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Jens Persson - One of the best experts on this subject based on the ideXlab platform.
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Refrigeration or anti-theft? Food-caching behavior of Wolverines (Gulo gulo) in Scandinavia
Behavioral Ecology and Sociobiology, 2020Co-Authors: Bert Van Der Veen, Jenny Mattisson, Barbara Zimmermann, John Odden, Jens PerssonAbstract:Food-caching animals can gain nutritional advantages by buffering seasonality in food availability, especially during times of scarcity. The Wolverine (Gulo gulo) is a facultative predator that occupies environments of low productivity. As an adaptation to fluctuating food availability, Wolverines cache perishable food in snow, boulders, and bogs for short- and long-term storage. We studied caching behavior of 38 GPS-collared Wolverines in four study areas in Scandinavia. By investigating clusters of GPS locations, we identified a total of 303 food caches from 17 male and 21 female Wolverines. Wolverines cached food all year around, from both scavenging and predation events, and spaced their caches widely within their home range. Wolverines cached food items on average 1.1 km from the food source and made between 1 and 6 caches per source. Wolverines cached closer to the source when scavenging carcasses killed by other large carnivores; this might be a strategy to optimize food gain when under pressure of interspecific competition. When caching, Wolverines selected for steep and rugged terrain in unproductive habitat types or in forest, indicating a preference for less-exposed sites that can provide cold storage and/or protection against pilferage. The observed year-round investment in caching by Wolverines underlines the importance of food predictability for survival and reproductive success in this species. Increasing temperatures as a consequence of climate change may provide new challenges for Wolverines by negatively affecting the preservation of cached food and by increasing competition from pilferers that benefit from a warmer climate. It is however still not fully understood which consequences this may have for the demography and behavior of the Wolverine. Food caching is a behavioral strategy used by a wide range of animals to store food for future use. Choosing appropriate caching sites appears important for slowing down decomposition rates and minimizes competition. In this study, we demonstrate that the Wolverine, an opportunistic predator and scavenger, utilizes available carrion to create caches all year around. By following Wolverines with GPS collars, we registered that they carried food far away to cache it in secluded and cold places, which are often located on steep slopes or in forest. However, when scavenging other carnivores’ prey, they move food in shorter distances, possibly to be able to quickly return for more. The observed efficiency in Wolverine caching behavior is likely vital for their survival and reproductive success in the harsh and highly seasonal environment in which they live.
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predation or scavenging prey body condition influences decision making in a facultative predator the Wolverine
Bulletin of The Ecological Society of America, 2017Co-Authors: Jenny Mattisson, Henrik Andrén, Geir Rune Rauset, John Odden, John D C Linnell, Jens PerssonAbstract:The interaction between predators and their prey is a key factor driving population dynamics and shaping wildlife communities. Most predators will scavenge in addition to killing their own prey, which alters predation effects and implies that one cannot treat these as independent processes. However, the relative importance of predation vs. scavenging and the mechanisms driving variation of such are relatively unstudied in ecological research on predator-prey relationships. Foraging decisions in facultative predators are likely to respond to environmental conditions (e.g., seasonality) and inter- or intraspecific interactions (e.g., prey availability, presence of top predators, scavenging competition). Using data on 41 GPS-collared Wolverines (Gulo gulo) during 2401 monitoring days, in four study sites in Scandinavia, we studied variation in diet and feeding strategies (predation vs. scavenging), along a gradient of environmental productivity, seasonality, density, and body mass of their main prey, semidomestic reindeer (Rangifer tarandus). The most important factor affecting the relative extent of predation and scavenging was mean prey body mass. Predation was more pronounced in summer, when vulnerable reindeer calves are abundant, and individual kill rates were negatively related to local reindeer body mass. This relationship was absent in winter. The probability of scavenging was higher in winter and increased with decreasing local reindeer body mass, likely as a response to increased carrion supply. Wolverine feeding strategy was further influenced by predictable anthropogenic food resources (e.g., slaughter remains from hunted ungulates) and the presence of a top predator, Eurasian lynx (Lynx lynx), which provided a continuous carrion supply promoting scavenging. Our results suggest that Wolverine feeding strategies are flexible and strongly influenced by seasonally dependent responses to prey body condition in combination with carrion supply. This study demonstrates that large-scale environmental variation can result in contrasting predator feeding strategies, strongly affecting trophic interactions and potentially shaping the dynamics of ecological communities.
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Paying for an Endangered Predator Leads to Population Recovery
Conservation Letters, 2015Co-Authors: Jens Persson, Geir Rune Rauset, Guillaume ChapronAbstract:Keeping viable predator populations on a human-dominated planet will require innovative approaches that promote local coexistence with human activities. Conservation performance payments, which are linked specifically to the production of a desired environmental output, have received increasing attention but their effectiveness in predator conservation remains undocumented. Here, we show that paying Sami reindeer herders for Wolverine (Gulo gulo) reproductions has been instrumental in the recovery of Wolverines in Sweden. Adult female Wolverines were significantly less exposed to illegal killing and this allowed the population to more than double in a decade. We argue that this program provides protection for adult female Wolverines through a combination of direct monetary value and indirect protection because of monitoring activities. The program's success, even in a system where livestock is the main prey for the predator, reveals an exceptional potential for future implementations in large carnivore conservation.
