Genetic diversity in clustered colonies of an Antarctic marine mesopredator: a role for habitat quality?

Genetic structure may be highly variable across seabird species, and particularly among those that are distributed over large geographical areas. The Adélie penguin (Pygoscelis adeliae) is a numerically dominant Antarctic seabird that is considered to be a key species in coastal ecosystems. Since the Last Glacial Maximum, penguin colonization of the Antarctic coastline occurred at varying geographical and temporal scales, contributing to an incomplete understanding of how modern colonies relate to each other at local or regional scales. We assessed the population genetic structure of Adélie penguins (n = 86 individuals) from three adjacent colonies along the Victoria Land coast using molecular genetic markers (i.e. seven microsatellite loci isolated through next-generation sequencing). Our results indicate meta-population dynamics and possibly relationships with habitat quality. A generally low genetic diversity (Nei's index: 0.322–0.667) was observed within each colony, in contrast to significant genetic heterogeneity among colonies (pairwise FST = 0.071–0.148), indicating that populations were genetically structured. Accordingly, an assignment test correctly placed individuals within the respective colonies from which they were sampled. The presence of inter-colony genetic differentiation contrasts with previous studies on this species that showed a lack of genetic structure, possibly due to higher juvenile or adult dispersal. Our sampled colonies were not panmictic and suggest a lower migration rate, which may reflect relatively stable environmental conditions in the Ross Sea compared to other regions of Antarctica, where the ocean climate is warming

Food habits of wolves and selection of wild ungulates in a prey-rich Mediterranean coastal area

Large carnivores are increasing throughout the western Holarctic, re-colonising large parts of their former ranges. Ecological (e.g., predator-prey relationships) and socio-economic (e.g., livestock depredation) consequences of this process need to be monitored to identify suitable management/conservation actions. We studied food habits and selection of main prey by wolves in a Mediterranean protected coastal area (Uccellina Hills in the Maremma Regional Park, c. 70 km2, central Italy, May 2016- April 2018), including sclerophyllic scrubwood, pinewood, wetlands and mixed rural-wood habitats. Potential prey include wild boar, fallow deer and roe deer (c. 25–30 individuals/100 ha, in summer, all species together), livestock (mainly cattle and sheep, c. 20 heads/100 ha, overall) and several species of meso-mammals. Overall, wild ungulates dominated the diet (c. 90% of absolute occurrence, relative occurrence or volume), with the fallow deer being the main prey (absolute occurrence, AO: 55%; relative occurrence, RO: 42%; estimated volume, V: 44%) followed by the wild boar (AO: 48%; RO: 36% V: 33%). Livestock was rarely used (2%, both AO and V); the coypu (AO: 8%; RO: 6%; V: 6%) was another important food item. Fallow deer and wild boar dominated summer diet, whereas the use of alternative prey increased in winter. Fallow deer were selected, wild boar were used according to their availability, whereas roe deer were used less than availability. Prey selection was probably driven by the greater accessibility and detectability of fallow deer, which are gregarious and attended mainly open habitats on lower ground, in respect to wild boar/roe deer. Most likely, availability of a diverse spectrum of meso-large prey and a comparatively lower accessibility of livestock were key-factors to limit livestock consumption.publishe

Splitting hairs: how to tell hair of hares apart for predator diet studies

Hares are a major prey for many carnivorous vertebrates worldwide. Their occurrence in the diet of predators is mostly assessed through the analysis of indigested remains (especially hair) in faeces or pellets. In Italy, four hare species are present, locally occurring in sympatry, and several studies confirmed they are preyed upon by 15 carnivorous vertebrates, overall. A reliable identification of hare species in their diet is only possible if specific diagnostic keys of their hair are available. To provide diagnostic features of the four Italian hare species, we collected 218 hair samples from 37 individuals belonging to 13 hare populations. Samples were measured and analysed at the microscope; five indices were assessed. Hair indices of morphology differed significantly across the four species, both in the cortex and in medulla structure. Species discrimination through hair may be crucial especially if the range overlap among hare species will increase, due to environmental/climatic changes and/or human management actions (e.g. restocking)

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