Golden lion tamarin

The golden lion tamarin (Leontopithecus rosalia; Template:Langx Template:IPA), less commonly known as the golden lion marmoset, is a small New World monkey of the family Callitrichidae. Endemic to the Atlantic coastal forests of Brazil, the golden lion tamarin is an endangered species. The geographic range is entirely within the state of Rio de Janeiro. A 2022/2023 census estimated about 4,800 individuals living in the current primary area of occurrence in the non-coastal area of the São João and Macaé river basins,<ref name="Dietz-2024">Template:Cite journal</ref> with unknown but smaller additional numbers in limited coastal forests<ref name="Rylands-2002">Template:Cite book</ref> and to the west of the primary area of occurrence.<ref name="Burity-2007">Template:Cite journal</ref><ref name="Rubião-2022">Template:Cite conference</ref> There is a captive population maintaining about 490 individuals among 150 zoos.<ref name="IUCN"/>

Physical characteristic

Closeup on the golden lion tamarin's face

The golden lion tamarin gets its name from its bright reddish orange pelage and the extra-long hairs around the face and ears which give it a distinctive mane.<ref>Template:Cite book</ref> Its face is dark and hairless. The bright orange fur of this species does not contain carotenoids, which commonly produce bright orange colors in nature.<ref>Template:Cite journal</ref> The golden lion tamarin is the largest of the callitrichid monkeys. It is typically around Template:Cvt and weighs around Template:Cvt. There is almost no size difference between males and females. As with all callitrichids, the golden lion tamarin has claw-like nails, instead of the flat nails found in other monkeys and apes, although callitrichids do have a flat nail on the big toe.<ref name="Garber 1980">Template:Cite journal</ref> Golden lion tamarins walk, run, and bound quadrupedally on top of branches, or, less frequently, they run and walk on the ground.<ref name=":3">Template:Cite journal</ref><ref name=":4">Template:Cite journal</ref> When golden lion tamarins run or bound, their hindlimbs alternately overstride their forelimbs, and their feet are set atop the support and grasp it almost perpendicular to the line of travel, making the body's angle of travel oblique rather than precisely parallel to the substrate, a pattern known as “transaxial bounding”.<ref name=":3" /><ref name=":4" /> In addition, facilitated by their claw-like nails, golden lion tamarins cling and climb on vertical tree trunks (see photographs in:<ref>Template:Cite book</ref> pp 108–117, 137, 155).

Habitat and distribution

The golden lion tamarin has a limited current area of occupancy, as most of the original habitat in the Brazilian state of Rio de Janeiro has been lost to deforestation.<ref name="Rylands-2002" /> Today, the species is confined to fragments of forest within the state, including Poço das Antas Biological Reserve, União Biological Reserve, other protected areas, and privately owned lands. Most of the area of occupancy is characterized by vegetation types classified as dense broadleaf evergreen or seasonal deciduous and semi-deciduous forest,<ref>Template:Cite book</ref> with some tamarins living in areas closest to the coast found in a sandy soil forest type called "arboreal restinga".<ref>Kierulff, M.C.M (2000) Ecology and behaviour of translocated groups of golden lion tamarins (Leontopithecus rosalia). PhD thesis, University of Cambridge. pp 41</ref> Golden lion tamarins are thought to occur primarily in low elevation forests, up to 150<ref>Template:Cite journal</ref> or 300<ref>Template:Cite journal</ref> meters above sea level, but a 1990–1992 survey identified two groups above 500 meters,<ref name="Kierulff-2003">Template:Cite journal</ref> and reports from the recently identified western geographic area include records above 700 meters.<ref name="Rubião-2022" /><ref>Nascimento, J. L.; Eckhardt, B. L.; Antunes, E. P.; Andrade, F. P. S.; Cronemberger, C.; Soares, R.; Souza, N. F.; Souza, C. S. F.; Ribeiro, E. A.; Pereira, J.; Mattos, E.; Silva, V. M.; Stump, L.; Rubião, E. C. N.; Dias, P. R.; Gomes, M. M.; Silva, C. A. M.; Moreira, S. B.; Pissinatti, A.; Oliveira, L. C. (2019). Novos registros, ampliação da distribuição altitudinal e conservação de Leontopithecus rosalia (Linnaeus, 1766) no oeste do Mosaico Central Fluminense [New records, expansion of altitudinal distribution and conservation of Leontopithecus rosalia (Linnaeus, 1766) in the west of the Central Fluminense Mosaic]. Abstract from the 2019 Brazilian Primatological Conference (in Portuguese).</ref>

Golden lion tamarin population estimates in the 1960s and 1970s ranged from only 100 to 600,<ref name="Coimbra-Filho-1973">Template:Cite journal</ref><ref name="Magnanini-1978">Template:Cite book</ref> although these estimates were not based on range-wide censuses. The first such census, carried out 1990–1992, counted about 560 wild individuals<ref name="Kierulff-1994">Template:Cite journal</ref><ref name="Kierulff-2003" /> and there were about 100 additional individuals from the reintroduction program living in the wild.<ref name="Kierulff-2003" /> Since then, following conservation efforts including reintroduction of zoo-born animals<ref name="Beck-2002">Template:Cite book</ref><ref name="Kierulff-2002">Template:Cite book</ref> and translocation of wild individuals from small, at-risk forest fragments<ref name="Kierulff-2002" /> (both largely to areas then unoccupied by tamarins), reforestation with a particular focus on connecting separated areas of habitat,<ref name="Dietz-2022">Template:Cite web</ref><ref name="Menegassi-2023">Template:Cite web</ref> and community-based conservation and engagement programs,<ref name="Padua-2002">Template:Cite book</ref><ref name="Matsuo-2008">Template:Cite book</ref> the population has grown significantly. Most recently, a 2022/2023 census estimated about 4,800 golden lion tamarins living in the current primary area of occurrence in the non-coastal area of the São João and Macaé river basins,<ref name="Dietz-2024" /> with unknown but smaller additional numbers in limited coastal forests<ref name="Rylands-2002" /> and to the west of the primary area of occurrence.<ref name="Burity-2007" /><ref name="Rubião-2022" />

