• Alpine ibex, Capra ibex, Linnaeus 1758

      Brambillla, Alice; Bassano, Bruno; Biebach, Iris; Bollmann, Kurt; Keller, Lukas; Toïgo, Carole; von Hardenberg, Achaz; University of Zurich, Gran Paradiso National Park, Swiss Federal Research Institute, Office National de la Chasse et de la Faune Sauvage, University of Chester
      In this chapter we review the current status of knowledge about Alpine ibex Capra ibex. We cover taxonomy, systematics, distribution, habitat, genetics, life history, behaviour, parasites and disease, population ecology and conservation. We conclude examining the future challenges for research and management of this species.
    • Direct and indirect causal effects of heterozygosity on fitness-related traits in Alpine ibex

      Brambilla, Alice; Biebach, Iris; Bassano, Bruno; Bogliani, Giuseppe; von Hardenberg, Achaz; Università di Pavia, Italy; University of Zurich, Switzerland; Gran Paradiso National Park, Italy; University of Chester, UK (The Royal Society, 2015-01-07)
      Heterozygosity–fitness correlations (HFCs) are a useful tool to investigate the effects of inbreeding in wild populations, but are not informative in distinguishing between direct and indirect effects of heterozygosity on fitness-related traits. We tested HFCs in male Alpine ibex (Capra ibex) in a free-ranging population (which suffered a severe bottleneck at the end of the eighteenth century) and used confirmatory path analysis to disentangle the causal relationships between heterozygosity and fitness-related traits. We tested HFCs in 149 male individuals born between 1985 and 2009. We found that standardized multi-locus heterozygosity (MLH), calculated from 37 microsatellite loci, was related to body mass and horn growth, which are known to be important fitness-related traits, and to faecal egg counts (FECs) of nematode eggs, a proxy of parasite resistance. Then, using confirmatory path analysis, we were able to show that the effect of MLH on horn growth was not direct but mediated by body mass and FEC. HFCs do not necessarily imply direct genetic effects on fitness-related traits, which instead can be mediated by other traits in complex and unexpected ways.
    • Distribution, status and recent population dynamics of Alpine ibex Capra ibex in Europe

      Brambillla, Alice; von Hardenberg, Achaz; Nelli, Luca; Bassano, Bruno; University of Zurich, University of Chester, University of Glasgow, Gran Paradiso National PArk (Wiley, 2020-04-20)
      1. Despite its recent successful and well-documented reintroduction history, a comprehensive and current update of the distribution and status of the Alpine ibex Capra ibex is lacking. As some concerns persist about its conservation, a status update appears essential for future conservation and management strategies on a large scale. 2. We provide an exhaustive update of the geographic range of the species, alongside estimates of its current abundance and population trends from 2004 to 2015. 3. We gathered census and distribution data for all the Alpine ibex colonies from management authorities and research groups that monitor them in different countries, and from the literature and publicly available reports. We produced a distribution map, reported the number of individuals observed in the most recent censuses, and estimated global, national, and local population trends using Bayesian hierarchical models. 4. Our model estimated that there were a total of 55297 Alpine ibex in the Alps in 2015 (lower 95% Credible Interval [CrI]: 51157; upper 95% CrI: 62710). The total number of individuals appears to have increased slightly over the last 10 years from the 47000-51000 estimated in previous reports. Positive population trends were observed in Switzerland and Italy, while no trend was apparent in France. For Austria, Germany, and Slovenia, there were insufficient data to estimate a trend. The slopes of the colonies’ trends were positively correlated with the year of colony foundation. 5. The geographic range of the Alpine ibex does not seem to have increased in size in recent years, although the accuracy of the spatial data varies among countries. 6. The periodic and standardised collection of census data for all colonies and a common policy of data-sharing at a European level appear essential for monitoring the global trend of this species and for planning balanced conservation and management actions.
    • Helpers influence on territory use and maintenance in Alpine marmot groups

      Pasquaretta, Cristian; Busia, Laura; Ferrari, Caterina; Bogliani, Giuseppe; Reale, Denis; von Hardenberg, Achaz; University of Pavia, Universiteé du Quebec a Montreal, Gran Paradiso National Park (2015-04-22)
      In social mammals, territory size and shape vary according to the number and strength of neighbour individuals competing for resources. Two main theories have been proposed to explain this variability: the Group Augmentation (GA) and the realized Resource Holding Potential (rRHP) hypotheses. The first states that the outcome of the interactions among groups depends on the total number of individuals in the group while the second states that only the number of animals directly involved in intergroup competition determines this outcome. We collected data on space use of individually tagged Alpine marmots ( Marmota marmota), a cooperative breeding species that overlaps part of its territory with neighbouring groups. In accordance with the rRHP hypothesis, we found that groups having higher proportion of helpers, rather than higher total number of individuals, had lower percentage of the territory overlapping with neighbouring groups and a larger area available for individual exclusive use.
    • Higher risk of gastrointestinal parasite infection at lower elevation suggests possible constraints in the distributional niche of Alpine marmots

