Current commitments to increase renewable energy generation have led to concern about the possible effects of such developments on shorebirds and waterfowl. To assess the future impact of industrial developments – of changes in the intensity or type of activity on an estuary – or to evaluate the cost effectiveness of proposed mitigating measures, ecologists must be able to predict accurately to new environmental conditions. The difficulty with predicting to new circumstances is often that there is no way of knowing whether the empirical relationships upon which models are based will hold under the new conditions, and so predictions are of uncertain accuracy. Individuals-based models of shorebirds feeding on estuaries have been developed in an attempt to overcome this problem. These models follow the behavioural responses of individual animals to changes in the environment and predict variables such as population mortality rate from the fates of all individuals. Birds in these models use optimal decision rules to determine their behaviour, which means that model birds are likely to respond to environmental changes in the same way as real ones would and are therefore expected to provide a reliable means of predicting how animal populations will be influenced by environmental change. We describe previous approaches to predicting the effects of development in estuaries using two estuarine barrage schemes as examples. We then describe the development of individuals-based models to overcome the limitations of these approaches and discuss examples of how the models have already been used to predict the consequences of habitat loss and disturbance. Finally, we describe two current applications that demonstrate how individuals-based models are being used to predict the effects of barrages and offshore wind farm developments on waterbirds. We believe that individuals-based modelling has the potential to play an important role in future investigations of the impacts of a wide range of renewable energy developments.