Behaviour and ecology

File:Callitrichidae - Leontopithecus rosalia - Golden Lion Tamarin.webm

Diet

In the wild, golden lion tamarins eat mostly fruits and small animal prey, in addition to smaller quantities of nectar and plant exudates (tree gum) (see<ref name="Kierulff2002">Template:Cite book</ref> for summary).

Plant Material

Fruits, mostly ripe,<ref name="Kierulff2002" /> are the plant part consumed by golden lion tamarins for more than 80% of plant species eaten.<ref name="Deitz1997">Template:Cite journal</ref><ref name="Miller-2006">Template:Cite journal</ref> Tamarins swallow the seeds of most fruits they consume and are considered to function as effective seed dispersers for many plant species.<ref name="Procópio de Oliveira-2008a">Template:Cite book</ref><ref>Template:Cite journal</ref><ref>Template:Cite journal</ref>

Wild golden lion tamarins eat from a wide variety of plant species, with 160 species noted in one multi-group study.<ref name="Procópio de Oliveira-2008a" /> Despite this variety of food plants, golden lion tamarins appear to get most of their plant food from a smaller subset of species.<ref name="Kierulff2002" /><ref name="Deitz1997" /><ref name="Miller-2006" /><ref name="Procópio de Oliveira-2008a" /> For example, just seven of the 160 plant species noted eaten by golden lion tamarins in the União Biological Reserve accounted for 56% of total plant feeding observations.<ref name="Kierulff2002" />

The most common reported source of nectar in golden lion tamarin diets are the flowers of the tree Symphonia globulifera.<ref name="Kierulff2002" /><ref name="Deitz1997" /><ref name="Procópio de Oliveira-2008a" /> Nectar consumption typically represents a small proportion of the golden lion tamarin plant diet (6%-10% of observations or time<ref name="Kierulff2002" /><ref name="Miller-2006" />). However, some golden lion tamarin groups may concentrate heavily on nectar during the cool, dry season in at least some years.<ref name="Kierulff2002" /><ref name="Deitz1997" /><ref name="Procópio de Oliveira-2008a" />

Exudates or tree gum are soft, semi-liquid substances produced by trees and lianas in response to damage to exterior bark or to disease, or within seed pods. Golden lion tamarins in the Poço das Antas Reserve fed occasionally on tree gum that they found opportunistically on trees and woody lianas,<ref>Template:Cite journal</ref> and gum consumption represented less than 2% of total feeding observations or time.<ref name="Kierulff2002" /><ref name="Deitz1997" /><ref name="Miller-2006" /> Lion tamarins (and other tamarins) lack the dentition and other specializations for gum-feeding characteristic of marmoset genera, e.g., Callithrix and Cebuella.<ref>Template:Cite book</ref><ref>Template:Cite book</ref><ref>Template:Cite journal</ref><ref>Template:Cite book</ref><ref name="Rosenberger-2020">Template:Cite book</ref>

Animal Prey

Animal prey reported as eaten by wild golden lion tamarins in at least one study include frogs and tree frogs, amphibian egg masses, lizards, snakes, nestling birds, bird eggs, snails, spiders, centipedes, katydids, grasshoppers, crickets, beetles and beetle larvae, cockroaches, ants, stick insects, butterflies, caterpillars, and insect-infested tree galls.<ref name="Kierulff2002" /><ref name="Deitz1997" /><ref name="Miller-2006" /><ref name="Procópio de Oliveira-2008a" /><ref>Template:Cite book</ref> Orthopteran insects (e.g., grasshoppers, katydids, and crickets) were the most commonly eaten prey in one study.<ref name="Miller-2006" />

Golden lion tamarins capture most of their prey animals from hidden crevices in tree bark, rotten wood, holes in trees, vine tangles, within curled dead leaves, between the leaves and in the basins of bromeliads, inside hollow bamboo, under the sheaths of palm leaves, or in leaf litter on the ground and debris accumulated in limb junctures and palm apices. A golden lion tamarin captures such hidden prey by inserting its fingers, hand, and even forearm into the visually inaccessible recesses, groping blindly by sense of touch, grasping an encountered prey item, and withdrawing and eating it.<ref name="Rosenberger-2020" /> This is a form of the foraging technique known as "extractive foraging on embedded foods",<ref>Template:Cite journal</ref> and in golden lion tamarins has been termed "micro-manipulation".<ref name="Miller-2006" /><ref>Bronikowski, E. J., Beck, B. B., and Power, M.L.. (1989) Innovation, exhibition and conservation: Free-ranging tamarins at the National Zoological Park. Proceedings of the 1989 American Association of Zoological Parks and Aquariums Conference: 540-546</ref><ref>Template:Cite journal</ref> Peres<ref name="Peres-1989">Template:Cite journal</ref> reported that such extractive foraging accounted for 98% of prey captures observed in one study in the Poço das Antas Biological Reserve. Lion tamarins (the genus Leontopithecus as a whole) have significantly longer and narrower hands (including longer fingers) than other callitrichids. This is considered to be an adaptation to their micro-manipulation foraging behavior for embedded prey.<ref>Template:Cite journal</ref>

