Callithrix aurita occurs in montane rain forests and forests of the inland plateau, at altitudes up to 1,300 m, where dry season temperatures can fall close to freezing (Ferrari et al. 1996, Brandão and Develey 1998). Callithrix aurita and C. flaviceps are the southernmost forms of marmosets within the natural range of the genus (C. jacchus, C. penicillata and C. geoffroyi have been introduced further south in Paraná, São Paulo, Santa Catarina and Argentina). There is what would appear to be a natural hybrid zone with Callithrix flaviceps, at the Serra do Brigadeiro, Carangola, in south-eastern Minas Gerais (Coimbra-Filho et al. 1993, Cosenza 1993, Cosenza and Melo 1998).

Marmosets and tamarins are distinguished from other Neotropical primates by their small size, modified claws rather than nails on all digits except the big toe, the presence of two as opposed to three molar teeth on either side of each jaw, and by the occurrence of twin births. They eat fruits, flowers, nectar, plant exudates (gums, saps, latex) and animal prey (including frogs, snails, lizards, spiders and insects). Marmosets have morphological and behavioural adaptations for gouging tree trunks and branches (and vines of certain species), to stimulate the flow of gum, which they eat, and in some species form a notable component of the diet (Coimbra-Filho 1972, Rylands 1984). They live in extended family groups of 4 to 15 individuals. Generally, only one female per group breeds during a particular breeding season. Brandão (1999) recorded a home range size of 39.9 ha (extending as high as 1,350 m asl) for one group at the Bananal Ecological Station, São Paulo.

The ecology and behaviour of C. aurita was studied by Muskin (1984a,b; Martins 1998a,b; Martins and Setz 2000; Santos and Martins 2000) in southern Minas Gerais and by Brandão (1999) and Brandão and Devely (1998) at the Bananal State Ecological Station in Brazil. Corrêa (1995), Ferrari et al. (1996), Corrêa et al. (2000), Coutinho (1996) and Coutinho and Corrêa (1995) studied the behavioural ecology of the species at the Núcleo Cunha of the Serra do Mar State Park in São Paulo, Brazil. Coutinho (1996) studied particularly the social and reproductive behaviour.

The dentition of Callithrix aurita is less specialized for tree-gouging to obtain gum than it is in C. jacchus and C. penicillata (see Natori 1986). Despite this, gum is an important part of their diet all year round, and largely obtained from sites where it is available without requiring gouging (Muskin 1984a, b; Coimbra-Filho 1991; Corrêa 1995; Ferrari et al. 1996; Martins and Setz 2000). Martins (2000) recorded them foraging on army ant (Eciton burchelli) swarms. Notable for this species is its consumption of fungi, otherwise recorded only in Callimico goeldii. They find the fruiting bodies of fungi on the stems of bamboo species (Merostachys spp.) and the South American mountain bamboo (Chusquea spp.), both of the family Poaceae.
Size:Female weight: 400-450 g (Garber 1992); Male weight: 400-450 g (Garber 1992)

Callithrix aurita occurs in the montane rain forests of south-eastern Brazil, in the southern part of the state of Minas Gerais, the state of Rio de Janeiro, and the East and North-east of the state of São Paulo (see Coimbra-Filho 1986b, Olmos and Martuscelli 1995, Brandão and Develey 1998, Ferrari et al. 1996). Hershkovitz (1977) marks the northern limit in Minas Gerais as the Rio Muriaé, but it occurs to the north in the Rio Doce State Park in Minas Gerais (Mittermeier et al. 1982), and hybrids (with C. flaviceps) have been recorded at Carangola in the Serra do Brigadeiro, Minas Gerais (Ferrari and Mendes 1991; Mendes 1997a,d; Cosenza and Melo 1998). Melo and Rylands (2008) described the geographical distribution of this taxon. The northern boundary of its distribution seems to be the Piracicaba River, in Minas Gerais; the southern limit is the river Doce. In the West, it seems to extend to Espinhaço in Minas Gerais, and to the transition areas of the Cerrado in São Paulo. To the East, in Rio de Janeiro, the species is limited to the tops of the slopes of the Serra do Mar, with the exception of the southern state, where C. aurita can be found almost at sea level.Its southern boundary is still unknown, because the great mass of Paranapiacaba in Sao Paulo can house relict populations, as well as Leontopithecus chrysopygus (Lima et al. 2003). Hershkovitz (1977) indicated the south-easternmost locality to be the Rio Ribeira de Iguapé in São Paulo. However, Olmos and Martuscelli (1995) failed to find evidence for this. They reported that extensive fieldwork (1982-1995) in such localities as the Fazenda Intervales State Park, Alto Ribeira State Park, Ilha do Cardoso and Carlos Botelho, and the Jureia Ecological Station and the muncipalities of Juquitiba amd Miracatú in the Serra da Paranapicaba consistently failed to find C. aurita. They proposed the southern limit to be near the city of São Paulo, north of the junction of the Rios Pinheiros and Tietê. The Rio Tieté forms the southernmost boundary and the most southerly record is close to Ipanema (23º26’S, 47º36’W), today Araçoiaba da Serra (the type locality for Leontopithecus chrysopygus). From there it extends west between the upper reaches of the Rios Tieté/Piracicaba. Again the exact limits are unclear, but believed to be the junction of these two rivers (Olmos and Martusecelli 1995).