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the Wolverine s niche linking reproductive chronology caching competition and climate
Journal of Mammalogy, 2012Co-Authors: Audrey J Magoun, Jens Persson, Robert M Inman, Jenny MattissonAbstract:Wolverines are demographically vulnerable and susceptible to impacts from climate change. Their distribution is correlated with persistent spring snow cover, but food-based explanations for this relationship have not been explored. We synthesize information on the timing of both Wolverine reproductive events and food availability to improve our understanding of the behaviors, habitat features, and foods that influence reproductive success. Wolverine births are constrained to a brief period of the year and occur at an earlier date than other nonhibernating, northern carnivores. Our examination suggests that this timing is adaptive because it allows Wolverines to take advantage of a cold, low-productivity niche by appending the scarce resources available during winter to the brief period of summer abundance. The Wolverine’s bet-hedging reproductive strategy appears to require success in 2 stages. First, they must fuel lactation (February–April) with caches amassed over winter or acquisition of a sudden food bonanza (e.g., winter-killed ungulates); otherwise, early litter loss occurs. Next, they must fuel the majority of postweaning growth during the brief but relatively reliable summer period of resource abundance. The 1st stage is likely dependent on scavenged ungulate resources over most of the Wolverine’s range, whereas the 2nd stage varies by region. In some regions the 2nd stage may continue to be focused on scavenging ungulate remains that have been provided by larger predators. In other regions the 2nd stage may be focused on predation by Wolverines on small prey or neonatal ungulates. During all seasons and regions, caching in cold, structured microsites to inhibit competition with insects, bacteria, and other scavengers is likely a critical behavioral adaptation because total food resources are relatively limited within the Wolverine’s niche. Habitat features that facilitate caching, e.g., boulders and low ambient temperatures, are likely important and could be related to the limits of distribution. This ‘‘refrigeration-zone’’ hypothesis represents a food-based explanation for the correlation between Wolverine distribution and persistent spring snow cover. Understanding regional differences in foods that fuel reproduction and underlying causes to the limits of distribution could be important for maintaining Wolverine populations in the future.
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Temporal and spatial interactions between an obligate predator, the Eurasian lynx (Lynx lynx), and a facultative scavenger, the Wolverine
Canadian Journal of Zoology, 2011Co-Authors: Jenny Mattisson, Jens PerssonAbstract:Interspecific interactions between sympatric carnivores can be important for the behaviour and demography of involved species. We studied spatial and temporal interactions between an obligate predator, the Eurasian lynx (Lynx lynx (L., 1758)), and a facultative scavenger, the Wolverine (Gulo gulo (L., 1758)). Wolverines are known to utilize lynx-killed reindeer (Rangifer tarandus tarandus (L., 1758)) and may benefit from being sympatric with lynx if interference competi- tion is low. We used individual location data from 9 lynx and 17 Wolverines to analyse interaction between inter- and in- tra-specific dyads (n = 195). We found no spatial segregation between lynx and Wolverines and we observed no attraction or avoidance between individuals of the two species, independent of proportion of home-range overlap. This opposed our prediction that Wolverines will show direct or delayed attraction to lynx. Wolverines may still benefit by scavenging lynx- killed reindeer while avoiding direct encounters with the lynx. Within species, we found attraction between males and fe- males, increasing with proportion of overlap for lynx. Attraction was also found between consexual lynx, while consexual Wolverines showed little home-range overlap (7%-9%) and neutral temporal interaction, indicating territoriality. Individual space use may be more influenced by conspecific interactions than by other species.
Jenny Mattisson - One of the best experts on this subject based on the ideXlab platform.
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Refrigeration or anti-theft? Food-caching behavior of Wolverines (Gulo gulo) in Scandinavia
Behavioral Ecology and Sociobiology, 2020Co-Authors: Bert Van Der Veen, Jenny Mattisson, Barbara Zimmermann, John Odden, Jens PerssonAbstract:Food-caching animals can gain nutritional advantages by buffering seasonality in food availability, especially during times of scarcity. The Wolverine (Gulo gulo) is a facultative predator that occupies environments of low productivity. As an adaptation to fluctuating food availability, Wolverines cache perishable food in snow, boulders, and bogs for short- and long-term storage. We studied caching behavior of 38 GPS-collared Wolverines in four study areas in Scandinavia. By investigating clusters of GPS locations, we identified a total of 303 food caches from 17 male and 21 female Wolverines. Wolverines cached food all year around, from both scavenging and predation events, and spaced their caches widely within their home range. Wolverines cached food items on average 1.1 km from the food source and made between 1 and 6 caches per source. Wolverines cached closer to the source when scavenging carcasses killed by other large carnivores; this might be a strategy to optimize food gain when under pressure of interspecific competition. When caching, Wolverines selected for steep and rugged terrain in unproductive habitat types or in forest, indicating a preference for less-exposed sites that can provide cold storage and/or protection against pilferage. The observed year-round investment in caching by Wolverines underlines the importance of food predictability for survival and reproductive success in this species. Increasing temperatures as a consequence of climate change may provide new challenges for Wolverines by negatively affecting the preservation of cached food and by increasing competition from pilferers that benefit from a warmer climate. It is however still not fully understood which consequences this may have for the demography and behavior of the Wolverine. Food caching is a behavioral strategy used by a wide range of animals to store food for future use. Choosing appropriate caching sites appears important for slowing down decomposition rates and minimizes competition. In this study, we demonstrate that the Wolverine, an opportunistic predator and scavenger, utilizes available carrion to create caches all year around. By following Wolverines with GPS collars, we registered that they carried food far away to cache it in secluded and cold places, which are often located on steep slopes or in forest. However, when scavenging other carnivores’ prey, they move food in shorter distances, possibly to be able to quickly return for more. The observed efficiency in Wolverine caching behavior is likely vital for their survival and reproductive success in the harsh and highly seasonal environment in which they live.
