Wild & Captive Tamarin Studies

Abstract

Cotton-top tamarins are a critically endangered species found only in the country of Colombia. They have been a subject of studies in situ and ex situ and represent one of the best studied callitrichids. This comprehensive species-specific chapter covers all aspects of the cotton-top tamarins biology, including taxonomy, distribution, genetics, morphology, life history, ecology, behavior, parasitology, human threats, and natural impacts on populations. Species conservation management and future research challenges are addressed. The chapter includes a distribution map, photographs of cotton-top tamarins, and a list of key literature.

Keywords: Callitrichidae, Saguinus oedipus, Oedipomidas oedipus

COMMON NAMES: cotton-top tamarin, cotton-headed tamarin (English), mono tití cabeciblano, titi pielroja, tití cabeciblanco, tití de cabeza blanca, bichichi (Spanish), tamarin d’oedipe, tamarin pinché, tamarin á perruque (French), lisztaffe (German), tamarino edipo, (Italian), pinchéaapje (Dutch), paryksilkeabe (Danish), sagui-de-cabeça-branca, sagui-cabeça-de-algodão (Portugese)

1. Taxonomy and Systematics

The genus Saguinus was originally described by Hoffmannsegg in 1807 and later refined by Hershkovitz (1977). More recent molecular studies by Buckner et al. (2015) have provided greater insight into the evolutionary relationships within the genus. These analyses revealed that Saguinus oedipus (cotton-top tamarin) is most closely related to Saguinus geoffroyi (Geoffroy’s tamarin), with Saguinus leucopus (white-footed tamarin) as their next nearest relative. The divergence between S. oedipus and S. geoffroyi is estimated to have occurred approximately 1.2 million years ago, while the split from other tamarin groups likely took place around 4.9 million years ago.

Building on these findings, recent genomic data have led to a proposed reorganization of the genus Saguinus into three distinct genera, as suggested by Brcko et al. (2022). Under this new classification, Saguinus oedipus has been reassigned to a newly designated genus, Oedipomidas, resulting in the updated name Oedipomidas oedipus (Brcko et al. 2022; Lopes et al. 2023) (Fig. 1). This taxonomic revision reflects the species’ unique evolutionary history and supports its recognition at the genus level.

2. Distribution

Cotton-top tamarins have an extremely limited geographic range, confined to the tropical forests of northwestern Colombia. Their distribution lies between the Atrato and Magdalena Rivers, encompassing the departments of Atlántico, Sucre, Córdoba, western Bolívar, northwestern Antioquia, and northeastern Chocó. (Hernandez-Camacho and Cooper 1976; Mast et al. 2018) They are found from sea level up to elevations of approximately 1,500m; however, population censuses conducted by Proyecto Tití have not observed cotton-top tamarins above 900 m (A. Savage, personal communication) (Fig. 2).

These tamarins inhabit both private and public lands and have been recorded in several protected areas and national parks within Colombia. Populations have also been observed outside of the historic distribution in the Islas del Rosario and Parque Nacional Natural Tayrona in the Sierra Nevada de Santa Marta, and privately owned forests in the department of Atlántico where the tamarins were established through the release of formerly captive individuals (Mast et al. 2018; A. Savage, personal observation).

3. Description

3.1 Morphology and Coloration

The cotton-top tamarin is a small-bodied callitrichid primate distinguished by a long, flowing sagittal crest of white hair that extends from the forehead to the nape. This dramatic feature, shared by both sexes, gives the species its common name and contributes to its striking visual appearance (Hershkovitz 1977). The face is black and largely hairless, enhancing the contrast with the white crest. The ears (pinnae) are relatively large and protrude from the white crown, placing this species within Hershkovitz’s “bare-face” tamarin group.

Pelage is distinctly patterned. The crown and crest are pure white, forming a striking mane-like fringe around the neck and shoulders. The dorsum, including the upper back and arms, is cloaked in grizzled gray-brown fur, while the lower back, rump, and thighs display a warm chestnut to reddish-orange coloration. The ventral surface, including the chest, belly, and inner limbs, is white or pale yellowish-white. The limbs are mostly white externally, with darker markings at the shoulders and hips. The non-prehensile tail is covered in fur, transitioning from reddish at the base to brown or blackish at the tip (Hershkovitz 1977).

Like other callitrichids, cotton-top tamarins exhibit claw-like nails (tegulae) on all digits except the big toe, an adaptation for vertical clinging and leaping. The dental formula is 2.1.3.2, with relatively large canines compared to incisors, which may facilitate both frugivory and occasional insectivory (Hershkovitz 1977).

3.2 Morphometric Characteristics

Adult cotton-top tamarins are among the smallest of the primates. Their head-and-body length typically ranges from 20 to 25 cm, with an additional 33 to 41 cm contributed by a long, non-prehensile tail, which is used for balance during arboreal locomotion (Hershkovitz 1977; Savage 1990, 1995). In the wild, adult body weight generally falls between 410 and 500 g (Savage 1995). However, in situ individuals can exceed 600 g, likely due to differences in diet and physical activity (Savage 1995).

At birth, neonates weigh between 39 and 45 g, with twin births being the norm. Although triplets can occur, they are rarely reared successfully (Jaquish et al. 1991, 1996; Savage et al. 2009, 2021). Neonatal body mass accounts for nearly 20% of the mother's weight, reflecting a substantial energetic investment in reproduction.

Cotton-top tamarins exhibit several distinctive anatomical and developmental traits. These include chimerism resulting from placental vascular anastomosis between fetuses, allowing the exchange of cells (Wislocki 1932), and widely spaced axillary nipples that enable simultaneous nursing of twins.

Craniometric analyses reveal a distinct morphotype within the tamarin clade. Cheverud (1996) identified a short, broad neurocranium, prominent zygomatic arches, and a moderately constricted postorbital region. The mandible is robust relative to cranial size, featuring deep corpora and elongated dental rows—traits likely associated with a diet comprising fruits, insects, and plant exudates. These cranial adaptations suggest a strong bite force relative to body size, a common trait among callitrichids. Additionally, Cheverud’s multivariate analysis revealed minimal sexual dimorphism in cranial characteristics, aligning with the species’ cooperative social structure and reduced male-male competition.

Reproductive morphology in males has also been studied in detail. Ginther et al. (2000) measured scrotal and testicular dimensions in unrestrained captive males, finding an average scrotal width of 8.4 mm and an estimated testicular volume of 0.54 cm³. No significant seasonal variation in testis size was observed, and testicular dimensions did not consistently correlate with male dominance or breeding status. In females, the combined surface area of the anogenital and suprapubic scent glands ranges from 7.89 to 8.31 cm² (Savage et al. 1988), underscoring the importance of olfactory communication in social and reproductive contexts.

3.3 Sexual Dimorphism

Sexual dimorphism in cotton-top tamarins is minimal. Males and females are virtually indistinguishable in pelage coloration, crest development, and body size (Hershkovitz 1977; Cheverud 1996). Both sexes average similar body masses in the wild and captivity, and skeletal measurements show little to no sexual differentiation (Cheverud 1996).

However, a notable dimorphism exists in scent-marking anatomy. Females possess larger and more active anogenital and suprapubic scent glands than males. (French and Cleveland 1984; Ziegler et al. 1993). The size of glands and scent marking activity in females are directly correlated with the amount of estrogen activity (Heistermann, et al. 1989; Savage et al. 1988, 1996a). While females are living in their family and are reproductively suppressed, the glands are small and not actively secreting sebum, and there are low levels of scent marking activity. However, these glands are well developed in dominant breeding females and are used extensively in olfactory communication. While males also scent-mark, their glands are less developed, and their contributions to olfactory signaling are typically less than those of females. Poirier et al. (2021) identified 41 compounds of possible semiochemical importance in tamarins.

3.4 Vision

Surridge and Mundy (2002) discovered that cotton-top tamarins exhibit a distinctive form of polymorphic color vision. Because males have only one X chromosome, they express a single opsin allele, making them dichromatic and capable of perceiving only two wavelengths of light. Females, however, possess two X chromosomes and can potentially inherit two different opsin alleles, enabling trichromatic vision. The X-linked opsin gene in this species includes three alleles, each encoding a photopigment sensitive to light at approximately 543 nm, 556 nm, or 563 nm.

Building on this, Jacobs and Deegan (2003) examined the types of cone photopigments in the retinas of cotton-top tamarins and confirmed the presence of short-wavelength-sensitive cones. These cones respond to light in the blue region of the spectrum, enhancing sensitivity to short wavelengths. This finding supports the conclusion that cotton-top tamarins have at least dichromatic color vision, allowing them to easily discriminate colors along the blue-yellow axis.

