Abstract
The impacts of wind farms on New Zealand bird species and populations are unknown. This document reviews available literature on the impacts of onshore wind farms on birds, based on studies in other countries. A key finding is that wind farms tend to have variable effects on bird populations, which can be species-, season- and/or site-specific. The impacts include collision fatalities, habitat loss and disturbance resulting in displacement. The main factors that contribute to collision fatalities are proximity to areas of high bird density or frequency of movements (migration routes, staging areas, wintering areas), bird species (some are more prone to collision or displacement than others), landscape features that concentrate bird movement, and poor weather conditions. In many instances, the numbers of carcasses reported are likely to be underestimates, as they are often based only on found carcasses, without accounting for scavenging and searcher efficiency. Habitat loss as a result of wind farm construction seems to have a minor impact on birds, as typically only 2–5% of the total wind farm area is taken up by turbines, buildings and roads. However, the cumulative loss of sensitive or rare habitats may be significant, especially if multiple large developments are sited at locations of high bird use. Disturbance of birds as a result of wind farm development may arise from increased activity of people at the site, and/or the presence, motion and noise of turbines. The level of disturbance to birds has been shown to vary, depending on the availability of alternative feeding or breeding habitat. Although some of the findings from this review may be relevant to the New Zealand situation, it is important to realise that each wind farm tends to be different as a result of topography, weather, habitats, land use, bird species and turbine characteristics.