Aotus vociferans
Silhouette: E. Lear, 1819 (vectorization by Yan Wong) · PhyloPic
In 3 days ~60% in a week ~90%
Spix's night monkey (Aotus vociferans), also known as the Colombian gray night monkey, noisy night monkey and Spix's owl monkey, is a night monkey species from South America. It is found in Brazil, Colombia, Ecuador and Peru.
The Spix's night monkey is a small bodied monkey species usually having a mass of around one kilogram. It belongs to the only nocturnal genus of New World primates, Aotus. This type of monkey can leap farther than most due to it having longer arms than
legs. The monkey averages 0.5 meters in height. The night monkey is considered to be a new world monkey. The social behavior of the Aotus vociferans is group based. These groups usually consist of breeding pairs and their offspring. This species has a
monogamous mating system. After the offspring are born, the father becomes the main caretaker, only giving up the offspring for them to suckle. The offspring will usually stay with their birth group until they reach two and a half to three and a half years
old. An exception to this if the male breeding partner is no longer present for any reason (usually only caused by death), then the offspring may stay with its birth group for only twelve weeks to the normal departure age. Social grooming in this species of monkey is
uncommon. The Aotus vociferans reproduce usually by giving birth to one offspring. Although, like with humans, there are cases of twins. The female breeding partner carries the offspring in interbirth for around one year. Both mating and birthing occur between November and
January. For this species, copulation attempts tend to be short and quick, starting with the male and female approaching one another. Then the male performs a social sniff. During the original sniff, the female may reciprocate but not always. Sexual intercourse usually consists of only three
to four thrusts by the male with him ejaculating on the final thrust. This species moves through the forest by swinging between horizontal branches and uses all four limbs to grab branches. They may also leap from tree to tree.
This species communicates through voice, sight, smell, and touch. Vocally, this monkey has different sounds for different situations. To startle a potential predator the night monkey will "scream," emitting a high pitched shriek. These monkeys use social sniffing to assess
potential breeding partners. They will also urinate on their hands and then rub it on different surfaces to show sexual attraction. Aggressive males will usually arch their backs with all of their limbs straightened. Wikipedia →
Recording1:27
Ecuador · 2022
© Alex Bentley · iNaturalist · CC BY-NC 4.0
| # | Park | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Cuyabeno Wildlife Reserve | 🇪🇨 Ecuador | |
| 2 | Anavilhanas National Park | 🇧🇷 Brazil | |
| 3 | Yasuní National Park | 🇪🇨 Ecuador |
Possible
About 20% of wildlife watchers report a Noisy Night Monkey sighting in Anavilhanas National Park on a given day, based on 5 verified sightings from GBIF citizen-science data from 2019 to 2026. It is the 3rd most-seen of the 5 mammals we can rate there. Over three days the chance rises to about 60%, and over a week to about 90%, if each day is a fresh chance.
August
In that month about 50% of wildlife watchers report a Noisy Night Monkey in Anavilhanas National Park on a given day, against under 5% in March–May, July, September–October and December, the lowest months. That is one of Anavilhanas National Park's driest months, with about 75 mm of rain against 340 mm in March.
Between 3 and 6 pm
Across all the parks we cover, that three-hour window holds the most Noisy Night Monkey sightings with a recorded time, and about 8 in 10 of them come between 6 am and 6 pm: it is a daytime animal.
2nd of 3
Of the 3 parks where we can rate Noisy Night Monkey sightings, Anavilhanas National Park ranks 2nd at about 20%. The best odds are in Cuyabeno Wildlife Reserve (Ecuador, about 30%).
GBIF citizen-science records
It is estimated from how often the Noisy Night Monkey is recorded against all the mammals logged in Anavilhanas National Park (5 verified sightings from 2019 to 2026), calibrated against known sighting rates. Figures are rounded to the nearest 10% because citizen-science data supports honest approximations, not decimals, and months with records from fewer than five people show "—". How it works.
