Geographic Distribution and Habitat
Lucifer titis, also known as yellow-handed titis and widow monkeys, are native to South America and are found in Brazil, Colombia, Ecuador, and Peru. The geographic area in which they dwell is delimited by four rivers: Rio Solimões, Rio Napo, Rio Japurá, and Rio Caquetá. The average temperature in the region is about 81 F (27 C). The rainy season brings about 98 inches (2.5 m) of rain every year. It is a very rich region for its biodiversity.
In Brazil, Lucifer titis inhabit the moist broad-leaf forests nested between Rio Solimões and Rio Japurá. In Colombia, they live in forests at altitudes up to 1,600 feet (500 m) in the departments of Caquetá, Putumayo, and Amazonas. In Ecuador, they settled in non-flooded forests of the Napo province, between Rios Aguarico and Putumayo. In Peru, they are found in forests where tall trees (80 feet/25 m) with narrow trunks grow on soil made of sand and clay.
As for the titis present in the area nested between the right bank of the Rio Nanay and the left bank of the lower Rios Tigre and Pucacuro, scientists are unsure they should be considered part of the Lucifer titi species.
Studies suggest that the Lucifer titi species (Cheracebus lucifer) likely appeared during the Pleistocene, around 1.26 million years ago; however, it was not officially recognized as its own species until 2002. In fact, until then, Lucifer titis were considered part of the collared titi family with two other species—the collared titi (C. torquatus) and the black titi (C. lugens), all of which—very confusingly—share the alternate common names yellow-handed titi and window monkey. Although they share genetic material, they are each considered unique species.
Until recently, the classification of titi monkeys was solely based on differences in the coloration and patterns of the fur. Nowadays other methods, such as DNA, molecular data, and analysis of vocalization patterns, are used to clearly delineate how titi monkeys species are related to—or differ from—each other. They are now divided into three groups called: Callicebus in the Atlantic Forest, Plecturocebus in the Amazon basin and Chaco region, and Cheracebus in the Orinoco, Negro, and upper Amazon. The Lucifer titi described in this profile belongs to the Cheracebus family.
Studies of mitochondrial DNA and nuclear gene markers of the Lucifer titi have recently revealed that the species is more closely related to the collared titi than it is to the black titi.
Size, Weight, and Lifespan
Lucifer titis are the largest of the titi monkeys. Males and females are similar in size and weigh between 2 and 3 pounds (1–1.5 kg). Their body length is between 11 and 17.5 inches (30–45 cm) and their tail is longer than their body, measuring 15–19.5 inches (39–50 cm).
They can live up to 12 years.
Lucifer titis’ small bodies are covered in a long soft coat of dark reddish-brown fur. Their triangular faces are pink and lit up by two beautiful expressive brown eyes. Their noses are flat and their nostrils are slanted. Their mouths are small and house short canines. This seems logical since their diet does not necessitate them having longer canines to cut through hard substances. Their ears are dissimulated by tick fur that surrounds their face. A band of creamy-white hair extends from the base of the ears onto the throat.
When Lucifer titi monkeys were first recognized as a unique species, scientists thought their orange hands were a distinctive characteristic. Recent studies reveal this is not necessarily the case. In fact, some Lucifer titi monkeys have creamy-white hands. Both their hands and feet have five digits with opposable thumbs and toes.
Their tail is dark brown or black at the base and ends with reddish hues at the tip. Unlike many New World monkeys, the tail of titi monkeys is not prehensile, which means that they cannot use it to grip or hang onto branches. They have strong thighs that allow them to leap with great dexterity between branches.
Lucifer titi monkeys are mostly fructivore. They consume the pulp of the fruit they forage. If fruit is not plentiful, they can supplement their diet by consuming leaves, insects, and the occasional bird eggs. The type and nutritional value of the food they eat varies depending on where they live. For example, the nutritional needs of Lucifer titis living in the white-sand forests of Peru are not met because the hard and leathery evergreen foliage is insufficient.
These monkeys search and capture prey on trunks and branches. They also unroll dead and green leaves and grab flying insects but do not look for prey by tearing open bark or breaking branches and they don’t look for prey in tree holes as other titi species might. They place the prey they grab directly into their mouth. Prey is usually small and includes caterpillars, beetles, spiders, larvae, grasshoppers, praying mantis, wasps, and flies.
Behavior and Lifestyle
Lucifer titis are diurnal, which means they are active during the day. They are arboreal and spend most of their time in the lower canopy. They travel across branches by walking on hands and feet (quadrupedally) or by leaping. They live in groups composed of two to five individuals that include an adult male and an adult female with their offspring. As with all titi monkeys, an adult male and an adult female form a bonded pair that remains together for several breeding seasons.
Titi monkeys can often be observed with their tails entwined—which means the tail of one individual is wrapped around the body of another and vice-versa. Such displays of affection reinforce the bonds between the adult male and adult female of the group, but also between family members.
Titi monkeys were first described in the early 19th century by Geoffrey Saint Hillaire. At the time, though, they were considered as belonging in the same family as marmosets and tamarins (Callithrix). It took another century for their classification to be updated and decoupled from marmosets and tamarins.
Daily Life and Group Dynamics
At dawn, male Lucifer titi monkeys produce a loud call, as they run and leap through trees. The females follow them. The call is believed to let other groups know where their territories start and end. Groups have a home range that usually covers 12 to 24 acres (4.5–9.5 hectares). Families forage together traveling from tree to tree until about noon, at which time they socialize and play. Bonded males and females groom each other the most, but juveniles and young offspring also join in allogrooming sessions that can last up to one hour. After this break, they spend the rest of the day foraging again.
When night falls, the group settles on the highest branches of a tree to rest. It is not unusual for the group to reuse the same tree night after night.
