Helicopter spraying of rotenone fish poison over Paardevlei, a lake near Cape Town, provided an opportunity to assess both the effect of helicopter disturbance on waterbirds and the immediate response of birds to fish poisoning. Birds were less disturbed by protracted helicopter activity than by a single fish eagle over-flight. Rotenone provided a food bonanza for pelicans and cormorants with no evidence of adverse effects on any birds.