Study objects
Red Uakari
| Scientific name | Cacajao calvus ucayalii |
| Head-body length | 54-57 cm |
| Tail length | 15-16 cm |
| Body mass | 2800-3500 g |
| Distribution | western Amazonia (south of Rio Amazonas between Rio Ucayali and Rio Yavarí) |
| Habitat | tropical rain forest of terra-firme type; seasonally in flooded forest and “aguajales” (swamps dominated by the palm Mauritia flexuosa) |
| Diet | seeds, fruits, flowers, arthropods |
| Social organization | very large groups of up to 150 individuals, probably organized into subgroups of 25-50 individuals consisting of one male-multiple female units |
| Mating system | polygyny? polygynandry? |
| Gestation length and infant care | gestation length not known; infant carried by mother |
| Social behavior | allogrooming probably the most frequent affiliative behavior |
| Communication | mainly through vocalizations and mimics |
| Home-range size | not exactly known; probably >10 km² |
| Interspecific relations | often associated with squirrel monkeys (Saimiri sciureus) |
| Predators | confirmed: harpy eagles |