Papers by manuela panzacchi
Journal of Complex Networks, 2020
Randomized shortest paths (RSPs) are tool developed in recent years for different graph and netwo... more Randomized shortest paths (RSPs) are tool developed in recent years for different graph and network analysis applications, such as modelling movement or flow in networks. In essence, the RSP framework considers the temperature-dependent Gibbs–Boltzmann distribution over paths in the network. At low temperatures, the distribution focuses solely on the shortest or least-cost paths, while with increasing temperature, the distribution spreads over random walks on the network. Many relevant quantities can be computed conveniently from this distribution, and these often generalize traditional network measures in a sensible way. However, when modelling real phenomena with RSPs, one needs a principled way of estimating the parameters from data. In this work, we develop methods for computing the maximum likelihood estimate of the model parameters, with focus on the temperature parameter, when modelling phenomena based on movement, flow or spreading processes. We test the validity of the deri...
'You shall not pass!': Quantifying barrier permeability and proximity avoidance... more 'You shall not pass!': Quantifying barrier permeability and proximity avoidance by animals
The project started in the snow-rich / roe deer poor areas of Østerdalen (Hedmark County) in 1995... more The project started in the snow-rich / roe deer poor areas of Østerdalen (Hedmark County) in 1995. In 2000 the study was expanded to also include the snow poor / roe deer rich habitats of Akershus and Østfold counties. These two study areas are hereafter referred to as north and south respectively. The project has collected data on between year and between individual variation in area use, survival and reproduction of lynx with different varying access to prey. In addition the project has focused on the population dynamics of the main prey of lynx, the roe deer. Our main method has involved the live-capture and radio-collaring of lynx and roe deer in contrasting habitats. Since the start in February 1995 the project has collared 68 lynx and 324 roe deer.
Denne rapporten oppsummerer kort mye av aktiviteten på gaupe- og rådyrprosjektet i Sørøst-Norge d... more Denne rapporten oppsummerer kort mye av aktiviteten på gaupe- og rådyrprosjektet i Sørøst-Norge de siste 10 åra.Rapporten er i hovedsak ment som en oversiktsrapport til våre hovedfinansieringskilder, Norges Forskningsråd,Direktoratet for naturforvaltning og ulike fylkesmenn. Prosjektet er et samarbeid mellom Norsk institutt for natur-forskning (NINA), Universitet for miljø- og biovitenskap (UMB), Norges teknisk-naturvitenskapelige universitet (NTNU) og Høgskolen i Hedmark
NINAs publikasjoner NINA Rapport Dette er en elektronisk serie fra 2005 som erstatter de tidliger... more NINAs publikasjoner NINA Rapport Dette er en elektronisk serie fra 2005 som erstatter de tidligere seriene NINA Fagrapport, NINA Oppdragsmelding og NINA Project Report. Normalt er dette NINAs rapportering til oppdragsgiver etter gjennomført forsknings-, overvåkings-eller utredningsarbeid. I tillegg vil serien favne mye av instituttets øvrige rapportering, for eksempel fra seminarer og konferanser, resultater av eget forsknings-og utredningsarbeid og litteraturstudier. NINA Rapport kan også utgis på annet språk når det er hensiktsmessig. NINA Temahefte Som navnet angir behandler temaheftene spesielle emner. Heftene utarbeides etter behov og serien favner svaert vidt; fra systematiske bestemmelsesnøkler til informasjon om viktige problemstillinger i samfunnet. NINA Temahefte gis vanligvis en populaervitenskapelig form med mer vekt på illustrasjoner enn NINA Rapport. NINA Fakta Faktaarkene har som mål å gjøre NINAs forskningsresultater raskt og enkelt tilgjengelig for et større publikum. De sendes til presse, ideelle organisasjoner, naturforvaltningen på ulike nivå, politikere og andre spesielt interesserte. Faktaarkene gir en kort framstilling av noen av våre viktigste forskningstema.