Brandão and Develey (1998) carried out surveys to better understand the range of C. aurita. Although generally believed to be largely montane in its range (600-1,200 m asl) according to Olmos and Martuscelli (1995), and (500-800 m asl) according to Rylands (1994), museum specimens have been collected on the foothills of the Serra do Mar, south of Rio de Janeiro (Pedra Blanca, municipality of Paratí at 80 m asl, and Mambucaba, municipality of Angra dos Reis at 100 m asl; Brandão and Develey 1998). Coimbra-Filho (1991) and Mendes (1993) also indicated that it occurred elsewhere in lowland Rio de Janeiro, including the North-east, but is probably today extinct there. All recent records are montane. Brandão and Develey (1998) carried out extensive surveys of the lowland coastal forests of São Paulo and Rio de Janeiro and were unable to obtain evidence of the species’ existence anywhere except at Mambucaba where they found one in captivity and observed a group at 165 m asl.

This marmoset has been recorded north of the Rio Paraíba do Sul at the following sites: Mogi-Guaçú (Rio Mogi-Guaçú) by R. A. Mittermeier (unpubl.) and Muskin (1984); Alfenas, upper Rio Grande, in Minas Gerais (Hershkovitz 1977, Muskin 1984a); Vargem Grande, São Paulo (Muskin 1984a); Fazenda Monte Alegre, Monte Belo, Minas Gerais (Muskin 1984a) and in the vicinity of Viçosa, Minas Gerais (Mendes 1993); Serra do Capanema, Rio de Janeiro (21º03’S, 42º03’W) (Mendes 1993), Fazenda João Abdo, Rio de Janeiro (21º27’S, 41º56’W) (Mendes 1993). The westernmost locality shown by Hershkovitz (1977) is Boracéia, north-east of Bauru, on the upper Rio Tieté (22°10'S, 48°45'W), but Olmos and Martuscelli (1995) found this to be an outlier and suggested that this locality actually refers to the Boracéia Biological Station near the headwaters of the Rio Tietê.Recent C. aurita records have been published, in the northwest of the state of Rio de Janeiro (Bergallo et al. 2009a,b;. D. Pereira, unpubl. data) and in enclaves of Cerrado in São Paulo and in the southern and southeastern areas of Minas Gerais (Bechara 2012). More samples to define the southern distributional limit are required. Regions such as the great mass of Paranapiacaba and the south bank of the Tiete River in Sao Paulo are areas of potential local occurrence of this taxon (Melo and Rylands 2008).

Callithrix aurita is listed on Appendix I of CITES. The species also occurs in a number of protected areas:

Minas Gerais

• APA Agua Santa da Minas (15,680 ha)
• Parque Natural Municipal Antônio Guimarães de Almeida, Tombos
• Parque Natural Municipal Cachoeira de Tombos, Tombos
• Rio Doce State Park (36,000 ha; Stallings and Robinson 1991)
• Serra do Brigadeiro State Park (32,500 ha; Cosenza and Melo 1998)
• RPPN Dr. Marcos Vidigal de Vasconcellos

Rio de Janeiro

• Serra dos Orgaos National Park (10,500 ha; Pereira 2006, 2010)
• Desengano State Park (22,400 ha)
• Pedra Branca State Park (12,500 ha)
• Tres Picos State Park (65,100 ha)
• Piraí Ecological Station (4,000 ha)
• RPPN Sitio do Café (Oliveira 2012)
• APA Petropolis (68,224 ha)
• APA Estadual da Bacia do Rio Macacu (19,508 ha)
• APA Estadual de Macae de Cima (35,308 ha)
• APA Municipal da Pedra Branca (5,388 ha)
• RPPN Fazenda Barra do Sana (162 ha)
• RPPN Maria Francisca Guimares (1 ha)

Rio de Janeiro/Sao Paulo

• Serra da Bocaina National Park (110,000 ha)
• APA de Cairucu (34,690 ha)

Rio de Janeiro/Minas Gerais

• Itatiaia National Park (30,000 ha. Ávila-Pires and Gouveia 1977; Mittermeier et al. 1982; Coimbra-Filho 1986b, 1991; Loretto and Rajão 2005)

 Sao Paulo

• APA Manancias do Rio Paraiba do Sul (292,000 ha)
• APA Sao Francisco Xavier (11,559 ha)
• APA do Sistema Cantareira (249,200)
• APA Cananeia-Iguape-Peruibe (202,308 ha)
• APA Estadual de Campos do Jordao (28,800 ha)
• APA Estadual Jundiai (43,200 ha)
• ARIE Cerrado Pe-de-Gigante (1,200 ha)
• ESEC Estadual Bananal (884 ha; Brandao 1999)
• ESEC Estadual Itapeti  (89 ha)
• ESEC Jureia-Itatins  (84,425 ha)?
• ESEC de Mogi-Guaçu (980 Ha)
• ESEC Valinhos (17 ha; Rylands et al 1993)
• Campos do Jordao State Park (8,341 ha)
• Cantareira State Park (7,917 ha; Coimbra-Filho 1981, Rylands et al 1993)
• Itaberaba State Park (15,000 ha)
• Itapetinga State Park (10,000 ha)
• Nascentes do Tiete State Park (134 ha, W. Lacerda pers. comm)
• Parque Natural Municipal Augusto Ruschi (200 hectares; W. Lacerda pers. comm.)
• Serra do Mar State Park (332,000 ha; Brandao and Dewey 1998, Correa 1995, Coutinho 1996, Ferrari et al 1996, Norris et al 2011)
• Parque Natural Municipal da Serra do Itapety (362 ha; Manzatti and Oliveira 1996, Oliveira et al 1999)
• Vassununga State Park (2,071 ha; Rylands et al 1993)
• Alto Ribeira Tourist State Park (35,712 ha)
• REBIO Estadual do Alto da Serra de Paranapiacaba (336 ha; Rylands et al 1993)
• RPPN Morro do Curussu Mirim (24 ha)
• RPPN Sitio Curucutu (11 ha)

 Rio de Janeiro/Sao Paulo/Minas Gerais

• APA Serra da Mantiqueira (437,524 ha)