Stone marten (Martes foina) habitat in a Mediterranean ecosystem: effects of scale, sex, and interspecific interactions

Spatial distribution pattern of mustelids in the eastern edge of the Qinghai-Tibet Plateau

Evolutionary theory predicts that the species of an evolutionarily successful taxon would not overlap in spatial distribution. To test the prediction, we document our research on the spatial associations of mustelids, an evolutionarily successful group of order Carnivore, using infrared camera trap data on species distribution collected from the national nature reserves (NNRs) of Liancheng, Wolong, Tangjiahe and Heizhugou in China in 2017-2021. Data showed seven mustelid species occurring in the study area, including Arctonyx collaris, Meles leucurus, Martes foina, Martes flavigula, Mustela altaica, Mustela nivalis and Mustela sibirica. Following Ricklef's definition of biological community, we identified five networks of species associations. The mustelids occurred in the networks. Species from the same genus, such as M. foina and M. flavigula, stayed in different networks to avoid competition owing to similar feeding habits or habitat preferences. Species with different feeding habits or habitat preferences either occurred in different networks, such as M. altaica and M. flavigula, or coexisted in the same networks but avoided direct spatial associations, such as M. foina and A. collaris. Asymmetrical associations were found between different genera, such as M. foina and M. altaica, or between different subfamilies, such as M. flavigula and A. collaris. These associations may be attributed to interspecific killing or seed dispersal. However, these associations accounted for only a small proportion and would not impact the species diversity of Mustelidae. It is thus concluded that the prediction is supported by our research findings and that spatial avoidance may be the biogeographic strategy of maintaining the species diversity of the family. We also found that the well protection of the mustelids may benefit the overall biodiversity conservation in Heizhugou, an NNR that has experienced severe deforestation.

Do Mesocarnivores Respond to the Seasonality in Management Practices in an Agroforestry Landscape?

In the Mediterranean, we find a mosaic of natural and cultural landscapes, where a variety of forest management practices created intermediate disturbance regimes that potentially increased biodiversity values. Nonetheless, it is essential to understand the species' long-term response to the dynamic management in agroecosystems, since the species tolerance to disturbance can change throughout the life cycle. Mammalian carnivores can be sensitive to human disturbance and are an essential part of ecosystems due to their regulatory and community structuring effects. We investigated the spatial response of five mesocarnivores species to spatially- and temporally- varying management practices in an agroforestry landscape. More specifically, we assessed the mesocarnivores' temporal changes in space use by implementing multi-season occupancy models in a Bayesian framework, using seasonal camera-trapping surveys for a 2-year period. All species had a weak response of local extinction to forestry management and livestock grazing pressure. For forest-dwelling species, occupancy was higher where productivity of perennial vegetation was high, while colonization between seasons was positively associated with vegetation cover. For habitat generalist species, we found that occupancy in the wet season increased with the distance to cattle exclusion plots. Most of these plots are pine stands which are subject to forestry interventions during winter. During the 2-year period we found seasonal fluctuations in occupancy for all species, with an overall slight decrease for three mesocarnivore species, while for the two forest-dwelling species there was an increase in occupancy between years. The weak species response to management practices supports the importance of traditional management for upholding a diverse mesocarnivore community in agroforestry systems but could also reflect these species' ecological plasticity and resilience to disturbance.

Mesocarnivore community structure under predator control: Unintended patterns in a conservation context

Across the Mediterranean, conservation programmes often operate concomitantly with hunting interests within game-lands. Carnivore guilds lie at the interface between contrasting management goals, being simultaneously fundamental components of ecosystems and targets of predator control to reduce predation on game species. Here, we evaluate the composition and spatial structure of a mesocarnivore community in a protected area of Southeast Portugal, with high economic investment in conservation and significant hunting activity. Between June and August 2015, we deployed 77 camera-traps across a ~80 km2 area. We report on interspecific disparities in mesocarnivore occupancy and associated environmental determinants. Contrasting occupancy states suggest an unbalanced community, biased towards the widespread occurrence of the red fox Vulpes vulpes ([Formula: see text]) compared to other species (stone marten Martes foina, European badger Meles meles, Egyptian mongoose Herpestes ichneumon, common genet Genetta genetta, and Eurasian otter Lutra lutra) exhibiting spatially-restricted occupancy patterns ([Formula: see text]). The feral cat Felis silvestris catus was the exception ([Formula: see text]) and, together with the stone marten, exhibited a positive association with human settlements. These findings are consistent with theoretical predictions on how mesocarnivore communities are shaped by the effects of non-selective predator control, paradoxically favouring species with higher population growth rates and dispersal abilities, such as the red fox. Our results reinforce the need to understand the role of predator control as a community structuring agent with potential unintended effects, while exposing issues hindering such attempts, namely non-selective illegal killing or biased/concealed information on legal control measures.

