Lowland seasonal rain forest of the Atlantic coast of Brazil with rainfall of about 2,000 mm a year, sub-xeromorphic restinga (sandy soil forest), low (8-10 m) inundated forest (caxetais), and secondary forest (Rylands 1993). Golden lion tamarins are an adaptable species well able to live in degraded and secondary forests, depending on sufficient year round food sources and foraging sites, along with the tree holes they use as sleeping sites (see Coimbra-Filho 1969, 1976; Coimbra-Filho and Mittermeier 1973).

Marmosets and tamarins are distinguished from the other monkeys of the New World 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 in either side of each jaw, and by the occurrence of twin births. They eat fruits, flowers, nectar, plant exudates (gums) and animal prey (including frogs, snails, lizards, spiders and insects) (see Rylands 1993; Kierulff et al. 2002a).

Kierulff et al. (2002a) provide a comprehensive review of the behavioural ecology of the lion tamarins. They differ from other callithrichids in having long fingers and hands, which allow them to forage for prey efficiently in nooks and crannies and in epiphytic tank bromeliads.

Lion tamarins live in extended family groups of usually 4 to 8 individuals. Generally, only one female per group breeds during a particular breeding season. They breed once a year. The groups defend home ranges of 40 to more than 100 ha (the size depending on availability and distribution of foods and second-growth patches). In the Superagüi National Park, L. caissara have been found to use very large home ranges (321 ha), travelling from 1,082 to 3,398 m a day (Prado 1999).

The first bevioural ecological study of this study of this species was carried out by Prado (Prado and Valladares-Padua 1997; Prado 1999; Prado et al. 2000).

French et al. (2002) review the reproductive biology of lion tamarins, Baker et al. (2002) review their mating system and group dynamics (focussing particularly on L. rosalia) and Tardif et al. (2002) aspects of infant care and development.