4. Physiology

4.1 Ovarian Physiology

Typical of most platyrrhines, cotton-top tamarins exhibit circulating ovarian steroids (estrone and progesterone) significantly higher than other catarrhines during the follicular and luteal phases (Coe et al. 1992). They also display the persistent presence of luteinized cells (interstitial glands) in the ovary throughout the ovarian cycle (Tardif 1985). Steroid hormones can be measured in the blood, urine, and feces (Brand 1981; French et al. 1983; Heistermann et al. 1993; Savage, et al. 1997; Ziegler and Wittwer 2005; Ziegler et al.,1987a, 1989, 1993a, 1996a) The urinary and fecal steroid profiles of ovarian cycles do not match the profiles of the corresponding circulating steroid hormones (Ziegler et al. 1987a, 1989a, 1993a). Urinary and fecal estrogen profiles do not exhibit a follicular surge prior to ovulation (Heistermann et al. 1993; Savage et al. 1997; Ziegler et al. 1987a). Instead, cotton-top tamarin estrogen metabolites increase similarly to progesterone metabolites with a sustained elevation throughout the luteal phase of the ovulatory cycle. While this unique pattern makes it more difficult to discern the timing of ovulation from urine or fecal samples, several studies have indicated that the onset of the sustained increase in urinary and fecal progesterone concentration occurs shortly after the serum LH peak, while the delay in the excretion of estrogens is more variable (Ziegler et al. 1993a, 1996a). The ovarian cycle is 15-24 days (French et al. 1983; Ziegler et al. 1993a). Cotton-top tamarins have a delayed implantation relative to humans and other catarrhines (Ziegler et al. 1987a).

4.2 Testosterone

Urinary testosterone concentrations in male cotton-top tamarins reflect gonadal testosterone production, as the hormone is excreted in its unaltered form (Ziegler et al. 2000a). Although urinary testosterone is a reliable indicator of testicular activity, reported concentrations are relatively low, typically expressed in (ng/mg) (Ziegler et al. 2000a), while fecal testosterone levels are reported in (pg/mg) (Fontani et al. 2014). While mature male offspring are in their natal group their hormone levels do not differ significantly from breeding males (Ginther et al. 2001). Male hormonal profiles are influenced by the ovarian cycle of closely associated females. Notably, levels of testosterone and dihydrotestosterone (DHT) begin to rise approximately five days before the female’s ovulatory luteinizing hormone (LH) surge and remain elevated for five days post-ovulation (Ziegler et al. 2004a). In addition to these cyclical patterns, paternal experience influences hormonal responsiveness. Experienced fathers—those who had participated in multiple births—exhibited significant increases in urinary estrogens, androgens, prolactin, and cortisol during the final two months of their mate’s pregnancy, whereas less-experienced males did not demonstrate these prepartum changes (Ziegler et al. 2004b).

4.3 Prolaction

In cotton-top tamarins, prolactin levels in fathers remain elevated throughout the first six weeks following the birth of their infants (Ziegler and Snowdon, 2000; Ziegler et al. 1996b, 2000b). In contrast, maternal prolactin elevation depends on the presence of viable, nursing offspring (Ziegler et al. 1990, 2000b). Among males, prolactin levels are positively correlated with paternal experience—those who have participated in more previous births and currently have offspring in their group, tend to exhibit higher postnatal prolactin concentrations (Almond et al. 2008). Notably, both experienced fathers and their adult sons show significantly elevated prolactin levels after the birth of infants when compared to non-fathers (Ziegler et al. 1996b).

4.4 Cortisol

In female cotton-top tamarins, cortisol levels are significantly higher during the periovulatory phase compared to the non-periovulatory phase; however, the suppression of fertility in postpubescent subordinate females is not associated with elevated cortisol levels (Ziegler et al. 1995). During pregnancy, females exhibit a marked rise in cortisol beginning in mid-gestation, which remains elevated through to parturition. This increase is driven by interactions within the fetal-placental-maternal endocrine axis, resulting in substantial urinary excretion of cortisol (Ziegler et al. 1995). Expectant fathers also show physiological responses to pregnancy: experienced males display elevated glucocorticoid levels that typically peak about one week after their mate’s mid-gestational cortisol rise (Ziegler et al. 2004b), suggesting coordinated hormonal changes between breeding partners during the prenatal period.

4.5 Oxytocin

In cotton-top tamarins, peripheral oxytocin levels vary in both males and females and are closely associated with sociosexual behaviors such as copulation, huddling, and grooming (Snowdon et al. 2010). Among mated pairs, oxytocin concentrations are highly correlated between partners, suggesting a strong hormonal synchrony within bonded relationships. In males, variations in oxytocin levels are most strongly predicted by the frequency of sexual behavior, whereas in females, oxytocin levels are more closely linked to affiliative behaviors such as huddling and grooming. These findings highlight sex-specific patterns in the behavioral regulation of oxytocin and underscore its role in maintaining pair bonds and social cohesion in this cooperatively breeding species (Snowdon et al. 2010).

5. Genetics

5.1 Disease/Health

In the early years of genetics, the cotton-top tamarins were used as a genetic model for several diseases, such as colon cancer and colitis (Cheverud et al. 1993), or to study the function of specific genes (Cheverud 1996; Cheverud et al. 1994). In comparative genetics studies, cotton-top tamarins were found to have low levels of polymorphisms within the major histocompatibility complex (MHC) class I (Gyllensten et al. 1994). High levels of MHC polymorphisms allow species to recognize a wide range of pathogens; thus, a limited number of polymorphisms would suggest that cotton-top tamarins are more susceptible to pathogenic infections. This may explain why cotton-top tamarins are susceptible to viral infections and express spontaneous colitis and colon cancer. A high rate of loci turnover is likely to have caused the limited diversity of the MHC class I genes (Cadavid et al. 1999). Moreover, Gyllensten (1994) found no support for low levels of polymorphisms in MHC class II; some restriction was discovered in the DRB loci, which is believed to be caused by bone marrow-chimeras, a result of twins sharing bone marrow during gestation.

5.2 Phylogeny

In more recent times, much of the genetic work on this species has focused on resolving the complex phylogeny of tamarins (Brcko et al. 2022; Lopes et al. 2023) (see discussion in the Taxonomy and Systematics section).

5.3 Population Genetics

Additionally, the sequencing of whole genomes from present-day and historical samples was used to describe the historical population structure and genetic diversity of the wild cotton-top population (Rasmussen et al. 2023). The findings of the study had implications for the conservation of this species. It revealed that the historical population was divided into two clusters. These two clusters are separated by a physical barrier – the Paramillo Massif mountains. This mountain range is located at the northern end of the Cordillera Occidental in the provinces of Antioquia and Córdoba. The Paramillo Massif mountains were not previously considered a physical barrier, due to the majority of the peaks in the area being below 1000m, and therefore within the elevation range of the cotton-top tamarins.

Genetic diversity analyses indicated that modern wild populations have not suffered extreme levels of inbreeding when compared to the historical population (pre-1960s); however, they indicated a loss of diversity and slight accumulation of inbreeding through time. The modern wild population has a significant 52% 1.68x loss of heterozygosity (average heterozygosity: historical – 0.000581 bp⁻¹; modern- 0.000276bp⁻¹), suggesting a loss of diversity in comparison to historical populations. Furthermore, runs of homozygosity reveal recent inbreeding stemming from approximately 12 generations ago (~73 years), which coincides with the mass exportation of cotton-top tamarins to biomedical facilities. However, in some individuals, the inbreeding events are as recent as 2-3 generations ago (~15 years), which could be the result of modern threats such as lack of habitat and illegal trade.

6. Life History

There is a wealth of information on cotton-top tamarins that stems from decades of study in situ and ex situ that allow us to examine the similarities and differences depending upon their environment. Wild cotton-top tamarins exhibit many similarities in reproductive profiles and behavior to those in situ.

6.1 Infant Development

Cotton-top tamarins are cooperative breeders whose infants rely heavily on social structures for survival and development. From the moment of birth, whether in situ or ex situ, a cotton-top tamarin’s life unfolds in a socially rich environment where physical and behavioral milestones emerge in a coordinated progression (Table 1).

Table 1. Developmental milestones in cotton-top tamarins

Age (Weeks)	Developmental Phase	Key Behaviors and Milestones	Relevant Studies
1-2	Neonatal Period	Infants are carried almost continuously. Cooperative care by father, siblings, and sometimes unrelated helpers. Initiation of contact calls within first few days. Frequent nursing initiated by infant. Emergence of head-lifting and basic postural control by week 2.	Cleveland and Snowdon 1984 Savage et al. 1996b
3-5	Early Motor Development and Sensory Engagement	Infants begin brief exploratory dismounts from caregivers. Visual and oral exploration (sniffing, mouthing food). Continued and increasingly deliberate grooming by adults.	Cleveland and Snowdon 1984
6-8	Locomotor Exploration and Weaning Onset	Emergence of independent locomotion. Movement between group members and into surrounding environment. Increased interest and consumption of solid food (fruits, insects). Onset of social play (e.g., chasing, vocalizations). Risks of injury, hypothermia, and predation increase.	Cleveland and Snowdon 1984 Price 1990 Savage et al. 1996b, 2009
9-14	Social Integration and Weaning Completion	Increased grooming (given and received). Play initiated with juveniles and adults. Weaning largely completed by week 10. Solid food is main dietary component. Development of adult-like behaviors: food begging, alarm call response, scent-marking interest.	Cleveland and Snowdon 1984 Savage et al. 2009
15-20	Maturation and Role Shifting	Functional independence in foraging and navigation. Maintenance of social bonds via grooming and vocal interactions. Early “helper-in-training” behaviors emerge (e.g., observing or aiding infant care).	Cleveland and Snowdon 1984 Savage et al. 2009

Cotton-top tamarin infants follow a structured developmental pathway, progressing from complete dependency to increasing independence and social competence over the first five months of life. This development is deeply embedded in a cooperative social framework. The role of caregivers, especially during the perinatal and early postnatal periods, is critical to survival and behavioral success.

