Black-and-white colobus

Black-and-white colobuses (or colobi) are Old World monkeys of the genus Colobus, native to Africa. They are closely related to the red colobus monkeys of genus Piliocolobus.<ref name=msw3/> There are five species of this monkey, and at least eight subspecies.<ref name=msw3/> They are generally found in high-density forests where they forage on leaves, flowers and fruit. Social groups of colobus are diverse, varying from group to group.<ref name=":03"/> Resident-egalitarian and allomothering relationships have been observed among the female population.<ref name=":1" /> Complex behaviours have also been observed in this species, including greeting rituals<ref name=":03" /> and varying group sleeping patterns.<ref name=":3" /> Colobi play a significant role in seed dispersal.

Etymology

The word "colobus" comes from the Greek Template:Wikt-lang (kolobós, "docked", "maimed") and refers to the stump-like thumb.

Taxonomy

Fossil species

• †Colobus flandrini
• †Colobus freedmaniTemplate:Cn

Behaviour and ecology

File:Multi-male unit of Rwenzori colobus in Nyungwe .jpg

A multi-male unit of Angolan colobus in a multilevel society

Colobus habitats include primary and secondary forests, riverine forests, and wooded grasslands; they are found more in higher-density logged forests than in other primary forests. Their ruminant-like digestive systems have enabled them to occupy niches that are inaccessible to other primates: they are herbivorous, eating leaves, fruit, flowers, lichen, herbaceous vegetation and bark. Colobuses are important for seed dispersal through their sloppy eating habits, as well as through their digestive systems.

Leaf toughness influences colobus foraging efficiency. Tougher leaves correlate negatively with ingestion rate (g/min) as they are costly in terms of mastication, but positively with investment (chews/g).<ref name=":0">Template:Cite journal</ref> Individuals spend approximately 150 minutes actively feeding each day.<ref name=":0" /> In a montane habitat colobus are known to utilise lichen as a fallback food during periods of low food availability.<ref>Template:Cite journal</ref>

Social patterns and morphology

Colobuses live in territorial groups that vary in both size (3-15 individuals) and structure.<ref name=":03">Template:Cite journal</ref><ref name=":04">Template:Cite journal</ref><ref name=":05">Template:Cite journal</ref> It was originally believed that the structure of these groups consisted of one male and about 8 female members.<ref>Template:Cite journal</ref> However, more recent observations have shown variation in structure and the number of males within groups, with one species forming multi-male, multifemale groups in a multilevel society, and in some populations supergroups form exceeding 500 individuals.<ref name=":04" /><ref name=":05" /> There appears to be a dominant male, whilst there is no clear dominance among female members.<ref name=":03"/> Relationships among females are considered to be resident-egalitarian, as there is low competition and aggression between them within their own groups. Juveniles are treated as a lower-rank (in regards to authority) than subadults and likewise when comparing subadults to adults.<ref name=":1">Template:Cite journal</ref> Colobuses do not display any type of seasonal breeding patterns.<ref>Template:Cite journal</ref>

As suggested by their name, adult colobi have black fur with white features. White fur surrounds their facial region and a "U" shape of long white fur runs along the sides of their body. Newborn colobi are completely white with a pink face. Cases of allomothering are documented, which means members of the troop other than the infant's biological mother care for it. Allomothering is believed to increase inclusive fitness or maternal practice for the benefit of future offspring.<ref>Template:Cite journal</ref>

Social behaviours

File:Angolan colobus with infant.jpg

Angolan black-and-white colobus with infant.

Many members participate in a greeting ritual when they are reunited with familiar individuals, an act of reaffirming.<ref name=":03"/> The greeting behaviour is generally carried out by the approaching monkey and often is followed with grooming. They participate in three greeting behaviours of physical contact. This includes mounting, head mounting (grasps the shoulders) and embracing.<ref name=":03" /> It seems as though these behaviours do not have any relationship with mating or courting.<ref name=":03" />

File:Eastern black-and-white colobus (Colobus guereza occidentalis) with juvenile.jpg

Adult Eastern black-and-white colobus with a juvenile

Black-and-white colobus have complex sleeping patterns. They sleep in trees near a food source, which may serve to save energy.<ref name=":3">Template:Cite journal</ref> Groups seem to regularly switch up sleeping locations (suggested due to reducing risk of parasites and placement prediction) and generally do not sleep near other groups. They also tend to sleep more tightly together on nights with great visibility.<ref name=":3" /> They sleep in mid- to upper sections of tall trees which allows for predator watch as well as protection from ground and aerial predators while they are asleep.<ref name=":3" /> Although there is no obvious preference for tree type, they have often been observed in Antiaris toxicaria.<ref name=":3" />

Conservation

They are prey for many forest predators such as leopards and chimpanzees,Template:Cn and are threatened by hunting for the bushmeat trade, logging, and habitat destruction.

Individuals are more vigilant (conspecific threat) in low canopy, they also spend less time scanning when they are around familiar group members as opposed to unfamiliar.<ref name=":2">Template:Cite journal</ref> There are no clear difference in vigilance between male and females. However, there is a positive correlation between mean monthly vigilance and encounter rates.<ref name=":2" /> Male vigilance generally increases during mating.<ref>Template:Cite journal</ref>

Sources

• Template:Cite book

External links

• Colobus Monkey: Wildlife summary from the African Wildlife Foundation
• Colobus Conservation
• Primate Info Net Colobus Factsheets
• Angolan Black & White Colobus