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A species’ potential distribution can be modelled adequately only if no factor other than habitat availability affects its occurrences. Space use by stone marten Martes foina is likely to be affected by interspecific competition with the strictly related pine marten Martes martes, the latter being able to outcompete the first species in forested habitats. Hence, to point out the environmental factors which determine the distribution and density of the stone marten, a relatively understudied mesocarnivore, we applied two non-invasive survey methods, camera-trapping and faecal-DNA based genetic analysis, in an Alpine area where the pine marten was deemed to be absent (Val Grande National Park N Italy). Camera trapping was conducted from October 2014 to November 2015, using up to 27 cameras. Marten scats were searched for between July and November 2015 and, to assess density, in spring 2017. Species identification was accomplished by a PCR-RFLP method, while 17 autosomal microsatellites were used for individual identification. The stone marten occurred in all available habitats (83% of trapping sites and 73.2% of scats); nonetheless, habitat suitability, as assessed using MaxEnt, depended on four major land cover variables—rocky grasslands, rocks and debris, beech forests and chestnut forests—, martens selecting forests and avoiding open rocky areas. Sixteen individuals were identified, of which 14 related to each other, possibly forming six different groups. Using capwire estimators, density was assessed as 0.95 (0.7–1.3) ind/km2. In the study area, the widespread stone marten selected forested areas, attaining density values like those reported for the pine marten in northern Europe and suggesting that patterns of habitat selection may depend on the relative abundance of the two competing martens.

To counteract the negative effects of forest fragmentation on wildlife, it is crucial to maintain functional ecological networks. We identified the ecological networks for 2 mammals with very different degrees of forest specialization, the European badger Meles meles and the Roe deer Capreolus capreolus, by differentiating 4 agroforestry elements as either nodes or connectivity elements, and by defining the distance that provides the functional connectivity between fragments. Species occurrence data were collected in a wide agroecosystem in northern Italy. To test the role of hedgerows, traditional poplar cultivations, short rotation coppices, and reforestations as ecological network elements for the 2 species we applied the method of simulated species perceptions of the landscape (SSPL), comparing the ability of different SSPLs to explain the observed species distribution. All analyses were repeated considering different scenarios of species movement ability through the matrix. Model outputs seem to show that the specialist and highly mobile Roe deer has the same movement ability throughout the matrix (2 km) as the European badger, a smaller, but generalist species. The ecological network identified for the European badger was widespread throughout the area and was composed of woodlands, poplar cultivations and hedgerows as nodes and short rotation coppices as connectivity elements. Conversely, the ecological network of the Roe deer was mostly limited to the main forest areas and was composed of woodlands, poplar cultivations and reforestations as nodes and short rotation coppices and hedgerows as connectivity elements. The degree of forest specialization strongly affects both species perception of habitat and movement ability throughout the matrix, regardless of species size. This has important implications for species conservation.

The focal species approach claims that a landscape managed for the conservation of a set of focal species, each of which identified as the most threatened by specific processes, also protects all the other species. We investigated the effects of two practical issues of this approach: the problems with identifying the species most affected by threatening processes, which often only target the most area-limited species, and the disregard for the different spatial scales at which processes affect different species. We focused on a fragmented landscape in Northern Italy and selected the most area-limited (Capreolus capreolus) and dispersal-limited (Muscardinus avellanarius) mammal species. We mapped and overlapped the suitable areas for the two species considering 2 suitability scenarios. We then evaluated whether the area-limited species was more effective as a surrogate for the dispersal-limited species, or the opposite held true (a surrogate is a species able to cover at least 50% of the area and the number of patches suitable for another species). Moreover, we evaluated if buffering the suitable areas for the two species with 4 buffer sizes affected their ability as surrogates. Neither the area-limited, nor the dispersal-limited species was found to be an effective surrogate for the other species because of the very different distribution patterns of their suitable areas. Conversely, when buffers around suitable areas were designed, the dispersal-limited species acted as a surrogate for the area-limited species in 7 out of 8 cases (2 suitability scenarios per 4 buffer sizes), while the area-limited species was a surrogate in only one case. Using area-limited species as focal species may thus be detrimental and lead to conservation plans unable to protect species for which the area is not the key factor affecting the distribution pattern. Conversely, when the suitable areas are buffered, dispersal-limited species could become effective focal species.