Shy, wide-eyed, and active only under the cover of darkness, the Grey-handed Night Monkey (Aotus griseimembra) is one of Colombia’s most enchanting primates. Found in forest canopies across Colombia and Venezuela, including those of Fundación Biodiversa Colombia’s (FBC’s) El Silencio Reserve. Though forest fragmentation and habitat loss has left them classified as Globally Vulnerable on the IUCN Red List, the expansion of El Silencio will provide more protection for this species and all those it shares the forest with.
Family Comes First
The Grey-handed Night Monkey lives in small family groups led by a monogamous pair. Thought to live several decades, the pair will mate for life and raise their offspring together. When the sun shines during the day, they spend the time sleeping hidden away in tree hollows, their small faces emerging together to investigate anything that disturbs them.
You might catch a glimpse of the monkeys during the day if you’re lucky. Credit: Fernando Arbeláez @ FBC
Moonlight Foragers
Found across northern Colombia and into western Venezuela, night monkeys are the only monkeys to occupy the nocturnal niche. For this, they have adaptations such as their large, striking eyes that are very sensitive to light, allowing them to see through the darkness. However, they cannot see in complete darkness and prefer foraging on nights when the moon offers a soft glow. On a night of a full moon, they can be active all night long but during a new moon they might only be seen in the twilight of dusk and dawn.
Keeping in Touch
Throughout the night, these monkeys can be heard vocalising with low, soft calls to keep in contact with each other and to move together throughout the forest. As a highly territorial species, when they encounter another group the males and females will jointly defend their home. Though this doesn’t happen often, they will quickly make their presence and territory known to another group with loud calls and hoots.
Though they may be smaller and shyer than some other primate species in El Silencio, the Grey-handed Night Monkeys make up for it with their fierce family bonds. Credit: FBC
Small and Mysterious
Fruit is a staple in the diet of the Grey-handed Night Monkey, but these opportunists also feed on leaves, flowers, nectar, insects, and even the occasional egg or small vertebrate when fruit is scarce. But one very interesting and unique behaviour has been seen in these monkeys. Very occasionally, a group will catch a giant millipede and rub its strong scent over their hands, feet, and tails. This behaviour is known as anointing, and because it is so rarely seen, we don’t know exactly why they do it.
Act now and support our autumn appeal to protect the Grey-handed Night Monkey before it is too late.
