The reproductive success of breeding birds can be determined by many different factors. Onefactor often associated with the failure of a brood is nest depredation. To avoid depredation,different bird species implement different adaptations. Some species have evolved a specificnesting-strategy, for example cavity-nesting. In addition to the top-down regulation bypredators, breeding birds are also subjected to changing climatic conditions. Bird species whichare breeding in the high Arctic, where the breeding season is short and the effects of Arcticwarming have already led to changes in the local climate, can be very sensitive to those factors.In this thesis, I explore the role of the Arctic fox (Vulpes lagopus) and its top-down effect onthe fledging success of a population of migratory snow buntings (Plectrophenax nivalis) onSvalbard. First, I investigated how the nest’s accessibility influences the daily probability ofsnow bunting broods being depredated by the Arctic fox and how the predation pressurechanges on snow bunting nests throughout the season. Then, I investigated the role of foxabundance in the reproduction of the snow bunting in comparison to weather factors, whichhave previously been found to impact the breeding success significantly. I used a 22-year longtime series from 1998 to 2020 of monitored snow bunting nests in Adventdalen. My analysisrevealed nest height to be the dominating factor influencing the daily probability of a nest beingdepredated. In addition, I found a tendency of broods that were started later in the season to bemore depredated than earlier broods. Arctic fox abundance had a rather small effect on the snowbuntings’ fledging success in comparison to the local climate. The mean temperature had astrong impact on the fledging success, as well as the timing of breeding. This study shows theArctic fox might not play an essential role in the snow bunting population’s breeding successat present. However, there are implications that future warming will impact both the snowbunting and the Arctic fox and might therefore also alter their interactions with each other.