Estimating wild boar density and rooting activity in a Mediterranean protected area

Spatio-temporal interactions between the red fox and the wolf in two contrasting European landscapes

Relationships among carnivore species are complex, potentially switching from competition to facilitation on a context-dependent basis. Negative associations are predicted to increase with latitude, due to limited resources emphasising competition and/or intra-guild predation. Accordingly, a stronger negative correlation between large- and meso-carnivore abundances should be expected at higher latitudes, with a substantial spatio-temporal partitioning favouring interspecific coexistence. Human presence may influence spatio-temporal relationships between (meso)carnivore species, as it can be perceived as a risk factor, but anthropogenic food can also provide an important additional food resource. Using camera-trap data, we studied the spatio-temporal associations between two of the most widespread carnivores in Europe, i.e., the red fox and wolf. We compared their monthly/daily spatio-temporal partitioning between two different landscapes: Białowieża Primeval Forest (Poland) and the Mediterranean Maremma Regional Park (Italy). We predicted a stronger interspecific partitioning, as well as more attraction of red foxes to humans in the northern site (Poland). Temporal activity patterns of the two carnivores overlapped in both sites, and their detection rates were positively associated, even though in weaker way in Poland. We observed a positive spatial association of red foxes with human activity in Białowieża, but not in Maremma. This association occurred only at a monthly temporal scale and disappeared at a daily scale, suggesting some disturbance in the shorter term. Our results provided partial support to our predictions and suggest that, despite the ecological differences between our study areas, only weak differences in wolf-fox relations were observed, suggesting that red fox responses to wolves may be relatively comparable over large spatial scales.

Integrating spatial and ecological information into comprehensive biodiversity monitoring on agricultural land

Biodiversity loss on agricultural land is a major concern. Comprehensive monitoring is needed to quantify the ongoing changes and assess the effectiveness of agri-environmental measures. However, current approaches to monitoring biodiversity on agricultural land are limited in their ability to capture the complex pattern of species and habitats. Using a real-world example of plant and habitat monitoring on Swiss agricultural land, we show how meaningful and efficient sampling can be achieved at the relevant scales. The multi-stage sampling design of this approach uses unequal probability sampling in combination with intermediate small-scale habitat sampling to ensure broad representation of regions, landscape types, and plant species. To achieve broad coverage of temporary agri-environmental measures, the baseline survey on permanent plots is complemented by dynamic sampling of these specific areas. Sampling efficiency and practicality are ensured at all stages of sampling through modern sampling techniques, such as unequal probability sampling with fixed sample size, self-weighting, spatial spreading, balancing on additional information, and stratified balancing. In this way, the samples are well distributed across ecological and geographic space. Despite the high complexity of the sampling design, simple estimators are provided. The effects of stratified balancing and clustering of samples are demonstrated in Monte Carlo simulations using modelled habitat data. A power analysis based on actual survey data is also presented. Overall, the study could serve as a useful example for improving future biodiversity monitoring networks on agricultural land at multiple scales.

Interactions between carnivore species: limited spatiotemporal partitioning between apex predator and smaller carnivores in a Mediterranean protected area

BACKGROUND

There is need of information on ecological interactions that keystone species such as apex predators establish in ecosystems recently recolonised. Interactions among carnivore species have the potential to influence community-level processes, with consequences for ecosystem dynamics. Although avoidance of apex predators by smaller carnivores has been reported, there is increasing evidence that the potential for competitive-to-facilitative interactions is context-dependent. In a protected area recently recolonised by the wolf Canis lupus and hosting abundant wild prey (3 ungulate species, 20-30 individuals/km², together), we used 5-year food habit analyses and 3-year camera trapping to (i) investigate the role of mesocarnivores (4 species) in the wolf diet; (ii) test for temporal, spatial, and fine-scale spatiotemporal association between mesocarnivores and the wolf.

RESULTS

Wolf diet was dominated by large herbivores (86% occurrences, N = 2201 scats), with mesocarnivores occurring in 2% scats. We collected 12,808 carnivore detections over > 19,000 camera trapping days. We found substantial (i.e., generally ≥ 0.75, 0-1 scale) temporal overlap between mesocarnivores-in particular red fox-and the wolf, with no support for negative temporal or spatial associations between mesocarnivore and wolf detection rates. All the species were nocturnal/crepuscular and results suggested a minor role of human activity in modifying interspecific spatiotemporal partitioning.

CONCLUSIONS

Results suggest that the local great availability of large prey to wolves limited negative interactions towards smaller carnivores, thus reducing the potential for spatiotemporal avoidance. Our study emphasises that avoidance patterns leading to substantial spatiotemporal partitioning are not ubiquitous in carnivore guilds.

