Editing Old World monkey (section)

== Behaviour and ecology ==
=== Diet ===

Most Old World monkeys are at least partially [[omnivore|omnivorous]], but all prefer plant matter, which forms the bulk of their diet. [[Colobinae|Leaf monkeys]] are the most vegetarian, subsisting primarily on leaves, and eating only a small number of insects, while the other species are highly opportunistic, primarily eating fruit, but also consuming almost any food items available, such as flowers, leaves, bulbs and [[rhizome]]s, insects, snails, and even small vertebrates.<ref name="EoM370-405" /> The [[Barbary macaque]]'s diet consists mostly of leaves and roots, though it will also eat insects and uses cedar trees as a water source.<ref name="cedar">{{cite journal|doi=10.1111/j.1523-1739.2001.99019.x|title=Effects of Water Availability and Habitat Quality on Bark-Stripping Behavior in Barbary Macaques |year=2001 |last1=Ciani |first1=Andrea Camperio |last2=Martinoli |first2=Loredana |last3=Capiluppi |first3=Claudio |last4=Arahou |first4=Mohamed |last5=Mouna |first5=Mohamed |journal=Conservation Biology |volume=15 |issue=1 |pages=259–265 |bibcode=2001ConBi..15..259C |s2cid=86080812 }}</ref>

=== Reproduction ===

[[Gestation]] in the Old World monkeys lasts between five and seven months. Births are usually single, although, as with humans, twins occur occasionally. The young are born relatively well-developed, and are able to cling onto their mother's fur with their hands from birth. Compared with most other mammals, they take a long time to reach sexual maturity, with four to six years being typical of most species.

=== Social systems ===

In most species, daughters remain with their mothers for life, so that the basic social group among Old World monkeys is a [[matrilineality|matrilineal]] troop. Males leave the group on reaching adolescence, and find a new troop to join. In many species, only a single adult male lives with each group, driving off all rivals, but others are more tolerant, establishing hierarchical relationships between dominant and subordinate males. Group sizes are highly variable, even within species, depending on the availability of food and other resources.<ref name="EoM370-405" />