Home range and use of space

Golden lion tamarin groups are highly territorial. They have areas of exclusive use, but engage in aggressive encounters with neighboring groups at borders and in areas of overlap.<ref name="Kierulff2002" /><ref name="Miller-2006" /><ref name="Peres-1989" /> These encounters feature chases and characteristic vocalizations and posturing, and can include brief physical contact and fights.<ref name="Peres-1989" /> Peres<ref name="Peres-1989" /> proposed that these encounters served to reinforce boundaries and preserve areas of exclusive use, "preventing neighbors from trespassing farther" (p 232).  The term "home range" is used here, representing the full area that a tamarin group uses, including both areas of exclusive use and areas of overlap with neighboring groups. For one study group in Poço das Antas Biological Reserve, about 60% of the study group's home range was overlapped by the home ranges of neighboring groups.<ref name="Peres-1989" />

A long-term study in Poço das Antas Biological Reserve calculated a mean home range size of 50.5 ha (124.8 acres) for golden lion tamarin groups over one-year periods<ref name="Hankerson">Hankerson, S. J. (2008) Resource and space use in the wild golden lion tamarin, Leontopithecus rosalia. PhD thesis, University of Maryland. http://hdl.handle.net/1903/8812</ref>(pp 66–67), with a range of 17.4-87.7 ha (43.0-216.7 acres).<ref>Template:Cite journal</ref> Reports from União Biological Reserve indicate larger home range sizes there,<ref name="Kierulff2002" /><ref name="Procópio de Oliveira-2008a" /><ref name="Lapenta-2007">Template:Cite journal</ref> which may be a result of lower population density in União at the time of the studies,<ref name="Kierulff2002" /><ref name="Procópio de Oliveira-2008a" /> as well as differences in calculation methods.<ref name="Hankerson" /> Golden lion tamarin home ranges are not static over time.<ref name="Peres-1989" /><ref name="Hankerson" /> One study found a mean of 77% home range overlap for a group between one year and the next.<ref name="Hankerson" />

Wild golden lion tamarins use their home ranges unevenly, with some areas used much more heavily than others.<ref name="Kierulff2002" /><ref name="Deitz1997" /><ref name="Peres-1989" /><ref name="Hankerson" /> In a study in Poço das Antas Biological Reserve, "core areas", where 50% of a group's location records were documented, averaged approximately 10% of a group's total home range.<ref name="Hankerson" />

Reports of average daily travel distances for individual groups of golden lion tamarins range from 1,339 to 2,135 m (4,393 to 7,005 feet).<ref name="Kierulff2002" /><ref name="Deitz1997" /><ref name="Procópio de Oliveira-2008a" /><ref name="Hankerson" /><ref name="Lapenta-2007" /> Single-day travel distances for groups vary more widely. For example, in one study of two groups in União Biological Reserve, single day travel distances ranged from 401 to 3,916 m (1,316 to 12,848 feet).<ref name="Kierulff2002" />

Sleeping sites

Golden lion tamarins usually spend more than half their time in overnight sleeping sites, and thus are active for less than half the day. Two groups in the União Biological Reserve spent an average of 14.2 hours and 13.1 hours in their sleeping sites<ref name="Lapenta-2007" /> (calculated from Table 1). Active periods are longer in the austral summer, when there are more hours of daylight. In the Poço das Antas Biological Reserve, golden lion tamarins left their sleeping sites in the morning an average of 10 min after sunrise and entered at the end of the day an average of 82 min before sunset.<ref name=":0">Template:Cite journal</ref>

Multiple authors have reported that golden lion tamarins prefer to sleep in naturally-occurring tree holes.<ref name="Deitz1997" /><ref name="Lapenta-2007" /><ref name=":0" /><ref name=":1">Template:Cite book</ref><ref name=":2">Kierulff, M.C.M (2000) Ecology and behaviour of translocated groups of golden lion tamarins (Leontopithecus rosalia). PhD thesis, University of Cambridge.</ref> Tree holes, also termed tree cavities or tree hollows, are reported as the predominant sleeping site for other lion tamarin species as well (summary in<ref name="Kierulff2002" />). In an extensive study of golden lion tamarins in the Poço das Antas Biological Reserve, tree holes were the most commonly used type of site (63.6% of “nights”), followed by (non-native) bamboo clusters at ground level (17.5%), vine tangles in trees (9.6%), and large bromeliads growing on trees (4.7%).<ref name=":0" /> Golden lion tamarin groups in the União Biological Reserve used tree holes exclusively or almost exclusively.<ref name="Lapenta-2007" /><ref name=":2" /> This heavy use of tree holes is in contrast to other callitrichid genera, which have been reported to use tree holes, but typically not predominantly, or to not use tree holes at all (see, for example, brief review in.<ref>Template:Cite journal</ref>

