Adult male howlers range in colour from black to brown, and the females and young are lighter in colour (a sandy yellow). Howlers grow to be between 2 and 4 feet (0.6 to 1.2 metres) tall and weigh from 8 to 22 pounds (3.5 to 10kgs). They have a long prehensile tail which acts as a powerful fifth limb. It is easily capable of supporting the full weight of a monkey as it hangs from a branch, freeing its hands and feet for other uses such as collecting food. The underneath of the tail – about 2/3rds of the entire length – has a palm of bare skin which allows for a firm grip. The tail also helps the monkey to balance as it moves and is wrapped around branches as security against falling.
Howlers have a short snout and wide-set round nostrils. Their sense of smell is very acute, meaning they can sniff out their food (primarily leaves but occasionally they supplement their diet with fruit and maggots) from a distance of up to 2 kilometres.
They live in the tops of trees in organized groups of between 3 and 20 individuals, with 1 to 3 adult males and multiple females. Adult females usually have one baby at a time.
When they feel threatened or are in difficulty, the group come together to defend themselves by screaming, cutting tree branches, or defecating on the intruder. Communication is crucial. All members of the group are joined together through a complicated communication system that includes gestures and sounds.
Established in 1990, the Argentina Monkey Project has been working for over 20 years with howler monkeys. It is the first and only centre for the rehabilitation of primates in Argentina and the only one in the world that works to rehabilitate howler monkeys.
The project’s programme consists of various stages of physical, psychological and social rehabilitation; in other words, they teach the monkeys to be monkeys again. At the project they work with orphan monkeys that have been "mistakenly" turned into pets. All have been taken from their natural habitats to satisfy the pet trade or to be held as exhibits in zoos. The monkeys have come to the project from throughout the country through voluntary hand-ins, seizures by the government, from zoos, etc. All have been pet monkeys. Unfortunately the pet trade still exists in South America and, although howler monkeys are a protected species in Argentina, enforcement of this status is not effective. The howler monkey is now listed in CITES (Convention on International Trade in Endangered Species) Appendix 2, as 'vulnerable.'
The Argentina Monkey Project is the first place in Argentina where the Black Howler monkeys have been bred successfully outside their native habitat. Throughout the world this species is considered difficult to maintain in captivity – generally they do not survive and/or reproduce in zoos.
At the project there are more than 100 monkeys that live freely in 9 sectors within the refuge. There are also a few monkeys that cannot live with other monkeys or prefer to be alone or with humans.
When a monkey is captured from the wild, more animals are sacrificed than are required to satisfy the demand for pets. The mother, who normally carries her offspring, is the first to be beaten down and killed in order to take the baby. However, the group’s social bonds are so strong that other monkeys try to defend the female, meaning they are also sacrificed. Thus, more animals are affected than those destined to be sold. From capture to final destination, as many as 5 or 6 monkeys die, either in the group or amongst the specimens captured.
Following an event like this, socio-ecological disorders develop within the group. Fluctuations in the level of population affect the social standards of all the individuals. The social organisation of the clan (which is essential for the survival of the group) is harmed, the group becomes unstable, and the hierarchy, affection and support between the members are all affected.
Until they reach their final destination the captured babies are kept in precarious conditions. They are neglected, badly fed, kept in stacked cages, etc, and those monkeys that do survive arrive in a terrible state (wounded, suffering from shock and dehydration, etc).
Just like a human baby, primate offspring suffer physically, mentally and emotionally. The people who acquire the monkey as a ‘pet’ will generally, out of ignorance, treat it like a puppy. Under these conditions the baby cannot survive.
It can only survive if treated like a human baby. This in itself brings forth another problem, the humanisation of the animal – the babies learn to behave and act like human beings.
Before the baby monkey was captured, it was progressing through a transition period of physical and psychological development, as well as learning different aspects of socialisation. The interruption of this process means that, by the time these pet monkeys reach adulthood, they will have been transformed into socially inept animals, they will be aggressive and depressed, and will have developed strange neurotic behaviour.
The project’s programme consists of various stages of physical, psychological and social rehabilitation; in other words, they teach the monkeys to be monkeys again.
Volunteers will therefore be expected to assist with tasks like feeding and caring for the monkeys; observing and studying the free social groups of monkeys and inputting that data into the project’s computer system; caring for the orphan monkeys; contructing, cleaning and maintaining the refuge areas at the project; and routine jobs like washing the monkeys’ plates.