6.2 Puberty and Reproductive Suppression

Female cotton-top tamarins in situ typically reach puberty between 15 and 17 months of age when living with their families, as indicated by rising levels of luteinizing hormone (LH) and estrone conjugates (E1C) (Ziegler et al. 1987b). However, puberty can be accelerated when a young female is removed from her family group at 9 months and paired with an unrelated male, signs of puberty—including elevated LH and E1C—can appear as early as 10 to 11 months (Savage et al. 1988; Tardif 1984; Ziegler et al. 1987b). These findings suggest that while females continue to mature sexually within their family group, fertility is behaviorally suppressed. Heistermann et al. (1989) found that females living in stable social groups where the mother had died showed the onset of ovarian cyclicity. However, only the eldest daughter, who was the highest-ranking female in the group, displayed ovarian cyclicity, and subordinate females exhibited acyclic hormonal patterns. No evidence of reproduction occurred in these groups probably as a result of incest avoidance. This indicates that social context plays a key role in regulating when females become reproductively active (French et al. 1984; Heistermann et al. 1989; Savage et al. 1988; Ziegler et al. 1987b).

In the wild, young females living in their natal group do not exhibit organized ovarian cycles until they emigrate or there is a disruption in the family group. Females reach puberty between 10–12 months of age while living in their natal group and appear to be reproductively suppressed while living in their family group (Savage et al. 1997). However, group disruptions can incite a female to begin cycling in her natal group. If a novel male immigrates into the family group, the onset of ovarian cycles will begin in females that are reproductively suppressed. The introduction of a novel male usually leads to considerable fighting between the reproductively active female and the younger post-pubescent females. Only one of the females will remain in the group and assume the role of reproductively active female (Savage et al. 1997). If the reproductively active female dies/emigrates and an unrelated male is present, then competition between the females in the group, as well as any potentially new females immigrating into the group will occur until there is only one reproductively active female in the group.

Pubertal hormone activity in in situ males begins with a rise in luteinizing hormone (LH) around week 37. This is followed by a testosterone surge between weeks 41 and 44. Around 48.6 weeks, testosterone appears to be increasingly converted into dihydrotestosterone (DHT), a potent form of the hormone linked to male development. Most body weight gain occurs by week 24, well before major hormonal changes or rapid testicular growth begin. The full growth of the testes typically concludes by 76 weeks, but the timing can vary widely (between 56 and 122 weeks), depending on the individual (Ginther et al. 2000, 2002).

6.3 Gestation

The gestation period in cotton-top tamarins lasts approximately 183 days (Wheaton et al. 2022; Ziegler et al. 1987a). Females typically give birth to twins, although singletons and triplets have been observed in situ and ex situ (Kirkwood et al. 1983; Price and McGrew 1990; Savage et al. 1997, 2009, 2021, Snowdon et al. 1985; Wheaton et al. 2022). Quadruplet births have only been recorded in situ (Boulton and Fletcher 2015).

Infant survival rates are lower for primiparous females than for multiparous females, both in situ and ex situ (Savage et al. 1996b, 1997, 2021, Snowdon et al. 1985). Boulton and Fletcher (2015) reported a male-biased sex ratio in singleton litters in situ, and Savage et al. (2021) observed a slight overall male bias in birth sex ratios ex situ. However, such findings should be interpreted with caution, as sex could not be determined for many wild-born infants who died shortly after birth.

6.4 Seasonal Breeding

Cotton-top tamarins engage in sexual behavior throughout their entire estrus cycle in situ and ex situ and do not typically experience seasonal breeding in situ (Evans 1983; Snowdon et al. 1985) unless they are exposed to natural light and given a similar diet year round (McGrew and Webster, 1995). Cotton-top tamarin females typically give birth every 28 weeks (Ziegler et al. 1987a). It is common for females to ovulate within 18 days postpartum, with no consistent suppression of fertility due to lactation (Ziegler et al. 1987a, 1990). However, nursing two infants is associated with significantly longer delays before the next ovulation, approximately twice as long as for females nursing a single infant or not nursing. While total nursing duration or time spent in physical contact with infants was not predictive of ovulation timing, the pattern of nursing played a critical role. Specifically, females who nursed one infant at a time more frequently experienced longer delays in ovulation. These findings suggest that although lactational suppression of ovulation exists, it is less pronounced in cotton-top tamarins than in many other primates, allowing for relatively onset of ovarian cycling (Ziegler et al. 1990).

In wild populations, adult breeding females usually give birth once per year, with a seasonal birth peak from April through August (Savage et al. 1997; Wheaton et al. 2022). Although births can occur year-round, off-peak births are often associated with social group changes, such as the introduction of a new breeding female or male. Disruptions to group stability increase the probability of both out-of-season births and multiple births within a single year (Savage et al. 1996a, 1997, 2021).

Conceptions most commonly occur during peak rainfall months (October–November), when fruit availability is declining, but nectar consumption is highest (Savage et al. 1997; Wheaton et al. 2022). Birth peaks during the fruit-abundant months, which aligns with lactation and weaning periods when nutritional demands are highest. Pregnancy losses are more frequent following off-peak conceptions, particularly during droughts or periods when nectar consumption increases due to scarcity of preferred foods (Savage et al. 1997, 2022; Wheaton et al. 2022).

6.5 Reproductive Senescence

Cotton-top tamarins show patterns of reproductive aging similar to other callitrichid primates, though the timing and progression of this decline can vary depending on each female’s reproductive history and social environment. Females in situ have been observed to ovulate up to at least 17 years of age, which approaches the species' known maximum lifespan in such conditions. Beyond 17 years, females typically become anovulatory or exhibit irregular ovarian cycles (Tardif and Ziegler 1992).

Signs of reproductive senescence include longer intervals between births, smaller litter sizes, reduced fertility, and a greater risk of reproductive failure or fetal loss. Consecutive pregnancies in females tend to result in an earlier or more pronounced fertility decline, likely due to the cumulative physical demands of reproduction (Tardif and Ziegler 1992; Tardif et al. 2008).

Histological studies comparing the ovaries of young (2–5.4 years), middle-aged (6.9–10.2 years), and older (12.9–15.9 years) tamarins confirm a typical age-related decrease in the total follicular pool (Tardif 1985). The number of large preantral follicles declines with age, and in the oldest group, these follicles are much less likely to develop into antral follicles. Only 58% of ovaries from the oldest tamarins had at least one normal antral follicle, compared to 100% in the younger groups (Tardif 1985).

Tardif et al. (2008) highlighted that while age-related reproductive decline occurs, its severity is influenced by reproductive history and workload. In this cooperatively breeding species, where reproduction is usually limited to a dominant female, some females only begin reproducing later in life after gaining social dominance. These late-breeding females may exhibit a shorter but more efficient reproductive period. In contrast, females who have reproduced over many years often experience an earlier decline in reproductive function.

Field observations align with findings in situ. One known-age female gave birth to her final litter at 15 years. Another female, of unknown age, but present in her social group for at least 14 years, was still reproducing and produced three litters of triplets. Her last triplet birth occurred during her 14th year in the group, indicating she was likely 15 or older (A. Savage, personal observation). These observations suggest that reproductive patterns in the wild closely mirror those documented in captivity.

Although no formal data exist on male reproductive senescence in this species, evidence from other callitrichids suggests that males experience age-related changes in androgen levels, though these changes tend to be modest (Tardif et al. 2008). Observations in the wild confirm that older males—over 12 years of age—remain capable of fathering offspring without any obvious decline in fertility (A. Savage, personal observation).

6.6 Lifespan

Cotton-top tamarins typically live between 13 and 17 years in situ, though some individuals have been documented living up to 26.2 years under optimal veterinary and husbandry conditions (Dyke et al. 1993; Huber et al. 2025; Tardif et al. 2008; Weigl 2005). Studies indicate no significant difference in lifespan between males and females, suggesting there is no sex-biased survival in this species (Huber et al. 2025).

In the wild, field-based studies estimate that adult cotton-top tamarins who reach maturity live an average of 9 to 12 years(Savage et al. 1997). The oldest individuals recorded in the wild include a female who lived to 16.8 years and a male who reached 17 years of age (A. Savage, personal observation).

6.6.1 Infant Survival

Infant survival in cotton-top tamarins is influenced by a range of social, experiential, and biological factors. Females cannot successfully rear offspring alone; they depend on help from other group members (Tardif et al. 1990). Caring for twins—the most common litter size—is especially demanding. Male caregivers in situ may lose up to 10% of their body weight during the infant dependency period (Achenbach and Snowdon 2002; Sánchez et al. 1999).

6.6.2 The Role of Experience in Infant Care

Research in situ has shown that both male and female tamarins without prior experience carrying infants are more likely to reject or mishandle their offspring (Snowdon 1996). Cotton-top tamarins typically gain this experience in their natal groups by helping care for younger siblings (Tardif et al. 1992). Individuals who are denied these early caregiving opportunities show significantly lower success in raising their own infants (Johnson et al. 1991; Snowdon et al. 1985; Tardif et al. 1986).

6.6.3 Maternal Experience and Infant Survival

Maternal experience is a critical determinant of infant survival. Across both in situ and ex situ populations, primiparous females experience lower infant survival rates than multiparous females. First litters are often rejected, regardless of whether the parents had prior infant care experience (Bardi et al. 2001; Johnson et al. 1991; Snowdon et al. 1985; Tardif et al. 1986). This is likely due to a combination of inexperience and the lack of support, as many first-time breeders in situ are newly formed pairs without established helpers.