Golden lion tamarin groups use multiple sleeping sites across time.<ref name=":0" /><ref name=":2" /><ref name="Franklin2003">Template:Cite journal</ref> Some groups in the Poço das Antas Biological Reserve used more than 40 sites across multiple years of study.<ref name="Franklin2003" /> Groups use a small subset of these sites frequently, suggesting that some sites are highly preferred over others.<ref name=":0" /><ref name=":2" /> In the Poço das Antas Biological Reserve, golden lion tamarin groups used the same sleeping site on consecutive nights in approximately 50% of the cases when sites for consecutive nights were identified.<ref name=":0" /> Two groups in the União Biological Reserve used the same site on consecutive nights at somewhat lower rates, 20% and 38%.<ref name="Lapenta-2007" /><ref name=":2" />

Multiple authors, for example,<ref name=":0" /><ref name=":1" /><ref name="Franklin2003" /> have discussed the role of sleeping site selection in relation to (overnight) predation, proposing that tree holes may provide greater protection from predators than other sleeping site types.

Predators

There are only a few published reports confirming identities of successful predators on golden lion tamarins, with these cases including a boa constrictor (Boa constrictor),<ref name="Kierulff2002" />Template:Rp a small cat identified as an ocelot (Felis pardalis),<ref name="Beck-1991">Template:Cite journal</ref> and a feral dog (Canis familiaris),<ref name="Beck-1991" /> the latter two incidents involving reintroduced zoo-born golden lion tamarins. However, circumstantial evidence suggests that additional species are golden lion tamarin predators as well: raptors;<ref name="Kleiman DG-2002">Template:Cite book</ref> capuchin monkeys (Cebus/Sapajus nigritus);<ref name="Kleiman DG-2002" /><ref name="Franklin2003" /> coatimundis (Nasua nasua);<ref name="Franklin2003" /> and tayra (Eira barbara).<ref name="Franklin2003" /><ref>Template:Cite journal</ref>

Tayra were strongly suspected as the primary predator in a series of deaths and disappearances in Poço das Antas Biological Reserve.<ref name="Franklin2003" /> From 1995 to 2000, a sharp increase in predation was noted in the golden lion tamarin study population in the reserve, substantially reducing the estimated reserve population from 350 to 220 individuals during this period.<ref name="Franklin2003" /> At least during this period, most documented predation appeared to have occurred overnight, at or in proximity to sleeping sites.<ref name="Franklin2003" /> Multiple authors have discussed the role of sleeping site selection in relation to (overnight) predation, noting that tree holes, a den type frequently used by golden lion tamarins, may provide greater protection from predators than other sleeping site types,<ref name="Franklin2003" /><ref>Template:Cite book</ref><ref>Template:Cite journal</ref> although most of the documented events at the Poço das Antas reserve occurred at such tree hole sleeping sites.

Wild golden lion tamarins approach and mob some arboreal and terrestrial predators, e.g., snakes and tayra, as well as perched raptors,<ref name="Kleiman DG-2002" /> but are reported to retreat quietly from capuchin monkeys<ref name="Kleiman DG-2002" /> p 240. Golden lion tamarins also use alarm vocalizations in reaction to predators. Calls associated with terrestrial/arboreal predators are reported to differ from those associated with flying predators in both captive situations<ref name="Kleiman-1986" /><ref>Template:Cite book</ref><ref name=":5">Castro, M. I. (1990) A comparative study of anti-predator behavior in three species of lion tamarins (Leontopithecus) in captivity. M.Sc. thesis, University of Maryland, College Park</ref> and the wild.<ref name="Kleiman DG-2002" />

Social structure

Family groups may consist of up to eight members.

Golden lion tamarins are social and groups typically consist of 2-8 members. These groups usually consist of one breeding adult male and female but may also have 2–3 males and one female or the reverse.<ref name=Dietz1993>Template:Cite journal</ref> Other members include subadults, juveniles and infants of either sex. These individuals are typically the offspring of the adults. When there is more than one breeding adult in a group, one is usually dominant over the other and this is maintained through aggressive behavior. The dominance relationship between males and females depends on longevity in the group. A newly immigrated male is subordinate to the resident adult female who inherited her rank from her mother.<ref name=Bales2000>Template:Cite thesis</ref> Both males and females may leave their natal group at the age of four, however females may replace their mothers as the breeding adult, if they die, which will lead to the dispersal of the breeding male who is likely her father. This does not happen with males and their fathers. Dispersing males join groups with other males and remain in them until they find an opportunity to immigrate to a new group. The vast majority of recruits to groups are males.<ref name=Baker1996>Template:Cite journal</ref> A male may find an opportunity to enter into a group when the resident male dies or disappears. Males may also aggressively displace resident males from their group; this is usually done by two immigrant males who are likely brothers. When this happens, only one of the new males will be able to breed and will suppress the reproduction of the other. A resident male may also leave a vacancy when his daughter becomes the breeding female and he must disperse to avoid inbreeding.<ref name=Baker2002>Template:Cite book</ref>

Communication

Like other callitrichids, golden lion tamarins use auditory, olfactory, and visual signals to communicate within and between groups.