      Zanet, Stefania; Miglio, Giacomo; Ferrari, Caterina; Bassano, Bruno; Ferroglio, Ezio; von Hardenberg, Achaz; Università di Torino; Gran Paradiso National Park; University of Chester (Public Library of Science, 2017-08-01)
      Alpine marmots Marmota marmota occupy a narrow altitudinal niche within high elevation alpine environments. For animals living at such high elevations where resources are limited, parasitism represents a potential major cost in life history. Using occupancy models, we tested if marmots living at higher elevation have a reduced risk of being infected with gastrointestinal helminths, possibly compensating the lower availability of resources (shorter feeding season, longer snow cover and lower temperature) than marmots inhabiting lower elevations. Detection probability of eggs and oncospheres of two gastro-intestinal helminthic parasites, Ascaris laevis and Ctenotaenia marmotae, sampled in marmot feces, was used as a proxy of parasite abundance. As predicted, the models showed a negative relationship between elevation and parasite detectability (i.e. abundance) for both species, while there appeared to be a negative effect of solar radiance only for C. marmotae. Site-occupancy models are used here for the first time to model the constrains of gastrointestinal parasitism on a wild species and the relationship existing between endoparasites and environmental factors in a population of free-living animals. The results of this study suggest the future use of site-occupancy models as a viable tool to account for parasite imperfect detection in ecoparasitological studies, and give useful insights to further investigate the hypothesis of the contribution of parasite infection in constraining the altitudinal niche of Alpine marmots.
    • An introduction to Phylogenetic Path Analysis

      Gonzalez-Voyer, A.; von Hardenberg, Achaz; Estación Biológica de Doñana, Gran Paradiso National Park (Springer Verlag, 2014)
      The questions addressed by macroevolutionary biologists are often impervious to experimental approaches, and alternative methods have to be adopted. The phy- logenetic comparative approach is a very powerful one since it combines a large number of species and thus spans long periods of evolutionary change. However, there are limits to the inferences that can be drawn from the results, in part due to the limitations of the most commonly employed analytical methods. In this chapter, we show how confirmatory path analysis can be undertaken explicitly controlling for non-independence due to shared ancestry. The phylogenetic path analysis method we present allows researchers to move beyond the estimation of direct effects and analyze the relative importance of alternative causal models including direct and indirect paths of influence among variables. We begin the chapter with a general introduction to path analysis and then present a step-by-step guide to phylogenetic path analysis using the d-separation method. We also show how the known statistical problems associated with non-independence of data points due to shared ancestry become compounded in path analysis. We finish with a discussion about the potential effects of collinearity and measurement error, and a look toward possible future developments.
    • Involvement of recreational anglers in the eradication of alien brook trout from high altitude lakes

      Tiberti, Rocco; Ottino, Michelle; Brighenti, Stefano; Iacobuzio, Rocco; Rolla, Matteo; von Hardenberg, Achaz; Bassano, Bruno; Gran Paradiso National Park, University of Pavia, Università degli studi di Trento, Fondazione E. Mach, Università degli Studi di Milano, Swansea University, University of Chester (Gran Paradiso National Park Agency, 2017)
      Stocking programmes for recreational angling are primarily responsible for the spread and ecological impact of introduced sh in high-altitude, originally shless lakes. In 2013, the Gran Paradiso National Park started an eradication campaign of brook trout by intensive gill-netting. Local anglers were invited to attend two angling sessions to start the eradication before gill-netting in an experimental lake, as part of an education action devoted to these critical stakeholders. The angling sessions turned out to be a valuable help for the eradication campaign and the aim of this study is to report on the outcomes of these angling sessions. Angling techniques were highly size-selective, removing a substantial part of the adult population and of the sh biomass, but their contribution to the eradication of small sh (<15cm) was irrelevant. Therefore, angling cannot completely eradicate age-structured populations. However, there is scope to use angling sessions as a support for eradication campaigns and as an emergency measure for recent sh introduc- tions. Similar actions should be considered whenever a sh eradication programme is planned. These ndings, however, do not imply a general endorsement for angling within protected areas.
    • MODIS time series contribution for the estimation of nutritional properties of alpine grassland

