The colobus monkey cannot be easily put into any one category when describing its social system and social relationships.  The reason for this is the great variety of environments that they inhabit and the different pressures that result from this.  The following pressures seem to be most important and determine what type of organization they exhibit:
 

• Food Distribution--Food that is superabundant and unpredictable cannot be defended.  Consequently, colobus monkeys living in areas with this type of food distribution live in home ranges.  Colobus monkeys living in areas with predictable, defensible food sources tend to be territorial. 
• Predation Pressure--Those colobus monkeys suffering from high predation pressure, particularly the red colobus, need to live in large groups to protect themselves from attack.  Those living in the absence of predation pressure tend toward smaller groups, sometimes one male units.
• Type of Kin Group--Colobus monkeys organized in matrilineal kin groups often are territorial and polygynous, because it is easier for a male to maintain a territory and a harem when the females are closely bonded.  Patrilineal kin groups show no territories or harems, because it would be too difficult to defend females who are not bonded and who will not necessarily stay in a territory.  These types of kin groups may be the result of the specific environmental pressures, rather than the cause of social spacing or mating systems.