Vocal Communication

Because the dense structure of their rainforest habitat limits opportunity for visual signaling, golden lion tamarins rely mostly on sound for real-time communication about group movement, availability of food, predator presence, and inter-group spacing,<ref name="Kleiman DG-2002" /> and they vocalize at a high rate during daily group activities. The most extensive published study on within-group vocal behavior in wild golden lion tamarins<ref name=":6">Template:Cite journal</ref> reported that adults emitted an average of 2.1 vocalizations/minute.

Ruiz-Miranda and Kleiman<ref name="Kleiman DG-2002" /> identified a repertoire of 15 to 21 vocalizations, grouped into six categories defined by acoustic similarities: tonal, atonal, clucks, trills, multisyllable calls, and combination calls. Note that other published reports<ref name=":6" /><ref name=":7">Template:Cite book</ref><ref name="Kleiman1988">Template:Cite book</ref> have each used different names and grouping systems for golden lion tamarin calls.

Most golden lion tamarin vocalizations appear to provide information about the caller: identity;<ref name="Kleiman DG-2002" /><ref>Template:Cite journal</ref> location;<ref name=":6" /> activity;<ref name=":6" /> and perhaps intent.<ref name=":6" /> However, some vocalizations appear to provide information external to the caller,<ref name="Kleiman DG-2002" /> including alarm calls to the presence of a predator.<ref name="Kleiman DG-2002" /><ref name=":5" /> Boinski and co-authors<ref name=":6" /> reported that different within-group call types tended to each be associated with specific behavioral or spatial contexts and thus provided accurate, “honest” information about the caller to the rest of the group.

“Long calls” are loud, relatively long vocalizations used by golden lion tamarins both for within-group communication and for between-group communication related to inter-group spacing, including during territorial encounters between neighboring groups.<ref name="Kleiman DG-2002" /><ref name=":7" /><ref>Template:Cite journal</ref>

Young golden lion tamarins are also highly vocal, and may call at up to three times the rate of adults.<ref name="Kleiman DG-2002" /> Up to nine months of age, young golden lion tamarins mostly use loud rasps (one of the “atonal” vocalizations), medium or long trills, or combinations of rasps and trills.<ref name="Kleiman DG-2002" /> Early, before two months of age, these vocalizations are given by an infant thought to be signaling to be nursed or picked up by an adult.<ref name="Kleiman DG-2002" /> As immature golden lion tamarins begin eating solid food, these rasps and trills are used persistently while begging for food from other group members.<ref>Template:Cite journal</ref>

Olfactory Communication

Like other marmosets and tamarins,<ref name=":8">Template:Cite book</ref> golden lion tamarins scent-mark using multiple glandular regions. Research on other callitrichids indicates that scent marks allow receivers to differentiate individuals and determine sex, dominance status, and female reproductive status,<ref name=":8" /><ref>Template:Cite journal</ref> and this may be true for golden lion tamarins as well.

Studies on scent-marking in zoo and wild golden lion tamarins have led researchers to propose  specific within- and between-group communication functions that may vary by sex and dominance status, and that scent may serve as a marker for important ecological resources.<ref>Template:Cite book</ref><ref>Template:Cite journal</ref><ref>Template:Cite journal</ref> However, challenges in ascribing or excluding particular functions for scent-marking in callitrichids have been noted in studies on other callitrichid species, including conflicting interpretations of scent-marking data from wild moustached tamarins (Saguinus mystax) (compare <ref>Template:Cite journal</ref> with <ref>Template:Cite journal</ref>) and saddleback tamarins (Saguinus fuscicollis) (compare <ref>Template:Cite journal</ref> and <ref>Template:Cite journal</ref> with <ref>Template:Cite journal</ref>). Further, a summary largely focused on cottontop tamarins (Saguinus oedipus) and common marmosets (Callithrix jacchus)<ref>Template:Cite journal</ref> demonstrates the complex relationship between social context and chemical communication in callitrichids.

Visual Communication

A small array of visual signals has been described for golden lion tamarins.<ref name="Kleiman1988" /> The most striking of the visual signals are the arch displays. Similar displays have been described for many New World monkeys, including  callitrichid and non-callitrichid species.<ref name=":9">Template:Cite journal</ref>  The arch walk, the highest intensity of the golden lion tamarins arch displays, is characterized by erected fur, lowered head, forward-directed gaze, strongly arched back, rigid limbs and tail held down and pressed forward<ref name=":9" />(p 130). The arch-walking individual typically walks away from the apparent target of the signal.<ref name=":9" /> It has been noted that the arch display “makes the animal look larger and more conspicuous”<ref name="Kleiman DG-2002" />(p 251). The within-group functional significance of this striking but infrequent behavior is not entirely clear; see <ref name="Kleiman DG-2002" />(p 252),<ref>Template:Cite book</ref> and particularly <ref name=":9" /> for discussion of this behavior’s context and potential meanings.

Other visual signals reported from zoo environments are summarized in<ref name="Kleiman1988" /> and additional behaviors from both zoos and the wild are reported elsewhere (Oliveira et al. 2003).<ref>Hoage, R. J. (1982) Social and physical maturation in captive golden lion tamarins, Leontopithecus rosalia rosalia. Smithsonian Contributions to Primatology. No. 354</ref><ref>Template:Cite journal</ref><ref>Template:Cite journal</ref><ref>Template:Cite journal</ref>

Reproduction

The mother provides transportation at the early stages of the infant's life.

