Den skandinaviska älgen

• I Skandinavien har varg och björn historiskt varit de dominerande predatorerna på älg. Stammarna av dessa två rovdjur reducerades kraftigt under slutet av 1800-talet och har först under 1900-talets senare hälft återtagit delar av sin historiska utbredning. • Våra studier visar att vargens jaktframgång på älg är klart högre i Skandinavien än i Nordamerika, där varg och grizzlybjörn under lång tid har samexisterat med älg. • Jaktframgången på älg i Skandinavien var inte lägre i områden där vargen hade varit etablerad under en längre tid (10–20 år) än i områden som vargen nyligen hade tagit i bruk (1–5 år). • Älgens beteende i Skandinavien skiljer sig från det hos älgar i Nordamerika. De senare är betydligt mer aggressiva mot både vargar och människor. • En trolig förklaring till denna beteendeskillnad hos älg är frånvaron av predation från de stora rovdjuren under 100–120 år i Skandinavien i kombination med att människan genom jakten har övertagit rollen som den dominerade predatorn på älgstammen under det sista århundradet

Agent-based models predict patterns and identify constraints of large carnivore recolonizations, a case study of wolves in Scandinavia

Large carnivores are recolonizing areas of their historical range in Europe. This process has strong implications for conservation and management related to human-wildlife conflicts. Analyses and modelling of the observed mechanisms of spatial expansion can predict recolonization patterns under human influences. We demonstrate how spatially-explicit, agent-based models can assist to identify and predict how humans impact shape large carnivore recolonizations. Using detailed data obtained through long-term surveillance of wolf territories, we identified the mechanisms of recolonization and predicted the spatio-temporal patterns of expansion of the wolf in the Scandinavian Peninsula. We disentangled the observed mechanisms of expansion to develop WOLVES (Wolf Virtual Expansion Simulator), an agent-based model software. We applied the model to investigate in silico the observed lack of wolf recolonization into the suitable but densely human-populated area of southern Sweden and projected the expansion into the future. We tested the impact of traffic barriers and territory termination (wolf mortality most likely due to culling and poaching) on the observed recolonization in the south. Simulations identified that traffic infrastructures impacted only at configurations of insurmountable barriers unlikely to occur in Scandinavia, while low rates of territory termination had a major impact on the recolonization. Simulating until 2030 predicts that wolves will not colonize southern Sweden, which highlights the complexities of this process in areas of increased human-influence. The capability of simulators to test hypotheses and discriminate constraints of future population development makes them a valuable tool for ecologists, managers, and decision-makers involved in regional and transboundary conservation challenges of large carnivore recolonizations

Wolf monitoring in Scandinavia: evaluating counts of packs and reproduction events

Large carnivores are elusive and use large areas, which causes monitoring to be challenging and costly. Moreover, management to reduce conflicts and simultaneously ensure long-term population viability require precise population estimates. In Scandinavia, the monitoring of wolves (Canis lupus) is primarily based on counting packs, identifying reproduction, and genetically identifying territorial wolves from noninvasive DNA samples. We assessed the reliability of wolf monitoring in Scandinavia by estimating the detectability of territorial pairs, packs, and reproduction. Our data, comprising snow-tracking data and DNA-identified individuals from 2005-2016, covered 11 consecutive winter monitoring seasons (Oct-Mar). Among 343 cases where we identified a wolf pack, territorial wolves were also detected in the same area during the previous season in 323 (94.2%) cases. In only 6 of the remaining 20 cases, there was no prior knowledge of territorial wolves in the area. Among the 328 detected reproduction events (litter born to a pack), we detected 97% during the monitoring period and identified the rest >= 1 year later from kinship assessments of all DNA-detected individuals. These results suggest that we failed to detect only few packs with reproduction events during the monitoring season that followed breeding. Yearly monitoring of territorial individuals and continuous updates of the pedigree allowed us to retrospectively identify reproduction events and packs that were not identified earlier

Wolf monitoring in Scandinavia: evaluating counts of packs and reproduction events

