Fast Fact Attack: Endangered Species No. 77 – The Northern Brown Howler


Brown howler monkey (Alouatta guariba)

Photographer – Peter Schoen

“We are living on the planet as if we have another one to go to”
Terry Swearingen

If you have ever been lucky enough to have heard a howler monkey calling in the wild, you will know how it got its name.  Arguably one of the loudest animals on the planet, they can be heard up to three miles away through the dense jungle.  Alexander von Humboldt said about howler monkeys, “their eyes, voice, and gait are indicative of melancholy”.  The howlers in this clip may not be of the sub-species guariba guariba, but the sound is typical of the species in general.  And, believe me, this is not something you need to take you by surprise in the dark.

The International Union for Conservation of Nature (IUCN) lists most of these sedentary, arboreal howler monkeys (fifteen species) as threatened, due to human activities such as ceaseless hunting for bush meat, and habitat loss and degradation.  But, for the most part, the howlers are still fairly plentiful, with the exception of the Mexican howler (Alouatta palliata mexicana – a sub-species of the mantled howler) and today’s highlighted species, the northern brown howler (Alouatta guariba guariba).  They have both suffered to the point of being driven to near extinction.

Howler monkeysHowler monkeys are a large and inexpensive source of protein.  One monkey could easily feed a family of four.  And, they are slow and docile, which makes them easy prey.  Then, there are the usual illegal logging activities and other forms of human encroachment that we see everywhere across the globe.  The locations change, but the threats remain the same.

Howlers are not only large themselves, but they are also among the largest of the New World monkeys.  They range in bodily height from two to three feet.  Added to that, they have extremely long, prehensile tails which can measure anything from three feet to an astounding three times the size of the monkey itself.  This tail is invaluable to the New World monkeys.  They use it to travel through the branches and can wrap it round and swing freely to pluck leaves and fruit with their hands.

Another helpful augmentation of the howlers is their incredibly keen sense of smell. They have short stumpy, round noses which Howler monkey (Alouatta guariba) in Santa Maria de Jetiba, Brazil.can sniff out nourishment (the nostrils have sensory hairs inside) at over two to three miles.  Possibly no coincidence that they can be heard that far away as well.

A further adaptation is the molars, specially designed to shear through tougher leaves.

But, it doesn’t end there.  These marvellous monkeys are also blessed with trichromatic colour vision, which is thought to have developed in the species to allow selection of the very best leaves available.

One last staggering attribute is, of course, that voice.  A combination of large throat with specialised vocal chords and larynx produces a whole range of growls, barks, howls and roars.  This ability is unique to the howler species.

Howler monkeys are slow-moving folivores.  They spend most of the daylight hours relaxing in the trees.  The rest of their time is shared between eating, travelling and grooming. They move quadrupedally along the tops of branches, using their hands and their long, strong tails.  They live in groups of four or five.  Occasionally there are more. One dominant male usually rules the troop.

Baby howler monkey at the Sloth Sanctuary, Costa Rica by Jonathan LeyHowler monkeys do not have a specific breeding season, but females are only able to produce offspring every twenty-two months.  One infant will be born as a result of the liaison, after a gestation period of six months.  Most infants are weaned at one year, and reach maturity at five years (male) and approximately three and a half years (female).

The species, brown howler monkey (Alouatta guariba), lives in forests in south-eastern Brazil and far north-eastern Argentina.  There are two sub-species; today’s featured northern brown howler (Alouatta guariba guariba), listed as ‘critically endangered’, and the southern brown howler (Alouatta guariba clamitans) listed as ‘of least concern’.

Habitat
Sub-montane, montane and lowland forests.
Where
Brazil:  The Northern brown howler is confined to a small area north of the  Rio Jequitinhonha.  The Jequitinhonha flows through the Brazilian state of Minas Gerais.
What they eat
Mature leaves, though younger leaves are preferred.  Mature fruit is also an important part of the diet.  And, they will also eat, buds, flowers, and nuts.
Threats
Hunting and  deforestation, hunting being the larger threat as they are ale to  survive in small fragments of forest if they are left alone by hunters.  They are both susceptible to, and carriers of, disease.
Status: Critically Endangered
The Northern brown howler (Alouatta guariba guariba), is listed on the  IUCN Red List of Threatened Species  as Critically Endangered.  It has been on the critical list since 1996.  It is also protected by  Cites Appendix 11.  Little over two hundred of the species still survive in the wild.  I have been unable to find any record of Northern howler monkeys being kept in zoos, either in captive breeding programs or as an attraction.

Related Articles
Howler monkey at risk of extinction because of stress

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15 thoughts on “Fast Fact Attack: Endangered Species No. 77 – The Northern Brown Howler

  1. Pingback: Fact Attack: Endangered Species No. 105 – Northern Muriqui | Mungai and the Goa Constrictor

  2. Yet another creature who is docile, slow-moving and with a low-birth rate, becomes vulnerable to poaching. If not enough, the related article cites “… the lack of food increases stress levels, which reduces chances of reproduction.” How fragile their world is. They are incredible beings and their trichromatic vision is extraordinary!.

    Thank you, Amelia, for sharing all these wonders and rasing awareness to their fragility.♥

  3. There are howler monkeys at the local zoo here. I don’t go in there, but you know they’re there, because you can hear them in the surrounding neighborhood (them and the peacocks!). I did not know there was an endangered subspecies. Thank you for the information. (I had to go read the Wikipedia article on trichromacy…howler monkeys see the world the way we do! :-))

    • I have never lived near howler monkeys, but I have lived near peacocks before. A neighbour had two which used to fly on to the roof of our house. They have this huge wingspan and when flying up to the roof used to terrify the dogs who all ran for cover the moment they saw them. It was quite comical really LOL They were really noisy, too, but very beautiful. 🙂

  4. Pingback: Suriname, 16th day, to Isadou island | Dear Kitty. Some blog

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