Windfarms are becoming increasingly common in Britain, and concerns about their possible effects on birds are increasing too. There are two main ways in which windfarms can affect birds: by collision with the turbines themselves, and through disturbance from a zone around them. Although no significant ornithological problems have yet been recorded at existing windfarms in the UK, there have been serious problems at windfarms in other countries, notably with birds of prey, and these are discussed. The evidence shows that birds and windfarms can coexist if the windfarm site is located appropriately. In particular, windfarm development should avoid areas: (i) with high-density raptor populations, where collisions could be significant; (ii) with high densities of other species vulnerable to a low level of additional mortality, and whose susceptibility to collision may be high; and (iii) where disturbance could potentially displace birds from important feeding or nesting habitats. It is vital to consider the potential problems of collisions and disturbance at windfarms on a case-by-case basis.