Marine renewable energy developments (MREDs) are becoming an increasing feature of the marine environment. Scotland has considerable potential for generating energy from the marine environment in the form of extensive wind, wave and tidal-stream resources. Scotland also hosts numerous internationally important breeding populations of seabirds and Scottish territorial waters represent a key overwintering area for many species. EU legislation requires that MREDs do not damage the integrity of protected seabird populations but potential effects of MREDs on seabirds are not yet fully understood. This thesis aims to address gaps in knowledge regarding how MREDs may affect seabird populations. I generate vulnerability and confidence indices to predict the effects of offshore wind, wave and tidal-stream renewable energy developments on Scottish seabird populations; track the movements of a seabird species identified as lacking in data to better understand overlap with MREDs; and investigate seabird use of a high current flow environment leased as a tidal-stream energy development site. Overall, this thesis indicates that seabird responses to MREDs are likely to be species-specific and will vary dependent on the development location and design of the energy generating technology. My findings indicate that effects of MREDs will differ dependent on individual foraging strategies, age and life stage of individuals, which implies that MREDs are likely to differently affect subsections of seabird populations.