Scale‐dependent strategies for coexistence of mesocarnivores in human‐dominated landscapes

publishedVersio

Small rodent cycles influence interactions among predators in a boreal forest ecosystem

Cyclic fuctuations of prey have profound efects on the functioning of ecosystems, for example, by changing the dynamics, behavior, and intraguild interactions of predators. The aim of this study was to assess the efect of rodent cyclic fuctuations in the interspecifc interactions of a guild of small- and medium-sized predators: red fox (Vulpes vulpes), pine marten (Martes martes), and weasels (Mustela erminea and Mustela nivalis) in the boreal ecosystem. We analyzed eight years (2007–2014) of snow tracking data from southeastern Norway using structural equation models to assess hypothesized networks of causal relationships. Our results show that fuctuations in rodent abundance alter the strength of predator’s interactions, as well as the efect of determinant environmental variables. Pine marten and weasel abundances were positively associated with rodent population growth rate, but not red fox abundance. All predators were positively associated with each other; however, the association between red fox and the other predators weakened when rodents increased. Rodent fuctuations had variable efects on the habitat use of the predators. The presence of agricultural land was important for all predators, but this importance weakened for the mustelids as rodent abundance increased. We discuss the shifting role of interference and exploitative competition as possible mechanisms behind these patterns. Overall, we highlight the importance of accounting for the dynamics of prey resources when studying interspecifc interactions among predators. Additionally, we demonstrate the importance of monitoring the predator populations in order to anticipate undesirable outcomes such as increased general ist predator abundances to the detriment of specialists.publishedVersio

Spatial and temporal variation in the distribution and abundance of red foxes in the tundra and taiga of northern Sweden

Variation in the distribution and abundance of animals in space and time are key concepts of population ecology. We studied these variations in a population of red foxes (Vulpes vulpes) in the tundra and taiga of northern Sweden. We analysed 12 years (1974–1985) of snow tracking data from a large area of 65,375 km2. Specifically, we evaluated to what extent the distribution of red foxes was explained by the presence of prey and how this interacted with snow depth and altitude. We also tested for temporal linear trends in the distribution and abundance of red foxes during the study period. The distribution of red foxes was explained by the presence of rodents, hares, tetraonid species, and ungulates (i.e. carcasses). Snow depth had a negative effect on the impact of small prey on the distribution of the red foxes, whereas it had a positive effect on the impact of ungulates. The influence of hares increased with altitude. Neither distribution nor abundance of red foxes showed a positive or negative linear trend, suggesting a stable population in northern Sweden during our study. This study showed that the distribution of red foxes was not only influenced by the presence of their main prey (rodents), but also by interactions between alternative prey, altitude, and snow depth. This study also emphasizes the importance of ungulate carcasses for red foxes and for wildlife management

The range of the mange: Spatiotemporal patterns of sarcoptic mange in red foxes (Vulpes vulpes) as revealed by camera trapping

Sarcoptic mange is a widely distributed disease that affects numerous mammalian species. We used camera traps to investigate the apparent prevalence and spatiotemporal dynamics of sarcoptic mange in a red fox population in southeastern Norway. We monitored red foxes for five years using 305 camera traps distributed across an 18000 km2 area. A total of 6581 fox events were examined to visually identify mange compatible lesions. We investigated factors associated with the occurrence of mange by using logistic models within a Bayesian framework, whereas the spatiotemporal dynamics of the disease were analysed with spacetime scan statistics. The apparent prevalence of the disease fluctuated over the study period with a mean of 3.15% and credible interval [1.25, 6.37], and our best logistic model explaining the presence of red foxes with mange-compatible lesions included time since the beginning of the study and the interaction between distance to settlement and season as explanatory variables. The scan analyses detected several potential clusters of the disease that varied in persistence and size, and the locations in the cluster with the highest probability were closer to human settlements than the other survey locations. Our results indicate that red foxes in an advanced stage of the disease are most likely found closer to human settlements during periods of low wild prey availability (winter). We discuss different potential causes. Furthermore, the disease appears to follow a pattern of small localized outbreaks rather than sporadic isolated events.publishedVersio

