We studied the impact of offshore wind farms on the distribution of Northern Gannets in the southern North Sea. Distributions were derived from ship-based and aerial-transect counts, and from global positioning system (GPS) tracking of chick-rearing adults from the colony on Helgoland. Foraging trips of tagged Gannets lasted from 0.4 to 53.5 h, with a total distance flown per trip of 4.7–937.9 km, and range of 2.0–320.8 km. Gannets largely avoided the wind farm area north of Helgoland. This avoidance behaviour implies that, although Northern Gannets may not be killed by rotor blades, they may experience substantial habitat loss. GPS tracking is well suited to the study of wind farm effects on birds and possible habituation processes at the individual level.