Mammal Research, 2020
In the boreal forest, the red fox (Vulpes vulpes) is a key species due to its many strong food we... more In the boreal forest, the red fox (Vulpes vulpes) is a key species due to its many strong food web linkages and its exploitation of niches that form in the wake of human activities. Recent altitudinal range expansion and a perceived population increase have become topics of concern in Scandinavia, primarily due to the potential impacts of red foxes on both prey and competitor species. However, despite it being a common species, there is still surprisingly little knowledge about the temporal and spatial characteristics of its population dynamics. In this study, we synthesized 12 years of snow-track transect data covering a 27,000-km2 study area to identify factors associated with red fox distribution and population dynamics. Using Bayesian hierarchical regression models, we evaluated the relationships of landscape productivity and climate gradients as well as anthropogenic subsidies with an index of red fox population size and growth rates. We found that landscapes with high human se...
Theoretical Ecology, 2020
Many animal populations providing ecosystem services, including harvest, live in seasonal environ... more Many animal populations providing ecosystem services, including harvest, live in seasonal environments and migrate between seasonally distinct ranges. Unfortunately, two major sources of human-induced global change threaten these populations: climate change and anthropogenic barriers. Anthropogenic infrastructure developments present a global threat to animal migrations through increased migration mortality or behavioral avoidance. Climate change alters the seasonal and spatial dynamics of resources and therefore the effects of migration on population performance. We formulated a population model with ideal-free migration to investigate changes in population size and harvest yield due to barriers and seasonal dynamics. The model predicted an increasing proportion of migrants when the difference between areas in seasonality or carrying capacity increased. Both migration cost and behavioral avoidance of barriers substantially reduced population size and harvest yields. Not surprisingl...
The cumulative impact of human activities has driven many species into severe declines across the... more The cumulative impact of human activities has driven many species into severe declines across the globe. However, the recent focus on conservation optimism has begun to highlight case studies that go against this trend. Reintroduction, reforestation, agricultural abandonment and legislative change has led to a situation where large mammals have recovered to the extent that they are now widespread across the European continent. In this study we summarize the knowledge about wild ungulate distribution in Europe and review the diversity of ways in which they interact with humans. Drawn from a wide range of sources, we have built distribution maps of European wild ungulates. Results show that 90% of Europe is home to at least 1 species of wild native ungulate, with roe deer and wild boar occupying 74% and 64% of Europe respectively. In contrast, mountain ungulates only occupy about 5% of Europe, and are often associate with protected areas. The wide distribution of most European ungulat...
Journal of Animal Ecology, 2015
Identifying and characterizing migration to identify the extent of the differences, and c) invest... more Identifying and characterizing migration to identify the extent of the differences, and c) investigating inconsistently classified cases as these may often be ecologically interesting (i.e., less-stereotyped migratory behaviours).
Journal of Animal Ecology, 2015
Annales Zoologici Fennici, 2015
In Norway, recovering populations of large carnivores commonly prey on roe deer (Capreolus capreo... more In Norway, recovering populations of large carnivores commonly prey on roe deer (Capreolus capreolus). Understanding predator habitat use and ecology requires spatial scales at which large carnivores use the landscape presents many practical and data from > 1000 km of transects gathered across southeastern Norway between 2005 and 2011 were used to derive a map of the relative prey abundance for roe deer. These variables in explaining both presence and abundance. Internal k model showed medium accuracy (Spearman's r = 0.35), whereas external evaluation r = 0.37) and hunting statistics (Spearman's r = 0.88) showed higher accuracy. The map generated can facilitate both the study of broad scale processes linking predators and prey as well as roe deer management in southeastern Norway.
Journal of Animal Ecology, 2014
There may be differences between this version and the published version. You are advised to consu... more There may be differences between this version and the published version. You are advised to consult the publisher's version if you wish to cite from it.