The mating system of the golden lion tamarin is largely monogamous. When there are two adult males in a group only one of them will mate with the female. There are cases of a male mating with two females, usually a mother and daughter.<ref name=Dietz1993/> Reproduction is seasonal and depends on rainfall. Mating is at its highest at the end of the rainy season between late March to mid-June and births peak during the September–February rains.<ref name=French2002>Template:Cite book</ref> Females are sexually mature between the ages of 15–20 months but it is not until they are 30 months old that they can reproduce.<ref name=Kleiman1988/> Only dominant females can reproduce and will suppress the reproduction of the other females in the group.<ref>Template:Cite journal</ref> Males may reach puberty by 28 months.<ref name=French2002/> Tamarins have a four-month gestation period. Golden lion tamarin groups exhibit cooperative rearing of the infants. This is due to the fact that tamarins commonly give birth to twins and, to a lesser extent, triplets and quadruplets. By way of example, 78% of recorded births in 2001 in the Poço das Antas Reserve consisted of twins.<ref>Template:Cite web</ref> A mother is not able to provide for her litter and needs the help of the other members of the group.<ref>Template:Cite book</ref> The younger members of the groups may lose breeding opportunities but they gain parental experience in helping to rear their younger siblings.<ref name=Bales2000/> In their first 4 weeks, the infants are completely dependent on their mother for nursing and carrying. By week five, the infants spend less time on their mother's back and begin to explore their surroundings. Young reach their juvenile stage at 17 weeks and will socialize with other group members. The sub-adult phase is reached at 14 months, when a tamarin first displays adult behaviors.

Conservation

Aerial view of Poço das Antas Biological Reserve.

The geographic range of and available habitat for golden lion tamarins have both shrunk drastically in the five centuries since the arrival of Portuguese explorers in Brazil in 1500.  However, there are no estimates of the size of the population pre-1500, and the first published estimates did not appear until the 1970s. By then, golden lion tamarin population estimates ranged from only 100 to 600 surviving individuals,<ref name="Coimbra-Filho-1973" /><ref name="Magnanini-1978" /> although these estimates were not based on range-wide censuses. The first such census, carried out in 1990-1992, counted approximately 560 wild individuals<ref name="Kierulff-2003" /><ref name="Kierulff-1994" /> and there were about 100 additional individuals from the reintroduction program living in the wild.<ref name="Kierulff-2003" /> Since then, the population has grown significantly, following conservation efforts that include reintroduction of zoo-born animals<ref name="Beck-2002" /><ref name="Kierulff-2002" /> and rescue and translocation of wild individuals from small, at-risk forest fragments<ref name="Kierulff-2002" /> (both largely to areas then unoccupied by tamarins), reforestation with a particular focus on connecting separated areas of habitat,<ref name="Dietz-2022" /><ref name="Menegassi-2023" /> and community-based conservation and engagement programs.<ref name="Padua-2002" /><ref name="Matsuo-2008" /> Most recently, a 2022/2023 census estimated more than 4,800 golden lion tamarins living in the current primary area of occurrence in the non-coastal area of the São João and Macaé river basins,<ref name="Dietz-2024" /> with unknown but smaller additional numbers in limited coastal forests<ref name="Rylands-2002" /> and to the west of the primary area of occurrence.<ref name="Burity-2007" /><ref name="Rubião-2022" />

The Associação Mico-Leão-Dourado (Golden Lion Tamarin Association) is a Brazilian not-for-profit focused on conservation of golden lion tamarins in the primary area of occurrence (the non-coastal area of the São João and Macaé river basins). The Association has identified a number of ongoing threats to continued recovery of the species.<ref name="Dietz-2022" /><ref name="Menegassi-2023" /><ref name="Ruiz-Miranda-2019">Template:Cite journal</ref><ref name="IUCN"/> Key threats include: habitat loss and fragmentation; hunting and trapping for the pet trade (see<ref>Anon. (2024) Brazil beat. The Golden Gazette. (www.savetheliontamain.org), 9 February 2024, unpaginated.</ref> for recent incidents); the recently highlighted threat of a yellow fever or other disease epidemic<ref name="Dietz-2019">Template:Cite journal</ref> and the potential impact of non-native species, most notably the introduced marmoset species that are now found in many of the forest areas occupied by golden lion tamarins,<ref>Template:Cite journal</ref><ref>Template:Cite journal</ref><ref>Template:Cite book</ref> and a feral population of introduced golden-headed lion tamarins (Leontopithecus chrysomelas) within 50 km of the geographic range of the golden lion tamarin, presenting a threat of hybridization (most of the golden-headed lion tamarins were removed between 2015 and 2018<ref name="Beck-2018" /><ref>Template:Cite journal</ref>).

Although not specifically identified in Association publications, climate change may also present a threat to long-term survival for golden lion tamarins. Meyer and co-authors<ref>Template:Cite journal</ref> used climate change modeling to estimate how much of the historic geographic ranges of the four lion tamarin (Leontopithecus) species would be suitable for their survival in 2050 and 2080. They concluded that the amount of climatically suitable habitat for golden lion tamarins would be severely reduced by 2050 and insufficient for population survival by 2080. The authors stressed caution in interpreting and acting on this conclusion because of numerous uncertainties in the modeling process.

Key events in the conservation of golden lion tamarins outlined below describe past and ongoing efforts to address many of these threats.