      Ranghetti, Luigi; Bassano, Bruno; Bogliani, Giuseppe; Polmonari, Alberto; Formigoni, Andrea; Stendardi, Laura; von Hardenberg, Achaz; Consiglio Nazionale delle Ricerche; Università di Pavia; Parco Nazionale Gran Paradiso; Università di Bologna; Università di Firenze; University of Chester (Taylor & Francis, 2017-02-17)
      Despite the Normalised Difference Vegetation Index (NDVI) has been used to make predictions on forage quality, its relationship with bromatological field data has not been widely tested. This relationship was investigated in alpine grasslands of the Gran Paradiso National Park (Italian Alps). Predictive models were built using remotely sensed derived variables (NDVI and phenological information computed from MODIS) in combination with geo-morphometric data as predictors of measured biomass, crude protein, fibre and fibre digestibility, obtained from 142 grass samples collected within 19 experimental plots every two weeks during the whole 2012 growing season. The models were both cross-validated and validated on an independent dataset (112 samples collected during 2013). A good predictability ability was found for the estimation of most of the bromatological measures, with a considerable relative importance of remotely sensed derived predictors; instead, a direct use of NDVI values as a proxy of bromatological variables appeared not to be supported.
    • One strategy doesn’t fit all: determinants of urban adaptation in mammals

      Santini, Luca; González‐Suárez, Manuela; Russo, Danilo; Gonzalez‐Voyer, Alejandro; von Hardenberg, Achaz; Ancillotto, Leonardo; Radboud University; University of Reading; University of Napoli; Universidad Nacional Autónoma de México; University of Chester (Wiley, 2018-12-20)
      Urbanisation exposes wildlife to new challenging conditions and environmental pressures. Somemammalian species have adapted to these novel environments, but it remains unclear which char-acteristics allow them to persist. To address this question, we identified 190 mammals regularlyrecorded in urban settlements worldwide, and used phylogenetic path analysis to test hypothesesregarding which behavioural, ecological and life history traits favour adaptation to urban environ-ments for different mammalian groups. Our results show that all urban mammals produce largerlitters; whereas other traits such as body size, behavioural plasticity and diet diversity were impor-tant for some but not all taxonomic groups. This variation highlights the idiosyncrasies of theurban adaptation process and likely reflects the diversity of ecological niches and roles mammalscan play. Our study contributes towards a better understanding of mammal association tohumans, which will ultimately allow the design of wildlife-friendly urban environments and con-tribute to mitigate human-wildlife conflicts.
    • Predicting the potential distribution of the Endangered huemul deer Hippocamelus bisulcus in North Patagonia

      Quevedo, Paloma; von Hardenberg, Achaz; Pastore, Hernan; Alvarez, Jose; Corti, Paulo; Ernst-Moritz-Arndt Universität, Greifswald, Germany; University of Chester; Administración de Parques Nacionales, Bariloche, Argentina;Corporación Nacional Forestal, Chile, Universidad Austral de Chile (2016-02-05)
      Habitat loss is one of the main threats to wildlife, particularly large mammals. Estimating the potential distribution of threatened species to guide surveys and conservation is crucial, primarily because such species tend to exist in small fragmented populations. The Endangered huemul deer Hippocamelus bisulcus is endemic to the southern Andes of Chile and Argentina. Although the species occurs in the Valdivian Ecoregion, a hotspot for biodiversity, we have no information on its occupancy and potential distribution in this region. We built and compared species distribution models for huemul using the maximum entropy approach, using 258 presence records and sets of bioclimatic and geographical variables as predictors, with the objective of assessing the potential distribution of the species in the Valdivian Ecoregion. Annual temperature range and summer precipitation were the predictive variables with the greatest influence in the best-fitting model. Approximately 12,360 km2 of the study area was identified as suitable habitat for the huemul, of which 30% is included in the national protected area systems of Chile and Argentina. The map of potential distribution produced by our model will facilitate prioritization of future survey efforts in other remote and unexplored areas in which huemul have not been recorded since the 1980s, but where there is a high probability of their occurrence.
    • Recapture rates and habitat associations of White-faced Darter Leucorhinnia dubia on Fenn's and Whixall Moss, Shropshire, UK

