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Field Research
Demography and Group Composition
Tamarins live in social groups of 2-10 individuals. Although, there have been a few cases of reported polygamy, most groups contain only one reproductively active male and female (Neyman 1977). Females, on average, give birth to twins annually. Social groups appear relatively stable, with an average rate of emigration of 0.71 ± 1.18 individuals/group/year. Males and females disperse to neighboring groups equally, however, adults move more frequently than juveniles and infants. Immigrant males are more likely to enter a group following the death of a resident male. Reproductive success of these immigrant males is difficult to quantify without paternity tests, however, an immigrant male may release subordinate females from reproductive suppression. A novel male avoids the constraints of incest avoidance, and may thus stimulate a reproductively inhibited female. If a female immigrates, she does not necessarily assume the breeding position. Emigration increased to 2.8 individuals/group/year during a drought , suggesting movement between groups may be a result of extreme environmental conditions leading to increased competition for limited resources. A proposed model to illustrate the potential reproductive strategies of cotton-top tamarins:
Reproductive Behavior and Hormone Determination
In collaboration with Drs. Bill Lasley and Susan Shideler of the University of California-Davis, we have developed methods for assaying estrone glucuronide (E1C) and progesterone (PdG) in both urine and feces of cotton-top tamarins. We have also successfully developed a technique to collect daily fecal samples from wild tamarins. We are in the process of further examining the factors controlling reproductive events of different populations of wild tamarins. This will allow us to compare the reproductive cycles of both wild and captive tamarins and examine the mechanisms regulating fertility in the wild. Captive female tamarins have a gestational length of 183 days and an ovulatory cycle of 18 days (Ziegler et al. 1987). Females have an 18-day post-partum estrus and 80% of these ovulations result in conception. In the wild, females have an average 144 day post-partum suppression of fertility, which appears to be influenced by environmental conditions. Assays reflect conception with E1C levels ranging >4,000 ng/g and PdG >8ug/g. Hormone levels drop following parturition (E1C to <1000 ng/g and PdG to <3 ug/g).
The cycles of wild daughters were monitored while in their natal group. One female cycled irregularly during her mother's period of postpartum infertility. When her mother conceived again, she was observed to ovulate and conceive herself. Resulting aggression between mother and daughter ended in the eviction of the daughter from the group prior to parturition. The second daughter exhibited normal cycles, however, following the birth of siblings, there was a dramatic decline in hormone levels that remained low through her mother's next conception. While females in captivity are observed to reproduce twice a year, wild females give birth only once a year, prior to the rainy season. The birth period appears to be correlated with the greatest consumption of fruit and insects in the diet. And diet composition may also influence fecundity, whether a female has a single infant or twins. See the list of plants cotton-tops feed from.
Savage A. Snowdon CT, Giraldo LH. 1996b. Parental care patterns and vigilance in wild cotton-top tamarins (Saguinus oedipus). In Adaptive Radiations of Neotropical Primates. Eds. M Norconk, A Rosenberger, P Garber. New York: Plenum Press. Parental care in this species is shared by all group members. Early infant caretaking experience, observed in captivity, has been found to influence future reproductive success in both males and females. If an animal has never carried an infant on its back while it was in its family it will abuse its own offspring. However, if the animal has experience caring for offspring prior to reproduction, it will successfully care for its offspring. Interestingly, non-natal animals are actively involved in infant care and are often observed assuming sentinel positions in their new groups. An animal never carries infants while involved in "sentry" duty. The sentry remains vigilant while the group forages or rests and is responsible for notifying the group of any potential threats to their safety.
Table 1. Infant survival as a function of group size.
Miller, L., Savage, A., Giraldo, H. Quantifying the remaining forested habitat within the historic distribution of the cotton-top tamarin (Saguinus oedipus) in Colombia: Implications for long-term conservation. American Journal of Primatology, 64:451-457, 2004 Landsat Thematic Mapper (TM) data was used to classify forested areas within the historic distribution of cotton-top tamarins (Saguinus oedipus) in Colombia. Cotton-top tamarins are an endangered species endemic to the northwest region of Colombia. This endangered species faces continued deforestation within its historical distribution in Colombia, thus, it is critical to develop strategies to protect tamarins and their habitat. Between 1990-2000, 31% of the forested habitat within the tamarins’ historic distribution has been lost. Agriculture, urban development, and logging have caused a significant decrease in remaining forested habitat on both private lands and in protected parks and reserves. It is estimated that since the inception of the protected lands (Parque Nacional Natural Paramillo, Santuarío de Fauna y Flora Los Colorados, and Reserva Forestal de Montes de Maria) almost 43% of the forested area within the parks boundaries have been lost. With an annual increase in human population in Colombia of 1.6% [Patel, 2002] it is important to target specific areas for protection while creating mitigation strategies to compensate for economic growth. The results of this study provide valuable information to assist in the long-term development of effective conservation strategies for this endangered primate.
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Proyecto Titi has been actively involved in studying wild cotton-top
tamarins for many years at our field sites in Colosó and Santa Catalina. We present a short overview of some of our
publications on the behavior, reproductive patterns, and parental care
strategies of this fascinating primate. As habitat for cotton-tops
continues to be threatened in Colombia, it is essential that we document
how this will effect this highly endangered primate for the future. We
will continue to post information on our publications as they become
available.
Savage A, Giraldo LH, Blumer ES, Soto LH, Snowdon CT. 1996a. Demography,
group composition, and dispersal in wild cotton-top tamarin (Saguinus
oedipus) groups. American Journal of Primatology 37:23-32.
Savage
A, Shideler SE, Soto LH, Causado J, Giraldo LH, Lasley BL, Snowdon CT.
1997. Reproductive events of wild cotton-top tamarins in Colombia.
American Journal of Primatology 43: 329-337.
Reproductively active females are also capable of influencing the
fertility of other females in the group. In both the wild and captivity,
post-pubescent females are reproductively suppressed, appearing acyclic,
while they remain in their family. In order for a female to become
reproductively active, she must be removed from her family and paired with
a novel male. Phermones have been implicated as one of the factors
mediating this suppression. Captive females removed from their family,
paired with a novel male and exposed to scent secretions from their
mother, took longer to ovulate than those females in a contol condition.
Males also influence a female's fertility. Males can accelerate puberty in
prepubescent females. Moreover, pairing a female with a "familiar" male (eg.
brother) will not cause the female to become reproductively active.
Females will ovulate only in the presence of a novel male. 
Observations of 12 births in the wild showed that infants are carried
exclusively during the first four weeks of development, with a gradual
decrease during weeks 5-9, such that by week 10, the infants are solo for
nearly 50% of the observation time. All individuals in the group carry the
infants, though adults were more likely to than juveniles. There was no
significant difference in carrying time between males and females.
Primiparous females, however, carry their infants more during their first
two weeks, than multiparous females. Infant survival to one year of age
increases with group size (see Table 1 below). Contribution of the mother
in infant care remains independent of group size, however, the larger the
group, the less time the
adult males carried infants. The adult male
however, exhibits more vigilant behavior and assumes the sentry position
more often that the adult female during this time. Adult vigilant behavior
also increases as the infant becomes more independent.
