For the first time, researchers have documented, using video recordings, a black lion tamarin (Leontopithecus chrysopygus) infant from birth through its first two months of life, as well as the development of a juvenile individual from four to twelve months of age, the subadult stage. The footage was captured using camera traps installed in the understory of the inland Atlantic Forest in the Pontal do Paranapanema region, western São Paulo State, and provides unprecedented records for biodiversity conservation.
The images are part of a recent study published in the International Journal of Primatology. Using 27 cameras installed in trees at heights ranging from 0.5 to 8 meters, researchers collected approximately 1,300 mammal records between November 2020 and December 2024, including around 130 records of black lion tamarins. The Pontal do Paranapanema region, where IPÊ has been active for over 40 years, is home to the largest known population of black lion tamarins, with approximately 1,800 individuals living in the wild.
Daniel Felippi, veterinarian with the Black Lion Tamarin Conservation Program, an initiative of IPÊ – Institute for Ecological Research, and first author of the article, highlights the insights gained from the images. “The fact that we were able to document, in a non-invasive way, both an infant and a juvenile over time already provides important indications regarding their survival. When the infant appeared in images during the first weeks and months after birth, we know it successfully passed through this initial stage, which is the most critical period of life. This contributes to research because data collection does not cause stress to the animals and expands monitoring possibilities across different areas.” For the study, researchers defined three focal groups of black lion tamarins.
Black lion tamarin infant riding on the back of an adult individual
Juvenile black lion tamarin at the top of the image
Maria Carolina Manzano, a researcher with the Black Lion Tamarin Conservation Program and a member of the team responsible for the study, explains that the research focused on evaluating the effectiveness of camera traps as a non-invasive monitoring tool for black lion tamarins and other arboreal mammals in forest fragments that are key to conservation efforts.
“We selected two forest fragments as study areas: the continuous forest of Morro do Diabo State Park and the San Maria Farm fragment. These sites differ in structure and resource availability, factors that may influence how black lion tamarins and other arboreal mammals use natural and artificial resources. Our objectives were to characterize daily activity patterns in a forest fragment and a continuous protected forest area; compare the use of specific arboreal resources, including natural structures such as tree cavities and structurally important trees, as well as complementary conservation resources such as nest boxes and feeding stations; and analyze population structure through the monitoring of black lion tamarin groups.”
Innovation in the Forest Canopy
Monitoring biodiversity through camera traps installed on tree trunks approximately half a meter above the forest floor is a well-established practice. However, the use of this technology in the understory, where in the inland Atlantic Forest, 50% of threatened mammal species occur, remains limited, mainly to specific contexts such as canopy bridges. Studies focused on evaluating demographic parameters, like this study, represent a significant methodological and research gap in conservation science. “I believe this is mainly due to the logistical and technical challenges of installing and maintaining equipment in the canopy and understory. In addition, monitoring in higher forest strata is still relatively recent and less standardized than ground-based monitoring, which limits its application. In our study, we also explored the potential of using arboreal cameras directed at resources specifically used by black lion tamarins, and this proved to be an effective approach for monitoring the species. Initiatives like this are therefore important for demonstrating the potential of this methodology and expanding its use in ecological and conservation studies,” explains Maria Carolina.
The camera traps, installed at heights ranging from 0.5 to 8 meters and equipped with passive infrared motion sensors, operated 24 hours a day, recording 15-second videos with a minimum interval of 10 seconds between recordings until no further movement was detected.
The Atlantic Forest, where the study was conducted, is among the most threatened biomes on the planet. Only 12% of its original vegetation cover remains, and it is recognized globally as a biodiversity hotspot due to its high levels of endemism, species found nowhere else, and the severe human pressures it faces, including habitat loss and fragmentation, the primary threats to black lion tamarin conservation. “Arboreal cameras provided us with an unprecedented view of these forests from the top down. In addition to black lion tamarins, we were able to observe how different species share the same resources and adapt their behavior in fragmented landscapes. This reinforces the idea that protecting a flagship species helps ensure the survival of many others,” says Gabriela Rezende, Coordinator of the Black Lion Tamarin Conservation Program.
In addition to black lion tamarins, the cameras recorded black-horned capuchins (Sapajus nigritus), grey mouse opossums (Marmosa paraguayana), white-eared opossums (Didelphis albiventris), bare-tailed woolly opossums (Caluromys philander), Brazilian squirrels (Guerlinguetus brasiliensis), and southern tamanduas (Tamandua tetradactyla). “We found that our conservation actions, such as the installation of nest boxes—also known as artificial tree cavities—for black lion tamarins, benefit other animals that depend on these resources for shelter. Of the seven species investigated in this study, three species in addition to the black lion tamarin were recorded interacting with the artificial cavities: the white-eared opossum, the black-horned capuchin, and the bare-tailed woolly opossum. Regarding the southern tamandua, contrary to previous assumptions, we observed a flexible pattern of activity throughout both day and night, revealing an important adaptation for survival in fragmented habitats,” Gabriela adds.
White-eared opossum
Black-horned capuchin
Behind the Scenes of Life in the Understory
nalysis of activity patterns revealed that the black lion tamarin reaches a peak of activity in the late morning (around 10:00–11:00 a.m.), followed by a secondary, less pronounced increase in activity during the late afternoon (approximately 4:00–6:00 p.m.). Activity then declines sharply after sunset and remains minimal throughout the night and early morning.
“This activity pattern differs from those identified through autonomous acoustic recorders. Based on vocalizations, the species appears to reach peak activity during the morning hours through midday, a behavior possibly associated with territorial defense and social group cohesion. In terms of locomotion, however, our accelerometer studies revealed a pattern similar to that observed with the camera traps, with two activity peaks: one in the morning and another at dusk. During the night, the species shelters inside natural tree cavities,” explains Maria Carolina Manzano.
The black-horned capuchin and the Brazilian squirrel exhibited predominantly diurnal activity patterns. Black-horned capuchins remained active throughout most of the day (6:00 a.m.–6:00 p.m.), while Brazilian squirrels concentrated their activity between early morning and midday (6:00 a.m.–12:00 p.m.).
The southern tamandua displayed a unique activity pattern, with modest activity between the pre-dawn hours and approximately 8:00 a.m., reduced activity during the day, and a secondary peak at dusk, suggesting a cathemeral pattern that combines crepuscular and nocturnal activity.
The grey mouse opossum, bare-tailed woolly opossum, and white-eared opossum showed predominantly nocturnal habits, with minimal daytime activity and marked activity from dusk through the early morning hours (6:00 p.m.–6:00 a.m.).
Among the four resource types evaluated—natural tree cavities, nest boxes (artificial cavities), cabreúva trees, and feeding platforms—the latter were used most frequently, accounting for 500 of the 1,277 independent events recorded (39.1% of all records).
Temporal overlap between species pairs varied according to resource type. Feeding platforms and nest boxes were characterized by high levels of temporal overlap among the species recorded. Natural tree cavities displayed a wider range of overlap values, including high overlap between some species pairs, intermediate overlap levels, and lower overlap values involving black lion tamarins and other species.
Sleeping sites, particularly natural tree cavities, emerged as critical shared resources for arboreal mammals.