Assessing Genetic Structure in Common but Ecologically Distinct Carnivores: The Stone Marten and Red Fox

The identification of populations and spatial genetic patterns is important for ecological and conservation research, and spatially explicit individual-based methods have been recognised as powerful tools in this context. Mammalian carnivores are intrinsically vulnerable to habitat fragmentation but not much is known about the genetic consequences of fragmentation in common species. Stone martens (Martes foina) and red foxes (Vulpes vulpes) share a widespread Palearctic distribution and are considered habitat generalists, but in the Iberian Peninsula stone martens tend to occur in higher quality habitats. We compared their genetic structure in Portugal to see if they are consistent with their differences in ecological plasticity, and also to illustrate an approach to explicitly delineate the spatial boundaries of consistently identified genetic units. We analysed microsatellite data using spatial Bayesian clustering methods (implemented in the software BAPS, GENELAND and TESS), a progressive partitioning approach and a multivariate technique (Spatial Principal Components Analysis-sPCA). Three consensus Bayesian clusters were identified for the stone marten. No consensus was achieved for the red fox, but one cluster was the most probable clustering solution. Progressive partitioning and sPCA suggested additional clusters in the stone marten but they were not consistent among methods and were geographically incoherent. The contrasting results between the two species are consistent with the literature reporting stricter ecological requirements of the stone marten in the Iberian Peninsula. The observed genetic structure in the stone marten may have been influenced by landscape features, particularly rivers, and fragmentation. We suggest that an approach based on a consensus clustering solution of multiple different algorithms may provide an objective and effective means to delineate potential boundaries of inferred subpopulations. sPCA and progressive partitioning offer further verification of possible population structure and may be useful for revealing cryptic spatial genetic patterns worth further investigation.

Spatiotemporal variation in resource selection of servals: insights from a landscape under heavy land-use transformation

Changes in habitat composition and structure along natural agricultural habitat gradient affect spatial ecology of carnivores at both intraspecific and interspecific levels. An important prerequisite for the conservation and management of habitat specialists is a sound understanding of how they use indigenous habitats within fragmented landscapes. We present the 1st comprehensive study on home range, overlap, and resource selection of 16 radiocollared servals ( Leptailurus serval ) in the Drakensberg Midlands, South Africa. Servals (11 males and 5 females) were livetrapped and radiotracked between May 2013 and August 2014 covering 4 seasons (winter, spring, summer, and autumn). Mean annual home range estimates (95% and 50% fixed kernel [FK], respectively) for males (38.07 km 2 ; 8.27 km 2 ) were generally larger than for females (6.22 km 2 ; 1.04 km 2 ). Although male core ranges varied slightly in spring, overall serval home ranges were stable across seasons. There was considerable intersexual home range overlap (> 85%), whereas intrasexual overlap was rare (< 10%). Home range size decreased with increase in age and less availability of wetland, while it increased in males at both levels (95% FK and 50% FK). For both sexes, Manley’s selection index indicated that natural habitats including wetlands and forest with bushland ranked higher than all other habitat classes. However, forested habitat was used approximately 2 times more frequently by males than females whereas cropland was avoided by both sexes. Overall, wetlands were ranked highest, followed by forest with bushland, grassland, plantations, and cropland in terms of serval resources selection. Our results emphasize that natural habitats, mainly wetlands and forests with bushland, are important predictors of spatiotemporal habitat use of servals in the agricultural mosaics of South Africa.

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.

Inferring Population Genetic Structure in Widely and Continuously Distributed Carnivores: The Stone Marten (Martes foina) as a Case Study