Small rodent monitoring at Birkebeiner road, Norway

Background. Northern small mammal populations are renowned for their multi-annual population cycles. Population cycles are multi-faceted and have extensive impacts on the rest of the ecosystem. In 2011, we started a student-based research activity to monitor the variation of small rodent density along an elevation gradient following the Birkebeiner Road, in southeast Norway. Fieldwork was conducted by staff and students at the University campus Evenstad, Inland Norway University of Applied Sciences, which has a long history of researching cyclic population dynamics. The faculty has a strong focus on engaging students in all parts of the research activities, including data collection. Small rodents were monitored using a set of snap trap stations. Trapped animals were measured (e.g. body mass, body length, sex) and dissected to assess their reproductive status. We also characterised the vegetation at trapping sites. New information. We provide a dataset of small rodent observations that show fluctuating population dynamics across an elevation gradient (300 m to 1,100 m a.s.l) and in contrasting habitats. This dataset encompasses three peaks of the typical 3-4-year vole population cycles; the number of small rodents and shrews captured show synchrony and peaked in years 2014, 2017 and 2021. The bank vole Myodes glareolus was by far (87%) the most common species trapped, but also other species were observed (including shrews). We provide digital data collection forms and highlight the importance of long-term data collection.publishedVersio

Predicting kill sites of an apex predator from GPS data in different multi-prey systems

© 2022 The Authors. Ecological Applications published by Wiley Periodicals LLC on behalf of The Ecological Society of America. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.Kill rates are a central parameter to assess the impact of predation on prey species. An accurate estimation of kill rates requires a correct identification of kill sites, often achieved by field-checking GPS location clusters (GLCs). However, there are potential sources of error included in kill-site identification, such as failing to detect GLCs that are kill sites, and misclassifying the generated GLCs (e.g., kill for nonkill) that were not field checked. Here, we address these two sources of error using a large GPS dataset of collared Eurasian lynx (Lynx lynx), an apex predator of conservation concern in Europe, in three multiprey systems, with different combinations of wild, semidomestic, and domestic prey. We first used a subsampling approach to investigate how different GPS-fix schedules affected the detection of GLC-indicated kill sites. Then, we evaluated the potential of the random forest algorithm to classify GLCs as nonkills, small prey kills, and ungulate kills. We show that the number of fixes can be reduced from seven to three fixes per night without missing more than 5% of the ungulate kills, in a system composed of wild prey. Reducing the number of fixes per 24 h decreased the probability of detecting GLCs connected with kill sites, particularly those of semidomestic or domestic prey, and small prey. Random forest successfully predicted between 73%–90% of ungulate kills, but failed to classify most small prey in all systems, with sensitivity (true positive rate) lower than 65%. Additionally, removing domestic prey improved the algorithm's overall accuracy. We provide a set of recommendations for studies focusing on kill-site detection that can be considered for other large carnivore species in addition to the Eurasian lynx. We recommend caution when working in systems including domestic prey, as the odds of underestimating kill rates are higher.publishedVersio

