27 publikasjoner og studentarbeider fra den opprinnelige Scandfox-databasen.
Viser 27 publikasjoner
Genetic footprints reveal geographic patterns of expansion in Fennoscandian red foxes. Global Change Biology.
To identify the relative roles of geographic and demographic factors and the sources of northern European red fox population expansion, we genotyped 21 microsatellite loci in modern and historical (1835–1941) Fennoscandian red foxes. We identified high connectivity and asymmetric migration rates across the region, consistent with source-sink dynamics, whereby more recently colonized sampling regions received immigrants from multiple sources. Migration inferences, demographic models and comparison to historical red fox genotypes suggested that the population expansion of the red fox is a consequence of dispersal from multiple sources, as well as in situ demographic growth.
Land cover effects on mesopredator abundance in the presence and absence of apex predators. Acta Oecologica 67 (2015) 40e48
Loss of larger predators implies that medium-sized mesopredators rise to the status of apex predators which are limited bottom-up rather than top-down. Our results showed that fox abundance was independent of land cover in presence of lynx. However, in absence of lynx, fox density was positively but asymptotically related to cropland, while negatively related to grassland. Cropland is favorable for red fox, but only in absence of top-down limitation by lynx. We suggest that there are two ecosystem states in Eurasia, one northern where lynx is present as an apex predator, and one south-eastern where red fox assumes the apex predator position and its abundance is subsidised by anthropogenic land cover.
Range shifts and community effects in the borderland between forest and tundra. AMBIO 2015, 44 (Suppl. 1):39–50
We suggest that the alpine and boreal ecosystems in Sweden have responded to climate warming, and that substantial changes occurred already in 1930–1960. Observed changes include range expansions and increases in southern species, retreat and decline in northern species, as well as changing dynamics. However, land-use change and other anthropogenic drivers probably worked in synergy with climate warming. Human use of boreal and Arctic ecosystems is likely to intensify with climate warming. Thus, understanding change in northern ecosystems requires a broad research approach that includes human use of the ecosystem.
Rough-Legged Buzzards, Arctic Foxes and Red Foxes in a Tundra Ecosystem without Rodents. PLoS ONE 10(2): e0118740. doi:10.1371/journal.pone.0118740
We studied diet and breeding performance of the rough-legged buzzard, red fox and arctic fox in the rodent-free Kolguev Island in Arctic Russia. Our study suggests that the three predators found breeding on Kolguev Island possess capacities for shifting to changing circumstances in low-arctic ecosystem as long as other small - medium sized terrestrial herbivores are present in good numbers.
Community-wide mesocarnivore response to partial ungulate migration. Journal of Applied Ecology 2014, 51, 1525–1533.
We found that boreal mesocarnivores, known to negatively impact the productivity of reindeer and arctic wildlife of conservation concern, steeply increased in tundra areas with many year-round resident reindeer due to increased partial migration. To avoid such negative impacts, actions should be taken to minimize residency in tundra reindeer.
Estimating ungulate carrion biomass and possible ecological effects on red fox (Vulpes vulpes) in central Norway
Sau på beite bidro til å opprettholde tilgangen på åtsel i begge områder om sommeren. Den estimerte årlige åtseltilgangen var høyest i skog/landbruksområder. Tilgangen var størst på høsten grunnet slakteavfall fra jakt.
Foraging ecology and spatial behaviour of the red fox (Vulpes vulpes) in a wet grassland ecosystem. Acta Theriol (2014) 59:377–389
We investigated diet composition, habitat selection and spatial behaviour of the red fox (Vulpes vulpes) in relation to the availability of wader nests in a coastal polder area in southwest Denmark. The predatory role of the red fox in wet grassland ecosystems has profound implications for conservation status of declining populations of grassland breeding waders. Our results indicate that red fox predation on wader nests is incidental, consistent with the notion that red foxes are generalist predators that opportunistically subsist on many prey groups.
Patterns of reproduction and body condition in Red fox (Vulpes vulpes)
Studien viser nylige mønster for kondisjon og reproduksjon i en rødrevpopulasjon i Sørøst-Norge. Obduserte rever hadde hovedsakelig normal kondisjon med lav variasjon i kroppsfett. Den relativt lave andelen av reproduserende tisper, sammen med en høyere kondisjon hos hanner skutt på åte sammenlignet med andre jaktformer indikerer at populasjonen er begrenset av mattilgangen.
Påverkar vargen (Canis lupus) förekomsten av rödräv (Vulpes vulpes) i Sverige?
Syftet med denna studie var att undersöka om närvaro av varg påverkar förekomst av rödräv. Rävspår räknades i 182 vilttrianglar i Örebro och Värmlands län under åren 2001-2003. Studien kunde inte påvisa någon effekt av vargförekomst på räv. Resultaten indikerar på att habitatet var nyckelfaktorn för rävförekomst istället för närvaro av varg. I och med att vargstammen ökar stadigt i Sverige är det dock av intresse med fortsatta studier i ämnet då vargen kan komma att spela en större roll i ekosystemet i framtiden.
