| 1. |
- Jarnemo, Anders, et al.
(författare)
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Hur reagerar kronvilt på drevjakt?
- 2015
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Ingår i: Svensk jakt. - 0039-6583. ; 153, s. 52-55
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Tidskriftsartikel (populärvet., debatt m.m.)
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| 2. |
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| 3. |
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| 4. |
- Andren, Henrik, et al.
(författare)
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De stora rovdjurens effekter på annat vilt och tamren
- 2018
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Den teoretiska bakgrunden ger en beskrivning av termer och fackuttryck, samt beskrivningar av hur olika faktorer påverkar relationerna mellan rovdjur och bytesdjur. Termen predator är synonymt med rovdjur, medan termen predation står för den process som består av dödande och konsumtion av bytesdjur, och omfattningen av den dödlighet hos bytesdjuren som rovdjuret orsakar. Rovdjurens påverkan på bytespopulationer varierar mellan områden och över tid, samtidigt som rovdjuren själva påverkas av bytespopulationerna. Rovdjur-bytesdjurssystemen är alltså inte bara dynamiska utan också interaktiva, d.v.s. de påverkar varandra. Rovdjurens påverkan på bytespopulationen beror i princip på fem faktorer: (1) bytespopulationens storlek, (2) bytespopulationens produktivitet/tillväxttakt, (3) rovdjurspopulationens storlek, (4) rovdjurspopulationens produktivitet/tillväxttakt samt (5) antalet bytesdjur tagna per rovdjur och tidsenhet (den s.k. funktionella responsen). Predation är ofta en kombination av additiv och kompensatorisk dödlighet. Med additiv dödlighet menar man att predationen läggs ovanpå (adderas till) annan dödlighet, med kompensatorisk dödlighet menar man att predationen ersätter annan typ av dödlighet. Ju större andel av predationen som är additiv desto större blir effekterna på bytesdjuren. Rovdjuren kan påverka sina bytesdjur inte bara genom direkt predation utan även genom att bytesdjuren ändrar sitt beteende i närvaron av rovdjuren. Rovdjuren är en del av ekosystemet, som förenklat består av producenter (växter), primärkonsumenter (växtätare) och sekundärkonsumenter (predatorer). Dessa delar kan också beskrivas som olika trofinivåer i ekosystemet. En mer komplex beskrivning av ett ekosystem är att arter är ordnade i ett nätverk av interaktioner både mellan och inom trofiska nivåer, s.k. näringsvävar. I komplexa näringsvävar ökar antalet interaktioner mellan arter både inom trofinivåer och mellan trofinivåer, vilket försvagar specifika interaktioner mellan enskilda arter. I Sverige saknas stora områden som är helt opåverkade av mänskliga aktiviteter, vilket gör människan till den viktigaste aktören för storskalig påverkan på ekosystem över hela landet. Människan påverkar ekosystemet på många sätt, t.ex. genom markanvändning, jakt, andra ingrepp och förvaltningsåtgärder, och kan helt förändra dynamiken mellan rovdjur och bytesdjur.Även ett kortfaktablad om rovdjurens effekter finns att ladda ned.Hur påverkar de stora rovdjuren bytesdjurens populationer?Grimsö forskningsstation vid Sveriges lantbruksuniversitet (SLU) har för Naturvårdsverkets räkning gjort en översikt av kunskapsläget om hur de stora rovdjuren påverkar de bytesdjur de jagar, det vill säga vilt och tamren. Hela rapporten, De stora rovdjurens effekter på annat vilt och tamren, kan du läsa här, eller på Naturvårdsverkets hemsida.
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| 5. |
- Ausilio, Giorgia, et al.
(författare)
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Hvordan påvirkes elgen av ulv og jakt?
- 2023
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Ingår i: Hjorteviltet. - 1502-3729. ; 2023, s. 60-63
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Tidskriftsartikel (populärvet., debatt m.m.)abstract
- Rovdyr kan påvirke byttedyr både direkte ved å drepe dem og indirekte ved å skape atferdsendringer. Risikoen for å bli drept av et rovdyr varierer i tid og rom og påvirkes av ulike faktorer, inkludert habitat, tid på døgnet, men også rovdyrets måte å jakte på.
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| 6. |
- Chapron, Guillaume, et al.
(författare)
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Estimating wolf (Canis lupus) population size from number of packs and an individual based model
- 2016
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Ingår i: Ecological Modelling. - : Elsevier BV. - 0304-3800 .- 1872-7026. ; 339, s. 33-44
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Tidskriftsartikel (refereegranskat)abstract
- Estimating wildlife population-size is fundamental for wildlife management and conservation. However, making monitoring of population size less resource demanding while still keeping a high monitoring accuracy and precision remains a recurrent challenge. One proposed alternative to count individuals is to instead focus on counting a segment of the population that is easier to monitor but at the same time well informative on total population size. We show how total population size can be estimated from group counts by using an individual-based population model in a social living species. We developed a wolf (Canis lupus) specific Individual Based Model and used Approximate Bayesian Computation (ABC) to fit this population model to the time series of annual number of packs, reproductions and pairs obtained from Scandinavian monitoring data. Model informative priors were obtained with data from collared individuals by the Scandinavian wolf research project. The fitted model was then used to estimate a conversion factor from number of packs to total number of individuals and to number of reproductions. There was a good fit between the retained simulations by ABC and the observed Scandinavian wolf population trajectory. The fitted simulations returned a conversion factor of 8.0 (95% CI = 6.62-10.07) from number of packs to total population size and of 1.0 (95% CI = 0.93-1.12) to number of reproductions in December. A sensitivity analysis revealed that the conversion factor from packs to total population size was positively correlated with pup survival and litter size and negatively correlated with subadult, vagrant and adult survivals. Using an individual based model allowed us to model the full complexity of demographic traits of a social-living species such as the wolf. The flexibility of the model also meant that the conversion factor could be estimated for any month during the year. Our approach to estimate total population size from counts of groups requires having a population model where both individuals and groups are explicitly described and can be applied to other wolf populations and group-living species where counting all individuals over a large area is unfeasible.