Inexperienced females may struggle with infant handling and nursing due to physiological immaturity (Savage et al. 2021; Tardif and Ziegler 1992). The highest infant mortality rates occur during the first week of life, particularly among first-time breeders both in situ and ex situ (Kirkwood et al.,1983; Savage et al. 2021; Snowdon et al. 1985).

6.6.4 Infant Survival In Situ vs. Ex Situ

Infancy is also the most vulnerable period for wild cotton-top tamarins, with mortality peaking in the first week postpartum—a pattern that mirrors what is seen in situ (Bardi et al. 2001; Kirkwood et al. 1983; Leong, et al. 2004). However, overall survival rates are significantly higher in the wild. Studies report that about 85–86% of wild infants survive to six months of age, compared to much lower rates in situ (Savage et al. 1996, 2009, 2021). This improved survival is attributed to the well-developed cooperative parenting in wild groups—a behavior learned and refined through years of shared caregiving responsibilities.

6.6.5 Impact of Litter Size

Litter size also plays a critical role. Cotton-top tamarins usually give birth to twins, with singletons occurring occasionally and triplets being extremely rare in situ and ex situ. Triplet litters, when they do occur, have significantly lower survival rates, likely due to the increased burden on caregivers (Jaquish et al. 1991; Johnson et al. 1991; Savage et al. 2009, 2021).

6.6.6 Group Composition and Helpers

Group size and the number of helpers are positively correlated with infant survival in situ (Price 1990; Snowdon 1996). Early field studies also found a similar trend in wild populations (Savage et al. 1996, 2009). However, in a comprehensive 20-year study involving more than 235 infants from 126 litters, Savage et al. (2021) found no direct correlation between group size and infant survival. Instead, the presence of at least two adult males in the group was the key threshold for improved survival outcomes. When this condition was met, infant survival remained consistently high regardless of overall group size.

6.6.7 Effects of Social Disruption

In wild populations, social instability—such as the eviction or disappearance of a breeding adult—can severely affect infant survival. More than 26% of missing infants in studied groups were linked to the eviction or death of a breeding male or female, or the subsequent disintegration of the group (Savage et al. 2021). These events often resulted in injury, abandonment or possible infanticide.

Pregnant females immigrating into a group had a significantly lower probability of their infants surviving than those females who immigrated into a new group and conceived for the first time within a new social group (Savage et al. 2021). More than half of the females who immigrated into a new group pregnant, delivered a live litter, however offspring were rarely observed in the group after 24 hours.

7. Social System

7.1 Social Organization

Cotton-top tamarins typically live in family groups consisting of a monogamous breeding pair and their offspring. However, in both in situ and ex situ, the introduction of step-parents or unrelated individuals often results in group instability. When novel males are introduced into groups with multiple potential breeding females—such as mothers and daughters—competition can arise. In some cases, both females become pregnant, but the group rarely remains stable. These situations often lead to only one set of twins surviving, or to group dispersal due to aggression between females (Price and McGrew 1991; Savage et al. 2009, 2021).

Introducing unrelated infants into established groups has been successful in situ (Dronzek et al. 1986). However, attempts to introduce juvenile or adult individuals typically result in severe aggression, necessitating the removal of the new animals (de la Ossa et al. 1988; Snowdon and Pickhard 1999).

In the wild, new groups commonly form from two related males—usually brothers—and one reproductively active female, sometimes accompanied by a younger female (sisters or mother and daughter). Typically, potential female competitors are evicted, leaving only one breeding female (Savage et al. 1996a). Despite these dynamics, wild cotton-top tamarin groups show no sex bias in group composition (Savage et al. 1996a).

Temporary associations between solitary individuals and established groups have also been observed in the wild (Neyman 1977; Savage et al. 1996a). While some individuals are actively repelled, others are tolerated. Unlike findings from captive intruder studies (French et al. 1981), not all same-sex conspecifics are rejected. In fact, some temporary associations occur without any apparent aggression (Savage et al. 1996a). Additionally, individuals who emigrated from their natal groups have occasionally been seen returning years later. These returnees may be tolerated on the periphery before eventually joining a new social group (A. Savage, personal observation).

7.2 Group Size

Group size in cotton-top tamarins typically ranges from 2 to 10 individuals, with an average of 5.8 ± 2.6 individuals (Savage et al. 1996a). Several factors influence group size, particularly the size of the home range in the wild and the size of the enclosure in situ. In the wild, group size is also shaped by the density of food resources and competition with other tamarin groups.

Group size has been linked to increased aggression in situ. Caperos et al. (2011) found that when large groups of cotton-top tamarins were temporarily put in smaller enclosures, breeding pairs showed increase rates of severe aggression toward their offspring. Snowdon and Pickhard (1999) found that fighting among males occurred in groups with an average size of 6.3 individuals, while fights among females were observed in groups averaging 7.8 individuals. Similarly, McGrew and McLuckie (1986) reported more frequent aggression in groups with a mean size of 9.3 tamarins. These findings suggest that as group sizes in situ approach the upper limits seen in the wild, social tension may increase, potentially reflecting natural processes such as expulsion or dispersal that would occur in wild populations (Snowdon and Pickhard 1999).

7.3 Patterns of Immigration and Emigration

McGrew and McLuckie (1986) explored choices of philopatry versus dispersion in cotton-top tamarins in situ. When given the opportunity to leave their family group, breeding adults tended to stay home, as did eldest sons and still-dependent young offspring, but eldest daughters tended to go exploring to an empty cage. Males and females disperse equally in the wild (Savage et al. 1996a), and typically, single animals are less successful in displacing the breeding individuals in established groups than if 2-3 individuals attempt to enter a group and displace the breeding male/female or pair (A. Savage, personal observation). Same sex single animals are successfully integrated into established groups when one of the breeding pair dies or leaves the group. Daughters can assume the position of the breeding female in her natal group if her mother dies or is evicted and an unrelated male is in the group (Savage et al. 1997).

8. Habitat

Cotton-top tamarins inhabit a range of forest types, including humid tropical forests, tropical dry forests, and areas of secondary growth (Hernández-Camacho and Cooper 1976; Mast et al. 2018). These tropical forests are structurally complex, characterized by distinct vertical strata, from the understory (typically <5 meters in height) to the emergent canopy layer, where trees can exceed 20 meters. Cotton-top tamarins make use of this vertical stratification, moving between the forest layers but showing a preference for the midstory.

The species demonstrates considerable ecological flexibility and is often observed in secondary forests, remnant forest patches, and forest edges. Cotton-top tamarins have also been documented persisting in human-altered environments, including mosaic landscapes composed of agricultural plots, pasturelands, and regenerating vegetation. Their ability to survive in such modified habitats reflects their ecological and dietary adaptability. However, long-term persistence in these fragmented environments depends on the availability of essential resources, such as fruits, exudates, and arthropods, as well as sufficient habitat connectivity through biological corridors. These conditions underscore the importance of maintaining a heterogeneous and functionally connected landscape to support viable populations.

A national survey conducted by INDERENA (1988) confirmed the species’ presence across regions with diverse rainfall regimes. In humid tropical forests, where annual precipitation can reach up to 13,000 mm and elevations range between 900–1,000 meters above sea level, cotton-top tamarins are found primarily in the departments of Córdoba and along the Gulf of Urabá (Mast et al. 2018). Conversely, they are also well-adapted to tropical dry forests characterized by pronounced seasonal variation in rainfall. In these deciduous forest regions, the dry season typically spans from December to April, followed by a wet season with peak rainfall between August and November. Annual precipitation in these habitats ranges from 500 to 2,680 mm, and periodic flooding of the forest floor may occur (Neyman 1977; Savage et al. 2022).

9. Diet

Field-based observational studies of wild populations of cotton-top tamarins inhabiting dry tropical forest habitat with a pronounced seasonal rainfall have revealed an omnivorous feeding strategy. Their diet consists primarily of fruits and invertebrates, supplemented by plant exudates, nectar, flowers, meristems, fungi, cactus tissues, and occasionally small vertebrates (García-Castillo and Defler 2018; Neyman 1977; Savage et al. 2022). This broad dietary repertoire underscores the importance of high-energy, nutritionally dense resources for maintaining physiological and ecological functions.

Cotton-top tamarins show a marked preference for consuming ripe fruits when available, as these typically offer greater nutritional value, including essential sugars and fiber. However, during periods of food scarcity, such as the dry season or in degraded habitats, they will also consume unripe fruits as a fallback resource.

Field studies have documented the consumption of food items from more than 80 plant species, including trees, shrubs, and lianas (García-Castillo and Defler 2018; Neyman 1977; Rodríguez 2001; Savage et al. 2022). While fruit remains the predominant food source, interannual variation in plant species selection reflects a highly adaptable foraging strategy. Fruit that provides essential sugars and fibers forms the dominant component of the diet in the wet season. In the dry season, exudates were more commonly consumed. Exudates are rich in minerals such as calcium, potassium, and magnesium and contain complex sugars, which may aid in providing additional nutrition in times of fruit scarcity. Nectar from Combretum fruticosum is also consumed, with peak feeding occurring in November, providing an important source of hydration during dry periods. Invertebrate consumption remains consistent year-round, offering a reliable source of protein and lipids.

