Body mass is one of the most important phenotypic attributes in animal ecology and life history. This trait is widely used in the fields of ecology and macroevolution, since it influences physiology, morphological functions, and a myriad of ecological and social interactions. In this data set, our aim was to gather a comprehensive bird and mammal body mass data set from northern South America. We report body mass, discriminated by sex, for 42,022 individual birds and 7,441 mammals representing 1,317 bird species (69% of Colombia’s avifauna) and 270 mammal species (51% of Colombian mammals) from the Neotropics. The data were sourced from vouchers collected between 1942 and 2020 and from individuals captured and released at banding stations over the last two decades for birds (2000–2020) and the last decade for mammals (2010–2020), by 10 research groups and institutions in Colombia. This data set fills gaps identified in other similar databases, as it focuses on northern South America, a highly diverse Neotropical region often underrepresented in morphological data sets. We provide wide taxonomic coverage for studies interested in information both at regional and local scales. There are no copyright restrictions; the present data paper should be appropriately cited when data are used for publication. The authors would appreciate learning about research projects, teaching exercises, and other uses given to this data set and are open to contribute in further collaborations using these data.

Although taxonomy, ecology, and natural history information of the arboreal spiny rats is available, many gaps in some species distribution still exist. We report here the first records of the Peruvian Toro, Toromys rhipidurus (Thomas, 1928), in southern Colombia. This arboreal spiny rat was only known from the Peruvian Amazonia. These new records extend the known geographical distribution of the species by about 61 km northward from its nearest known locality, at Río Yavarí, Peru. In addition, we provide some notes on the natural history of the species.

The Colombian Speckled Tree Rat, Pattonomys semivillosus, is a little-known rodent endemic to the Lower Magdalena River basin at the Caribbean Coast of Colombia. To date it is the only species of Pattonomys documented in the country. We provide information on the rarity, and conservation status of P. semivillosus based on the current and potential distribution, population density and size using information from the literature, new records, and museum vouchers. We confirmed 66 occurrences that belong to 25 localities in six departments (Atlántico, Bolívar, Cesar, La Guajira, Magdalena, Santander, and Sucre) in northern Colombia, including 18 new localities not previously reported in the literature, mostly in the highly threatened Tropical Dry Forest ecosystem. The population density in three sites of Department of Cesar was 5.4 ind/km2, 5.9 ind/km2, and 32.4 ind/km2. The species matches with the Category D of rarity, and we suggest an update to the threatened assessment (from Least Concern to Near Threatened). This information will contribute to update the current IUCN assessment of the species.

La colección de mamíferos del Instituto de Investigación de Recursos Biológicos Alexander von Humboldt es la tercera colección de mayor número de especímenes en el país con 9.471 determinados en 400 especies, 212 géneros, 51 familias y 14 órdenes, procedentes de ocho países, siendo Colombia el de mayor representatividad (66,5% de la diversidad registrada para el país en este grupo). Los órdenes mejor representados son Chiroptera, Rodentia y Primates. Alberga un neotipo y dos paratipos de Cebus albifrons albifrons, un paratipo de Aotus hershkovitzi y un paratipo de Vampyressa sinchi. La colección ha sido un referente para el estudio de mamíferos colombianos y se continúan realizando esfuerzos para mejorar el estado curatorial y la información asociada a los especímenes.

Diferentes iniciativas han permitido conocer los sonidos de los mamíferos neotropicales. Aunque en Colombia hay algunos repositorios de registros bioacústicos, la Colección de Sonidos Ambientales Mauricio Álvarez-Rebolledo del Instituto Humboldt (IAvH-CSA) es la única de acceso público. Nuestro objetivo fue explorar la representatividad de mamíferos en la IAvH-CSA y promover su uso entre la comunidad mastozoológica colombiana. Encontramos 129 registros, la mayoría de Primates. Los registros incluyen representación de todas las regiones geográficas, excepto el Catatumbo, y 21 de los 32 departamentos del país. Aun así, solo el 3 % de las especies de mamíferos de Colombia están representadas en la colección. Éstas han sido grabadas en su mayoría por ornitólogos. Por tanto, hacemos un llamado a apoyar los repositorios públicos en nuestro país, depositar los registros acústicos para garantizar accesibilidad a estos y abordar futuras preguntas en la bioacústica de mamíferos de Colombia.