Despite many explorations and surveys, the geographic distribution of many primate species, particularly in the neotropics, is not yet well known. In this paper, we provide evidence that extends the range of Spix's saddle-back tamarin in Peru.

Alfaxalone is a general anesthetic used widely in veterinary medicine and has a chemical structure similar to progesterone. Here we report an unexpectedly high serum progesterone value in a female common marmoset following the treatment with alfaxalone. Cross-reactivity of the antibody used in the progesterone assay with alfaxalone most likely explains this finding, and therefore evaluation of serum progesterone results in animals treated with alfaxalone should be done with caution.

A camera trap captured the moment in which a group of collared peccaries attacked and killed a howler monkey at a clay lick in the Taricaya Ecological Reserve, Madre de Dios, Peru. This novel behaviour helps us understand the myriad risks howler monkeys face when descending to the forest floor while also indirectly emphasizing the importance of geophagy for these animals.

From November 2011 through to November 2019, we carried out seasonal road transect surveys and estimated population densities of Manyara monkeys and vervet monkeys in Lake Manyara National Park. Both species occurred at relatively high densities, and their population trends remained fairly stable over the study period. Our research highlights the value of long-term monitoring and the importance of Lake Manyara National Park as a stronghold for the endemic and endangered Manyara monkey.