Cotton-top tamarins have not been observed drinking from standing water sources, such as streams or ponds, however, they are able to obtain moisture from fruit, nectar, dew collected on leaves, and rainwater trapped in tree branches (Savage et al 2022).

9.1 Foraging Behavior and Manipulation Strategies

Cotton-top tamarins employ a variety of manipulative behaviors to access and process food items. Fruits are typically harvested directly using the hands; smaller fruits are often taken with the mouth while the animal maintains stability on the branches. In some cases, individuals suspend themselves by their hind limbs to reach distal fruit-bearing branches. Once acquired, fruits are brought to the mouth using their hands.

Smaller fruits (e.g., Stylogyne turbacensis, Allophylus racemosus) are swallowed whole. In contrast, larger fruits (e.g., Maclura tinctoria, Trichilia acuminata, Spondias mombin) are consumed incrementally, with individuals taking repeated bites to ingest manageable portions until the fruit is fully processed.

During feeding, individuals selectively consume pulp or aril while avoiding tougher outer pericarps. Seeds of small to intermediate size are frequently ingested. Passage through the gastrointestinal tract results in both mechanical and chemical scarification, enhancing germination potential without compromising seed viability (García-Castillo and Defler 2018; Rodríguez 2001; Savage et al. 2022). This behavior establishes cotton-top tamarins as an effective agent of seed dispersal, with functional implications for forest regeneration.

During mass flowering events of species such as Clusia fruticosa, nectar consumption increases and may temporarily displace fruit or invertebrate intake (Savage et al. 2022). While feeding, tamarins insert their faces into floral structures and extend the tongue to extract nectar, inadvertently facilitating pollen transfer, thus acting as incidental pollinators.

Plant exudates become particularly important during the dry season when fruit availability declines (García-Castillo & Defler 2018; Savage et al. 2022). Although cotton-top tamarins are not specialized gumnivores and lack the dentition required for gouging bark, they readily consume exudates from natural wounds or those produced by other animals. These are accessed by licking directly from tree surfaces or by removing fragments using their hands. The sticky nature of dried exudates often results in the tamarins licking their hands after feeding, maximizing resource acquisition and minimizing waste.

Animal prey, primarily invertebrates, are an essential dietary component (Savage et al. 2022). Individuals spend a considerable portion of their daily activity budget foraging for insects. This includes probing under leaves, within bark crevices, and among folded foliage. The species’ elongated fingers and claw-like nails aid in extracting prey such as caterpillars, orthopterans, phasmids, lepidopterans, and arachnids. Once captured, prey are restrained with both hands and consumed orally. Remnants such as wings or legs are often discarded and fall to the forest floor.

Other dietary items, including flowers, meristems, fungi, cactus tissues, and small vertebrates, are consumed less frequently but may hold seasonal importance. For example, meristems are more commonly ingested during dry periods when other food resources are limited.

10. Behavior

10.1 Social Behavior

Cotton-top tamarins are a highly social species that exhibit high levels of social interactions. Mates are highly bonded and high levels of grooming are noted between mated pairs (Price 1992). Olfactory investigations are also common between mated pairs, as females do not exhibit any obvious physical signs of ovulation. Copulations are not restricted to the time of ovulation but occur throughout the female’s cycle. Cotton-top tamarins are observed to huddle where individuals maintain close, stationary, side-by-side contact with their tails curled to their abdomen. Huddling occurs when animals are resting/sleeping and it helps to strengthen the social bonds within the family group (Savage et al 1988; Snowdon and Ziegler 2007).

Newly established pairs are more likely to spend time in contact, grooming, huddling, and copulating with their mates than did established breeding females in situ (Savage et al. 1988). However, as the duration of the pair bond lengthens, compounded by the addition of offspring, established pairs will spend less time in affiliative behavior with one another and direct more of their attention toward their offspring.

10.2 Parental Care

In both in situ and ex situ settings, the sire, along with non-reproductive helpers, begin assisting mothers in carrying infants within the first few days after birth (Ziegler et al. 2022). As infants grow older, males and helpers gradually increase the amount of time they spend carrying them (Cleveland and Snowdon 1984; Savage et al. 1996b; Washabaugh et al. 2002; Zahed et al. 2008; Ziegler et al. 2000). Interestingly, males and helpers have been observed to increase their weight starting at mid-pregnancy as a presumed means of preparing themselves for the increased energetic costs of caring for infants (Rodriguéz et al. 2008), Ziegler et al. 2006). Studies have demonstrated an energetic cost for the caregivers. Male cotton-top tamarins in situ may lose up to 10% of their body weight during the most intensive period of infant care (Achenbach and Snowdon, 2002; Sanchez et al. 1999), suggesting that having additional helpers reduces the energetic demands on the adult pair. Tamarins also move slower as infant mass increases (Caperos et al 2012). As infants grow, caregivers reject and transfer twin infants more frequently than singletons, possibley due to the greater effort required to care for twins (Price 1991; Snowdon 1996). Males also retrieve infants more frequently (Joyce and Snowdon 2007; Roush and Snowdon 2001). Kostan and Snowdon (2002) found that in fearful situations, infants sought comfort from individuals who had carried them most often and frequently shared food—typically their father or oldest brothers.

In the wild, adult males play a prominent role in group vigilance during periods when infants are most vulnerable. Male vigilance is highest during the first nine weeks of an infant’s life. This vigilance further increases between Weeks 10 and 15, as infants begin to spend the majority of their time moving independently. Given that infant mortality peaks during this developmental window, the heightened vigilance displayed by males may reflect a protective strategy aimed at safeguarding the young during this critical stage (Savage et al. 1996b).

Providing animals with early infant caretaking experience is critical for the future ability to rear their own offspring. In situ studies have found that both males and females denied infant caretaking experience in their natal group are less successful and often abuse or kill their own offspring when they are given the opportunity to breed (Ginther et al. 2001; Snowdon 1996; Snowdon et al. 1985; Tardif 1986, 1992). Experience carrying at least one, but ideally two sets of litters, results in animals that can successfully rear their own offspring (Cleveland and Snowdon 1984; Snowdon et al. 1985).

Food sharing is common in situ and ex situ, with adults giving up highly desired food sources with the youngest individuals in the group (Feistner and Price 1990; Joyce and Snowdon, 2007; Rousch and Snowdon, 2001; A. Savage, personal communication). Food sharing begins when infants are approximately 5 weeks old. Interestingly, a study found that when adults vocalized while having food in their hand or consuming food, then they were more likely to share food with infants than if no vocalizations were observed (Roush and Snowdon 2001). Males are more likely to share food with infants and commonly vocalize (C and D chirps) to which infants respond by approaching and taking food out of the adult’s hands Cleveland and Snowdon 1982; Joyce and Snowdon 2007). Twins begin to beg and to receive food through food sharing earlier than singletons. Twins also begin to feed independently sooner and at a higher rate than singletons. Twins obtained almost twice as much of their food through independent feeding than singletons (Joyce and Snowdon 2007).

10.3 Play Behavior

Infants play primarily with their twin or youngest sibling and have affiliative interactions with all family members both in situ and ex situ (Cleveland and Snowdon 1984; A. Savage personal observation). By week 14, infants are frequently observed in solitary play (chasing tail, swinging on rope/vines, investigating/chewing novel objects) and social play (wrestling, chasing, batting, vocal play). Twins have been observed to exhibit more social play than singletons. Adults rarely engage in play with the youngest infants and are often observed to behave aggressively toward the instigator.

10.4 Scent Marking

Scent marking is an important method for communication in cotton-top tamarins. Females possess much larger scent glands than males and scent mark more frequently than males (French and Snowdon 1981). Anogential marking is performed in a sitting position and results in the application of glandular secretion, urine, and perhaps genital discharge and fecal residues. Suprapubic marking results in the application of skin secretions and other material adhering to the suprapubic part of the glands as the animals, assuming a sprawling position, rub this portion of the gland across the substrate (French and Snowdon 1981). French and Snowdon (1981) have suggested that anogenital marking may be involved in sexual communication, and suprapubic marking is used primarily in situations of aggressive arousal. Reproductively active females show more scent marking activity than subadult females (French and Cleveland 1984; French and Snowdon 1981; French et al. 1984; Savage et al. 1988). It has been suggested that scent marking is important in delineating territorial boundaries between groups. While scent marking is more difficult to observe in the wild due to the dense vegetation, females are commonly observed scent marking during territorial encounters (A. Savage, personal observation).

In the cotton-top tamarin scent secretions carry information regarding species (Belcher et al. 1988), individual identity (Epple et al. 1988), own vs. novel scent mark (Washabaugh et al. 1998), cycling vs. non-cycling female (Washabaugh et al. 1998) and timing of ovulation (Ziegler et al. 1993b).

10.5 Aggression

Despite their reputation as cooperative breeders, with high levels of social cohesion and relatively low levels of aggression, cotton-top tamarins can display severe and injurious aggression under certain conditions, particularly in situ.

Cotton-top tamarins in situ must be visually isolated from neighboring groups. In colonies where there are multiple pairs/families within one large area, each pair/family must be in an enclosure that is visually isolated from their neighbors. If not, opportunities to see a neighboring group will result in displaced aggression within groups and groups displaying more territorial and mate guarding behavior (Snowdon et al. 1985).

