Disturbance of emperor penguin Aptenodytes forsteri chicks by helicopters

Creching emperor penguin (Aptenodytes forsteri) chicks were exposed to two overflights by a Sikorsky S-76, twin engine helicopter at 1000 m (3300 ft), a current operational guideline of the Australian antarctic Division for h elicopter activity in Antarctica. The flights were conducted on the same da y but under different wind conditions: a morning flight with a 10-knot (18 km h(-1)) katabatic wind blowing perpendicular to the direction of helicopt er travel, and an afternoon flight with virtually no wind. Background noise levels recorded in the morning before the helicopter flight were significa ntly higher than in the afternoon, but these differences were not detectabl e when the helicopter was overhead. There were also no significant differen ces in the way chicks responded to helicopters between the morning and afte rnoon flight. All chicks became more vigilant when the helicopter approache d and 69% either walked or ran, generally moving less than 10 m toward othe r chicks (i.e. not scattering). Most chicks (83%) displayed flipper-flappin g, probably indicating nervous apprehension. This behaviour was seldom disp layed in the absence of disturbance. Although all effects were relatively t ransitory, the results support the introduction of a more conservative guid eline of 1500 m (5000 ft) minimum overflight altitude for helicopter operat ions around breeding localities of this species.