We reviewed 64 published investigations concerning effects of human disturb
ance on nesting colonial waterbirds. We summarized and reviewed articles, b
ased on taxonomy, examining investigator, ecotourist, recreator, watercraft
, and aircraft activity. effects on physiology, reproductive behavior, repr
oductive success, and population trends of waterbirds. Though most studies
found significant negative effects, taking careful measures minimized impac
t on some species. Guidelines for minimizing investigator and visitor distu
rbance are outlined. Little practical information for visitor management is
available. Increasing pressure from the ecotourism industry to visit water
bird colonies makes research that develops scientifically-defensible touris
m policies imperative.