Inventering av järv 2019

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) aid the CABs by reporting suspected den sites, which can then be evaluated in the field by CAB field personnel. During the 2019 census a total of 165 wolverine reproductions were registered in Scandinavia, a 9% decrease compared to 2018. Of these, 104 reproductions were found in Sweden and 61 in Norway. This corresponds to a 16% decrease in Sweden and a 5% increase in Norway compared to 2018. 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 (2017–2019), the Scandinavian population size is estimated to 1011 adult wolverines, defined as 1-year old or older (95% CI = 869–1268), which is a higher estimate for Scandinavia than last year. Of the 1011 wolverines, 332 wolverines (95% CI = 273–427) are estimated to be in Norway and 679 wolverines (95% CI = 565–891) in Sweden. The Norwegian part of the population has thus increased with 7% and the Swedish part of the population increased with 16% in comparison to the estimated population size in 2018.