Over the last few years, great efforts have been made to improve the methodologies used to assess bird and bat fatalities at wind farms. For that purpose, several mortality estimators have been proposed. In general, these estimators account for: 1) partial coverage; 2) carcass removal (e.g. by scavengers or decay); and 3) imperfect detection. Perhaps surprisingly, a universal estimator that ensures good quality estimates under general circumstances is still lacking. Further, the existing estimators include different adjustment approaches and a variety of often implicit and misunderstood assumptions that may not be valid, making it difficult for practitioners to choose between them. Focusing on bird and bat fatality at onshore wind farms, we summarise and discuss implementation aspects and the assumptions involved in seven commonly used estimators. This should provide researchers requiring these methods with a basis to choose the most appropriate estimator under a given set of conditions, and contribute to increased standards in wind farm wildlife fatality estimation.

Wind energy developments can be responsible for negative impacts on birds, including displacement. In this study we performed a systematic review of the literature available on bird displacement due to wind turbines, both onshore and offshore, to: (i) assess overall trends in scientific research; (ii) review the existing knowledge; and (iii) outline recommendations for future studies on this topic in order to overcome the major gaps and limitations found. Our results are based on 286 trials extracted from 71 peer-reviewed studies. The literature on this topic has increased in the past decade but is concentrated in Europe and United States, despite the fact that the wind industry has worldwide coverage. Open habitats—as agricultural fields and grasslands—were the most represented and Accipitriformes, Galliformes, Charadriiformes, Anseriformes and Passeriformes were the most frequently studied taxa. Displacement was recorded in 40.6% of the trials, and Gaviiformes, Anseriformes, Suliformes, Accipitriformes and Falconiformes were the most affected groups. Pelecaniformes, Passeriformes and Charadriiformes were the groups for which no significant effects were more often observed. We provide a list of recommendations, focused on study design, reporting and result dissemination, that should contribute to more robust conclusions of future studies on this topic.