We evaluated the possible predation on eggs and the disturbance to waterbird nests by coypus by monitoring the breeding success of four bird species and a sample of dummy and natural nests by photo-cameras. The monitoring of waterbirds activity showed that 14.8% of Fulica atra and 9.5% of Gallinula chloropus nests failed, possibly as a consequence of disturbance by coypus. In 2009, 7.4% of ground dummy nests and 10.8% of water dummy nests showed signs of coypu activity with eggs either preyed or removed. Camera surveys confirmed that coypus used the nests as resting platforms, thus destroying or sinking the eggs. This study showed that in areas with high coypu density the disturbance to bird nests floating amid the vegetation or built in open water may be severe.