Large carnivores are elusive and use large areas, which causes monitoring to be challenging and costly. Moreover, management to reduce conflicts and simultaneously ensure long‐term population viability require precise population estimates. In Scandinavia, the monitoring of wolves (Canis lupus) is primarily based on counting packs, identifying reproduction, and genetically identifying territorial wolves from noninvasive DNA samples. We assessed the reliability of wolf monitoring in Scandinavia by estimating the detectability of territorial pairs, packs, and reproduction. Our data, comprising snow‐tracking data and DNA‐identified individuals from 2005–2016, covered 11 consecutive winter monitoring seasons (Oct–Mar). Among 343 cases where we identified a wolf pack, territorial wolves were also detected in the same area during the previous season in 323 (94.2%) cases. In only 6 of the remaining 20 cases, there was no prior knowledge of territorial wolves in the area. Among the 328 detected reproduction events (litter born to a pack), we detected 97% during the monitoring period and identified the rest ≥1 year later from kinship assessments of all DNA‐detected individuals. These results suggest that we failed to detect only few packs with reproduction events during the monitoring season that followed breeding. Yearly monitoring of territorial individuals and continuous updates of the pedigree allowed us to retrospectively identify reproduction events and packs that were not identified earlier.publishedVersio

Predator-dependent functional response in wolves: from food limitation to surplus killing

The functional response of a predator describes the change in per capita kill rate to changes in prey density. This response can be influenced by predator densities, giving a predator-dependent functional response. In social carnivores which defend a territory, kill rates also depend on the individual energetic requirements of group members and their contribution to the kill rate. This study aims to provide empirical data for the functional response of wolves Canis lupus to the highly managed moose Alces alces population in Scandinavia. We explored prey and predator dependence, and how the functional response relates to the energetic requirements of wolf packs. Winter kill rates of GPS-collared wolves and densities of cervids were estimated for a total of 22 study periods in 15 wolf territories. The adult wolves were identified as the individuals responsible for providing kills to the wolf pack, while pups could be described as inept hunters. The predator-dependent, asymptotic functional response models (i.e. Hassell-Varley type II and Crowley-Martin) performed best among a set of 23 competing linear, asymptotic and sigmoid models. Small wolf packs acquired >3 times as much moose biomass as required to sustain their field metabolic rate (FMR), even at relatively low moose abundances. Large packs (6-9 wolves) acquired less biomass than required in territories with low moose abundance. We suggest the surplus killing by small packs is a result of an optimal foraging strategy to consume only the most nutritious parts of easy accessible prey while avoiding the risk of being detected by humans. Food limitation may have a stabilizing effect on pack size in wolves, as supported by the observed negative relationship between body weight of pups and pack size

Environmental and anthropogenic features mediate risk from human hunters and wolves for moose

This is an open access article under the terms of theCreative Commons AttributionLicense, which permits use, distribution and reproduction in any medium, providedthe original work is properly cited. © 2022 The Authors.Ecospherepublished by Wiley Periodicals LLC on behalf of The Ecological Society of AmericaLandscape characteristics, seasonal changes in the environment, and daylight conditions influence space use and detection of prey and predators, resulting in spatiotemporal patterns of predation risk for the prey. When predators have different hunting modes, the combined effects of multiple predators are mediated by the physical landscape and can result in overlapping or contrasting patterns of predation risk. Humans have become super-predators in many anthropogenic landscapes by harvesting game species and competing with large carnivores for prey. Here, we used the locations of wolf (Canis lupus)-killed and hunter-killed moose (Alces alces) in south-central Scandinavia to investigate whether environmental and anthropogenic features influenced where wolves and hunters killed moose. We predicted that the combined effects of wolves and hunters would result in contrasting spatial risk patterns due to differences in hunting modes. We expected these contrasting spatial risk patterns also to differ temporally. During the hunting season, the probability of a wolf kill increased with distance to bogs, whereas it decreased with increasing building density and distance to clearcuts and young forests. After the hunting season, the probability of a wolf kill increased with increasing terrain ruggedness and decreased with increasing building density, distance to main roads, and distance to clearcuts and young forests. The probability of a hunter kill was highest closer to bogs, main and secondary roads, in less rugged terrain and in areas with lower building density. Hunters killed all moose during the day, whereas wolves killed most moose at night during and after the hunting season. Our findings suggest that environmental and anthropogenic features mediate hunting and wolf predation risk. Additionally, we found that hunter- and wolf-killed moose exhibited contrasting spatial associations to landscape features, most likely due to the different hunting modes displayed by hunters and wolves. However, wolf predation and hunting risks also contrasted over time since wolves killed mostly at night and hunters were restricted to hunting during daytime and during the hunting season. This temporal segregation in risk might therefore suggest that moose could minimize risk exposure by taking advantage of spatiotemporally vacant hunting domains.publishedVersio