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| 7. |
- Chapron, Guillaume, et al.
(författare)
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Habitat segregation between brown bears and gray wolves in a human-dominated landscape
- 2018
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Ingår i: Ecology and Evolution. - : Wiley. - 2045-7758. ; 8, s. 11450-11466
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Tidskriftsartikel (refereegranskat)abstract
- Identifying how sympatric species belonging to the same guild coexist is a major question of community ecology and conservation. Habitat segregation between two species might help reduce the effects of interspecific competition and apex predators are of special interest in this context, because their interactions can have consequences for lower trophic levels. However, habitat segregation between sympatric large carnivores has seldom been studied. Based on monitoring of 53 brown bears (Ursus arctos) and seven sympatric adult gray wolves (Canis lupus) equipped with GPS collars in Sweden, we analyzed the degree of interspecific segregation in habitat selection within their home ranges in both late winter and spring, when their diets overlap the most. We used the K-select method, a multivariate approach that relies on the concept of ecological niche, and randomization methods to quantify habitat segregation between bears and wolves. Habitat segregation between bears and wolves was greater than expected by chance. Wolves tended to select for moose occurrence, young forests, and rugged terrain more than bears, which likely reflects the different requirements of an omnivore (bear) and an obligate carnivore (wolf). However, both species generally avoided human-related habitats during daytime. Disentangling the mechanisms that can drive interspecific interactions at different spatial scales is essential for understanding how sympatric large carnivores occur and coexist in human-dominated landscapes, and how coexistence may affect lower trophic levels. The individual variation in habitat selection detected in our study may be a relevant mechanism to overcome intraguild competition and facilitate coexistence.
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| 9. |
- Di Bernardi, Cecilia, et al.
(författare)
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Experimental feeding validates nanofluidic array technology for DNA detection of ungulate prey in wolf scats
- 2023
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Ingår i: Environmental DNA. - 2637-4943. ; 5, s. 723-732
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Tidskriftsartikel (refereegranskat)abstract
- The study of carnivores' diet is a key component to enhance knowledge on the ecology of predators and their effect on prey populations. Although molecular approaches to detect prey DNA in carnivore scats are improving, the validation of their accuracy, a prerequisite for reliable applications within ecological frameworks, is still lagging behind the methodological advances. Indeed, variation in detection probability among prey species can occur, representing a potentially insidious source of bias in food-habit studies of carnivores. Calibration of DNA-based methods involves the optimization of specificity and sensitivity and, whereas priority is usually given to the former to avoid false positives, sensitivity is rarely investigated so that false negatives may be largely overlooked. We conducted feeding trials with captive wolves (Canis lupus) to validate a nanofluidic array technology recently developed for the detection of multiple prey species in scats. Using 371 scat samples from 12 wolves fed with a single-prey diet, the sensitivity of our nanofluidic array method varied between 0.45 and 0.95 for the six main ungulate prey species. The method sensitivity was enhanced by using multiple markers per species and by a relatively low threshold of number of amplifying markers required to confirm a detection. Yet, at least two markers should be used to avoid false positives. By acknowledging sources of bias in sensitivity to reliably interpret the results of DNA-based dietary methods, our study highlights the relevance of feeding experiments to optimally calibrate the relative thresholds to define a positive detection and investigate the occurrence and extent of biases in sensitivity.
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| 10. |
- Di Bernardi, Cecilia, et al.
(författare)
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Multiple species-specific molecular markers using nanofluidic array as a tool to detect prey DNA from carnivore scats
- 2021
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Ingår i: Ecology and Evolution. - : Wiley. - 2045-7758. ; 11, s. 11739-11748
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Tidskriftsartikel (refereegranskat)abstract
- Large carnivore feeding ecology plays a crucial role for management and conservation for predators and their prey. One of the keys to this kind of research is to identify the species composition in the predator diet, for example, prey determination from scat content. DNA-based methods applied to detect prey in predators' scats are viable alternatives to traditional macroscopic approaches, showing an increased reliability and higher prey detection rate. Here, we developed a molecular method for prey species identification in wolf (Canis lupus) scats using multiple species-specific marker loci on the cytochrome b gene for 18 target species. The final panel consisted of 80 assays, with a minimum of four markers per target species, and that amplified specifically when using a high-throughput Nanofluidic array technology (Fluidigm Inc.). As a practical example, we applied the method to identify target prey species DNA in 80 wolf scats collected in Sweden. Depending on the number of amplifying markers required to obtain a positive species call in a scat, the success in determining at least one prey species from the scats ranged from 44% to 92%. Although we highlight the need to evaluate the optimal number of markers for sensitive target species detection, the developed method is a fast and cost-efficient tool for prey identification in wolf scats and it also has the potential to be further developed and applied to other areas and large carnivores as well.
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