Three primates (Alouatta caraya, Sapajus nigritus and Sapajus cay) are found in riparian areas of the Upper Paraná River in southern Brazil. Population densities of these three species were estimated from October 2004 through September 2005 by counts on linear transects in riparian forests on two riverine islands and adjacent shores in the states of Mato Grosso do Sul and Paraná. A total of 397 sightings of these species were accumulated in 188 km of traversed transects. Alouatta caraya was the most abundant species on the large island (2.56 ind ha-1) and on the Mato Grosso do Sul side (0.84 ind ha^-1). This density was greater than twice that of the sympatric S. cay (0.31 ind ha^-1). Sapajus nigritus was the most abundant species on the Paraná side (0.51 ind ha^-1) followed by A. caraya (0.40 ind ha^-1). The folivorous A. caraya was the most abundant in flooded forests, while the omnivorous Sapajus species were less so. Differences in forests, conservation status, dispersal restrictions and autecology of the primates help explain differences in primate abundance.

On 7 and 8 December 2011, students, researchers, and conservationists with a vested interest in golden-headed lion tamarins (Leontopithecus chrysomelas; GHLTs) gathered at the State University of Santa Cruz (UESC; Ilhéus, Bahia, Brazil) for the symposium ‘Golden-Headed Lion Tamarin Research in the 21^st Century: Recent Advances and Potential Areas of Future Research ’ with the aim of sharing recent work and discussing potential future avenues for research. Within the last 5 years, several doctoral dissertations and masters theses were completed that focused on the biology, ecology, and/or conservation of GHLTs in addition to the ongoing work of established scientists who have devoted their professional lives to the study of this species and the Atlantic Forest. However, language barriers and the fact that many members of the GHLT community are based at institutions throughout the world have complicated widespread access to these results and collaborations among researchers. The primary goals of this symposium were to (1) promote the exchange of existing information, (2) contribute towards a better synchronization of research efforts, and (3) identify important steps for more efficient/ collaborative conservation efforts for GHLTs and their habitat. This symposium brought together 30 participants from 12 institutions in Brazil, Belgium and the USA and allowed for the dissemination of information to the global GHLT community, compilation of recent advances in research, and identification of gaps in knowledge of GHLT biology, ecology and conservation, which ultimately fostered discussions on how attendees could collaborate to fill knowledge gaps.