Analysis of Scat for Gut Microbiome Identification in Wolves from a Mediterranean and an Alpine Area

The gut microbiome can play a fundamental role in several processes associated with an organism’s ecology, and research on the microbiota of wild animals has flourished in the last decades. Microbiome composition can vary across and within species according to taxonomy and environmental variability, including the availability of food resources. Species with a large distribution may exhibit spatial patterns acting at local/regional scales. We considered one of the most widespread and ecologically important predators in the world, i.e., the grey wolf Canis lupus, for which microbiome data is unduly limited. We studied four packs in different ecological conditions in Italy—two packs from a Mediterranean coastal area and two packs from an Alpine range—using an amplicon sequencing barcoding approach. Overall, our results are consistent with food habits entailing a diet largely based on wild prey and agree with findings obtained on other species of canids. If confirmed through a larger sample, they would support the hypothesis of an influence of the shared evolutionary history across canids on the composition of the gut microbiome. Some emerging differences were observed among packs in terms of species composition (Jaccard) and diversity, providing partial support to recent indications on pack identity as a significant determinant of microbiome composition. These results should be considered preliminary results of gut microbiome composition in our study areas.

Spatio-temporal patterns of the European wildcat in a Mediterranean coastal area

Like most small felids, the European wildcat Felis silvestris is a rather elusive species, poorly detectable in the wild, due to several aspects of its biology. Camera trapping can represent a suitable tool to understand temporal activity patterns and habitat preferences of such elusive species. We used intensive camera trapping over two full years to investigate spatio-temporal patterns of the wildcat in a Mediterranean coastal protected area (Maremma Regional Park, central Italy). At the seasonal scale, the wildcat showed a marked twilight activity in summer and winter (mating period), and nocturnal activity in autumn. Conversely, a peak of activity during the day, i.e., in broad daylight, was reported in spring. Reproductive females may limit their nocturnal movements in spring to increase protection from predators to their kittens at the den, although further data are required to support this conclusion. At seasonal, semestral, and yearly temporal scales, the frequency of wildcat detections increased along with availability of shrubwood. These results emphasise the importance for this small felid of areas with dense vegetation cover (Mediterranean maquis and shrubwood, in our study area). Areas densely covered with shrubby vegetation are expected to provide benefits to this elusive small cat in terms of reduced human disturbance (included tourists), availability of prey (e.g., small mammals), as well as shelter, essential to ensure protection towards potential larger predators.

Alien versus alien: spatiotemporal overlaps among introduced ungulates in a Mediterranean island ecosystem

Assessing the spatiotemporal behaviour of alien species is pivotal to designing effective management plans. Interspecific niche partitioning among ungulates is reported as a strategy to avoid direct interactions. The Mediterranean mouflon and wild boar are two ungulates introduced to Elba island for hunting and aesthetic purposes. We used intensive camera trapping to test whether species occupancy and temporal activity rhythms would vary in response to the presence or absence of the co-occurring species through multi-species occupancy modelling. Our findings report a lack of spatial and temporal segregation between the two species for the late spring–summer and late summer–autumn seasons. In contrast, results for the winter–early spring period suggest that spatial partitioning between wild boar and mouflon is present in areas with high artificial cover (e.g., paved roads). Animals may indeed exploit roads to move more rapidly in search of food; however, their occurrence in these areas seems to be influenced by the presence of the other species.

Wild Boar Effects on Fungal Abundance and Guilds from Sporocarp Sampling in a Boreal Forest Ecosystem

Simple Summary

Native wild boar populations are expanding across Europe, causing concern due to their significant soil disturbances and considerable impact on ecosystems. However, little is known about how wild boar activities affect other organisms. This study investigated the effects of wild boars on the abundance of fungal sporocarps and their respective fungal guilds (i.e., symbiotic, saprophytic and pathogenic) in boreal forests in Sweden. We selected 11 forested sites in central Sweden: six with and five without the presence of wild boar. We determined the presence or absence of wild boar and rooting intensity at each site. Simultaneously, we investigated the abundance of fungal sporocarps and their fungal guilds. We found that the presence of wild boar and rooting intensity were associated with the abundance of fungal sporocarps. Wild boar rooting was positively correlated with saprotrophic fungi and negatively with symbiotic fungi. Pathogenic fungi were more abundant in plots with no rooting but in the presence of wild boar. We conclude that wild boar represents a recurrent disturbance agent and, based on sporocarp abundance, could eventually affect entire fungal populations.

