Howler Monkey Eating Astrocaryum Fruit (IMAGE) Smithsonian Tropical Research Institute Caption According to the fifth census of Mantled Howler Monkeys, Alouatta palliata, on Barro Colorado Island in Panama, monkey numbers have changed little since the late 1970s. Credit Greg Willis Usage Restrictions Credit: Greg Willis 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.