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predation or scavenging prey body condition influences decision making in a facultative predator the Wolverine
Bulletin of The Ecological Society of America, 2017Co-Authors: Jenny Mattisson, Henrik Andrén, Geir Rune Rauset, John Odden, John D C Linnell, Jens PerssonAbstract:The interaction between predators and their prey is a key factor driving population dynamics and shaping wildlife communities. Most predators will scavenge in addition to killing their own prey, which alters predation effects and implies that one cannot treat these as independent processes. However, the relative importance of predation vs. scavenging and the mechanisms driving variation of such are relatively unstudied in ecological research on predator-prey relationships. Foraging decisions in facultative predators are likely to respond to environmental conditions (e.g., seasonality) and inter- or intraspecific interactions (e.g., prey availability, presence of top predators, scavenging competition). Using data on 41 GPS-collared Wolverines (Gulo gulo) during 2401 monitoring days, in four study sites in Scandinavia, we studied variation in diet and feeding strategies (predation vs. scavenging), along a gradient of environmental productivity, seasonality, density, and body mass of their main prey, semidomestic reindeer (Rangifer tarandus). The most important factor affecting the relative extent of predation and scavenging was mean prey body mass. Predation was more pronounced in summer, when vulnerable reindeer calves are abundant, and individual kill rates were negatively related to local reindeer body mass. This relationship was absent in winter. The probability of scavenging was higher in winter and increased with decreasing local reindeer body mass, likely as a response to increased carrion supply. Wolverine feeding strategy was further influenced by predictable anthropogenic food resources (e.g., slaughter remains from hunted ungulates) and the presence of a top predator, Eurasian lynx (Lynx lynx), which provided a continuous carrion supply promoting scavenging. Our results suggest that Wolverine feeding strategies are flexible and strongly influenced by seasonally dependent responses to prey body condition in combination with carrion supply. This study demonstrates that large-scale environmental variation can result in contrasting predator feeding strategies, strongly affecting trophic interactions and potentially shaping the dynamics of ecological communities.
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the Wolverine s niche linking reproductive chronology caching competition and climate
Journal of Mammalogy, 2012Co-Authors: Audrey J Magoun, Jens Persson, Robert M Inman, Jenny MattissonAbstract:Wolverines are demographically vulnerable and susceptible to impacts from climate change. Their distribution is correlated with persistent spring snow cover, but food-based explanations for this relationship have not been explored. We synthesize information on the timing of both Wolverine reproductive events and food availability to improve our understanding of the behaviors, habitat features, and foods that influence reproductive success. Wolverine births are constrained to a brief period of the year and occur at an earlier date than other nonhibernating, northern carnivores. Our examination suggests that this timing is adaptive because it allows Wolverines to take advantage of a cold, low-productivity niche by appending the scarce resources available during winter to the brief period of summer abundance. The Wolverine’s bet-hedging reproductive strategy appears to require success in 2 stages. First, they must fuel lactation (February–April) with caches amassed over winter or acquisition of a sudden food bonanza (e.g., winter-killed ungulates); otherwise, early litter loss occurs. Next, they must fuel the majority of postweaning growth during the brief but relatively reliable summer period of resource abundance. The 1st stage is likely dependent on scavenged ungulate resources over most of the Wolverine’s range, whereas the 2nd stage varies by region. In some regions the 2nd stage may continue to be focused on scavenging ungulate remains that have been provided by larger predators. In other regions the 2nd stage may be focused on predation by Wolverines on small prey or neonatal ungulates. During all seasons and regions, caching in cold, structured microsites to inhibit competition with insects, bacteria, and other scavengers is likely a critical behavioral adaptation because total food resources are relatively limited within the Wolverine’s niche. Habitat features that facilitate caching, e.g., boulders and low ambient temperatures, are likely important and could be related to the limits of distribution. This ‘‘refrigeration-zone’’ hypothesis represents a food-based explanation for the correlation between Wolverine distribution and persistent spring snow cover. Understanding regional differences in foods that fuel reproduction and underlying causes to the limits of distribution could be important for maintaining Wolverine populations in the future.
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influence of intraguild interactions on resource use by Wolverines and eurasian lynx
Journal of Mammalogy, 2011Co-Authors: Jenny Mattisson, Ens J PerssonAbstract:It is important to the conservation and management of threatened or endangered carnivores to recognize interspecific interactions that can influence demography or behavior of the species involved. We studied the Eurasian lynx (Lynx lynx), an efficient predator, and Wolverine (Gulo gulo), an opportunistic predator and scavenger, that coexist in the reindeer husbandry area in northern Sweden. Both species are major predators on semidomestic reindeer (Rangifer tarandus), but Wolverines frequently scavenge ungulate carcasses. We examined the composition and use of food resources by Wolverines and in particular the relative importance of lynx-killed reindeer in Wolverine diet. We also examined the influence of Wolverine scavenging on lynx kill rate. We found that 52% of carcasses visited by Wolverines were lynx-killed reindeer, but only 11% were Wolverine-killed reindeer. Of all Wolverine locations at carcasses, 28% were on lynx-killed and 24% on Wolverine-killed reindeer. Remaining locations were mainly on reindeer that died from accidents (23%) or were killed by unknown carnivores (9%). Lynx predation rate on reindeer was nine times higher than that of Wolverines. Wolverines scavenged 68% of available lynx-killed reindeer, 29% of which were still being used by lynx at Wolverine arrival. Still, Wolverine scavenging had a limited influence on lynx kill rate. Time to next kill decreased only when the lynx kill was an adult reindeer in forest; however, most lynx-killed reindeer were found on tundra. Wolverines appear to benefit from coexistence with lynx through increased scavenging opportunities. We suspect that lynx presence reduces Wolverine predation on reindeer due to increased scavenging opportunities. These results may have important implications for carnivore management in reindeer husbandry areas.