Abstract

Native wild boar (Sus scrofa) populations are expanding across Europe. This is cause for concern in some areas where overabundant populations impact natural ecosystems and adjacent agronomic systems. To better manage the potential for impacts, managers require more information about how the species may affect other organisms. For example, information regarding the effect of wild boar on soil fungi for management application is lacking. Soil fungi play a fundamental role in ecosystems, driving essential ecological functions; acting as mycorrhizal symbionts, sustaining plant nutrition and providing defense; as saprotrophs, regulating the organic matter decomposition; or as plant pathogens, regulating plant fitness and survival. During autumn (Sep–Nov) 2018, we investigated the effects of wild boar (presence/absence and rooting intensity) on the abundance (number of individuals) of fungal sporocarps and their functional guilds (symbiotic, saprotrophic and pathogenic). We selected eleven forested sites (400–500 × 150–200 m) in central Sweden; six with and five without the presence of wild boar. Within each forest, we selected one transect (200 m long), and five plots (2 × 2 m each) for sites without wild boar, and ten plots for sites with boars (five within and five outside wild boar disturbances), to determine the relationship between the intensity of rooting and the abundance of sporocarps for three fungal guilds. We found that the presence of wild boar and rooting intensity were associated with the abundance of sporocarps. Interestingly, this relationship varied depending on the fungal guild analyzed, where wild boar rooting had a positive correlation with saprophytic sporocarps and a negative correlation with symbiotic sporocarps. Pathogenic fungi, in turn, were more abundant in undisturbed plots (no rooting) but located in areas with the presence of wild boar. Our results indicate that wild boar activities can potentially regulate the abundance of fungal sporocarps, with different impacts on fungal guilds. Therefore, wild boar can affect many essential ecosystem functions driven by soil fungi in boreal forests, such as positive effects on energy rotation and in creating mineral availability to plants, which could lead to increased diversity of plants in boreal forests.

Habitat correlates of wild boar density and rooting along an environmental gradient

In wild ungulates, habitat choice usually is influenced by foraging constraints and predator avoidance, potentially leading to spatial variation of population density (e.g., greater densities in food rich or safer habitats). Assessing habitat-correlates of abundance and foraging activity in turn is important in understanding determinants of distribution. We assessed habitat correlates of presence, density, and rooting, for wild boar Sus scrofa, the most widespread ungulate in the world, in six protected areas of central Italy. We worked along an altitudinal gradient ranging from the coast to mountains, in late spring-summer 2019. We surveyed 617 sampling plots randomly placed onto study areas with tessellation stratified sampling, where we used fecal counts to estimate wild boar density and visually estimated the proportion of rooted area. Overall estimates of density and rooting (± standard error) varied from 3.5 ± 2.0 to 17.9 ± 5.4 individuals/km2 and from 1.4 ± 0.8% to 10.9 ± 1.1% of rooted ground. Density and rooting showed a moderate yet nonsignificant correlation across sites. Probability of presence, abundance, and rooting in sampling plots were higher in ecotone habitats (transition habitats between wooded and open areas). Topography did not influence boar presence or local abundance. Rooting increased with decreasing slope and rock cover, as well as increasing elevation, possibly due to soil supporting forage of higher nutritional quality. Our results support the importance of ecotone habitats for wild boar, emphasizing the role of these transitional areas in the period of nursing/weaning of offspring, as well as when crops are actively growing. Differences in overall estimates of rooting across study sites may depend on site-specific features (soil moisture and availability of alternative food resources). Future studies should test the correlation between inter-annual differences of rooting and changes in population density. Notwithstanding the latter, we identified significant ecological drivers of wild boar density and rooting activity.

Recolonizing wolves and opportunistic foxes: interference or facilitation?

The mechanisms of interactions among carnivore species range from facilitation (mainly through increased availability of prey carcasses) to competition. We assessed the potential for facilitative/competitive interactions between the two most widespread carnivores in the world, the wolf and the red fox, in a prey-rich area recently recolonized by the apex predator. One could expect that the superior competitor would ecologically suppress the inferior one, leading to avoidance of the former by the latter. In a Mediterranean coastal area (2017–2018), we assessed spatiotemporal and dietary interspecific overlap and investigated whether the recovery of wolves affected food habits of foxes. Spatiotemporal overlap was extensive (0.84–0.89). Wild ungulates were the staple of the wolf diet (~88–90%); foxes used mainly invertebrates and fruits (~78%), with ungulates being a substantial food category (13% of diet; 66% of occurrences among vertebrate prey). Interspecific dietary overlap was low (0.23), but extensive (0.89) for vertebrate prey. In comparison to a preceding wolf-free period, the volume and occurrence of large mammals in the diet of foxes showed a 2.8- to 3.5-fold increase. Apparently, foxes did not avoid wolves, which provided additional food to the foxes as prey leftovers. In a rich community, the presence of wolves may increase the food spectrum of foxes. Temporal variation of facilitation vs. competition should be assessed in relationship to spatiotemporal changes of predator–prey numbers.