Spatial ecology of the stone marten in an Alpine area: combining camera-trapping and genetic surveys

Abstract

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.

Nutritional ecology of martens (Martes foina and Martes martes) in the western Italian Alps

“…In the Lepontine Alps, where pine marten occurrence was negligible (see also Balestrieri et al, 2021), the proportional contribution of protein energy to stone marten's diet did not differ from pine martens'. The only other study which, to our knowledge, investigated the diets of both martens in an area where the stone marten was dominant in terms of relative abundance was carried out in northern Portugal, at the southwestern limit of pine marten distribution (Monterroso et al, 2016).…”

“…With the aim of comparing the diets of pine and stone martens in mountain areas of either sympatry or allopatry, we (1) carried out an extensive genetic survey for marten scats in the western Italian Alps in 2019 (Figure 1c) and (2) analyzed genotyped fecal samples collected in NE Piedmont in 2015–2017 (Figure 1a,b), as part of a study aimed at assessing the distribution of mustelids in the Val Grande National Park and neighboring areas (Lepontine Alps; Balestrieri et al, 2018). In the first area both martens are known to occur (based on museum archives and records collected in the period 1990–2010; Sindaco & Carpegna, 2010), while the pine marten is suspected to have recolonised the latter area only in the last decade (Balestrieri et al, 2021). Following Remonti et al (2016) the estimated volumes of food items used by both martens were then transformed in macronutrient energy ratios to allow the sound comparison of their feeding requirements (Gazzola & Balestrieri, 2020).…”

Occupancy data improves parameter precision in spatial capture–recapture models

“…Probably owing to the challenges involved in their individual identification, stone marten density estimates are lacking in the literature. Exceptions include Balestrieri et al (2021), who estimated 0.95 (0.7 – 1.3) individuals/km 2 in the Alpine areas of N Italy using the R package capwire (Pennell et al, 2013). To the best of our knowledge, only two studies reported stone marten density in Mediterranean region of Iberia, both in places of Extremadura (SW Spain) and estimated $$$ \hat{D}=0.24;\mathrm{SD}:0.08 $$$ and $$$ \hat{D}=0.26;\mathrm{SD}:0.14 $$$ individuals/km 2 for Valdecigüeñas (Jiménez et al, 2017) and Matachel Valley (Jiménez, Nuñez‐Arjona, et al, 2019), respectively.…”

Nutritional ecology of a prototypical generalist predator, the red fox (Vulpes vulpes)

“…Between September 2021 and February 2022, we collected 30 samples per area, selecting fresh-looking faeces to obtain amplifiable, non-degraded DNA. Following Ebert et al 57 , sample size for genetic analysis was calculated as 2.5-3 times the "assumed" number of foxes in each population and based on expected genotyping success (50%, average of previous studies [58][59][60] ). The assumed number of foxes was assessed using available home range sizes for Alpine areas (358 ha) 46 .…”