Every so often, you see a paper that appears to be put together by all the scientists in the world at once – and this felt a lot like one of those instances. This conglomeration of researchers has worked diligently on this manuscript for several years, coordinating across a large group efficiently and with nary a off-note in the entire process. Just that deserves applause!
We collaborated to collect data from 86 studies conducted in 65 different sites where the Callicebinae were found to be terrestrial (upon occasion). Within the group, terrestrial activity was recorded frequently for Callicebus and Plecturocebus spp., but rarely for Cheracebus spp. Across the board, these arboreal primates came to the ground to rest, as an anti-predator strategy, to eat soil (geophagy), to play and forage on terrestrial invertebrates and soil. The longer a researcher studied these animals, the more likely it was that they would observe terrestriality. Although it was difficult to identify patterns across so many disconnected studies, while keeping scientific rigor high, we did discover that unlike the other pitheciids, titi monkeys hit the floor rather a lot more than expected!
But, they’re not alone in this behavior – lots of other primates come to the ground despite being primarily arboreal:
Please see the full paper for a lot more avenues of research! We also made the cover of this volume:)
Souza-Alves JP, Watsa, M, 62 other authors & Barnett AA. (2019) Terrestrial behavior in titi monkeys (Callicebus, Cheracebus and Plecturocebus): Potential correlates, patterns and differences between genera. International Journal of Primatology. pp1-20. https://doi.org/10.1007/s10764-019-00105-x