Individuell atferd hos ulv ovenfor menneskelig infrastruktur i Skandinavia

Ulv er kjent for å være en habitatgeneralist med ynglende bestander i mange ulike typer habitat fra arktiske strøk, boreale skoger, åpne landbruksområder og til tettbefolkede områder i varme strøk. En viktig faktor for ulvens habitatvalg er tilgang til byttedyr, og flere studier har vist at i områder hvor menneskelig infrastruktur overlapper med tilgang til byttedyr, utnytter ulven natten for å jakte. Ikke bare ytre faktorer kan påvirke ulvers habitatvalg. Ulveindivider har ulik personalitet formet av nedarvede og lærte egenskaper, og det kan derfor forventes en stor variasjon i hvordan ulike individer oppfører seg overfor menneskelig infrastruktur. Vi kategoriserte Skandinaviske ulvers individuelle atferd langs en gradient fra unnvikende til oppsøkende, der unnvikende betyr unngåelse av infrastruktur og oppsøkende betyr preferanse for eller større bruk av infrastruktur enn forventet fra tilgjengeligheten. Vi brukte GPS-posisjoner fra 55 forsknings- og forvaltningsmerkede ulver i tidsperioden 2001-2017 i individuelle stegvalganalyser for å beskrive habitatvalget for hvert individ, for deretter å teste om variasjonen i habitatvalget kan forklares med årstid, tid på døgnet, alder, kjønn og andre individ- og revirspesifikke egenskaper. Ulvene viste oftest ikke noe spesielt seleksjonsmønster eller var unnvikende overfor infrastruktur, og oppsøkende atferd var sjeldent, med et unntak: mer enn halvparten av ulvene viste en oppsøkende atferd overfor skogsbilveier, trolig for bruk til energieffektiv forflytning. Ulvene foretrakk områder med veldig lav bygningstetthet. På dagtid var ulvene mer unnvikende, trolig for å unngå møter med folk, og på natten var de mindre unnvikende eller mer oppsøkende, trolig for å jakte på byttedyr. Ulvene, og spesielt tispene, var mer unnvikende på sommeren, trolig for å skjerme valpene på hi- og valpeplassene fra menneskelig forstyrrelse. Om vinteren var ulvene mindre unnvikende eller mer oppsøkende, trolig for å jakte elg og rådyr som oppholdt seg nær menneskelig infrastruktur når det er snødekke. Ulvene nord i norsk ulvesone og tilgrensende områder var mer oppsøkende enn ulvene lenger sør, trolig som en effekt av elgfordelingen i dalbunnene vinterstid i områder med elgtrekk. Vi fant ikke noen tydelig effekt av ulike individers eller flokkers særegenhet på deres atferdsmønster og antar derfor at ulvene i Skandinavia utviser en stor grad av fleksibilitet og tilpasningsevne i deres atferd overfor menneskelig infrastruktur

A Standardized Method for Experimental Human Approach Trials on Wild Wolves

"Copyright © 2022 Eriksen, Versluijs, Fuchs, Zimmermann, Wabakken, Ordiz, Sunde, Wikenros, Sand, Gillich, Michler, Nordli, Carricondo-Sanchez, Gorini and Rieger. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms"As wolves recolonize areas of Europe ranging from moderate to high anthropogenic impact, fear of wolves is a recurring source of conflict. Shared tools for evaluating wolf responses to humans, and comparing such responses across their range, can be valuable. Experiments in which humans approach wild wolves can increase our understanding of how wolves respond to humans, facilitating human-wolf coexistence. We have developed the first standardized protocol for evaluating wolf responses to approaching humans using high-resolution GPS data, and tested it on wild wolves. We present a field protocol for experimentally approaching GPS-collared wolves, a descriptive comparison of two statistical methods for detecting a measurable flight response, a tutorial for identifying wolf flight initiation and resettling positions, and an evaluation of the method when reducing GPS positioning frequency. The field protocol, a data collection form, and the tutorial with R code for extracting flight parameters are provided. This protocol will facilitate studies of wolf responses to approaching humans, applicable at a local, national, and international level. Data compiled in a standardized way from multiple study areas can be used to quantify the variation in wolf responses to humans within and between populations, and in relation to predictors such as social status, landscape factors, or human population density, and to establish a baseline distribution of wolf response patterns given a number of known predictors. The variation in wolf responses can be used to assess the degree to which results can be generalized to areas where GPS studies are not feasible, e.g., for predicting the range of likely wolf behaviors, assessing the likelihood of wolf-human encounters, and complementing existing tools for evaluating reports of bold wolves. Showing how wolves respond to human encounters should help demystify the behavior of wild wolves toward humans in their shared habitat.publishedVersio