Big brown bat 2 (IMAGE) University of Chicago Caption The big brown bat (Eptesicus fuscus) is a species of Yangochiroptera bat that uses complex, varying sounds to echolocate. Credit Sherri and Brock Fenton Usage Restrictions Please credit as indicated License Original 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.