Vandringsmönster hos GPS-försedda älgar i GRENSEVILT – konsekvenser för förvaltningen

The fact that different species of mammals migrate between different areas during the year (so-called seasonal migrations) is a well-known phenomenon in many areas around the world. In deer animals such as moose, red deer and roe deer in the boreal forest zone, the tendency to migrateseems to be strongly linked to the type of living environment where the climate isan important driving factor. The tendency to seasonallymigratealso has major consequences for the management of moose and forests, as movements occuracross administrative boundaries and management areas. One of the most important goals in the research project GRENSEVILT has been to create better conditions for the management of moose in a moose population that lives along the Swedish-Norwegianborder in Värmland,Dalarna and Innlandet countiesby studying the moose's movement patterns. During the winter of 2018, 2019 and 2020, 30 cows and 11 bulls were equipped with GPS transmitters thatwere programmed to position at regular intervals of 2 hours. The study includes data from 41 GPS-collared moose from the first markingevent in February 2018 until the autumn of 2021. Twenty(49%) showed a strict migratory pattern between summer and winter areas, 14 (34%) used the same area both winter and summer (stationary). The remaining 7 (17%) moose showed a combination of the two types of migration strategiesbetween different years. There were no statistically significant differences between the sexes in the distribution of the migration strategies. The average dates for the start and end of the spring migration were 20 and 30 Aprilfor females, respectively, while the bulls started their spring migration on average on 30 April and arrived in the summer area on 16 May. Most moose migrated to their winter areas in December and January, with 49% of them arriving in the winter area on 1 January, while 92% of them had arrived on 1 February. On average, bulls moved52 kmstraight linefrom summer to winter area while the cows moved19 km. The longest straight line movementdistance between seasonal home areas was 87 kmand 38 km for bulls cows, respectively.Start and end dates of migrations differed significantly between years. A corresponding variation between years could also be identified for the snow depth and the length of the total snow period. Moose migrated mostly from southeast (winter areas mostly in Sweden) to northwest (summer areas mostly in Norway). The average size of annual home rangesfor stationary cows and bulls was 6,700 and 9,200 ha, respectively, while this for migrating cows and bulls was 17,000 and 65,000 ha. Among the stationary moose, the majority (70%) overlappedonly one administrativemanagementareaduring one year, while 59% of the migrating moose movements overlapped 3-5 different units. From a management perspective, the results from this study show that more than half of the moosepopulationuseddifferent areas during the winter and during the part of the hunting season whenthe majority of the moose are killed, which leads to anuneven distribution between costs (forest damage) and income (hunting) between different areas.Heavy grazing pressure and extensive forest damage in an area is thus largely controlled by the current moose management 10-50 km away and which in this study area mainly takes place in a northern and north-western directionduring early fall. A future management strategy should take place across ÄFO and municipal borders, across county borders,and in some areas also across national borders, which in this case isbetween Sweden and Norway.