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Temporal and spatial interactions between an obligate predator, the Eurasian lynx (Lynx lynx), and a facultative scavenger, the Wolverine
Canadian Journal of Zoology, 2011Co-Authors: Jenny Mattisson, Jens PerssonAbstract:Interspecific interactions between sympatric carnivores can be important for the behaviour and demography of involved species. We studied spatial and temporal interactions between an obligate predator, the Eurasian lynx (Lynx lynx (L., 1758)), and a facultative scavenger, the Wolverine (Gulo gulo (L., 1758)). Wolverines are known to utilize lynx-killed reindeer (Rangifer tarandus tarandus (L., 1758)) and may benefit from being sympatric with lynx if interference competi- tion is low. We used individual location data from 9 lynx and 17 Wolverines to analyse interaction between inter- and in- tra-specific dyads (n = 195). We found no spatial segregation between lynx and Wolverines and we observed no attraction or avoidance between individuals of the two species, independent of proportion of home-range overlap. This opposed our prediction that Wolverines will show direct or delayed attraction to lynx. Wolverines may still benefit by scavenging lynx- killed reindeer while avoiding direct encounters with the lynx. Within species, we found attraction between males and fe- males, increasing with proportion of overlap for lynx. Attraction was also found between consexual lynx, while consexual Wolverines showed little home-range overlap (7%-9%) and neutral temporal interaction, indicating territoriality. Individual space use may be more influenced by conspecific interactions than by other species.
Hans Ellegren - One of the best experts on this subject based on the ideXlab platform.
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dna based monitoring of two newly founded scandinavian Wolverine populations
Conservation Genetics, 2007Co-Authors: Eva Hedmark, Hans EllegrenAbstract:The Wolverine is an endangered carnivore that in northwestern Europe is restricted to the mountain range along the border between Sweden and Norway. The Scandinavian Wolverine population experienced a severe decline in numbers due to human persecution during the 20th century, although with legislative protection the population has recently implied that the population slowly has started to recover (current population size estimate of 800 individuals). In the mid 1990s, Wolverines appeared in two new and isolated areas east of the mountain range, in the forest landscape close to the Gulf of Bothnia. Using non-invasive, DNA-based monitoring, we show here that these new subpopulations were likely founded by as few as 2 and 2–4 individuals, respectively, and that little, if any, genetic contact with the main population since colonisation has been established. A high degree of genetic similarity among individuals in the two areas indicates inbreeding. We estimate the minimum number of Wolverines known to be alive in these areas during the period of 2001–2005 to 5 and 17, respectively, with one subpopulation showing decreasing (currently 2) numbers and the other increasing (10). For the somewhat larger population, we infer a tentative pedigree from relatedness values and parentage tests, which indicates the occurrence of brother–sister matings. This study illustrates the usefulness of non-invasive monitoring in the management of endangered carnivore populations.
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dna based individual and sex identification from Wolverine gulo gulo faeces and urine
Conservation Genetics, 2004Co-Authors: Eva Hedmark, Arild Landa, Øystein Flagstad, Jens Persson, Peter Segerstrom, Hans EllegrenAbstract:Non-invasive genetic analyses are important for studies of species that are rare, sensitive or at risk of extinction. This study investigates the possibility of using faeces and urine to obtain microsatellite genotypes for individual identification of Wolverines (Gulo gulo). The reliability of the employed method was assessed by analysing independent amplifications of non-invasive samples (a multiple-tube approach) and by comparing genotypes obtained from faeces to genotypes obtained from blood or tissue of the same individual. Ten microsatellite markers were successfully amplified in 65% of the faecal samples (n = 32) and 40% of the urine samples (n = 22). Allelic dropout was found in 12 and 14% of the amplifications from extracts of faeces and urine, respectively. Nevertheless, all multi-locus genotypes were correct, as judged from comparison to data from tissue or blood samples, after three replicates. These results suggest that a non-invasive approach based on DNA-analysis of faeces can be a powerful tool in population monitoring of Wolverines, potentially providing reliable estimates of population size and immigration rate. A second objective of the study was to develop markers for DNA-based sex identification in Wolverines using non-invasive samples. We developed two Y-linked markers, one that was specific to Wolverine and one that also successfully identified sex in another mustelid. Importantly, none of the markers amplified potential prey species such as reindeer or rodents.
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colonization history and noninvasive monitoring of a reestablished Wolverine population
Conservation Biology, 2004Co-Authors: Øystein Flagstad, Arild Landa, Jens Persson, Henrik Broseth, Roy Andersen, Peter Segerstrom, Eva Hedmark, Hans EllegrenAbstract:The southern Norwegian Wolverine (Gulo gulo) population was considered functionally extinct in the 1960s but has partly recovered in recent years. Proper management of this population is highly dependent on reliable estimates of critical population parameters such as population size, sex ratio, immigration rate, and reproductive contribution from immigrants. We report on a large-scale population monitoring project assessing these parameters through genetic tagging of individuals, with feces as the source of DNA. Sixty-eight different individuals were detected among 147 successfully genotyped samples collected in 2000 and 2001. Sixty of these individuals were represented in the 2001 sample, which may be considered a minimum estimate of the population size. Almost 50% of these animals were sampled only once, however, indicating that the true population size may be markedly higher. Accordingly, a capture-recapture estimate based on the observed resampling rates suggested a population size of 89 Wolverines (95% confidence interval (CI) = 74-104), which is approximately 35% higher than an estimate of 64 obtained from the number of active natal dens (95% CI = 46-95; p = 0.08). Indirect estimates of dispersal distances inferred from mother-offspring relationships sug- gested that Wolverine males have the ability to disperse up to 500 km, a distance exceeding anything previously reported in the literature. Dispersal distances of more than 100 km were detected for females. Bayesian clus- tering analysis and subsequent assessment of individual relationships suggest that immigrants from northern Scandinavia have contributed and still contribute to the southern Norwegian gene pool, counteracting genetic erosion and reducing the risk of inbreeding depression. Additional sampling efforts will be undertaken during the coming years to allow for observations of population trends, immigration rate, and reproductive variance among individuals. Such data will provide an important basis for the design of an appropriate conservation plan for this small and vulnerable population.
