antibodies to canine parainfluenza virus were detected in 1% of European mink, 1% of American mink and 5% of tested polecats but were not detected in Martes species. Antibodies to Rabies virus (RV) were detected in three animals, possibly because of interspecies transmission of bat lyssaviruses as the sampling area is considered to be free of RV, or to a lack of test specificity, as antibody titers were low. The high antibody prevalence to potentially lethal CDV suggests that this pathogen could have significant effects on the free-ranging populations and has implications for the conservation efforts for the endangered European mink.     

Habitat requirements of Eurasian pine marten <Emphasis Type="Italic">Martes martes</Emphasis> in a Mediterranean environment

Evaluating presence and habitat requirements of small carnivores is essential for their conservation. The Eurasian pine marten Martes martes, often described as a habitat specialist associated primarily with forest habitats, has been recently found to live even in patchily wooded country and in shrublands. We evaluated the environmental factors that determine the distribution of the pine marten in a Mediterranean landscape on the island of Sardinia (central Italy). Camera trapping sessions and scat surveys were carried out to assess the presence of the species, then a potential distribution model was developed using ecological niche factor analysis (ENFA), which requires only presence data. The pine marten selected highest altitudes, shrublands, rocky areas, and woodlands, and avoided urban areas and arable lands. Our results indicate that pine marten distribution in our study area is constrained by these variables. The ENFA analysis provided important clues about the distribution range of M. martes and its preferential environmental conditions, updating knowledge of its ecological requirements in Italy.     

Genetic variability and structure of the water vole Arvicola amphibius across four metapopulations in northern Norway

Water vole Arvicola amphibius populations have recently experienced severe decline in several European countries as a consequence of both reduction in suitable habitat and the establishment of the alien predator American mink Neovison vison. We used DNA microsatellite markers to describe the genetic structure of 14 island populations of water vole off the coast of northern Norway. We looked at intra‐ and inter‐population levels of genetic variation and examined the effect of distance among pairs of populations on genetic differentiation (isolation by distance). We found a high level of genetic differentiation (measured by F_ST) among populations overall as well as between all pairs of populations. The genetic differentiation between populations was positively correlated with geographic distance between them. A clustering analysis grouped individuals into 7 distinct clusters and showed the presence of 3 immigrants among them. Our results suggest a small geographic scale for evolutionary and population dynamic processes in our water vole populations.     

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.     

Long‐distance dispersal of non‐native pine bark beetles from host resources

1. Dispersal and host detection are behaviours promoting the spread of invading populations in a landscape matrix. In fragmented landscapes, the spatial arrangement of habitat structure affects the dispersal success of organisms. 2. The aim of the present study was to determine the long distance dispersal capabilities of two non‐native pine bark beetles (Hylurgus ligniperda and Hylastes ater) in a modified and fragmented landscape with non‐native pine trees. The role of pine density in relation to the abundance of dispersing beetles was also investigated. 3. This study took place in the Southern Alps, New Zealand. A network of insect panel traps was installed in remote valleys at known distances from pine resources (plantations or windbreaks). Beetle abundance was compared with spatially weighted estimates of nearby pine plantations and pine windbreaks. 4. Both beetles were found ≥25 km from the nearest host patch, indicating strong dispersal and host detection capabilities. Small pine patches appear to serve as stepping stones, promoting spread through the landscape. Hylurgus ligniperda (F.) abundance had a strong inverse association with pine plantations and windbreaks, whereas H. ater abundance was not correlated with distance to pine plantations but positively correlated with distance to pine windbreaks, probably reflecting differences in biology and niche preferences. Host availability and dispersed beetle abundance are the proposed limiting factors impeding the spread of these beetles. 5. These mechanistic insights into the spread and persistence of H. ater and H. ligniperda in a fragmented landscape provide ecologists and land managers with a better understanding of factors leading to successful invasion events, particularly in relation to the importance of long‐distance dispersal ability and the distribution and size of host patches.