Patterns of aggression in cotton-top tamarins follow predictable trends and manifest along a spectrum from ritualized dominance displays to overt conflict. Aggressive encounters can include direct fighting or more subtle dominance behaviors such as “face-offs,” in which two individuals separate from the group, display piloerection, engage in tongue-flicking, and vocalize while staring at each other. Another common behavior, “face-pressing,” involves one tamarin grasping another’s head and pressing its open mouth against the opponent’s open mouth. (Savage et al. 1988). These interactions are often accompanied by specific vocalizations, including squeals, squawks, Type A trills, and rapid whistles (Cleveland and Snowdon 1982).

When confronted with aggression, cotton-top tamarins exhibit a range of submissive and defensive behaviors. A common response is a facial grimace, characterized by a partially open mouth with the corners pulled back, exposing the teeth. This is often accompanied by submissive vocalizations—specifically, high-pitched squeals and squawks (Cleveland and Snowdon 1982).

Defensively, the tamarin may assume a posture that involves standing upright on the hindlimbs, pulling the body away from the aggressor, raising the arms in front of the face for protection, and making efforts to avoid physical contact. These defensive movements are typically paired with facial grimacing and submissive vocalizations. Another observed behavior is crouching: the subordinate tamarin sits in a low, hunched position with flattened fur and avoids direct eye contact by turning away from the aggressor.

Aggression is most frequently observed between individuals of the same sex, with male–male aggression occurring significantly more often than female–female aggression. Interestingly, female–female aggression typically emerges only in larger social groups, suggesting that females may have a higher tolerance for social density or require greater provocation to initiate aggressive behavior (Snowdon and Pickhard 1999).

Aggression between males and females is rare, and when it does occur, it typically involves specific individuals who exhibit repeated incompatibility with a succession of mates (McGrew and McLuckie 1986; Snowdon and Pickhard 1999). Mild aggression has been observed during the birth of new infants, primarily directed by infant carriers toward juveniles of both sexes who attempt to interact with the newborn. Interestingly, this aggression is also occasionally directed toward post pubertal eldest daughters, but not toward eldest sons (Achenbach and Snowdon 1998; Price 1992; Snowdon et al. 1993).

The most frequent and intense aggression occurs between brothers, especially following the birth of infants (Snowdon and Pickhard 1999). When aggression occurs between family members in situ, the animal that is being “attacked” should be removed and no attempts to reintroduce the animal back to its natal group will result in success (McGrew and McLuckie 1986).

When encountering unfamiliar conspecifics in situ, male cotton-top tamarins exhibit overt aggressive responses, including threat displays, piloerection, and physical attacks, particularly toward other males. In contrast, females respond to unfamiliar intruders with increased suprapubic scent marking rather than direct aggression (French and Snowdon 1981).

In the wild, aggression is most prominently observed when unfamiliar individuals attempt to join an established group. If the resident breeding male and/or female are still present, they, along with the eldest group members, will actively chase or attack the unrelated conspecifics seeking to integrate into the group (Savage et al. 1996a).

10.6 Territorial Behavior

Cotton-top tamarins exhibit pronounced territoriality and actively defend their home ranges through both vocal and physical means. In the wild, territorial behaviors are typically concentrated along the boundaries of a group's range, where some overlap may occur, particularly in areas with highly desirable food resources (A. Savage personal observation). Group interactions during territorial encounters are primarily conducted by the breeding pair and other adult members, while juveniles and dependent young are less involved. When infants are present, the adults carrying them typically withdraw from the area of conflict to minimize risk to the young. Adult males display higher levels of vigilance than adult females during territorial encounters (Savage et al. 1996b) and are more frequently observed with scars indicative of previous injuries sustained during aggressive interactions (A. Savage, personal observation).

McConnell and Snowdon (1986) experimentally simulated territorial interactions by opening doors between adjacent colony rooms, effectively removing visual barriers. This resulted in a significant increase in the amplitude of normal intragroup vocalizations, indicating heightened arousal. The groups engaged in extended bouts of calling accompanied by behaviors typical of encounters with unfamiliar groups, such as increased scent marking and piloerection.

The vocal repertoire during these simulated territorial interactions varied by sex. Females most often produced normal long calls, whereas males typically gave "F chirps." These calls frequently escalated into more complex vocalizations such as "F chirp trills," which were also predominantly produced by males. A third vocalization, the "F chirp-whistle," which blends features of the F chirp and the normal long call, was produced by both males and females.

These findings underscore the importance of both acoustic and visual cues in mediating social and territorial dynamics in cotton-top tamarins and highlight the complex vocal and behavioral strategies they employ in situ and ex situ.

10.7 Locomotion

The most common modes of locomotion for cotton-top tamarins include quadrupedal running, bounding, or galloping along medium to small branches as well as clinging and leaping between trees on thin or small branches. Limb kinematics and kinetics of cotton-top tamarins have been studied to illustrate how well cotton-top tamarins can navigate on fine branch inclines and declines (Hess et al. 2015; Nyakatura et al. 2008). In the wild, cotton-top tamarins are rarely observed on the forest floor. When they are observed on the forest floor, typically after a fall, they tend to run and hop to the nearest tree to return to the safety of forest canopy.

10.8 Ranging Behavior

Cotton-top tamarins follow a consistent daily rhythm of foraging, resting, and traveling. They sleep together in a group and typically begin their day about an hour and 20 minutes after dawn, when the entire group leaves the sleeping tree simultaneously. Their movements follow well-established travel routes that help them locate food sources, and they usually cover between 1.5 to 1.9 kilometers each day across home ranges that vary from 7.8 to 10 hectares (Neyman 1977).

Foraging dominates the early part of their morning, lasting around an hour before the tamarins begin taking short rest breaks. During these breaks, they may stretch out on branches or engage in social grooming. Younger animals in the group will use this time to play. This pattern of travel and foraging continues throughout the day, with rest periods gradually becoming longer, especially around midday.

In the late afternoon, the group shifts to faster and more cohesive travel with fewer foraging stops, heading toward a chosen sleeping site. (Neyman 1977). They generally begin this movement between one to one and a half hours before sunset (Savage 1990). Savage (1990) observed that home range sizes varied depending on resource availability, ranging from 10.5 to 12.4 hectares, with tamarins inhabiting environments from narrow vegetation corridors along arroyos to full patches of secondary forest.

10.9 Sleeping Site Selection

Cotton-top tamarins exhibit selective sleeping site preferences, typically choosing trees with dense foliage provided by broad leaves, vines, epiphytes, or lianas (Savage 1990). They are also frequently observed sleeping in trees with thorn-covered bark, such as Hura crepitans and Ceiba pentandra. Within their home range, tamarins tend to reuse a set of preferred sleeping trees, although they rarely sleep in the same tree on consecutive nights.

Sleeping sites are usually located in the central portion of the home range, with trees near territorial boundaries rarely used. This spatial pattern may serve to reduce the risk of intergroup conflict or predation.

Behaviorally, cotton-top tamarins tend to begin their daily activities later than many other primate species. They also accelerate their foraging and travel activities in the late afternoon, returning to sleeping sites well before dusk. This combination of selective sleeping site use, delayed morning activity, and early evening retreat likely helps them avoid predation from crepuscular and nocturnal predators.

10.10 Predator Avoidance

Some of the main predators of cotton-top tamarins include raptors, mustelids, felids, and snakes (Barbosa et al. 1988; Neyman 1977). Neyman (1977) described cotton-top tamarins emitting an extended series of alarm vocalizations to both arboreal and aerial predators. Cotton-top tamarins are extremely vigilant, constantly scanning for potential predators above and around them and even in captivity can be observed stopping their activities to look around (Price 1992). In the wild, when the group rests during the day, one group member separates itself from the resting animals and remains vigilant, alarming the group through vocalizations if it detects danger (Savage 1990).

Buchanan-Smith et al. (1993) presented fecal extracts from margay and tayra to captive cotton-top tamarins and found they exhibited high anxiety responses to predator vs non-predator scents suggesting a potentially innate fear of predators. However, Friant et al. (2008) found that vocalizations from predators (hawk, jaguar, and tayra) elicited similar responses to vocalizations from non-predator vocalizations (antthrush and red howler monkey), suggesting that there is a learning component to identifying predators. Hayes and Snowdon (1990) found that cotton-top tamarins do not demonstrate an alarm response specific to snakes but may simply display fear to moving objects.

10.11 Vocal Behavior

Cotton-top tamarins have a highly developed vocal repertoire composed of distinct chirps, modulated vocalizations, and long calls (Cleveland and Snowdon 1982) . These calls are critical for intra-group communication and are shaped by social and developmental factors.

Table 2 summarizes the variety of chirps identified in the vocal repertoire, their behavioral contexts, and associated responses.