Rangifer, 2013
The development of roads and associated infrastructure has interrupted several traditional migrat... more The development of roads and associated infrastructure has interrupted several traditional migrations of wild reindeer (Rangifer tarandus tarandus) in Norway. The population in the Setesdal Austhei wild reindeer area still migrates from winter to calving grounds by semi-annually crossing a cabin-lined road through a narrow corridor, in which further anthropogenic development is planned. To understand if and how infrastructure affected reindeer migration patterns we studied the movements of 10 female reindeer equipped with GPS collars between 2002 and 2010. First, we identified the start and end of the migration period, and then we compared trajectory parameters (net displacement, step length and turning angles) recorded during migration with those recorded in proximity of the road. The analysis of the net displacement indicated that during spring migration reindeer moved at a constant pace towards the calving ground covering a net linear distance of 25 km in 40 days. In the middle o...
Remote Sensing of Environment, 2014
Reindeer and caribou are keystone species in the circumpolar region, and rely on lichens as their... more Reindeer and caribou are keystone species in the circumpolar region, and rely on lichens as their main winter forage to survive in some of the most extreme environments on Earth. Lichen mats, however, can be heavily overgrazed at high deer densities, triggering area abandonment or population declines. Although the species' management and conservation require precise information on the quality of winter grazing areas, no reliable and cost-efficient methods are available to date to measure lichen volume across wide and remote areas. We developed a new Lichen Volume Estimator, LVE, using remote sensing and field measurements. We used a Landsat TM land cover mask to separate lichen heath communities from other vegetation types and, therein, we predicted lichen volume from a two dimensional Gaussian regression model using two indexes: the Normalized Difference Lichen Index, NDLI (Band 5 − Band 4 / Band 5 + Band 4), and the Normalized Difference Moisture Index, NDMI (Band 4 − Band 5 / Band 4 + Band 5). The model was parameterized using 202 ground measurements equally distributed across a gradient ranging from 0 to 80 lichen dm 3 /m 2 (R 2 = 0.74 between predicted and observed ground measurements), and was validated with a tenfold cross validation procedure (R 2 = 0.67), which also showed a high parameter stability. The LVE can be a valuable tool to predict the quality of winter pastures for reindeer and caribou and, thus, help to improve the species' management and conservation.
Ecography, 2014
Early View (EV): 1-EV applied consequences for a range of disciplines such as conservation ecolog... more Early View (EV): 1-EV applied consequences for a range of disciplines such as conservation ecology, community ecology, global change biology and landscape management. However, strictly speaking a complete Hutchinsonian hypervolume is intrinsically inestimable for two reasons (Whittaker et al. 1973). First, its estimation would need to rely on observations of realized niches, in which the species is bound by an intricate web of biotic and abiotic constraints (Sober ó n 2010). Hence, measurements of the species ' response to each variable would be biased by their intrinsic correlational structure (Whittaker et al. 1973). Second, the number of axes composing the hypervolume in environmental space is virtually infi nite. As a consequence, fundamental niches cannot be properly predicted in geographic space, as it is not possible to identify all areas characterised by all combinations of biotic and abiotic conditions where the species could persist (Sober ó n 2007, Peterson et al. 2012). Unaff ected by these limitations, the hunt for the fundamental niche is intensifying, and researchers attempt to make the challenge more achievable by focussing on an increasing
Wildlife Biology, 2007
BioOne Complete (complete.BioOne.org) is a full-text database of 200 subscribed and open-access t... more BioOne Complete (complete.BioOne.org) is a full-text database of 200 subscribed and open-access titles in the biological, ecological, and environmental sciences published by nonprofit societies, associations, museums, institutions, and presses.