Seasonal diets of red foxes in a boreal forest with a dense population of moose: the importance of winter scavenging Acta Theriol (2014) 59:391–398.
In our study, we investigated seasonal and annual variations in diet composition of red fox in Varaldskogen, SE Norway, an area with cyclic voles and a high density of moose Alces alces. Analyses of scats revealed significant differences among seasons in the occurrence of ungulates—mainly moose—and ungulates were the dominating food category during winter. Snow tracking of red fox in winter confirmed the importance of ungulate carcasses, i.e. one case of scavenging per 3 km. The proportions of voles were high during all seasons in spite of variation in available abundances, no significant seasonal or annual differences were detected.
Disentangling the importance of interspecific competition, food availability, and habitat in species occupancy: Recolonization of the endangered Fennoscandian arctic fox. Biological Conservation 160 (2013) 114–120.
The study used a large-scale spatio- temporal study combined with an extensive red fox removal intervention to test these two hypotheses by evaluating the relative importance of diverse environmental factors affecting the recolonization of arctic foxes in Northern Norway. The results highlight the presence of red foxes as the factor most limiting arctic fox recolonization in this part of its distribution.
Red fox expansion in alpine areas: Relations to climate, productivity, humans and ungulates
Red foxes were limited by winter climate, with increased demand for supplemental food with increased snow depth and snow cover duration, and at colder temperatures. Presence of red fox increased with increasing landscape productivity at a local scale and in lower alpine regions, with increasing presence in proximity to human infrastructure and an increase on sites with presence of reindeer in winter, summer and spring
Rødrevens (Vulpes vulpes) kondisjon : et studie av faktorer som kan påvirke kondisjonen til rødreven i Hedmark
Oppgaven har sett på hvorvidt åtejakt gir utslag på kondisjonen. Rødrev som er skutt på åte er i bedre kondisjon enn de som er felt under andre jaktformer. Dette kan tyde på at åte er viktig vinterføde, når annen næring er vanskelig å finne. Rødreven trives i kulturlandskapet og kondisjon øker i takt med økende andel landbruk i kommunen. Det ser ut til at rødreven lagrer næring i form av kroppsfett utover høsten, som den tærer på gjennom vinteren
Towards good practice guidance in using camera-traps in ecology: influence of sampling design on validity of ecological inferences. Methods in Ecology and Evolution 2013.
Results showed that raw error rates in daily presence varied between 5 and 30% among species when using time-triggered cameras with a 5-min interval. Using movement-triggered cameras resulted in larger raw error rates, between 30 and 70%, as well as a lower number of daily presences detected. Increasing the time interval from 5 to 20 min greatly increased the raw error rate in daily presence, but it had negligible impacts on estimates and precision of occupancy and detection probability. Occupancy estimates were mostly influenced by variation in the number of days included during the sampling period. The article provides guidelines that are likely to be directly applicable to a large range of species and ecosystems.
Nest predation in capercaillie and black grouse - increased losses to red fox and pine marten
In our study we identified the predators of 44 grouse nests. Most were depredated by mammals. Red fox and pine marten were the most important predators. The remaining nests were depredated by badger, hooded crow, raven and golden eagle. The increased nest predation is most likely related to increased densities of red fox and pine marten due to increased prey base and decreasing predation on these species by man.
How ecological neighbourhoods influence the structure of the scavenger guild in low arctic tundra. Diversity and Distributions, (Diversity Distrib.) (2011) 1–12
We found short-range neighbourhood effects of forest and coast within the tundra scavenger guild. Species richness declined steeply with decreasing distance from the neighbouring ecosystems, in particular subarctic forest, and with increasing altitude. The two most abundant guild members, the common raven Corvus corax and the red fox Vulpes vulpes, exhibited no spatial patterns within the range of neighbourhoods and altitudes examined. Presence of red fox appeared to exclude the arctic fox Vulpes lagopus, the only endemic tundra species within the guild, from carcasses.
Rødrevens (Vulpes vulpes) vinterdiett: en sammenlikning mellom skog- og landbruksdominert landskap i sørøst Norge.
Diettbredden var større i området med høyere produktivitet og menneskelig aktivitet, her var avfall fra husholdning og landbruk samt korn (Cerealier spp) av større betydning. Korn i ekskrementene kan ha stammet fra elgvom (Alces alces) etter høstens elgjakt. I området med relativt lav produktivitet og liten menneskelig aktivitet var rester av hjortevilt og bærlyng (Vaccinium spp) viktigere. Smågnagere var av like stor betydning for reven i begge områdene.
Subsidiering i høyfjellet og konsekvenser for rødrev og fjellrev
Tilgangen på søppel, slakteavfall, m.m. er størst på Hardangervidda sammenlignet med Børgefjell og Dovrefjell. Dette kan være med og forklare hvorfor fjellreven forsvant fra Hardangervidda, mens den klarte seg i Børgefjell der tilgangen på subsidier er mindre.
The importance of marine vs. human-induced subsidies in the maintenance of an expanding mesocarnivore in the arctic tundra. Journal of Animal Ecology 2011, 80, 1049–1060.
