Night monkey

Night monkeys live in the trees.

They are awake at night. They have very big eyes. These eyes help them see in the dark.

They do not see colors. They only see in black and white. This helps them find food at night. They like to eat fruit.

Some night monkeys also eat bugs. They use their hands to catch them. They press the bug against a branch. Then they eat it.

These monkeys live in small families. A mom and dad live together. They have babies too. The dad helps take care of the baby.

They sleep in holes in trees. This keeps them safe from rain. It also keeps them out of the sun. They are very special monkeys.

Night monkeys are very special. They are the only monkeys that are truly nocturnal. This means they are active at night.

Their big brown eyes help them see in the dark. They have monochromatic vision. This means they see in black and white instead of colors. This helps them find things at night. They mostly eat fruit. Some also eat insects. They use their palms to press bugs against tree branches. This makes the bugs easy to eat.

These monkeys live in small family groups. A mated pair lives with their young babies. The father is the main caregiver. He looks after the baby for most of its life. This helps the mother stay strong.

During the day, they sleep in trees. They pick safe spots like holes in trunks. They also sleep in thick leaves or vines. These spots keep them safe from rain and heat. They live in many forests across South America and Panama. Some live in high, misty cloud forests.

Night monkeys use many sounds to talk. They make grunts, screams, and hoots. These calls help them protect their homes.

Night monkeys are very special animals. They are the only monkeys that are truly nocturnal. This means they are active during the night and sleep during the day.

Most other monkeys are active when the sun is up. These monkeys belong to the genus Aotus. Their name means "earless" because their ears are hard to see. They live in many forests across Panama and South America. Some live in rainforests, while others live in misty cloud forests.

These monkeys have amazing ways of seeing in the dark. They have large brown eyes that help them see at night. They have monochromatic vision, which means they see in black and white. This helps them find visual cues in low light. They also use their sense of smell to find fruit. Most night monkeys eat fruit, but some also eat insects. To catch a bug, they use their palms to flatten it against a branch.

Scientists have spent a long time studying these monkeys. Before 1983, people thought there were only one or two species. A scientist named Hershkovitz changed this in 1983. He looked at their shapes and their chromosomes. Chromosomes are tiny structures inside cells. He used this evidence to suggest there were nine species. Now, scientists recognize different groups. There is a gray-necked group in the north and a red-necked group in the south.

There are many different types of night monkeys to learn about. The heaviest is Azara's night monkey, which weighs about 1,000 grams. The lightest is Brumback's night monkey, which is only 300 grams. Some species live in the Andes mountains at high spots. The Peruvian night monkey is listed as an Endangered species. Other species are listed as Vulnerable or Least-concern. They can be found in countries like Brazil, Peru, and Colombia.

Night monkeys live in small, loving families. A mated pair lives with their young babies. The father is the main caregiver for the infant. He carries the baby so the mother can stay strong.

During the day, they sleep in safe spots in trees. They might sleep in holes in a trunk or in thick leaves. These spots protect them from heavy rain and heat. They use many sounds to talk to each other. They make grunts, screams, and even hoots to stay in touch.

Night monkeys, also known as owl monkeys or douroucoulis, belong to the genus *Aotus*. They are members of the family Aotidae. Most importantly, they are the only truly nocturnal monkeys in the world. This means they are active during the night and sleep during the day.

While some populations, like Azara's night monkey, show irregular activity during the day, most stay strictly nocturnal. They live in diverse habitats across Panama and much of South America. These include primary forests, secondary forests, tropical rainforests, and high-altitude cloud forests.

To survive in the dark, these monkeys have developed specialized physical traits. Their genus name, *Aotus*, actually means "earless" because their ears are mostly hidden from view. They possess large brown eyes that significantly improve their nocturnal vision. Unlike many other nocturnal animals, they lack a tapetum lucidum made of riboflavin crystals. Instead, some sources suggest they have a reflective layer composed of collagen fibrils. They also have monochromatic vision, meaning they see in black and white. This lack of color vision is thought to be an advantage for detecting visual cues in low light.

The taxonomy of night monkeys has changed significantly over time. Until 1983, scientists classified them into only one or two species. However, researcher Hershkovitz used morphological and karyological evidence to propose nine different species. Karyological evidence refers to the study of chromosomes, which are the structures inside cells. This evidence showed that there was much more variety than previously thought. Today, the genus is generally split into two main groups. The northern group is the gray-necked group, which includes species like *Aotus lemurinus*. The southern group is the red-necked group, which includes species like *Aotus azarae*.

These two groups are often separated by geography. Gray-necked night monkeys are typically found north of the Amazon River. In contrast, red-necked night monkeys are localized south of the Amazon River. The distribution of these species spans many countries, including Brazil, Peru, Colombia, and Argentina. Some species, like the black-headed night monkey, prefer cloud forests. These are areas with high moisture and consistent low clouds. Other species, like the Peruvian night monkey, live at higher elevations in the Andes.

Night monkeys have specific dietary needs and social structures. They are primarily frugivorous, which means they mainly eat fruit. They use their sense of smell to find food in the dark. Some species, such as *A. azarae*, also eat leaves and insects. When catching insects, they use their palms to flatten the prey against a branch. Socially, they are monogamous and live in small family groups. A group usually consists of one mated pair and their immature offspring. Interestingly, the male is the primary caregiver. He carries the infant to reduce the metabolic costs on the mother.

During the day, these monkeys must find safe places to rest. They use several types of tree nests to protect themselves from heat, sunlight, and heavy rain. They might sleep in holes in tree trunks or in concave sections of branches. They also use dense areas of vines, climbers, or thick foliage. These nests are usually found at low to mid-level vegetation rather than high in the canopy. To protect their territory, they use scent marking and a wide variety of vocalizations. They can make up to eight distinct types of calls, including grunts, screams, and hoots.

Conservation is a major concern for many *Aotus* species. They face threats from habitat loss, the pet trade, and hunting for bushmeat. They are also affected by biomedical research. Because they are one of the few monkey species affected by the malaria parasite *Plasmodium falciparum*, they are used in malaria research. The International Union for Conservation of Nature (IUCN) classifies their status differently. The Peruvian night monkey is listed as Endangered. Other species are classified as Vulnerable, Least-concern, or are data deficient.