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genetic variation and population structure in scandinavian Wolverine gulo gulo populations
Molecular Ecology, 2001Co-Authors: C W Walker, M. Van Der Linden, A Landa, Carles Vila, Hans EllegrenAbstract:Wolverine ( Gulo gulo ) numbers in Scandinavia were significantly reduced during the early part of the century as a result of predator removal programmes and hunting. Protective legislation in both Sweden and Norway in the 1960s and 1970s has now resulted in increased Wolverine densities in Scandinavia. We report here the development of 15 polymorphic microsatellite markers in Wolverine and their use to examine the population sub-structure and genetic variability in free-ranging Scandinavian Wolverine populations as well as in a sample of individuals collected before 1970. Significant subdivision between extant populations was discovered, in particular for the small and isolated population of southern Norway, which represents a recent recolonization. Overall genetic variability was found to be lower than previously reported for other mustelids, with only two to five alleles per locus and observed heterozygosities ( H O ) ranging from 0.269 to 0.376 across the examined populations, being lowest in southern Norway. Analysis of the mitochondrial DNA control region revealed no variation throughout the surveyed populations. As the historical sample did not show higher levels of genetic variability, our results are consistent with a reduction in the genetic variation in Scandinavian Wolverines that pre-dates the demographic bottleneck observed during the last century. The observed subdivision between populations calls for management caution when issuing harvest quotas, especially for the geographically isolated south Norwegian population.
Mattisson Jenny - One of the best experts on this subject based on the ideXlab platform.
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GPS collars have an apparent positive effect on the survival of a large carnivore
2021Co-Authors: Milleret, Cyril Pierre, Odden John, Brøseth Henrik, Bischof Richard, Dupont Pierre, Mattisson JennyAbstract:Are instrumented animals representative of the population, given the potential bias caused by selective sampling and the influence of capture, handling and wearing bio-loggers? The answer is elusive owing to the challenges of obtaining comparable data from individuals with and without bio-loggers. Using non-invasive genetic data of a large carnivore, the Wolverine (Gulo gulo) in Scandinavia, and an open-population spatial capture–recapture model, we found a 16 (credible interval: 4–30) percentage points lower mortality probability for GPS-collared individuals compared with individuals without GPS collars. While the risk of dying from legal culling was comparable for collared and non-collared Wolverines, the former experienced lower probability of mortality due to causes other than legal culling. The aforementioned effect was pronounced despite a potentially lower age—and therefore likely higher natural mortality—of collared individuals. Reports of positive effects of bio-loggers on the survival of individuals are uncommon and we argue that GPS collars could shield animals from poaching. Our results highlight the challenges of drawing population-level inferences for populations subjected to poaching when using data from instrumented individuals. ecology, population level, representativeness, population dynamic
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Inventering av järv 2021. Bestandsovervåking av jerv i 2021.
Rovdata (NINA) og SLU Viltskadecenter, 2021Co-Authors: Hedmark Eva, Mattisson Jenny, Tovmo MariAbstract:The Norwegian Environment Agency (Miljødirektoratet) and the Swedish Environmental Protection Agency (Naturvårdsverket) have co-developed standard methodology and guidelines for the monitoring of Wolverines in Scandinavia, that have been implemented in both Norway and Sweden since 2014. To estimate size, and assessing trends, of the Wolverine population in Scandinavia, Wolverine reproductive areas (female territories) are annually surveyed during late winter and spring to register whether reproductions have occurred. The population size is estimated based on the number of Wolverine reproductions that fulfil the criteria for Documented or Considered as certain reproduction. The monitoring of Wolverine reproductions, and registration of data into the shared database Rovbase, is conducted by field staff from the County Administration Boards CAB (Länsstyrelserna) in Sweden and the Norwegian Nature Inspectorate (Statens Naturoppsyn) in Norway. In Sweden, the Sami villages (administrative units for reindeer herding) assist the CABs by reporting suspected den sites, which can then be evaluated in the field by CAB field personnel. During the 2021 census, a total of 160 Wolverine reproductions were registered in Scandinavia, which are similar to the year before (164 reproductions). Of these, 100 reproductions were found in Sweden and 60 in Norway. This corresponds to one reproduction less (1%) in Sweden and three reproductions less (4.8%) in Norway, compared to 2020. The model used to estimate population size, i.e. extrapolate number of reproductions to adult individuals in the population, accounts for annual variation in reproductive success by using the average number of reproductions in the past three years. Based on the number of Wolverine reproductions during the last three years (2019–2021), the Scandinavian population size is estimated to 1023 adult Wolverines (95% CI = 871–1273), defined as 1-year old or older, which is 4% less then the estimate last year. Of the 1023 Wolverines, 386 Wolverines (95% CI = 324–493) are estimated to be in Norway and 637 Wolverines (95% CI = 518–826) in Sweden. The estimated population size in Norway in 2021 is similar to the estimate from 2020 (382 Wolverines; 95% CI = 323–486). For the Swedish part of the population the estimate is 7% lower than the estimate from 2020 (687 Wolverines; 95% CI = 572–891).Miljødirektoratet och Naturvårdsverket har utarbetat gemensamma riktlinjer och metodik för övervakning av järv vilka följs gemensamt av Norge och Sverige sedan inventeringssäsongen 2014. Populationsstorleken och populationsutvecklingen för järv i Skandinavien övervakas genom registrering av föryngringslokaler (revir) där föryngring skett under vårvintern. Det görs en årlig beräkning av populationsstorleken som baseras på det inventerade antalet järvföryngringar som uppnått statusen Dokumenterad eller