Table 2. Chirps Used by Cotton-top Tamarins Under Varying Conditions

Chirp Type	Eliciting Context	Behavioral Responses	References
A	Visual threats	Rapid, erratic approach–retreat movements; mobbing behavior	Cleveland and Snowdon 1982
B	Calm movement or investigation	General locomotion, exploration	Cleveland and Snowdon 1982
C	Approaching food	Anticipatory movement toward food	Cleveland and Snowdon 1982 Elowson et al. 1991 Roush and Snowdon 1994, 2001
D	Manipulating or consuming food	Handling and ingestion of food items	Cleveland and Snowdon 1982; Elowson et al. 1991 Roush and Snowdon 1994,2001
E	Alarming auditory stimuli	Scanning, piloerection, leaping, crouching, rapid escape	Cleveland and Snowdon 1982
F	Hearing conspecifics from other groups; antiphonal calling	Stationary posture, slow scanning, mild piloerection, counter-calling	Cleveland and Snowdon 1982 McConnell and Snowdon 1986
G	Calm movement or investigation	Similar to Type B, acoustically distinct	Cleveland and Snowdon 1982 Bauers and Snowdon 1990
H	Mildly alarming events	Mild alertness; context based on observation	Cleveland and Snowdon 1982

Playback experiments confirmed that tamarins can distinguish between acoustically similar chirps, such as F and G (Bauers and Snowdon 1990). Elowson et al. (1991) demonstrated that C and D chirps increase in rate with food preference, suggesting a graded response reflecting motivational state. Territorial stimuli, such as the opening of doors between adjacent rooms, elicit F chirps in captive settings (McConnell and Snowdon 1986).

10.11.1 Social Influences on Vocal Production

Social status plays a pivotal role in shaping vocal behavior in situ. Subordinate individuals often exhibit underdeveloped or structurally immature C and D chirps and rely more heavily on a broader array of vocalizations not typically observed in adults (Roush and Snowdon 1994). However, when subordinates transition to dominant roles (e.g., upon pairing), they rapidly adopt adult vocal forms, often within several weeks, indicating that social inhibition rather than developmental incapacity suppresses mature vocalizations (Roush and Snowdon 1999).

10.11.2 Group Composition Effects

Adults and subadults in family groups with infants vocalize less frequently than non-reproductive pairs, particularly for food-associated C chirps (Roush and Snowdon 2001). Similarly, tamarins without infants are more reactive to novel group calls, suggesting infant presence modulates group vocal reactivity (McConnell and Snowdon 1986).

10.11.3 Representational Use of Calls: Tamarins respond to their mate's food calls even in the absence of visual cues, indicating that these vocalizations convey symbolic or representational information (Roush and Snowdon 2001).

10.11.4 Developmental Trajectory of Vocalizations

The development of adult chirp types in infants follows a predictable timeline (Castro and Snowdon 2000) (Table 3).

Table 3. The ontogeny of chirps.

Chirp Type	First Appearance (Weeks)
E	6–20
D	7–20
C	10–20
A	13–17
F	15–17

Although capable of responding to adult calls early (Roush 1996), infants and subadults often display inconsistent use of context-appropriate vocalizations. They exhibit variable structures in C and D chirps and produce more non-food-related calls during feeding than adults (Castro and Snowdon 2000; Roush and Snowdon 1994).

This immature vocal behavior may serve an adaptive function. Subordinates may intentionally maintain juvenile-like vocalizations to signal non-breeding status and reduce aggression from dominant group members (Roush and Snowdon 1999). This "infantile strategy" allows prolonged group membership and reduces conflict over access to resources.

10.11.5 Vocal Maturation and Social Transition

Roush and Snowdon (1999) identified three phases of change in food-related vocal behavior as subadults transition from subordinate to dominant social roles:

1. Immediate Reduction of Immature Calls: Upon removal from natal groups, non-food-associated calls in feeding contexts decrease rapidly.

2. Affiliation-Linked Refinement: The rate of this reduction correlates with affiliative behaviors between newly formed pairs.

3. Gradual Acquisition of Adult Vocal Forms Accurate C and D chirps emerge over approximately 8 weeks, suggesting a need for vocal practice and social affirmation.

10.11.6 Additional Vocalizations in Juveniles

Juveniles and subadults also produce long calls that combine short, modulated chirps with prolonged, whistle-like elements. However, reproductively subordinate individuals rarely produce adult long-call forms (Cleveland and Snowdon 1982; Snowdon et al. 1983).

10.11.7 Long calls

Cotton-top tamarins produce long calls that occur in different situations (Cleveland and Snowdon 1982; Snowdon et al. 1983). “Normal Long Calls” are used in intergroup communication or upon hearing vocalizations or neighboring groups and “Quiet Long Calls” are used for within group cohesion. Combination Long Calls are produced by individuals that become separated from their group, serving as a means to reestablish contact and reunite.

In cotton-top tamarins, vocal development and usage are influenced more by social dynamics than by physiological maturation alone. The production of adult-like calls depends on both learning and social context, with subordinate individuals modifying their vocal strategies to reflect their position within the group. This socially mediated vocal plasticity underscores the complex interplay between communication, dominance, and group cohesion in this species.

11. Cognition

Cognitive studies in situ have focused on foraging strategies in cotton-top tamarins. Savage et al. (1987) examined cotton-top tamarins’ ability to distinguish color and found they were able to discriminate hues across the visual spectrum, suggesting that they were able to distinguish between ripe and unripe fruit. Other studies have found that both males and females can use color cues to obtain food (Hauser et al. 1999, 2002; Mocovice and Snowdon 2006). Gaudio and Snowdon (2008) investigated the relative importance of spatial versus color cues in the foraging behavior of cotton-top tamarins and found that spatial cues are more robust and salient in guiding foraging behavior. Deipolyi et al. (2001) found evidence that cotton-top tamarins possess sophisticated spatial foraging strategies, integrating both geometric and specific non-geometric features – particularly shape – to navigate their environment effectively. Their ability to generalize learned spatial relationships to novel situations highlights advanced cognitive mapping capabilities.

Cotton-top tamarins also appear to have advanced social memory capabilities, as they exhibit lower arousal responses to calls from both current mates and long-separated relatives compared to unfamiliar individuals. Even after separations exceeding four years, tamarins recognized the calls of their relatives, suggesting that they possess a long-term memory for vocal signatures, which may be crucial for social interactions and avoiding inbreeding after dispersal (Matthews and Snowdon 2011).

12. Parasites and Diseases

Baseline hematologic and serum biochemical values have been established for cotton-top tamarins in situ (Hawkey et al. 1983; Shukan et al. 2012), providing useful indicators of individual and population health. Studies of wild cotton-top tamarins have shown that their hematological values generally fall within the normal ranges reported for in situ populations (Nassar et al. 2010; Wehdeking et al. in review), supporting the use of these reference values across contexts.

Cotton-top tamarins have played an important role in biomedical research, particularly in studies of colonic adenocarcinoma, as they are the only known non-human primate species to spontaneously develop this form of cancer (Clapp 2018). While colonic adenocarcinoma has been frequently observed in cotton-top tamarins in situ, there is no evidence of this disease in wild populations in Colombia (Wood et al. 1998). This contrast suggests that environmental conditions in captivity may contribute to the development of colitis and cancer. Stonerook et al. (1994) proposed that cotton-top tamarins are poorly adapted to temperate climates and may experience metabolic stress at temperatures below 32°C, which could be a contributing factor in colitis and other conditions such as wasting marmoset syndrome and colonic adenocarcinoma.

Leong et al. (2004) analyzed causes of mortality in zoo-housed cotton-top tamarins and found that adult deaths were primarily due to infectious diseases. Other significant causes included trauma, idiopathic conditions, and neoplasms. The incidence of spontaneous lymphomas is rare (Hofman et al. 2001). The majority of deaths resulted from undiagnosed bacterial infections, though several specific pathogens were identified, including Yersinia spp., Francisella tularensis, callitrichid hepatitis virus, and Toxoplasma gondii. Additional infectious agents reported in tamarins include Escherichia coli, Campylobacter, Clostridium spp., Helicobacter spp., Aeromonas spp., Bacillus piliformis, Encephalitozoon cuniculi, Salmonella spp., Klebsiella spp., Streptococcus zooepidemicus, Staphylococcus spp., adenoviruses, and corona-like viruses (Hall et al. 2012; Juan-Sallés et al. 2006; Leong et al. 2004; López et al. 2014; Reetz et al. 2004; Rolland et al. 1997; Sasseville et al. 2007).

Geiszler-Monsalve et al. (2013) reported the presence of microfilaria in cotton-top tamarins rescued from the illegal pet trade and housed in a managed care facility in Colombia. Despite being infected, these animals showed no notable changes in electrocardiogram (ECG) wave patterns, suggesting that microfilarial infection did not affect heart function. Microfilaria, including Mansonella spp. and Dipetalonema perstans, have also been identified in wild tamarins through blood smear analysis (Barrera et al. 2010; Savage 1990). Filariform larvae compatible with Strongyloides cebus were recovered from fecal cultures, and larval mites (Eutrombicula alfreddugesi) from the Trombiculidae family have been found in the retro-auricular region during physical exams.

Vitamin D deficiency has been recognized as a significant cause of bone disease in primates (Hampton et al. 1966). To address this, high levels of vitamin D₃ have been incorporated into commercial primate diets. Power et al. (1997) found that the average serum 25-hydroxyvitamin D (25-OH-D) concentration in wild cotton-top tamarins was 76.4 ng/ml and suggested that a range of 50–120 ng/ml be considered normal. Juveniles had higher levels than adults, but no sex-based differences were observed. A later study by Ullrey et al. (1999) demonstrated that an in situ diet with 2,500 IU of vitamin D₃ per kilogram of dry matter maintained serum 25-OH-D levels comparable to those found in wild tamarins.

