Howler Monkey (IMAGE) Smithsonian Caption Howler monkeys (Alouatta) include over a dozen species, and several are vulnerable or endangered. Credit Marylin Veiman Echeverria Usage Restrictions This photo is available for publication in media articles, provided the photographer is credited as noted here. 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.