Bedömd som säker utifrån de gemensamma kriterierna. Järvföryngringar inventeras och registreras i Rovbase främst av fältpersonal från Länsstyrelserna i Sverige och Statens Naturoppsyn (SNO) i Norge, som utför fältkontrollerna. På svensk sida sker inventeringen i renskötselområdet i nära sammarbete med samebyarna. De rapporterar misstänkta lyelokaler till länsstyrelsens personal som därefter kvalitetssäkrar i fält. Under inventeringssäsongen 2021 registrerades 160 järvföryngringar i Skandinavien, vilket är fyra färre föryngringar än 2020. Av dessa återfanns 100 föryngringar i Sverige och 60 i Norge. I Sverige motsvarar det en föryngring mindre (1%) och i Norge tre föryngringar mindre (4,8%) jämfört med 2020. Genom en populationsmodell som baserar sig på ett genomsnittligt antal föryngringar de senaste tre åren, beräknas antalet föryngringar om till antal individer. Modellen tar hänsyn till att både årets och föregående års reproduktionsframgång påverkar den totala populationsstorleken. Baserat på de antal föryngringar som hittats 2019–2021 beräknas den skandinaviska populationen 2021 till 1023 vuxna järvar som är ett år eller äldre (95 % CI = 871–1273), vilket är 4% färre än fjolårets populationsuppskattning för Skandinavien som helhet. Av de 1023 järvarna återfinns uppskattningsvis 386 individer (95 % CI = 324–493) i den norska delen av järvpopulationen och 637 individer (95 % CI = 518–826) i den svenska delen av populationen. Uppskattningen för den norska delen av populationen är i princip oförändrad jämfört med 2020 (1 % högre än uppskattningen på 382 individer, 95% CI= 323–486), medan uppskattningen för den svenska delen av population är 7 % lägre jämfört med uppskattningen 2020 (687 individer; 95% CI= 572–891).Miljødirektoratet og Naturvårdsverket har utarbeidet felles retningslinjer og metodikk for overvåkingen av jerv som har vært gjeldende i både Norge og Sverige siden registrerings- sesongen 2014. Bestandsstørrelse og –utvikling for jerv i Skandinavia overvåkes ved registrering av ynglelokaliteter (revir) hvor det har blitt født ungekull i løpet av vårvinteren. Det gjøres en årlig beregning av bestandsstørrelsen som baseres på antall påviste ynglinger som er Dokumentert eller Antatt sikre ut i fra de felles skandinaviske overvåkingskriteriene. Jervynglingene overvåkes og registreres i Rovbase i hovedsak av feltpersonell fra Statens Naturoppsyn (SNO) i Norge og Länsstyrelsene i Sverige, som utfører feltkontrollene. På svensk side skjer registreringen i reinbeiteområdene i tett samarbeid med samebyene. De rapporterer mulige hilokaliteter til länsstyrelsens personell, som deretter kvalitetssikrer i felt. I løpet av registreringssesongen 2021 ble det totalt registrert 160 ynglinger av jerv i Skandinavia, noe som er fire færre ynglinger enn i 2020. Av disse ble 100 ynglinger påvist i Sverige og 60 i Norge. I Sverige tilsvarer dette en reduksjon på 1 yngling (1 %) og i Norge en reduksjon på tre ynglinger (4,8 %) sammenlignet med 2020. Det gjennomsnittlige antallet påviste jervynglinger de tre siste årene brukes som grunnlag for bestandsestimeringen fra antall ynglinger til antall voksne jerver i populasjonen. Modellen som brukes i bestandsestimeringen tar hensyn til at både årets og foregående års reproduksjoner påvirker størrelsen på bestanden. Basert på antall ynglinger i perioden 2019–2021 beregnes den skandinaviske bestanden i 2021 til 1023 voksne jerver som er ett år eller eldre (95 % CI = 871–1273), noe som er 4 % mindre enn fjorårets populasjonsestimatet for Skandinavia som helhet. Av de 1023 jervene utgjør anslagsvis den norske delen av bestanden 386 individer (95 % CI = 324–493), og den svenske delen av bestanden 637 individer (95 % CI = 518–826). Estimatet for den norske delen av bestanden er omtrent det samme som i 2020 (1 % høyere enn i 2020: 382 individer, 95% CI=323–486), mens estimatet for den svenske delen av bestanden er 7 % lavere sammenlignet med 2020 (687 individer, 95% CI=572–891)
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Refrigeration or anti-theft? Food-caching behavior of Wolverines (Gulo gulo) in Scandinavia
'Springer Science and Business Media LLC', 2020Co-Authors: Van Der Veen Bert, Odden John, Mattisson Jenny, Zimmermann Barbara, Persson JensAbstract:Food-caching animals can gain nutritional advantages by buffering seasonality in food availability, especially during times of scarcity. The Wolverine (Gulo gulo) is a facultative predator that occupies environments of low productivity. As an adaptation to fluctuating Food availability, Wolverines cache perishable food in snow, boulders, and bogs for short- and long-term storage. We studied caching behavior of 38 GPS-collared Wolverines in four study areas in Scandinavia. By investigating clusters of GPS locations, we identified a total of 303 food caches from 17 male and 21 female Wolverines.Wolverines cached food all year around, from both scavenging and predation events, and spaced their caches widely within their home range.Wolverines cached food items on average 1.1 km from the food source andmade between 1 and 6 caches per source.Wolverines cached closer to the source when scavenging carcasses killed by other large carnivores; this might be a strategy to optimize food gain when under pressure of interspecific competition.When caching, Wolverines selected for steep and rugged terrain in unproductive habitat types or in forest, indicating a preference for less-exposed sites that can provide cold storage and/or protection against pilferage. The observed year-round investment in caching by Wolverines underlines the importance of food predictability for survival and reproductive success in this species. Increasing temperatures as a consequence of climate change may provide newchallenges for Wolverines by negatively affecting the preservation of cached food and by increasing competition from pilferers that benefit from awarmer climate. It is however still not fully understood which consequences this may have for the demography and behavior of the Wolverine.publishedVersio
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Refrigeration or anti-theft? Food-caching behavior of Wolverines (Gulo gulo) in Scandinavia
