Brown Bears and
Knowledge about the loss of domesticated reindeer to bears in Scandinavia today stems mainly from two research projects. The first project ran in Udtja and Gällivare Sami reindeer herding communities in Norrbotten County in Sweden from 2010 to 2016, and an ongoing project that started in 2019 in Idre Sami reindeer herding community in Dalarnas County, Sweden.
Idre Sami Reindeer Herding Community – Predation studies in mountainous reindeer herding areas (2019 - 2024)
The brown bear in Scandinavia is primarily a forest-dwelling animal, but it can also go up into the mountains. Reindeer utilize both mountain and forest habitats in Idre. During the calving season in May until mid-June when the calves are most vulnerable for bear predation the reindeer are primarily in the mountain, but they may use the forest as well depending on snow, weather and wind conditions. We started a research project in Idre Sami reindeer herding community in Sweden in the spring of 2019 in order to understand how bears and reindeer interact in a combination of mountain and forest ecosystems.
The project in Idre is being carried out in close cooperation with the Sami reindeer herders, and we have so far completed four out of six planned field seasons. The project uses a so-called 'virtual fence' where the bears' GPS collars are pre-programmed to take a position every 5 minutes as they move within calving grounds during spring. All places where the bears stayed for more than 10-15 minutes are then visited by a field team consisting of a researcher and a reindeer herder.
So far, we have followed 20 individual bears in and around the calving ground. Twelve of these bears have so far been on the calving ground and seven of them have killed a total of 112 calves and 13 adult reindeer. The kill rate on reindeer calves in the mountain in Idre is much higher than in the forest, but because the bears spend little time on the mountain the average kill rates for bears in the calving grounds are similar to the forested areas in Norrbotten. We also see that the losses in Idre occur for a longer period during the summer compared to the forest Sami Villages in Norrbotten and the predation of adult reindeer follow the same time pattern as the predation calves.
The ongoing project in Idre is mainly funded by the Norwegian Environment Agency in connection with the new compensation scheme for domesticated reindeer, which was postponed in 2017 to gain more knowledge about the loss of domesticated reindeer to predators. The project is also funded by the Swedish Sami Parliament and the Swedish Environmental Protection Agency and is planned to run until 2024.
Norrbotten Sami Reindeer Herding Communities - Predation studies in forested reindeer herding areas (2010 - 2016)
The project in Norrbotten was carried out in the Sami reindeer herding communities of Udtja and Gällivare between 2010 and 2016. The reindeer in these two areas spend the whole year in the forest. This project was relatively unique in several ways. First, the project was carried out as a collaborative project between the Sami reindeer herders and the researchers, from study design, fieldwork, data processing, and through to report writing. In this way, traditional knowledge was included throughout the study. Second, the project used completely novel technology. All female reindeer (~2600) were equipped with so-called 'UHF proximity transmitters' that emitted a weak radio signal. This signal was picked up by the collar of radio-collared bears in the area. If one of the 25 bears collared in the area were within 100 meters of the reindeer, the GPS on the bear collar started taking positions every minute for an hour. Accumulations of positions where the bears had been more than 3 minutes within a 30 m radios were visited the next day by a field team consisting of a scientist and a reindeer herder, to search for carcasses.
The bears were followed from late April to late September 2010-2012. This yielded the discovery of 335 calves and 18 females killed by 16 of the 23 bears that were within close proximity to the reindeer. Most of the calves were killed by bears from mid-May through the end of May, and predation declined rapidly until mid-June. After this, only 1 of the 335 calves was killed by a bear. Bear-killed adult females followed the same time pattern as the calves, but relatively more of the females were killed over the summer.
Females with yearling cubs were the category of bears that on average killed most calves, but how long the bear was residing on the calving ground was the most important factor in how many calves bears killed. We calculated that 63-100% of calf loss in these Sami villages may have been caused by bears.
Calving in corrals were carried out in 2013-2016 to test its effectiveness and economic sustainability as a mitigation against brown bear predation on reindeer. The results show that the calves were protected from brown bear predations, but the cost of corralling and feeding the reindeer during calving outweighed economic gain of saved calves. In addition, corralled reindeer are more prone to diseases and corralling are not compatible with the Sami reindeer herding culture.