1970's: Following their field studies, which indicate a small, declining wild population of golden lion tamarins, Adelmar Coimbra-Filho and Alceo Magnanini champion efforts that result in the 1974 creation of the federal Poço das Antas Biological Reserve.<ref name="Magnanini-1978" /><ref>Template:Cite journal</ref><ref name="Pessamilio-2016">Template:Cite book</ref> In 1980, there were an estimated 75 to 150 golden lion tamarins living within the reserve.<ref>Green, K. M. (1980) An Assessment of the Poco D'Anta [sic] Reserve, Brazil, and Prospects for the Survival of the Golden Lion Tamarin, Leontopithecus rosalia rosalia. Unpublished report.</ref>

1983: The Golden Lion Tamarin Conservation Program begins activities in Brazil, launching the first systematic field studies of behavioral ecology of golden lion tamarins in the Poço das Antas Biological Reserve, later expanding to the União Biological Reserve and reintroduction sites, and initiating a community-based environmental education program in the area surrounding Poço das Antas.<ref name="Kierulff-1994" /><ref name="Matsuo-2008" /><ref name="Kleiman-1986" /><ref>Template:Cite book</ref><ref>Template:Cite book</ref> The program's successor, the Associação Mico-Leão-Dourado (Golden Lion Tamarin Association), a Brazilian not-for-profit, was launched in 1992 and is active today.

1984: The first zoo-born tamarins are reintroduced into the wild.<ref name="Beck-2002" /><ref name="Beck-2018" /><ref name="Kleiman-1986" /> Reintroductions, totaling 146 zoo-born golden lion tamarins, continue between 1984 and 2000. Additional details appear in a separate section below.

1994 (through 1997): Forty-three wild tamarins are rescued from small, at-risk forest fragments and translocated to the site of the future União Biological Reserve.<ref name="Kierulff-2002" /><ref name="Procópio de Oliveira-2008" /> Additional details appear in a separate section below.

1997: Reforestation efforts are begun by the Associação Mico-Leão-Dourado, with a focus on creating forested corridors to connect separated forest fragments,<ref>Template:Cite book</ref> and thus connect separated subpopulations of golden lion tamarins. By 2022, the Association had planted a total of Template:Cvt with native forest trees, in Poço das Antas Biological Reserve and on 15 private farms with tamarins.<ref name="Dietz-2022" /><ref name="Menegassi-2023" />

1998: A second federal protected area for golden lion tamarins, the União Biological Reserve, is created.<ref name="Kierulff-2002" /><ref name="Pessamilio-2016" /> This area had been the release site for tamarins translocated from smaller forest fragments in 1994-1997.

2003: Golden lion tamarin conservation status improves from Critically Endangered to Endangered in the IUCN Red List of Threatened Species.<ref name="IUCN"/>

2007-2024: The Associação Mico-Leão-Dourado acquires several privately held properties.<ref>Anon. (2016) A success story of forest restoration: Fazenda Dourada corridor – NEWS – Save the Golden Lion Tamarin, 10 June 2016. www.savetheliontamarin.org.</ref><ref>Anon. (2018) União – Expanding protection for GLTs – NEWS – Save the Golden Lion Tamarin, 30 January 2018. www.savetheliontamarin.org.</ref><ref>Anon. (2018) Land purchase gives GLTs a chance to survive – NEWS – Save the Golden Lion Tamarin, 20 April 2018. www.savetheliontamarin.org.</ref><ref name="Menegassi-2025">Template:Cite web</ref> Each provides opportunities for reforestation to establish critical forest connections between separated golden lion tamarin subpopulations.

2016: The Associação Mico-Leão-Dourado adopts an overall 2025 goal of 2,000 wild golden lion tamarins living in 25,000 ha (61,766 acres; 250 km², 97 miles²) of connected and protected habitat, which computer modeling suggests would achieve 100% probability of species survival for the next 100 years, with retention of 98% of (then current) genetic diversity during that period.<ref name="Ruiz-Miranda-2019" />

2016-2019: An outbreak of yellow fever causes extensive mortality among golden lion tamarins, killing approximately 30% of the wild population, including most or all of the tamarins in the Poço das Antas Biological Reserve.<ref name="Dietz-2019" /> The Brazilian primatological and public health communities recognize yellow fever as an existential threat to nonhuman primate populations, and develop a dosage of surplus human yellow fever vaccine appropriate for smaller body size animals.<ref name="Possas-2018">Template:Cite journal</ref> After the Rio de Janeiro Primate Center tests the vaccine's efficacy and safety on lion tamarins housed there,<ref name="Possas-2018" /> Associação Mico-Leão-Dourado biologists begin vaccinating wild tamarins in 2021, apparently the first such program for wild individuals of an endangered primate.<ref>Template:Cite journal</ref> As of the end of 2024, 489 individuals had been vaccinated.<ref name="Menegassi-2025" />

2020: Wildlife passageways across the recently widened highway BR-101 are completed, including one land bridge (in process of being forested) and ten canopy overpasses.<ref name="Dietz-2022" /><ref name="Secco-2022">Template:Cite journal</ref> BR-101 runs adjacent to a portion of Poço das Antas Biological Reserve and between the two sections of União Biological Reserve, as well as separating Poço das Antas and one section of União from relatively large tamarin subpopulations on the northern side of the highway. The company that designed and constructed the highway expansion was legally required to fund these mitigating actions to maintain and expand fragment connectivity and reduce traffic-related wildlife deaths on this busy<ref>Template:Cite journal</ref> highway. Tamarins were already using two of the canopy overpasses by late 2021.<ref name="Secco-2022" />

