Prince Bernhard’s titi, Plecturocebus bernhardi
PRINCE BERNHARD'S TITI
Plecturocebus bernhardi
Geographic Distribution and Habitat
Prince Bernhard’s titi monkeys are endemic to Brazil in the states of Amazonas and Rondônia.
At the border of Bolivia, the state of Rondônia is located in west-central Brazil to the south and west of Amazonas. Close to the borders of Colombia and Venezuela in the northwest, Amazonas is the largest state in the country. It sits at an elevation of no more than 300 feet (90 meters) above sea level. Most of the state is not populated by humans, except for Manaus and a couple of other cities. Titi monkeys are found in various habitats, including disturbed environments. Prince Bernhard’s titi monkeys live in secondary forests, liana forests, and forests near plantations of rubber, nuts, or cocoa. Some populations are also found in protected areas, including Ipixuna Indigenous Land.
Scattered populations of Prince Bernhard’s titi monkeys may be present in the state of Mato Grosso, but this is not confirmed.
Prince Bernhard’s titi monkeys share forest patches with the ashy black titi monkeys (P. cinerascens), Hershkovitz’s titi monkeys (P. dubius), and brown titi monkeys (P. brunneus). Other animals living in this part of the world include rodents, birds, caymans, turtles, boas, anacondas, and iguanas.
About twelve million years ago, the ancestor of titi monkeys lived in a large area that spread from the Amazon forest to the Atlantic forest. Initially, all titi monkeys were placed in a single genus. However, recent DNA studies allowed scientists to reclassify titi monkeys into three genera (Cheracebus, Plecturocebus, and Callicebus).
This is how, since 2016, Prince Bernhard’s titi monkeys belong to the genus Plecturocebus, when originally, they were included in the Callicebus genus.
Size, Weight, and Lifespan
Prince Bernhard’s titi monkeys measure about 15 inches in head and body length. The tail adds about 22 inches (56 cm) more. They weigh between 1.5 and 2.6 pounds (700-1200 grams). Males and females are about the same size.
Their lifespan is not known, however, titi monkeys are generally expected to live between 15 and 20 years in the wild, so we can surmise it is similar for this species.
Appearance
Prince Bernhard’s titi monkeys are strikingly beautiful with their dark orange sideburns, beard, underparts, and inner limbs—a dramatic contrast with their black faces and the shaggy and thick gray and brown fur of their bodies. The hair at the nape of the neck is long (1.9 inches/5 cm). Their feet and hands are light grey and the long digits are covered in fur. Their faces could easily be sketched with three circles forming a triangle — two large circles around the big brown eyes and a larger one around the mouth. Their black ears are high up on each side of the face and end in a white tuft. Their tail is long and black, bushy with a white tip, and looks soft to the touch.
Diet
Prince Bernhard’s titi monkeys spend their foraging time up in the canopy. Fifty percent of their diet consists of fruits of palm trees and various other plants; thirty percent consists of young leaves, shrubs, and lianas; and twenty percent of invertebrates and seeds.
Behavior and Lifestyle
Titi monkeys are diurnal (i.e. active during the day). Their modes of locomotion are quadrupedal walking, climbing, and leaping.
To keep their metabolism in balance, they thermoregulate—which means they maintain the same body temperature no matter what the external temperature is. To do so, they avoid sunny places when it is over 88 °F (31 °C), and to dissipate body heat, they sit or stretch out on a well-shaded branch. At night and in the early morning hours, when temperatures fall, they huddle together, intertwining their tails to keep warm. During the day, if it is cold, they choose high branches that get more sun exposure.
The name “Plecturocebus” comes from ancient Greek: “plektos” which means “twist”; “oura” which means “tail”; and “kebos” which means long-tailed monkey. Put together, these three words refer to long-tailed monkeys that intertwine (or twist) their tails together.
The Prince Bernhard’s titi monkey was named in honor of Prince Bernhard of the Netherlands, who created the Order of the Golden Ark, an award for conservationists.
Titi monkeys form small pair-bonded groups that cover a territory ranging from 0.9 to 18 square miles (1.5- 30 km²). They typically travel 0.3 to 0.9 square miles (0.5-1.5 km²) every day to forage.
They start foraging in the morning, rest a bit during the afternoon, and forage again before retiring for the night. They do not make nests but sleep sitting on a branch.
The members of the group socialize throughout the day by grooming, which reinforces their bonds, or by engaging in playful chases. They huddle together and sleep side by side.
Like all primates, titi monkeys communicate in many different ways: vocalizations, body postures, and scent marking.
Their vocalizations are varied and convey different meanings. For instance, they produce high-pitch calls, such as squeaks, trills, chirps, whistles, and sneezes to address individuals in their group. They produce alarm calls to alert their friends and family members about specific predators, so everyone can run to safety.
In the early morning, before dawn, all bonded pairs begin to perform duet calls together. These singing bouts overlap one another and are thought to advertise the status of a mated pair and their territory.
