Golden lion tamarin

The golden lion tamarin (Leontopithecus rosalia; Portuguese: mico-leão-dourado [ˈmiku leˈɐ̃w do(w)ˈɾadu, - liˈɐ̃w -]), 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. Its 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, with unknown but smaller additional numbers in limited coastal forests and to the west of the primary area of occurrence. There is a ca...

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. 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 semideciduous forest, with some tamarins living in areas closest to the coast found in a sandy soil forest type called "arboreal restinga". Golden lion tamarins are thought to occur primarily in low-elevation forests, up to 150 or 300 meters above sea level, but a 1990–1992 survey identified two groups above 500 meters, and reports from the recently identified western geographic area include records above 700 meters. Golden lion tamarin population estimates in the 1960s and 1970s ranged from only 100 to 600, although these estimates were not based on range-wide censuses. The first such census, carried out 1990–1992, counted about 560 wild individuals and there were about 100 additional individuals from the reintroduction program living in the wild. Since then, following conservation efforts including reintroduction of zoo-born animals and translocation of wild individuals from small, at-risk forest fragments (both largely to areas then unoccupied by tamarins), reforestation with a particular focus on connecting separated areas of habitat, and community-based conservation and engagement programs, the population has grown significantly. Most recently, a 2022-23 census estimated about 4,800 golden lion tamarins living in the current primary area of occurrence in the noncoastal area of the São João and Macaé River basins, with unknown but smaller additional numbers in limited coastal forests and to the west of the primary area of occurrence.

Brazil

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). ==== Plant material ==== Fruits, mostly ripe, are the plant part consumed by golden lion tamarins for more than 80% of plant species eaten. Tamarins swallow the seeds of most fruits they consume and are considered to function as effective seed dispersers for many plant species. Wild golden lion tamarins eat from a wide variety of plant species, with 160 species noted in one multiple-group study. Despite this variety of food plants, they appear to get most of their plant food from a smaller subset of species. 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. The most common reported source of nectar in golden lion tamarin diets are the flowers of the tree Symphonia globulifera. Nectar consumption typically represents a small proportion of the plant diet (6%-10% of observations or time), but some groups may concentrate heavily on nectar during the cool, dry season in at least some years. Exudates or tree gum are soft, semiliquid substances produced by trees and lianas in response to damage to exterior bark or to disease. Golden lion tamarins in the Poço das Antas Reserve fed occasionally on tree gum that they found opportunistically on trees and woody lianas, and gum consumption represented less than 2% of total feeding observations or time. Lion tamarins (and other tamarins) lack the dentition and other specializations for gum-feeding characteristic of marmoset genera, e.g., Callithrix and Cebuella. ==== 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. Orthopteran insects (e.g., grasshoppers, katydids, and crickets) were the most commonly eaten prey in one study. 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 junctions 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. This is a form of the foraging technique known as "extractive foraging on embedded foods", and in golden lion tamarins has been termed "micro-manipulation". Peres 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.

Golden lion tamarins are social and groups typically consist of two to eight members. These groups usually consist of one breeding adult male and female but may also have two or three males and one female or the reverse. Other members include subadults, juveniles, and infants of either sex. These individuals are typically the offspring of the adults. When more than one breeding adult is in a group, one is usually dominant over the other, which 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 that inherited her rank from her mother. Both males and females may leave their natal groups at the age of four, but 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. 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 that are likely brothers. When this happens, only one of the new males is able to breed and suppresses 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.

longest observed 31.6 years.

The mating system of the golden lion tamarin is largely monogamous. When two adult males are in a group, only one of them mates with the female. There are cases of a male mating with two females, usually a mother and daughter. 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. Females are sexually mature between 15 and 20 months old, but they cannot reproduce until 30 months old. Only dominant females can reproduce and will suppress the reproduction of the other females in the group. Males may reach puberty by 28 months. Tamarins have a four-month gestation period. Golden lion tamarin groups exhibit cooperative rearing of the infants, because tamarins commonly give birth to twins, and to a lesser extent, triplets and quadruplets. For example, 78% of recorded births in 2001 in the Poço das Antas Reserve consisted of twins. A mother is not able to provide for her litter and needs the help of the other members of the group. The younger members of the groups may lose breeding opportunities, but they gain parental experience in helping to rear their younger siblings. 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 begin to socialize with other group members. The subadult phase is reached at 14 months, when a tamarin first displays adult behaviors.

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. 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. The golden lion tamarin is the largest of the callitrichid monkeys. It is typically around 261 mm (10.3 in) and weighs around 620 g (1.37 lb). Almost no size difference exists 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. Golden lion tamarins walk, run, and bound quadrupedally on top of branches, or, less frequently, they run and walk on the ground. 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". In addition, facilitated by their claw-like nails, golden lion tamarins cling and climb on vertical tree trunks (see photographs in Serra (2019), pp 108–117, 137, 155).

Only a few published reports confirm the identities of successful predators on golden lion tamarins, with these cases including a boa constrictor (Boa constrictor) (p 158), a small cat identified as an ocelot (Felis pardalis), and a feral dog (Canis familiaris), 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; capuchin monkeys (Cebus/Sapajus nigritus); coatimundis (Nasua nasua); and tayra (Eira barbara). Tayra were strongly suspected as the primary predator in a series of deaths and disappearances in Poço das Antas Biological Reserve. 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. At least during this period, most documented predation appeared to have occurred overnight, at or near sleeping sites. Several 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, 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, but are reported to retreat quietly from capuchin monkeys(p 240). Golden lion tamarins also use alarm vocalizations in reaction to predators. Calls associated with terrestrial and arboreal predators are reported to differ from those associated with flying predators, in both captive situations and the wild.

