Tree Sampling (IMAGE) Field Museum Caption Co-author Abigail Derby Lewis of The Field Museum tagging and measuring howler monkey feeding trees as part of this study in Yasuni National Park, Ecuador. Credit Courtesy of Abigail Derby Lewis Usage Restrictions Please include 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.