The stone marten is a widely distributed mustelid in the Palaearctic region that exhibits variable habitat preferences in different parts of its range. The species is a Holocene immigrant from southwest Asia which, according to fossil remains, followed the expansion of the Neolithic farming cultures into Europe and possibly colonized the Iberian Peninsula during the Early Neolithic (ca. 7,000 years BP). However, the population genetic structure and historical biogeography of this generalist carnivore remains essentially unknown. In this study we have combined mitochondrial DNA (mtDNA) sequencing (621 bp) and microsatellite genotyping (23 polymorphic markers) to infer the population genetic structure of the stone marten within the Iberian Peninsula. The mtDNA data revealed low haplotype and nucleotide diversities and a lack of phylogeographic structure, most likely due to a recent colonization of the Iberian Peninsula by a few mtDNA lineages during the Early Neolithic. The microsatellite data set was analysed with a) spatial and non-spatial Bayesian individual-based clustering (IBC) approaches (STRUCTURE, TESS, BAPS and GENELAND), and b) multivariate methods [discriminant analysis of principal components (DAPC) and spatial principal component analysis (sPCA)]. Additionally, because isolation by distance (IBD) is a common spatial genetic pattern in mobile and continuously distributed species and it may represent a challenge to the performance of the above methods, the microsatellite data set was tested for its presence. Overall, the genetic structure of the stone marten in the Iberian Peninsula was characterized by a NE-SW spatial pattern of IBD, and this may explain the observed disagreement between clustering solutions obtained by the different IBC methods. However, there was significant indication for contemporary genetic structuring, albeit weak, into at least three different subpopulations. The detected subdivision could be attributed to the influence of the rivers Ebro, Tagus and Guadiana, suggesting that main watercourses in the Iberian Peninsula may act as semi-permeable barriers to gene flow in stone martens. To our knowledge, this is the first phylogeographic and population genetic study of the species at a broad regional scale. We also wanted to make the case for the importance and benefits of using and comparing multiple different clustering and multivariate methods in spatial genetic analyses of mobile and continuously distributed species.

Inter-individual variability of stone marten behavioral responses to a highway

Efforts to reduce the negative impacts of roads on wildlife may be hindered if individuals within the population vary widely in their responses to roads and mitigation strategies ignore this variability. This knowledge is particularly important for medium-sized carnivores as they are vulnerable to road mortality, while also known to use available road passages (e.g., drainage culverts) for safely crossing highways. Our goal in this study was to assess whether this apparently contradictory pattern of high road-kill numbers associated with a regular use of road passages is attributable to the variation in behavioral responses toward the highway between individuals. We investigated the responses of seven radio-tracked stone martens (Martes foina) to a highway by measuring their utilization distribution, response turning angles and highway crossing patterns. We compared the observed responses to simulated movement parameterized by the observed space use and movement characteristics of each individual, but naïve to the presence of the highway. Our results suggested that martens demonstrate a diversity of responses to the highway, including attraction, indifference, or avoidance. Martens also varied in their highway crossing patterns, with some crossing repeatedly at the same location (often coincident with highway passages). We suspect that the response variability derives from the individual's familiarity of the landscape, including their awareness of highway passage locations. Because of these variable yet potentially attributable responses, we support the use of exclusionary fencing to guide transient (e.g., dispersers) individuals to existing passages to reduce the road-kill risk.

A comparison of locomotor performance of the semiarboreal Pacific marten (Martes caurina) and semiaquatic mustelids

The relatively long body and short limbs of mustelids allow them to exploit resources from a diversity of habitat types. This body plan also has important implications for energetics because of increased heat loss from a high surface to volume ratio and muscular support of an elongated spine. Past research suggests that dorsal flexion of the spine enables semiaquatic mustelids to be relatively economical runners at faster speeds. We evaluated locomotor performance in a semiarboreal mustelid, the Pacific marten (Martes caurina (Merriam, 1890)), and compared our results from three females and one male to those previously observed in semiaquatic mustelids. At slower speeds, when martens used a walking or trotting gait, they were less economical than predicted; at higher speeds, martens were as economical as predicted. Nonetheless, martens did not switch to a bounding gait earlier than expected based on an allometric relationship between body mass, running speed, and gait. At the highest speed, martens increased stride length and decreased stride frequency. These observations suggest that unlike the semiaquatic river otters (Lontra canadensis (Schreber, 1777)) and mink (Neovison vison (Schreber, 1777)), martens do not use spinal flexion but instead employ other adaptations that result in energy savings at high speeds.

Diet composition and feeding strategies of the stone marten (Martes foina) in a typical Mediterranean ecosystem

Stone martens (Martes foina) are documented as generalist throughout their distributional range whose diet composition is affected by food availability. We tested if this occurs and what feeding strategies it follows in a typical Mediterranean ecosystem in Central Greece by analysing contents from 106 stomachs, seasonally collected from three different habitats during 2003–2006. Seasonal variation in diet and feeding strategies was evident and linked to seasonal nutritional requirements, but possibly imposed by strong interference competition and intraguild predation. Fleshy fruits and arthropods predominated in the diet, but also mammals and birds were frequently consumed. An overall low dietary niche breadth (B_A = 0.128) indicated a fruit specialization tendency. A generalised diet occurred in spring with high individual specialisation, whereas more animal-type prey was consumed than fruits. A population specialization towards fruits was indicated during summer and autumn, whereas insects were consumed occasionally by males. In those seasons it switched to more clumped food types such as fruits and insects. In winter it selectively exploited both adult and larvae insects and partially fruits overwinter on plants. The tendency to consume particular prey items seasonally reflected both the population specialist behaviour and the individual flexibility preyed on different food resources.