The red uakari is primarily a frugivorous species, but will also eat seeds, buds, leaves, and insects. This species forages for seeds of immature fruits (Kinzey, 1997). Also fruits chosen for their seeds tend to be large and hard-shelled (Barnett and Brandon-Jones, 1997). Cacajao calvus ucayalii was found to consume the seeds of the species Micrandra spruceana and Parkia oppositifolia (Barnett and Brandon-Jones, 1997). The most important fruit species consumed for the subspecies Cacajao calvus calvus is the hard-shelled fruit of Eschweilera turbinata (Barnett and Brandon-Jones, 1997). The diet of the subspecies Cacajao calvus calvus was found to be made up of immature seeds (69.7%), mesocarps of ripe fruits and arils (18.4%), nectar (6.2%), and insects (5.2%) (Ayres, 1986). Ayres (1987) found that the seeds consumed by this subspecies were of the hard-shelled type high in fats and the husks having low amounts of secondary compounds. The important fruit species consumed for the subspecies Cacajao calvus ucayalii are Couma macrocarpa (Apocynaceae), Schistostemon spp. (Humiraceae), Eschweilera spp. (Lechythidace), Mauritia flexuosa, Pouteria spp. (Sapotaceae), Rhigospira quadrangularis (Apocynaceae), and Parahancornia peruviana (Apocynaceae) (Aquino, 1995). Cacajao calvus ucayalii feeds on the seeds of Micrandra spruceana (Euphorbiaceae) (Heymann, 1990). During the dry season this species consumes caterpillars and nectar to supplement the reduction in fruit productivity (Barnett and Brandon-Jones, 1997). Cacajao calvus ucayalii during the dry season will feed upon epiphytes, which includes bromeliads (Aquino, 1995). During the dry season Cacajao calvus calvus feeds on catepillars of a noctuid moth that lives on the tree Piranhea trifoliata (Ayres and Johns, 1987). This primarily arboreal species will migrate to the ground in search of food in times of fruit scarcity, mainly during the dry season (Kinzey, 1997). On the ground they forage for newly germinating seeds that largely remain uneaten because of a lack of large terrestrial mammals (Ayres, 1989). The red uakari will obtain water from hollows in trees, streams, and from precipitation licked from leaves (Fontaine, 1981). The food that this species eats also contributes to the water needed (Fontaine, 1981). When foraging this species will suspend itself by one or both hindlimbs, suspend by paired hind and forelimb, suspend by paired hindlimbs and a forelimb, or suspend by one or both arms (Fontaine, 1981). This species will also foraging while standing bipedally (Fontaine, 1981). The primary locomotor pattern used when foraging is pronograde clamber (Walker and Ayres, 1996). Adult females tend not to forage on the ground which differs from males (Fontaine, 1981). When feeding this species primarily sits (Walker and Ayres, 1996). The trees utilized for feeding most often are 20 and 25 meters in height (Walker and Ayres, 1996). This species will forage on the terminal branches of trees then take the food back to more solid supports to feed (Walker and Ayres, 1996). Feeding bouts for the subspecies Cacajao calvus ucayalii last from 3 to 35 minutes, feeding bout described as "time spent feeding from the moment they went into the feeding tree(s) to when they left" (Aquino, 1998).

The group size for this species ranges from 30 to 48 individuals (Kinzey, 1997). The subspecies Cacajao calvus ucayalii was found to have a maximum group size of 120 individuals, with most group sizes ranging from 30 to 50 individuals (Aquino, 1995; Aquino, 1998). Cacajao calvus ucayalii was found to split up into subgroups ranging from 3 to 12 individual in size (Aquino, 1998). Cacajao calvus calvus has group sizes up to 50 individuals, and groups split during the day for foraging (Ayres, 1986; Ayres and Johns, 1987). The subspecies Cacajao calvus novaesi has a mean group size of 21.7 individuals (Peres, 1989). The red uakari migrates to terra firme forest during the dry season (Barnett and Brandon-Jones, 1997), although the subspecies Cacajao calvus calvus is unable to due to that it's range is restricted to a huge fluvial island (Barnett and Brandon-Jones, 1997). This species begins daily activity at around sunrise (Fontaine, 1981). The first two hours of the day are spent foraging (Fontaine, 1981). This species was found to occur at a mean height of 16.2 meters in the forest canopy (Walker and Ayres, 1996). This is a diurnal and an arboreal species.

This species has been found to sleep in the multiple crotches in the crowns of trees (Fontaine, 1981). The red uakari will go to the sleeping site about 30 minutes before sunset (Fontaine, 1981). Cacajao calvus ucayalii was found to use trees as sleeping sites that ranged in height from 17 to 32 meters and were primarily of the species Pouteria sp. and Eschweilera sp. (Aquino, 1998).

Last Updated: October 7, 2003.
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