Like all other diurnal primates living in dense vegetation, Lucifer titi monkeys use vocalization as their primary mode of communication. They express themselves through solos, duets, and choruses.
When they first wake up, around dawn, groups generally produce loud calls to let other groups know which territory is theirs. The male usually initiates the vocalizations, then the female joins in. Her vocalizations are so precisely and harmoniously fused with those of her mate that, to the human ear, the song seems to come from a single individual. The sound produced by two titi monkeys joining in bouts of vocalizations is called a duet.
Unlike other titi monkeys, Lucifer titis have a low-pitched voice. Their duets are produced at a low frequency and have fewer phrases. Each phrase is composed of pairs of syllables accompanied by rapid inhalations and exhalations. Several phrases together form a sequence. A song, or “bout,” is composed of a set of sequences. When offspring join in the vocalization bouts, the sound produced is called a chorus. Other vocalizations include pants, hoots, chirrups, and whinnies.
Both male and female Lucifer titi monkeys reach sexual maturity when they turn 2 or 3 years old. Mature males disperse in an attempt to start their own families. Unlike females of many other primate species, female Lucifer titi monkeys do not exhibit any external sign when they go into estrus, like gential swelling. When a female and a male bond, they stay together for several years, but they usually do not have their offspring until they have been together for about one year.
Expecting females give birth to one infant after a gestation period of 5 months. It is rare for them to have twins. Most births have been observed to occur in the winter months, although these primates are thought to be able to breed any time during the year. Females usually don’t have a second offspring until about eight months after the first one is born. However, if they lose an infant, they can get pregnant within a shorter time interval.
Once an infant is born, the father takes on the arduous duty of carrying it everywhere. Because the infants are with their fathers all the time, they are protected from predators. Mothers only have close contact with the baby to feed it until it is weaned.
In some titi monkey species, adult females that remain within their natal group do not go into estrus and therefore cannot have offspring. Scientists call this phenomenon “social suppression of reproduction.” It prevents inbreeding. It is probable that such is the case with adult Lucifer titi monkeys.
Since Lucifer titi monkeys are fruit eaters, they probably play a role in seed dispersal.
Although overall population numbers are unknown, the International Union for Conservation of Nature assesses the Lucifer titi’s conservation status as Least Concern (IUCN, 2015), appearing on the IUCN’s Red List of Threatened Species. These titi monkeys live in a remote part of the Amazon forest and can also be found in protected areas, such as ESEC Juami-Japurá and RDS Mamirauá in Brazil.
The situation is different in Ecuador, where the species is considered Vulnerable because the region in which they live, north of the Aguarico River, is threatened by deforestation.
In Peru, large forested areas are being converted for palm oil plantations, so the titi monkeys are losing their habitat. Primates are also often killed by subsistence hunters.
The species is listed on the Convention on International Trade in Endangered Species (CITES) Appendix II.
In Brazil, hunting of primates and other wild animals is controlled by the Environmental Crimes Law, which was enacted in 1998. This law, however, is not efficient to protect animals from hunters. Indeed, it states that hunting is not a crime when the hunter is in need. Since the need of the hunter is not clearly defined, there is a lot of room for interpretation, so it is difficult to implement the law.
The Colombian Strategy for Low Carbon Development and the Amazon Vision Program share a common goal: slowing down deforestation by promoting low-emission rural development—especially in areas where forest cover has shrunk more than 50% in the last decade. If the programs are successful, this could be good news for Lucifer titis and other primates.
- IUCN Red List
- Duetting Patterns of Titi Monkeys (Primates Pitheciidae: Callicebinae) and Relationships with Phylogeny – Patrice Adret, Kimberly A Dingess, Christini B Caselli, Jan Vermeer, Jesus Martinez, Jossy C Luna Amancio, Silvy M van Kuijk, Lucero M Hermani Lineros, Robert B Wallace, Eduardo Fernandez-Duque and Anthony Di Fiore.
- Grooming behavior in the titi monkey (Callicebus torquatus) – Patricia Wright – American Journal of Primatology
- Geographic Distribution and Possible Taxonomic Distinction of Callicebus torquatus Populations (Pitheciidae: Primates) in Peruvian Amazonia – Rolando Aquino, Wagner Terrones, Fanny Cornejo, Richard Heymann
- Evolutionary History and Taxonomy of the Titi Monkeys (Callicebinae) – Hazel Byrne
- Neotropical Primate Family-Group Names Replaced by Groves (2001) in Contravention of Article 40 of the International Code of Zoological Nomenclature – Douglas Brandon-Jones, Colin P Groves
- Spatial patterns of primate hunting in riverine communities in Central Amazonia – Priscilla Maria Pereira, João Valsecchi and Helder Queiroz
- Primate Adaptation and Evolution (third edition) – Chapter 5 – New World Anthropoids – John G.Feagle
- A Taxonomic Review of the Titi Monkeys, Genus Callicebus Thomas 1903, with the description of two new species Callicebus Bernhardi and Callicebus Stephannashi, from Brazilian Amazonia – Marc G. M. van Roosmalen1, Tomas van Roosmalen2, and Russell A. Mittermeier
- Insectivory and prey foraging techniques in Callicebus – a case study of Callicebus cuprous and comparison to other pitheciids – Eckhard W Heymann and Mirjam N Nadjafzadeh
- www.etropics.org Caqueta & Guaviare, Colombia
- Smithsonian’s national zoo and conservation biology institute – Titi monkeys
- Reproductive Biology of Female Titi Monkeys (Callicebus moloch) in Captivity – C. R. Valeggia, S. P. Mendoza, E. Fernandez-Duque, W. A.Mason and B Lasley
Written by Sylvie Abrams, January 2022