In addition, Lemere et al. (2008) observed that cotton-top tamarins in situ may naturally develop early-stage Alzheimer’s-like pathology after the age of 12, offering a potential non-human model for studying neurodegenerative diseases associated with aging.

13. Conservation Status

Historically, between 20,000 to 40,000 cotton-top tamarins were exported from Colombia to the United States for biomedical research (Hernandez-Camacho and Cooper 1976). In 1973, these primates were officially declared endangered, prompting CITES regulations (CITES Appendix I) to reduce the number of wild cotton-top tamarins captured for export. The majority of the biomedical research colonies have been disbanded and there remains a healthy population of cotton-top tamarins in zoological gardens throughout the world. These animals are in cooperatively managed programs throughout the world with husbandry guidelines (Savage 1995) allowing healthy, genetically diverse, and demographically stable populations to exist.

While the animals in managed care have thrived, estimating the number of animals remaining in the wild was challenging given the small size and secretive nature of the species. Savage et al. (2010b) developed techniques that combined the use of playbacks of territorial vocalizations with traditional transect surveys to effectively estimate the number of cotton-top tamarins remaining in Colombia. Initial estimates suggested that 7,394 animals remained in the wild. Miller et al. (2004) found than more than 1/3 of the available forest habitat had been destroyed between 1990-2000 and a 9-13% loss of forest cover has been observed between 2000-2018 (Butler 2021). Due to continued habitat loss and continued population decline, the status of the cotton-top tamarin was revised and they were declared critically endangered in 2008 (Rodríguez et al. 2021; Schipper et al. 2008).

Increased national and international attention was rallied to create conservation plans for the species resulting in the formation of several new protected areas, totaling more than 7,000 ha (Fundación Proyecto Tití Annual Report 2024). A second population survey was conducted within the historic distribution of cotton-top tamarins in Colombia (Savage et al. 2016) and results indicated that there was a population decline of approximately 1.3% per year, suggesting a relatively stable population. The stability of the population was attributed to increased conservation efforts of conservation NGO’s and the Colombian government.

14. Management

14.1 Habitat Destruction

Cotton-top tamarins are found exclusively in the tropical forests of northern Colombia and have a restricted range within the country. Unfortunately, the most significant threat to their survival today is the rapid deforestation of their habitat (Estrada et al. 2017; Miller et al. 2004). This destruction is driven by agriculture, mining, illegal logging, and urban expansion. Habitat loss in Colombia is happening at an alarming rate. Between 2002 and 2024, 39% of tree cover loss occurred within natural forests, leading to a 6.8% decrease in forested areas since 2000 (Global Forest Watch 2025). The most significant tree cover loss occurred in the departments of Atlántico and Bolivar, home to some of the most vulnerable forest habitats where cotton-tops reside.

Critical to the long-term survival of the cotton-top tamarin is securing long-term protection for vital forest habitat. Colombia has created the “Sistema Nacional de Áreas Protegidas” (SINAP) that combines the national park system, flora and fauna sanctuaries, flora sanctuaries, nature reserves, and unique natural areas that are publicly or privately owned to help increase efforts to protect habitat. Efforts to increase the number of forest hectares available for wildlife continue to be a priority within the historic distribution of cotton-top tamarins in Colombia. Additional projects to connect isolated forest fragments and create mega corridors are also underway as a means to create more viable habitat for wildlife (Guillen and Rodriguez 2020).

14.2 Cotton-top Tamarins in the Illegal Pet Trade

Illegal wildlife trade is a serious issue in Colombia as many animals have been illegally smuggled out of the country (Noboa et al. 2024). Owning native wildlife as pets is also a prevalent practice in Colombia, rooted deeply in cultural traditions (Nassar et al. 2001). Wildlife trafficking, particularly within the country, has a longstanding history, with animals primarily serving as “companions” and a perceived connection to nature (Sollund 2017). A review by Proyecto Tití, revealed that local authorities confiscated more than 687 cotton-top tamarins between 2016 and 2023 (F. Forreo-Sánchez, unpublished. data). This figure markedly underrepresents the actual count of illegally captured cotton-top tamarins, many of which continue to be held in captive conditions or have succumbed to adverse conditions. The phenomenon extends to social media, where individuals frequently share posts about their pet cotton-top tamarins (WCS, 2021).

Proyecto Tití leads cotton-top tamarin conservation efforts in Colombia and has a long history of working with local communities to reduce the desire to have cotton-top tamarins as pets. Through effective community conservation and education programs (Feilen et al. 2018; Savage et al. 2010a, 2023, 2024) people of all ages are learning about the impacts to cotton-top tamarins kept as pets and to their long-term survival. The desire to keep cotton-top tamarins as pets has decreased significantly due to the variety of methods that Proyecto Tití uses to disseminate information and to increase cultural pride in protecting this iconic species.

Despite the existence of a specific regulation aimed at mitigating the illegal wildlife trade (Ministerio de Ambiente, Vivienda y Desarrollo Territorial 2010), Colombia is challenged by an institutional weakness of the enforcement agencies and a lack of resources to maintain animals confiscated from the illegal wildlife trade. Animals rescued from the illegal pet trade are often sent to local authorities and few, if any, people are prosecuted for illegal possession of wildlife (Noboa et al. 2024). There are limited number of rehabilitation centers in Colombia and space for animals rescued from the pet trade are limited. Many local authorities are often faced with releasing confiscated cotton-top tamarins into forested areas with the hope that animals survive. Very few document their reintroduction techniques or provide long-term follow up on the survival of these animals (Arango Guerra et al. 2013, Contraloría 2014).

The reintroduction of captive cotton-top tamarins from facilities outside of Colombia is not recommended. Currently genetic data indicates that the wild population does not suffer from a severe loss of genetic diversity that would necessitate the introduction of genes from captive individuals (Rasmussen et al. 2023). Moreover, habitat availability, rather than population genetics, is the primary constraint on the species' recovery. Rapid habitat destruction in Colombia has left insufficient forest to support a significant increase in the wild population.

Cotton-top tamarins in captivity are known to develop colonic adenocarcinoma, a condition not reported in wild populations. The cause of this disease in animals in situ remains unknown, and the potential for introducing a new health threat into the wild raises significant concern for conservation.

Reintroduction efforts also require substantial financial investment and do not guarantee success. Survival, reproduction, and infant viability are often low following release. Cotton-top tamarins acquire essential survival skills such as identifying food sources, recognizing predators, and locating appropriate sleeping sites through learning from others, not through instinct. Captive-born individuals would therefore need an extended period of rehabilitation to acquire the knowledge and behaviors necessary to survive in the wild.

15. Future Challenges For Research And Management

15.1 Conservation Priorities

To secure the long-term survival of cotton-top tamarins, continued focus must be on securing forest habitat within their historic distribution. This requires additional efforts to formally protect and manage existing large tracts of forests that remain in the region, connect isolated forest fragments to create larger forest corridors for wildlife, and restore degraded forest habitat so that larger intact forest ecosystems can remain for cotton-top tamarins and other native Colombian wildlife. In order to secure forests in Colombia a multi-faceted approach is needed that 1) combats illegal activities like logging and mining, 2) promotes sustainable agriculture, 3) supports alternative livelihoods and economic opportunities for communities that depend on forests for their livelihoods, 4) implements comprehensive land use planning that integrates forest conservation with agricultural develop and other land uses, and 5) secure land tenure to reduce conflict over land use. It is critical that Colombia continues to strengthen and expand the protected areas (SINAP) and strengthen local capacity to effectively manage protected areas and increase the capacity of environmental agencies to monitor, regulate, and enforce environmental laws or management plans. Achieving significant forest conservation requires international collaboration and financial support which can provide funding to reduce deforestation and promote forest conservation.

While Colombia has a robust policy framework addressing the implementation of the “Agenda 2030 In Colombia” to help reach its Sustainable Development Goals (SDGs), climate change related goals and land use change, which are all tied directly to reducing rates of deforestation. However, implementation obstacles and conflicting objectives with the policy landscape perpetuate this incoherence. Colombia struggles to balance trade-offs between economic, social and environmental goals. This conflict contributes to inconsistencies in policy formulation and implementation, which can hinder progress toward achieving deforestation reduction goals (Lobos Alva and Cárdenas Vélez 2024).

While large-scale governmental policy and programs can help provide the framework for forest protection, some of the best examples of effective forest conservation and management programs come from community-driven initiatives where local landowners are actively involved in decision-making and management. Programs that provide training in sustainable agricultural techniques, demonstrate tangible economic benefits to land-owners, and increase livelihoods, while reducing the use of forest products result in more forests being effectively protected for wildlife (Guillen 2020; Wright et al. 2016).

Ultimately, the long-term survival of the cotton-top tamarin depends not only on protecting habitat and enforcing policy, but also on fostering a deep cultural commitment to conservation. People are far more likely to protect what they understand, value, and see as part of their own future. Through innovative education programs, community-based initiatives, and sustained local partnerships, Proyecto Tití and their partners have successfully embedded conservation into the daily lives and identities of the communities that share their home with cotton-top tamarins. By helping individuals recognize how their choices—from land use to waste disposal—impact the forest and its inhabitants, a powerful sense of stewardship has been cultivated. This local engagement has generated tangible shifts in behavior, strengthened political will, and built a conservation ethic that is both enduring and locally owned—laying the foundation for a future where cotton-top tamarins and communities thrive together.