2022/2023: The fourth census of wild golden lion tamarins shows an estimated population of more than 4,800 in the species' primary area of occurrence, indicating rapid recovery from the yellow fever epidemic.<ref name="Dietz-2024" />

Reintroduction

In the early 1980's, the Smithsonian National Zoological Park and the Rio de Janeiro Primate Center initiated a program to reintroduce captive-born golden lion tamarins to bolster the existing wild population, thought to be no more than 600 individuals at the time.<ref name="Coimbra-Filho-1973" /><ref name="Magnanini-1978" /> From 1984 to 2000, as part of the Golden Lion Tamarin Conservation Program (and later the Associação Mico Leão Dourado), 146 captive-born and seven confiscated wild-born golden lion tamarins were released into the wild. Seventeen of these were released in the Poço das Antas Biological Reserve , early in the program, and the remainder on 20 privately owned ranches and farms in the species' historic area of occurrence (Kleiman et al. 1986, 1990, 1991.<ref name="Dietz-2024" /><ref name="Beck-2002" /><ref name="Kierulff-2002" /><ref name="Beck-2018" /><ref name="Procópio de Oliveira-2008" /><ref name="Beck1991">Template:Cite journal</ref><ref name="Kleiman-1986">Template:Cite book</ref><ref>Template:Cite book</ref><ref>Template:Cite news</ref> The animals had been born at or lived in 43 different zoos and research centers in Brazil, Europe, and the United States. None of the release sites, including the specific release sites in Poço das Antas, was thought to have wild golden lion tamarins at the time of the reintroductions.

The reintroduced captive-born golden lion tamarins all had pre-release veterinary examinations. Those from Europe or the United States were quarantined for 30 days, either at one of several designated zoo quarantine facilities before shipment or at the Rio de Janeiro Primate Center after arrival in Brazil. All of the captive-born individuals were acclimated for at least 24 hours in outdoor cages at the reintroduction sites before their release.<ref name="Beck-2002" /> The animals were monitored on five or six days per week for at least three months after being released. Most were given supplementary food and artificial shelter boxes for at least several months, and were captured and returned to the release site if they got lost.<ref name="Beck-2002" /> This intensive post-release support improved early survival rate, although efforts to train tamarins in survival-critical skills pre-release did not appear to affect post-release survival.<ref name="Beck-2002" />

Over time, some of the reintroduced golden lion tamarins and/or their offspring were translocated to eight other privately owned locations<ref name="Matsuo-2008" /> and recovery of forests on private lands has also allowed the tamarins to expand on their own to additional ranches and farms. As of 2022, 22 of the farms and ranches with golden lion tamarins were official private nature reserves.<ref name="Menegassi-2023" /> At the time of the most recent census, in 2022/2023, there were estimated to be 2,256 surviving descendants of reintroduced golden lion tamarins, representing almost half (46%) of the total estimated population in the species' primary area of occurrence, in the non-coastal area of the São João and Macaé river basins in the Brazilian state of Rio de Janeiro (calculated from,<ref name="Dietz-2024" /> Supplementary Material).

Golden lion tamarin on the Brazilian Real R$20 banknote.

Translocation

During a 1990-1992 survey, a number of golden lion tamarin groups were identified in very small and/or immediately imperiled forest fragments in the Rio de Janeiro State municipalities of Cabo Frio, Búzios, Saquarema, and Araruama.<ref name="Kierulff-2003" /> Between 1994 and 1997, under the administration of the Associação Mico-Leão-Dourado (Golden Lion Tamarin Association), 43 individuals from some of these forest remnants, in Cabo Frio, Búzios, and Saquarema (6 family groups and one single individual), were rescued and translocated to the location of what would become (in 1998) the União Biological Reserve<ref name="Kierulff-2002" /><ref name="Procópio de Oliveira-2008">Template:Cite book</ref><ref>Template:Cite journal</ref><ref name=":2"/><ref name="Beck-2018">Template:Cite book</ref>). The reserve lies within the species' historic area of occurrence but had no resident golden lion tamarins at the time. The two primary goals of the translocation program were to rescue imminently threatened golden lion tamarins and to add genetic diversity to the more protected part of the population.<ref name="Kierulff-2002" /><ref name="Procópio de Oliveira-2008" />

The population at the União reserve has grown substantially since the initial translocations. The population had already grown to 120 by December 2000,<ref name="Kierulff-2002" /> and to more than 220 in 30 family groups by 2006.<ref name="Procópio de Oliveira-2008" /> The most recent census, carried out in 2022-2023 estimated that there were 473 descendants of the original translocated golden lion tamarins.<ref name="Dietz-2024" /> This represented 10% of the total estimated 2022-2023 population of 4,869 in the species' primary area of occurrence in the non-coastal area of the São João and Macaé river basins (calculated from,<ref name="Dietz-2024" /> Supplementary Materials).

External links

• Images and movies of the golden lion tamarin (Leontopithecus rosalia) ARKive
• Leontopithecus rosalia Factsheet Primate Info Net
• Associação Mico-Leão Dourado (Golden Lion Tamarin Association) Brazilian NGO focused on golden lion tamarin conservation.
• Save the Golden Lion Tamarin US NGO focused on golden lion tamarin conservation