Physical contact or posturing are other ways titi monkeys communicate. They may hold hands or feet, nuzzle, groom, and greet each other by touching each other’s mouths. When interacting with external titi monkey groups, they produce low-pitch vocalizations like grunts, moans, and bellows accompanied by acrobatics meant to intimidate intruders and dissuade them from stepping into their territory.
Titi monkeys have scent glands on their chests and often rub their chest on branches to mark territory or leave messages to group members. Scent is also a good indicator of the status of an individual in the group and a good way for females to advertise when they are ready to start a family.
The specific reproduction behavior of Prince Bernhard’s titi monkeys is not well studied, however it is likely similar to what is currently known about titi monkeys in general.
For instance, all titi monkeys form lifelong monogamous mating pairs. Babies are born after a gestation period of approximately 145 to 180 days, usually when food is most abundant, even though mating can occur anytime during the year. Mothers give birth to a single offspring (very rarely to twins) and fathers do most of the rearing. They carry their baby, protect it, and share food with it. Mothers are not very “maternal.” They nurse their baby for about a month until it is weaned but don’t spend much time grooming or cuddling with it.
As they grow, the offspring becomes more independent and learns to run, leap, and climb up branches. They reach adulthood at five months of age and, sometime later, leave their natal group. Females usually leave when they find a mate of their own, whereas males can leave and form bachelor groups before they get hitched.
Prince Bernhard’s titi monkeys play an important role in their ecosystem. Since they eat fruit, they spread seeds through their feces, thereby aiding in plant reproduction and enhancing the health of the forests they dwell in.
As prey, they also provide food for various predators living in the same environment. Predators of Prince Bernhard’s titi monkeys include birds of prey, such as hawks and eagles, and small carnivores like ocelots, as well as large snakes.
The International Union for Conservation of Nature lists the Prince Bernhard’s titi monkey as Least Concern (IUCN, 2015), appearing on the IUCN Red List of Threatened Species. This is because, until recently, the forests they inhabit were, for the most part, untouched by human activities. There are no known major threats to the species at this time.
Prince Bernhard’s titi monkey is listed in Appendix II of the Convention on International Trade in Endangered Species (CITES), an international agreement between governments whose goal is to ensure that international trade in specimens of wild animals and plants does not threaten their survival.
Although the populations of Prince Bernhard’s titi monkeys are thought to be relatively stable, recent research found that their habitat in the southeastern Amazon rainforest is at risk of losing almost 45% of its current range in the next quarter century. Indeed, some bills allowing mining and hydropower dams within indigenous lands, and the so-called “land grabbing” bills, encourage illegal logging, mining, and fire, thereby increasing the rate of deforestation.
The “Arcs of Restoration” policy aims to achieve zero deforestation by 2030 by avoiding forest degradation, restoring forests in protected areas and undesignated lands, and restoring private lands that have been cleared above the legal allowance. The policymakers hope to succeed by strengthening existing policies and their enforcement, empowering local communities, and through the use of technology.
- Orys International Journal of Conservation – Deforestation in Brazilian Amazon: concern for titi monkey conservation
- IUCN redlist
- www.worldspecies.org – Plectorocebus Bernhard
- Ecologia e Comportamento bernhardi em un fragmento florestal em Rondônia, Brasil – Karine Galisteo Diemer Lopes
- Phylogeny, molecular dating and zoogeographic history of the titi monkeys (Callicebus, Pitheciidae) of eastern Brazil – Jeferson Carneiro, Iracilda Sampaio, José de Sousa e Silva-Júnior, Izeni Farias, Tomas Hrbek, Alcides Pissinatti, Ronylson Silva, Antônio Martins-Junior, Jean Boubli, Stephen Francis Ferrari, Horacio Schneider
- wikipedia.org – Prince Bernhard’s titi monkey
- zenodo.org – Callicebus bernhardi M. G. M. van Roosmalen 2002
- Ambient temperature and humidity modulate the behavioural thermoregulation of a small arboreal mammal (Callicebus bernhardi) – Karine G.D. Lopes; Júlio César Bicca-Marques
- www.britannica.com – Amazonas state / Rondônia state
- www.laisladelosmonos.org
- www.primate.wisc.edu/primate-info-net/pin-factsheets/pin-factsheet-dusty-titi-monkey/
- https://pmc.ncbi.nlm.nih.gov/articles/PMC6211037/ – Duetting Patterns of Titi Monkeys (Primates, Pitheciidae: Callicebinae) and Relationships with Phylogeny – Patrice Adret , Kimberly A Dingess, Christini B Caselli, Jan Vermeer, Jesus Martínez, Jossy C Luna Amancio, Silvy M van Kuijk, Lucero M Hernani Lineros, Robert B Wallace, Eduardo Fernandez-Duque, Anthony Di Fiore
- www.theamazonwewant.org – “Transforming the Amazon through Arcs of Restoration”
- A Taxonomic Review of the Titi Monkeys, Genus Callicebus Thomas, 1903, with the Description of Two New Species, Callicebus Bernhardi and Callicebus Stephennashi from Brazilian Amazonia – Marc G. M. van Roosmalen, Tomas van Roosmalen, and Russell A. Mittermeier
Written by Sylvie Abrams, March 2024