2020Co-Authors: Van Der Veen Bert, Odden John, Mattisson Jenny, Zimmermann Barbara, Persson JensAbstract:Food-caching animals can gain nutritional advantages by buffering seasonality in food availability, especially during times of scarcity. The Wolverine (Gulo gulo) is a facultative predator that occupies environments of low productivity. As an adaptation to fluctuating Food availability, Wolverines cache perishable food in snow, boulders, and bogs for short- and long-term storage. We studied caching behavior of 38 GPS-collared Wolverines in four study areas in Scandinavia. By investigating clusters of GPS locations, we identified a total of 303 food caches from 17 male and 21 female Wolverines.Wolverines cached food all year around, from both scavenging and predation events, and spaced their caches widely within their home range.Wolverines cached food items on average 1.1 km from the food source andmade between 1 and 6 caches per source.Wolverines cached closer to the source when scavenging carcasses killed by other large carnivores; this might be a strategy to optimize food gain when under pressure of interspecific competition.When caching, Wolverines selected for steep and rugged terrain in unproductive habitat types or in forest, indicating a preference for less-exposed sites that can provide cold storage and/or protection against pilferage. The observed year-round investment in caching by Wolverines underlines the importance of food predictability for survival and reproductive success in this species. Increasing temperatures as a consequence of climate change may provide newchallenges for Wolverines by negatively affecting the preservation of cached food and by increasing competition from pilferers that benefit from awarmer climate. It is however still not fully understood which consequences this may have for the demography and behavior of the Wolverine
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Bestandsovervåking av jerv i 2020
Rovdata (NINA) og Viltskadecenter (SLU), 2020Co-Authors: Mattisson Jenny, Höglund Linda, Brøseth HenrikAbstract:The Norwegian Environment Agency (Miljødirektoratet) and the Swedish Environmental Protection Agency (Naturvårdsverket) have co-developed standard methodology and guidelines for the monitoring of Wolverines in Scandinavia, that have been implemented in both Norway and Sweden since 2014. To estimate size, and assessing trends, of the Wolverine population in Scandinavia, Wolverine reproductive areas (female territories) are annually surveyed during late winter and spring to register whether reproductions have occurred. The population size is estimated based on the number of Wolverine reproductions that fulfil the criteria for Documented or Considered as certain reproduction. The monitoring of Wolverine reproductions, and registration of data into the shared database Rovbase, is conducted by field staff from the County Administration Boards CAB (Länsstyrelserna) in Sweden and the Norwegian Nature Inspectorate (Statens Naturoppsyn) in Norway. In Sweden, the Sami villages (administrative units for reindeer herding) assist the CABs by reporting suspected den sites, which can then be evaluated in the field by CAB field personnel. During the 2020 census, a total of 164 Wolverine reproductions were registered in Scandinavia, which are similar to the year before (166 reproducations). Of these, 101 reproductions were found in Sweden and 63 in Norway. This corresponds to 3 fewer reproductions (2.9%) in Sweden and one more reproduction (1.6%) in Norway, compared to 2019. The model used to estimate population size, i.e. extrapolate number of reproductions to adult individuals in the population, accounts for annual variation in reproductive success by using the average number of reproductions in the past three years. Based on the number of Wolverine reproductions during the last three years (2018–2020), the Scandinavian population size is estimated to 1069 adult Wolverines (95% CI = 922–1335), defined as 1-year old or older, which is a 5.5% higher estimate for Scandinavia than last year. Of the 1069 Wolverines, 382 Wolverines (95% CI = 323–486) are estimated to be in Norway and 687 Wolverines (95% CI = 572–891) in Sweden. The Norwegian part of the population has thus increased with 14 % from an estimated 334 Wolverines (95% CI = 273–429) in 2019. In Sweden, the estimated population size in 2020 was similar to the estimate from 2019 (679 Wolverines; 95% CI = 565–891)
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modelling broad scale Wolverine occupancy in a remote boreal region using multi year aerial survey data
Journal of Biogeography, 2018Co-Authors: Justina C Ray, Audrey J Magoun, Lucy G Poley, Cheryllesley B Chetkiewicz, Meg F Southee, Neil F Dawson, Chris ChenierAbstract:AIM: We used data from aerial surveys of Wolverine tracks collected in seven winters over a 10‐year period (2003–2012) within a 574,287 km² study area to evaluate the broad‐scale pattern of Wolverine occurrence across a remote northern boreal forest region, identifying areas of high and low occupancy. LOCATION: Northern Ontario, Canada. TAXON: Wolverine (Gulo gulo Linnaeus, 1758). METHODS: We collected Wolverine tracks and observations in 100‐km² hexagonal survey units, making a total of 6,664 visits to 3,039 units, visiting each 1–9 times. We used hierarchical Bayesian occupancy modelling to model Wolverine occurrence, and included covariates with the potential to affect detection and/or occupancy probability of Wolverines. RESULTS: we detected Wolverines on 946 visits, 14.2% of total visits. Probability of detecting a Wolverine varied among years and between the two ecozones in the study area. Wolverine occupancy was negatively related to two important covariates, the geographical coordinate Easting and thawing degree‐days. A site occupancy probability map indicated that Wolverine occupancy probabilities were highest, and standard error lowest, in the western and northern portions of the study area. MAIN CONCLUSIONS: The occupancy framework enabled us to use observation data from tracks of this elusive, wide‐ranging carnivore over a vast, remote area while explicitly considering detectability and spatial autocorrelation, yielding a map of probable Wolverine distribution in northern Ontario that would not be possible using other methods of detection across a large region. With resource development pressures increasing in this globally significant region in the face of a changing climate, it is important to monitor changes in distribution of species like Wolverines that have low population growth rates, large spatial requirements and sensitivity to human disturbance. This study demonstrates a relatively cost‐effective and non‐invasive alternative to monitoring based on Wolverine harvest records, which have not been available since 2009 in Ontario due to changes in the provincial regulatory regime for this threatened species.
