In REINFEED, we want to investigate whether extensively managed animals that are provided easily accessible feed during winter, when natural feed is limited, may be trapped in a "feeding pitfall", using reindeer (Rangifer tarandus) as the model species. We are i) interviewing herders in Sweden and Finland who have a long experience of winter feeding, and ii) conducting an experiment to reveal possible effects of winter feeding of reindeer calves on future foraging behavior. We are testing this in two reindeer herds, where fed calves are compared to free-ranging control animals. We are using GPS- and accelerometer sensors to follow animal movements and grazing behavior directly after feeding, and in the following winter. Animal body weight and condition scoring are used to assess the animals' ability to utilise natural pastures after feeding.