During different phases of a multi-annual rodent cycle, we investigated the seasonal dynamics and spatial pattern of resource use by red foxes across a coast to inland low arctic tundra gradient, Varanger Peninsula, Norway. We found that inland red foxes primarily subsisted on reindeer carrions during the low phase of a small rodent population cycle. Lemmings became the most important food item towards the peak phase of the rodent cycle, despite being less abundant than sympatric voles.
Using artificial nests as a measure of predator abundance and predator composition: A comparative study between two contrasting forest areas
Studien benyttet kunstige reir for å sammenligne predatortetthet og predatorsammensetning mellom Varaldskogen i sørøst-Norge og to områder i Pinega i nordvest-Russland. Total predasjon (påle og bakke kombinert) og bakkepredasjon alene var høyest på Varaldskogen. Der var også bakkepredasjon også høyere enn pålepredasjon. I de to områdene i Pinega var det ingen forskjell hverken i total predasjon eller mellom pålereir og bakkereir. Disse resultatene indikerer at bakkepredatorer var viktigere enn flygende predatorer på Varaldskogen, mens de var like viktige i de to områdene i Pinega.
Interaksjoner rødrev-jerv - diettstudier rødrev, jerv og fjellrev
Denne oppgaven ble vinterdietten hos sympatriske populasjoner av jerv, fjellrev og rødrev kartlagt og sammenlignet ved ekskrementanalyse. En analyse av rødrevens og fjellrevens vinterdiett i smågnagertoppåret viste en totalt høy forekomst av smågnagere i dietten hos begge arter. Rødrev hadde forøvrig en høyere nisjebredde og mer variert diett enn fjellreven.
Predasjon på kunstige reir i forhold til menneskelig aktivitet og rypetetthet langs lanskapsgradienter i et borealt økosystem
Studien fant i motsetning til Asmyhr (2008) ingen sammenheng mellom total predasjonsrate og tetthet av lirype. De vanligste eggpredatorene var ravn, mår og kråke. Noen predatorarter utførte lite predasjon på de falske reirene. Disse artene var skjære, rødrev, røyskatt og snømus. Predasjonsratene ble vurdert opp mot menneskelige påvirkninger og de fant at den totale predasjonsraten økte i samsvar med økende tettheter av vei og sti.
Sources of spatial variation in food web structure in low Arctic tundra
We found that both changes in winter climate and a range expansion in the red fox may influence the abundance of the arctic fox population in our study region. Dens where arctic fox breeding have ceased seemed more productive than where arctic fox are still breeding, and are today used by the red fox. In addition we found that the increase in red fox population may be linked to an increase in abundance of large ungulates. The increase in the number of semi-domesticated reindeer in northernmost Fennoscandia during the last decades likely represents the most dramatic change in secondary productivity and increase in resources for generalist predator in northern Fennoscandia.
Changing circumstances: Implications for trophic dynamics and species conservation in the Fennoscandian Tundra. Universitetet i Tromsø.
Overall this thesis aims to outline and evaluate the recent dramatic changes in multi-annual population cycles of many herbivores and the possible implications of such changes on the trophic dynamics and species conservation in the Fennoscandian tundra ecosystem. The effect of recent and future projections of climate change may facilitate the establishment of novel predator species, which may act as dominant competitors for native species for habitat and prey. I here show that increased competition with red fox may be detrimental to arctic fox viability, especially if subsidies (e.g. reindeer carcasses) are available to the dominant competitor.
Predasjon på kunstige reir i boreale økosystem med forskjellig rypetetthet. UMB.
Dette studiet viste at de totale predasjonsratene i de tre områdene samsvarte med rypetettheten i områdene ved at det var lavest predasjonsrate i området med høyest rypetetthet. Predasjonsratene fra mår var høyest i bjørkeskogen og på tregrensen og arten unngikk det åpne landskapet i det lav alpine habitatet. Predasjonsratene fra ravn og kråke var høyest i det lav alpine habitatet.
The ecology of red fox predation on roe deer fawns with respect to population density, habitat and alternative prey.
Predasjon var den viktigste dødsårsaken for rådyrkje i studieområdet og rødreven var den viktigste predatoren. Men virkningen av predasjon på rådyr avheng av tettheten av rådyr, med høyere predasjon i områder med høyere tetthet av rådyr. Generelt fant vi en høyere predasjonsrisiko for rådyrkje i åpent habitat. I tilfeller der en rødrev dreper et kje påvirker det overlevelsen til eventuelle søsken uavhengig av morens adferd.
Interference competition between arctic and red foxes. Department of Zoology, Stockholm University.
In this thesis, I investigate the relationship between arctic foxes and red foxes in Swedish mountain tundra habitat. The results of this thesis indicate that interference competition with red foxes has hampered arctic fox recovery after the initial population decline, by causing a substantial reduction in arctic fox habitat. Further, red foxes have taken over the most productive areas and remaining arctic fox habitats is of such low quality that it is uncertain whether it can maintain even a small arctic fox population.