Grey Crowned Central American Squirrel Monkey
The mono tití, or the grey crowned red-backed squirrel monkey (Saimiri oerstedii citrinellus), is the smallest primate in Costa Rica. This subspecies is only found in and around Quepos/Manuel Antonio National Park on the Central Pacific Coast of Costa Rica. They have been listed as Critically Endangered by IUCN Red List since 1996; and Endangered in 2008.
The Mono Titi as an Indicator of Environmental Degradation of Costa Rica’s Central Pacific Region
According to a study in 2006 by the University of Florida anthropologist Sue Boinski, approximately 1,500 individuals of this subspecies and 4,000 individuals of the species on the whole, remained in the area at that time. That’s down from a population estimated at 200,000 in 1983! Urgent action must be taken to save this beautiful monkey.
The conservation status of the grey-crowned squirrel monkey Saimiri oerstedi citrinellus was last assessed in 2008, at which time the subspecies was listed as Endangered due to its small range (~3,500 km² extent of occurrence), severe fragmentation, and continuing loss of habitat. The national primate experts believe there are 2.000 individuals, all in the Central Pacific area of Costa Rica. The other subspeciesSaimiri oerstedii oerstedii, whose habitat extends to Central America, is currently listed as vulnerable by the IUCN Red List.
The squirrel monkeys’ fall from a status of Critically Endangered to Endangered is a positive sign, displaying the real, tangible results of research and conservation efforts already in place. Now, it is up to us all to continue this work, and ensure the titis’ continued rise out of the danger of extinction.
At the Titi Conservation Alliance, we promise to continue to preserve and protect this peaceful primate. We hope that you will join us in this fight.
Species: S. boliviensis, S. oerstedti, S. sciureus, S. ustus, S. vanzolinii
Subspecies: S. b. boliviensis, S. b. peruviensis, S. o. citrinellus, S. o. oerstedti, S. s. albigena, S. s. cassiquiarensis, S. s. macrodon, S. s. sciureus
The social organization of S. boliviensis at Manu National Park, Peru is markedly different from that seen in S. oerstedti. In Peru, squirrel monkeys live in multi-male/multi-female groups of 45 to 75 individuals in which males emigrate from their natal groups at sexual maturity and females remain in their natal groups throughout their lives (Mitchell 1994). Both sexes have independent dominance hierarchies, but females within this species are behaviorally dominant over all males within the group. Females often spatially segregate males to the periphery of the group through aggressive interactions, and exhibit aggressive behavior to other females except when interacting with their relatives. Males within the group, on the other hand, are not related but are extremely aggressive towards one another, especially during the mating season when they compete for mates (Mitchell 1994). When males disperse from their natal groups they form all-male bands, or coalitions, in order to immigrate into a new group and begin breeding (Mitchell 1994; Boinski 1999; Boinski et al. 2005). Members of these bachelor groups are usually members of the same age class and they work together to take over the highest positions in their new groups’ dominance hierarchy. These alliances remain strong if the males remain in the same group as is evidenced by cooperative aggression toward immigrating males. Males may move in and out of several groups over their lifetimes (Mitchell 1994).
Females prefer the sexually mature males that gain the most weight during the two months prior to the breeding season, which lasts from early August to early October. The first signs of “fatting” among males are seen in June (Boinski 1987a). While the largest males monopolize the majority of copulations, young females in their first or second breeding seasons are not as selective as experienced females and will mate with other sexually mature males who may not be as large (Boinski 1987a). In order to determine sexual receptivity, groups of males, usually related because of dispersal patterns among S. oerstedti, chase and grab a female, holding her down to inspect her genitalia. Presumably the males are using olfactorycues to determine her reproductive state because they remain nearby until the female shows interest in the largest males (Boinski 1987a). Gestation lasts 145 days and the birth season lasts from February to early April. This is the dry season and period of highest arthropod abundance (Boinski 1987c). All squirrel monkeys exhibit birth synchrony to decrease chances of predation, though S. oerstedti and S. sciureus exhibit more intense synchrony than S. boliviensis. All of the pregnant females in S. oerstedti groups give birth within two weeks of each other while pregnant S. sciureus females give birth within less than a week. This concentration is much higher than S. boliviensis, who give birth within the same two months (Boinski 1987c; 1999). Most S. oerstedti females give birth every year while S. boliviensis give birth every other year (Kinzey 1997).