There is a regulatory need to understand the potential for marine renewable energy developments to significantly impact the marine environment and a site’s integrity. To increase certainty, it is necessary to identify whether marine renewable energy devices have any impact on the abundance and distribution on wildlife in the vicinity. The European Marine Energy Centre (EMEC), in Orkney, Scotland, has completed an extensive wildlife observation programme to collect surface-visible wildlife observation data since the site’s inception. Following the observation programme, an in-depth analysis has been undertaken to understand species displacement relative to the operational status of devices. The analysis has been completed on observational data from both EMEC’s wave and tidal test sites. The data analysis utilised statistical package MRSea to quantify any spatially-explicit change attributable to marine renewable energy devices. The results from the analysis demonstrated a change in distribution and, in some cases, abundance with installation works, but typically the density recovered during the operational phase of the development. The study found little evidence to suggest that there are any long-term effects on seabirds or marine mammals associated with the installation and operation of marine renewable energy devices and it is anticipated that they will continue to use the waters around such devices when operational.