One of the research objectives of WCS is the study of threatened medium and large mammals. The Greater Madidi-Tambopata Conservation Program systematized published and unpublished scientific information and created a data base for mammal records of the landscape, which later was extended nationally and used as the basis for the elaboration and publication in 2010 of the book "Distribution, Ecology and Conservation of Medium and Large Mammals of Bolivia".
Between 2000 and 2009 several evaluations of mammals were conducted in the Madidi protected area and its area of influence: Asariamas and Tuichi, Hondo, Quendeque, Madidi and Heath rivers, using line transects for direct observation and camera traps in forest and savanna areas. Also in 2006, an evaluation was conducted on the presence of mammals around the Tequeje and Undumo streams in the Tacana Indigenous Territory, and in 2007 a survey was conducted on the Peruvian side of the landscape along the Tambopata river and its tributaries.
These studies allowed the detection of several species previously unrecorded or not confirmed for Bolivia, such as the white-tailed deer (Odocoileus peruvianus), sighted in the area of Pusupunku of the Apolobamba range. This is the second record for Bolivia after 25 years. Another species recorded for the first time was the mountain paca (Cuniculus taczanowskii) that inhabits the Apolobamba montane forests, it can also be found in Peru.
In the montane forests of the higher part of the Tuichi river, around Asariamas and Pata in the Madidi park, groups of woolly monkeys (Lagothrix cf. cana tschudii) were observed, becoming the first record of this genus for Bolivia. Studies have also registered several mammalian species that are difficult to observe, like the greater grison (Galictis vittata), the short-eared dog (Atelocynus microtis), the maned wolf (Chrysocyon brachyurus), the margay (Leopardus wiedii), the marsh deer (Blastocerus dichotomus), the bush dog (Speothos venaticus) and the pacarana (Dinomys branickii).
A total of 3,241.25 kilometers of line transects were conducted, identifying the presence of 25 medium and large mammals species. Information was obtained on the relative abundance and population density of several species, including 7 monkey species, white-lipped peccaries, collared peccaries, agoutis and squirrels. Likewise, standard camera trap studies generated information on the relative abundance of more nocturnal species like tapirs, deer and spotted pacas.