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detecting snow at the den site scale in Wolverine denning habitat
Wildlife Society Bulletin, 2017Co-Authors: Audrey J Magoun, Martin D Robards, Mark L Packila, Tom W GlassAbstract:The relationship of Wolverines (Gulo gulo) to persistent spring snow (PSS) may be obligate at the den-site scale but this relationship has yet to be examined at this scale. Our objective was to detect snow at the den-site scale in late May using low-altitude aerial photography in Wolverine denning habitat both in the Rocky Mountains of western United States and northwestern Alaska, USA. In the Rocky Mountains, we detected snow on 31 May 2016 in low to heavy categories in 82% of 40 transect segments flown through home ranges of 4 reproductive female Wolverines that had denned in Idaho and Montana, USA, prior to our study. In the Alaska study area, we detected snow on 29 May 2016 at 4 den sites of reproductive female Wolverines that denned in 2016. By then, snow remained only in occasional, widely scattered patches. Remnant snowdrifts remained at all 4 den sites. High-latitude tundra habitats in Alaska may lose PSS sooner than montane habitats at the southern extent of Wolverine distribution. To manage Wolverines and their habitat and incorporate PSS in models of future Wolverine habitat, we must understand the relationship of Wolverines to snow and measure PSS at an appropriate resolution and scale that is biologically meaningful for the species. © 2017 The Wildlife Society.
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the Wolverine s niche linking reproductive chronology caching competition and climate
Journal of Mammalogy, 2012Co-Authors: Audrey J Magoun, Jens Persson, Robert M Inman, Jenny MattissonAbstract:Wolverines are demographically vulnerable and susceptible to impacts from climate change. Their distribution is correlated with persistent spring snow cover, but food-based explanations for this relationship have not been explored. We synthesize information on the timing of both Wolverine reproductive events and food availability to improve our understanding of the behaviors, habitat features, and foods that influence reproductive success. Wolverine births are constrained to a brief period of the year and occur at an earlier date than other nonhibernating, northern carnivores. Our examination suggests that this timing is adaptive because it allows Wolverines to take advantage of a cold, low-productivity niche by appending the scarce resources available during winter to the brief period of summer abundance. The Wolverine’s bet-hedging reproductive strategy appears to require success in 2 stages. First, they must fuel lactation (February–April) with caches amassed over winter or acquisition of a sudden food bonanza (e.g., winter-killed ungulates); otherwise, early litter loss occurs. Next, they must fuel the majority of postweaning growth during the brief but relatively reliable summer period of resource abundance. The 1st stage is likely dependent on scavenged ungulate resources over most of the Wolverine’s range, whereas the 2nd stage varies by region. In some regions the 2nd stage may continue to be focused on scavenging ungulate remains that have been provided by larger predators. In other regions the 2nd stage may be focused on predation by Wolverines on small prey or neonatal ungulates. During all seasons and regions, caching in cold, structured microsites to inhibit competition with insects, bacteria, and other scavengers is likely a critical behavioral adaptation because total food resources are relatively limited within the Wolverine’s niche. Habitat features that facilitate caching, e.g., boulders and low ambient temperatures, are likely important and could be related to the limits of distribution. This ‘‘refrigeration-zone’’ hypothesis represents a food-based explanation for the correlation between Wolverine distribution and persistent spring snow cover. Understanding regional differences in foods that fuel reproduction and underlying causes to the limits of distribution could be important for maintaining Wolverine populations in the future.
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integrating motion detection cameras and hair snags for Wolverine identification
Journal of Wildlife Management, 2011Co-Authors: Audrey J Magoun, Clinton D Long, Kristine L Pilgrim, Michael K Schwartz, Richard E Lowell, Patrick ValkenburgAbstract:ABSTRACT We developed an integrated system for photographing a Wolverine's (Gulo gulo) ventral pattern while concurrently collecting hair for microsatellite DNA genotyping. Our objectives were to 1) test the system on a wild population of Wolverines using an array of camera and hair-snag (C&H) stations in forested habitat where Wolverines were known to occur, 2) validate our ability to determine identity (ID) and sex from photographs by comparing photographic data with that from DNA, and 3) encourage researchers and managers to test the system in different Wolverine populations and habitats and improve the system design. Of the 18 individuals (10 M, 8 F) for which we obtained genotypes over the 2 years of our study, there was a 100% match between photographs and DNA for both ID and sex. The integrated system made it possible to reduce cost of DNA analysis by >74%. Integrating motion-detection cameras and hair snags provides a costeffective technique for wildlife managers to monitor Wolverine populations i...
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density estimation in a Wolverine population using spatial capture recapture models
Journal of Wildlife Management, 2011Co-Authors: Andrew J Royle, Audrey J Magoun, Patrick Valkenburg, Beth Gardner, Richard E LowellAbstract:Classical closed-population capture-recapture models do not accommodate the spatial infor- mation inherent in encounter history data obtained from camera-trapping studies. As a result, individual heterogeneity in encounter probability is induced, and it is not possible to estimate density objectively because trap arrays do not have a well-defined sample area. We applied newly-developed, capture-recapture models that accommodate the spatial attribute inherent in capture-recapture data to a population of Wolverines (Gulo gulo) in Southeast Alaska in 2008. We used camera-trapping data collected from 37 cameras in a 2,140-km 2 area of forested and open habitats largely enclosed by ocean and glacial icefields. We detected 21 unique individuals 115 times. Wolverines exhibited a strong positive trap response, with an increased tendency to revisit previously visited traps. Under the trap-response model, we estimated Wolverine density at 9.7 individuals/1,000 km 2 (95% Bayesian CI: 5.9-15.0). Our model provides a formal statistical framework for estimating density from Wolverine camera-trapping studies that accounts for a behavioral response due to baited traps. Further, our model-based estimator does not have strict requirements about the spatial configuration of traps or length of trapping sessions, providing considerable operational flexibility in the development of field studies. 2011 The Wildlife Society.