      Davies, Rachel; von Hardenberg, Achaz; Geary, Matthew; Conservation Biology Research Group, Department of Biological Sciences, University of Chester, CH1 4BJ (British Dragonfly Society, 2018-10-01)
      Land-use change and habitat loss are important drivers of biodiversity decline at both global and local scales. To protect species from the impacts of land-use change it is important to understand the population dynamics and habitat associations across these scales. Here we present an investigation into the survival and habitat preferences of Leucorrhinia dubia at the local scale at Fenn’s and Whixall Moss, Shropshire, UK. We used mark-release-recapture methods to investigate survival and used sightings of individual dragonflies along with habitat data to investigate habitat preference. We found that survival between capture-visits was very low and that L. dubia showed a clear preference for the open moss habitat on this site. In both cases, we found that the detectability, either through sightings or recaptures, was potentially very low and suggest that this should be taken into account in future analyses. We suggest that by encouraging recorders to submit complete lists and to repeat visits to sites detectability could be easily estimated for dragonfly species and incorporating this into analyses would improve estimates fo population trends and habitat associations.
    • Recovery of high mountain Alpine lakes after the eradication of introduced brook trout Salvelinus fontinalis using non-chemical methods

      Tiberti, Rocco; Bogliani, Giuseppe; Brighenti, Stefano; Iacobuzio, Rocco; Liautaud, Kevin; Rolla, Matteo; von Hardenberg, Achaz; Bassano, Bruno; University of Pavia; Gran Paradiso National Park; University of Trento; Fondazione Edmund Mach; Swansea University; University of Chester (Springer, 2018-10-31)
      Fish stocking is a serious threat to originally fishless mountain lakes. We used non-chemical eradication methods (i.e. gillnetting and electrofishing) in four high mountain lakes in the Gran Paradiso National Park (Western Italian Alps) to eradicate alien brook trout Salvelinus fontinalis. Data of amphibians, macroinvertebrates, zooplankton, chlorophyll-a, nutrient concentrations, and water transparency were used as indicators of the recovery process. All treated lakes were returned to their original fishless condition in spite of their different sizes and habitat complexity, without permanent negative side-effects for native species. Several ecological indicators showed that many impacts of introduced fish can be reversed over a short time period following eradication. The present study adds to a still growing body of specialized literature on the recovery of habitats after the eradication of alien species and provides further evidence that physical eradication methods are effective and can be part of a more general strategy for the conservation of high mountain lake biota.
    • The role of brain size on mammalian population densities

      González-Suárez, Manuela; Gonzalez-Voyer, Alejandro; von Hardenberg, Achaz; Santini, Luca; University of Reading; Universidad Autonoma de Mexico; University of Chester; Italian National Research Council (Wiley, 2020-12-22)
      1. The local abundance or population density of different organisms often varies widely. Understanding what determines this variation is an important, but not yet fully resolved question in ecology. Differences in population density are partly driven by variation in body size and diet among organisms. Here we propose that the size of an organism’ brain could be an additional, overlooked, driver of mammalian population densities. 2. We explore two possible contrasting mechanisms by which brain size, measured by its mass, could affect population density. First, because of the energetic demands of larger brains and their influence on life history, we predict mammals with larger relative brain masses would occur at lower population densities. Alternatively, larger brains are generally associated with a greater ability to exploit new resources, which would provide a competitive advantage leading to higher population densities among large‐brained mammals. 3. We tested these predictions using phylogenetic path analysis, modelling hypothesized direct and indirect relationships between diet, body mass, brain mass and population density for 656 non‐volant terrestrial mammalian species. We analysed all data together and separately for marsupials and the four taxonomic orders with most species in the dataset (Carnivora, Cetartiodactyla, Primates, Rodentia). 4. For all species combined, a single model was supported showing lower population density associated with larger brains, larger bodies and more specialized diets. The negative effect of brain mass was also supported for separate analyses in Primates and Carnivora. In other groups (Rodentia, Cetartiodactyla and marsupials) the relationship was less clear: supported models included a direct link from brain mass to population density but 95% confidence intervals of the path coefficients overlapped zero. 5. Results support our hypothesis that brain mass can explain variation in species’ average population density, with large‐brained species having greater area requirements, although the relationship may vary across taxonomic groups. Future research is needed to clarify whether the role of brain mass on population density varies as a function of environmental (e.g. environmental stability) and biotic conditions (e.g. level of competition).
    • Social Network Analysis of small social groups: application of a hurdle GLMM approach in the Alpine marmot (Marmota marmota)