Mammal Review, 2011
In predator-prey theory, habitat heterogeneity can affect the relationship between kill rates and... more In predator-prey theory, habitat heterogeneity can affect the relationship between kill rates and prey or predator density through its effect on the predator's ability to search for, encounter, kill and consume its prey. Many studies of predatorprey interactions include the effect of spatial heterogeneity, but these are mostly based on species with restricted mobility or conducted in experimental settings. 2. Here, we aim to identify the patterns through which spatial heterogeneity affects predator-prey dynamics and to review the literature on the effect of spatial heterogeneity on predator-prey interactions in terrestrial mammalian systems, i.e. in freely moving species with high mobility, in non-experimental settings. We also review current methodologies that allow the study of the predation process within a spatial context. 3. When the functional response includes the effect of spatial heterogeneity, it usually takes the form of predator-dependent or ratio-dependent models and has wide applicability. 4. The analysis of the predation process through its different stages may further contribute towards identifying the spatial scale of interest and the specific spatial mechanism affecting predator-prey interactions. 5. Analyzing the predation process based on the functional response theory, but separating the stages of predation and applying a multiscale approach, is likely to *Correspondence author.
Journal of Animal Ecology, 2011
1. Understanding the role of predation in shaping the dynamics of animal communities is a fundame... more 1. Understanding the role of predation in shaping the dynamics of animal communities is a fundamental issue in ecological research. Nevertheless, the complex nature of predator-prey interactions often prevents researchers from modelling them explicitly. 2. By using periodic Leslie-Usher matrices and a simulation approach together with parameters obtained from long-term field projects, we reconstructed the underlying mechanisms of predatorprey demographic interactions and compared the dynamics of the roe deer-red fox-Eurasian lynx-human harvest system with those of the moose-brown bear-gray wolf-human harvest system in the boreal forest ecosystem of the southern Scandinavian Peninsula. 3. The functional relationship of both roe deer and moose k to changes in predation rates from the four predators was remarkably different. Lynx had the strongest impact among the four predators, whereas predation rates by wolves, red foxes, or brown bears generated minor variations in prey population k. Elasticity values of lynx, wolf, fox and bear predation rates were)0AE157,)0AE056,)0AE031 and)0AE006, respectively, but varied with both predator and prey densities. 4. Differences in predation impact were only partially related to differences in kill or predation rates, but were rather a result of different distribution of predation events among prey age classes. Therefore, the age composition of killed individuals emerged as the main underlying factor determining the overall per capita impact of predation. 5. Our results confirm the complex nature of predator-prey interactions in large terrestrial mammals, by showing that different carnivores preying on the same prey species can exert a dramatically different demographic impact, even in the same ecological context, as a direct consequence of their predation patterns. Similar applications of this analytical framework in other geographical and ecological contexts are needed, but a more general evaluation of the subject is also required, aimed to assess, on a broader systematic and ecological range, what specific traits of a carnivore are most related to its potential impact on prey species.
Ecosphere, 2013
Mortality rates and patterns are fundamental demographic traits for understanding the dynamics of... more Mortality rates and patterns are fundamental demographic traits for understanding the dynamics of populations of large herbivores in different environments. Despite the ongoing recovery of large carnivores in Europe and North America, few European studies on ungulate mortality are available from areas where both large carnivores and human hunters are present. We applied known fate models to estimate cause-specific mortality rates and Cox proportional hazard models to estimate the effects of environmental covariates on mortality risks of 330 radio-collared roe deer (Capreolus capreolus) (1995-2005) along a gradient in roe deer abundance in southeastern Norway. The study area is characterized by the presence of human hunters, Eurasian lynx (Lynx lynx), red foxes (Vulpes vulpes) and occasionally wolves (Canis lupus). The main mortality causes were: hunter harvest, predation by lynx, predation by foxes (on fawns) and others (including wolves, dogs, diseases, vehicle collisions and accidents). The individual risk of roe deer being killed by lynx or by foxes was differently affected by covariates. In keeping with the specialist foraging behavior of lynx, predation risk by lynx decreased with increasing roe deer abundance. Conversely, consistent with the opportunistic habits of red fox, the risk of being preyed upon by foxes, tended to increase with increasing roe deer abundance, although the pattern was not so marked. Human hunters did not adjust their killing rate to changing roe deer abundance and annually harvested between 11% and 28% of the population according to different sexes and age classes.
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Papers by manuela panzacchi