The geographic ranges of and available habitats for golden lion tamarins have both shrunk drastically in the five centuries since the arrival of Portuguese explorers in Brazil in 1500. However, no estimates of the size of the population before 1500 are known, 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, although these estimates were not based on range-wide censuses. The first such census, carried out in 1990-1992, counted about 560 wild individuals and about 100 additional individuals from the reintroduction program were living in the wild. Since then, the population has grown significantly, following conservation efforts that include reintroduction of zoo-born animals and rescue and translocation of wild individuals from small, at-risk forest fragments (both largely to areas then unoccupied by tamarins), reforestation with a particular focus on connecting separated areas of habitat, and community-based conservation and engagement programs. Most recently, a 2022/2023 census estimated more than 4,800 golden lion tamarins living in the current primary area of occurrence in the noncoastal area of the São João and Macaé River basins, with unknown but smaller additional numbers in limited coastal forests and to the west of the primary area of occurrence. The Associação Mico-Leão-Dourado (Golden Lion Tamarin Association) is a Brazilian not-for-profit focused on conservation of golden lion tamarins in their primary area of occurrence. The association has identified a number of ongoing threats to continued recovery of the species. Key threats include habitat loss and fragmentation, hunting and trapping for the pet trade, the recently highlighted threat of a yellow fever or other disease epidemics, 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, 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). Although not specifically identified in association publications, climate change may also present a threat to long-term survival for golden lion tamarins. Meyer and coauthors 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. 1970s: Following their field studies, which indicate a small, declining wild population of golden lion tamarins, Adelmar Coimbra-Filho and Alceo Magnanini championed efforts that resulted in the 1974 creation of the federal Poço das Antas Biological Reserve. In 1980, there were an estimated 75 to 150 golden lion tamarins living within the reserve. 1983: The Golden Lion Tamarin Conservation Program began 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. The program's successor, the Associação Mico-Leão-Dourado, a Brazilian not-for-profit, was launched in 1992 and is active today. 1984: The first zoo-born tamari…

Golden lion tamarins usually spend more than half their time in overnight sleeping sites and thus they 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 (calculated from Table 1). Active periods are longer in the austral summer, which have 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. Multiple authors have reported that golden lion tamarins prefer to sleep in naturally occurring tree holes. Tree holes, also termed tree cavities or tree hollows, are reported as the predominant sleeping site for other lion tamarin species as well. 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%). Golden lion tamarin groups in the União Biological Reserve used tree holes exclusively or almost exclusively. 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. Golden lion tamarin groups use multiple sleeping sites across time. Some groups in the Poço das Antas Biological Reserve used more than 40 sites across multiple years of study. Groups use a small subset of these sites frequently, suggesting that some sites are highly preferred over others. In the Poço das Antas Biological Reserve, golden lion tamarin groups used the same sleeping site on consecutive nights in roughly 50% of the cases when sites for consecutive nights were identified. Two groups in the União Biological Reserve used the same site on consecutive nights at somewhat lower rates, 20% and 38%. Multiple authors 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 (for example,) Bigger (heavier) brains, relative to body weight, are said to be correlated with, and are implied to be causally linked to, better cognitive performance on a variety of tasks, e.g., Jerison, but see Reader and Laland and van Schaik et al.. Primates tend to have relatively larger brains than other mammalian orders, or any other group of living animals, but tamarins and marmosets have relatively smaller brains than apes and other monkeys. Reader et al. (2011), using a single measure of nonhuman primate intelligence that combined performance on a variety of cognitive laboratory tasks, showed that callitrichid primates (lion tamarins, tamarins, and marmosets) perform poorly compared to apes, macaques, baboons, capuchin monkeys, and even lemurs and lorises. Lion tamarins (species of the genus Leontopithecus) had the lowest value of this intelligence measure among all primate genera in this dataset. In similar comparative studies of primate cognitive performance, by Deaner et al., members of the marmoset genus Callithrix were ranked 23rd of 24 primate genera, lower than even the lemurs and lorises that were included. Lion tamarins were not tested in these studies, and extrapolation from the performance of the genus Callithrix to that of Leontopithecus should be made cautiously. Deaner et al. and Dunbar and Schulz both concluded that, in general, marmosets and tamarins (including lion tamarins) perform poorly relative to other primates on laboratory tests of non-social problem-solving and strategic thinking. Other papers have included or focused on lion tamarin cognitive performance. Day et al. studied the extraction of foods from novel puzzle-boxes by captive lion tamarins, other tamarins, and marmosets. The lion tamarins (study subjects included black and golden-headed lion tamarins in addition to golden lion tamarins) began working on the tasks significantly faster and had more successful task solutions than either the other tamarins or the marmosets. Menzel and Beck conducted a study of spatial memory and detour behavior by a family group of six golden lion tamarins that were living in a large, outdoor free-ranging zoo exhibit. When their preferred arboreal travel routes were severed, the tamarins learned quickly how to find and navigate detours.