Predationsstudier på varg inom projekt GRENSEVILT – en jämförelse mellan nya och tidigare studier

I Skandinavien har tidigare genomförda studier visat att tätheten av både älg och varg utgör de viktigaste faktorerna som styr effekterna av vargens predation på älgstammen. Tätheten av varg är i sin tur starkt kopplad till både flockstorleken och storleken på befintliga revir i det aktuella området. Dessa studier har framförallt skett under populationens etableringsfas med relativt sett låg täthet av varg, stora revir, och i områden med relativt hög täthet av älg. Syftet med denna studie var att skatta storleken på vargens predation på älg under mer aktuella förhållanden på samma sätt som tidigare genomförda studier. För de tidigare (1999-2017) genomförda predationsstudierna i SKANDULV var det genomsnittliga antalet angränsande revir under vintern 1,0 (n=21) och under sommaren 1,8 (n=14). För de sju studerade reviren i GRENSEVILT var antalet angränsande revir 3,0 i genomsnitt. Vi undersökte effekterna av vargens predation genom att utgå från det enskilda vargreviret och med kunskap om vargens predationstakt, storleken på reviret (tätheten av varg) och en skattning av älgstammens täthet. Studierna av vargens predation genomfördes under åren 2017-2019 och var koncentrerade till fyra vargrevir belägna i norra Värmland och angränsande områden i Innlandet fylke samt södra Dalarna. Totalt genomfördes 13 predationsstudier under åren 2017-2019 fördelade på 6 vinterstudier, 4 sommarstudier och 3 höststudier i fyra vargrevir. Totalt registrerades 154 vargdödade bytesdjur. Av de större slagna bytesdjuren var 131 älgar, 5 kronhjortar, 7 rådjur och ett vildsvin. Det totala årligta uttaget av älg varierade mellan 69 och 92 med ett medeluttag på 82 (75-89 95% KI) älgar per vargrevir och år. Detta är lägre än det beräknade uttaget av älg som har registrerats i tidigare studier i SKANDULVs regi som uppgår till 121 (100-144 95% KI) älgar per år och vargrevir. Storleken på de studerade reviren i GRENSEVILT var dock något mindre än i tidigare studier vilket medförde att det genomsnittliga predationstrycket för samtliga revir och år blev detsamma som i tidigare studier (0,11 älgar per km2 eller 1,1 älgar per 1000 ha). Tidigare studier har även visat att vargens uttag ur den lokala älgpopulationen dvs inom reviret (räknat från 1 juni direkt efter kalvning) har varit ca 8% i medeltal. Studierna i GRENSEVILT visar på ett lika högt eller marginellt högre genomsnittligt uttag (9%) men också med en betydande variation mellan reviren. Motsvarande uttag från jakt i reviren uppgick till ca 19% i medeltal och varierade mellan 12% och 23%. Därmed uppgick vargens genomsnittliga uttag ur populationen till 31% av det totala uttaget från både jakt och varg. Denna studie visar på stora likheter med tidigare resultat och beräkningar av vargens inverkan på älgstammen och på möjligheterna till jaktlig beskattning i vargreviren. Dock antyder våra nya resultat från dessa studier att vargens inverkan på den lokala älgstammen i medeltal kan vara något högre jämfört med tidigare funna resultat. Detta kan tillskrivas dels att de nu studerade vargreviren var något mindre i medeltal jämfört med tidigare studier, dels att tätheten av älg var något lägre i de studerade vargreviren jämfört med tidigare studier. Dessutom var den relativa andelen vuxna älgar av vargens predation på älg något högre i GRENSEVILT studierna