Bulwer's Petrel (IMAGE) University of Barcelona Caption During the breeding season, males and females take turns to incubate the only laid egg and cover the same distribution areas in time and space with no gender differences. Credit Raül Ramos (UB-IRBio) Usage Restrictions The image may only be used with appropriate caption or credit. License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.