      Stanley, Christina; von Hardenberg, Achaz; Panaccio, Matteo; Ferrari, Caterina; Bassano, Bruno; University of Chester; University of Turin; Alpine Wildlife Research Centre, Gran Paradiso National Park
      Social Network Analysis (SNA) has recently emerged as a fundamental tool to study animal behavior. While many studies have analyzed the relationship between environmental factors and behavior across large, complex animal populations, few have focused on species living in small groups due to limitations of the statistical methods currently employed. Some of the difficulties are often in comparing social structure across different sized groups and accounting for zero-inflation generated by analyzing small social units. Here we use a case study to highlight how Generalized Linear Mixed Models (GLMMs) and hurdle models can overcome the issues inherent to study of social network metrics of groups that are small and variable in size. We applied this approach to study aggressive behavior in the Alpine marmot (Marmota marmota) using an eight-year long dataset of behavioral interactions across 17 small family groups (7.4 ± 3.3 individuals). We analyzed the effect of individual and group-level factors on aggression, including predictors frequently inferred in species with larger groups, as the closely related yellow-bellied marmot (Marmota flaviventris). Our approach included the use of hurdle GLMMs to analyze the zero-inflated metrics that are typical of aggressive networks of small social groups. Additionally, our results confirmed previously reported effects of dominance and social status on aggression levels, thus supporting the efficacy of our approach. We found differences between males and females in terms of levels of aggression and on the roles occupied by each in agonistic networks that were not predicted in a socially monogamous species. Finally, we provide some perspectives on social network analysis as applied to small social groups to inform subsequent studies.
    • Thermal niche predicts recent changes in range size for bird species

      Scridel, D.; Bogliani, G.; Pedrini, P.; Iemma, A.; von Hardenberg, Achaz; Brambilla, M.; Museo delle Scienze, Trento; University of Pavia, University of Chester, Fondzione Lombardia per l'Ambiente (Inter-Research Science Center (IR), 2017-08-30)
      Species’ distributions are strongly affected by climate, and climate change is affecting species and populations. Thermal niches are widely used as proxies for estimating thermal sensitivity of species, and have been frequently related to community composition, population trends and latitudinal/elevational shifts in distribution. To our knowledge, no work has yet explored the relationship between thermal niche and change in range size (changes in the number of occupied spatial units over time) in birds. In this study, we related a 30 yr change in range size to species thermal index (STI: average temperature at occurrence sites) and to other factors (i.e. birds’ associated habitats, body mass, hunting status) potentially affecting bird populations/range size. We analysed trends of breeding bird range in Italy for a suite of poorly studied cold-adapted animals potentially sensitive to global warming, and for a related group of control species taxonomically similar and with comparable mass but mainly occurring at lower/warmer sites. We found a strong positive correlation between change in range size and STI, confirming that recent climatic warming has favoured species of warmer climates and adversely affected species occupying colder areas. A model including STI and birds’ associated habitats was not so strongly supported, with forest species performing better than alpine open habitat and agricultural ones. In line with previous works highlighting effects of recent climate change on community composition, species’ population trends and poleward/upward distributional shifts, we found STI to be the most important predictor of change in range size variation in breeding birds.
    • White-faced Darter distribution is associated with coniferous forests in Great Britain

      Geary, Matthew; von Hardenberg, Achaz; Conservation Biology Research Group, Department of Biological Science, University of Chester, Chester, CH1 4BJ (Wiley, 2020-08-11)
      Abstract 1) Understanding of dragonfly distributions is often geographically comprehensive but less so in ecological terms. 2) White-faced darter (Leucorhinnia dubia) is a lowland peatbog specialist dragonfly which has experienced population declines in Great Britain. White-faced darter are thought to rely on peat-rich pool complexes within woodland but this has not yet been empirically tested. 3) We used dragonfly recording data collected by volunteers of the British Dragonfly Society from 2005 to 2018 to model habitat preference for white-faced darter using species distribution models across Great Britain and, with a more detailed landcover dataset, specifically in the North of Scotland. 4) Across the whole of Great Britain our models used the proportion of coniferous forest within 1km as the most important predictor of habitat suitability but were not able to predict all current populations in England. 5) In the North of Scotland our models were more successful and suggest that habitats characterised by native coniferous forest and areas high potential evapotranspiration represent the most suitable habitat for white-faced darter. 6) We recommend that future white-faced darter monitoring should be expanded to include areas currently poorly surveyed but with high suitability in the North of Scotland. 7) Our results also suggest that white-faced darter management should concentrate on maintaining Sphagnum rich pool complexes and the maintenance and restoration of native forests in which these pool complexes occur.