img 3 (IMAGE) University of Vienna Caption Horn and colleagues tested prosociality in a cooperatively breeding bird species. Credit Copyright: Gantulga Bayandonoi 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.