The monk saki is an unusual primate for many reasons. At first glance, they may appear to be an arboreal termite mound or a burl on a branch, but what gives them away as being a monkey is their very long tail, usually hanging straight down below the branch upon which they sit.
Monk sakis are certainly amongst the hairiest primate species found in the Peruvian Amazon. They are extremely shaggy which makes one wonder — as you sit in 90 degree heat and 97% humidity — why would an animal support such a wealth of hair in such temperatures. It occasionally even makes the observer feel even more uncomfortable in the heat of the day! Well, the shaggy coat insulates the body from heat and it certainly provides a wonderful raincoat in the very moist climate of the Amazon.
The long shaggy tail is not prehensile. Rather than wrapping around a branch as spider monkeys, woolly monkeys and capuchins do, the monk saki’s tail just hangs straight down. The tail is the best way to spot a monk saki as they usually sit quietly in small groups of two to four members and are fond of perching on fairly large branches in the mid-story of the rainforest. During IE's Amazon River cruises , daily naturalist-guided excursions will take you deep into the river’s tributaries. As your excursion boat glides along a black-water stream, many more monk sakis see you than you see of them. Once found, these endearing primates will often just sit and watch you, providing a wonderful lengthy observation of these shaggy old men of the forest. Additionally, monk sakis are mainly fruit and leaf-eaters and spend a great deal of time in one place, especially if the tree provides them with delightful fruit!
Naturalist Greg Greer  is a favorite among IE travelers, and has gained a reputation for his friendliness and good humor, along with his incomparable knowledge of natural history, photos and articles have been widely published in books and magazines, including Georgia Outdoor News, Bird Watcher’s Digest, Alabama Outdoor News, Riversedge and Southern Wildlife.