Greenwich Academic Literature ArchiveOro-facial contact behaviors in wild white uakaris (Cacajao calvus): first documentation of direct facial contact and facial investigation in PitheciidaeRenann H. P.Dias da SilvaauthorMatheus JoséCastro-SáauthorAdrian A.BarnettauthorCarlosPeresauthorMarceloGordoauthorOro-facial contact behaviors, including direct facial touching and mouth-to-mouth proximity interactions, serve important functions in primate social and reproductive systems, yet such behaviors have received limited documentation in neotropical primates, particularly within Pitheciidae. We document the first formally described instances of oro-facial contact behaviors in wild white bald uakaris (Cacajao calvus) during systematic field observations (September 2022–August 2023) at the Seringal São João Biological Reserve, Juruá River, Brazil. We present two distinct oro-facial contact events: (1) prolonged muzzle-to-muzzle contact ("kiss-like" behavior) lasting approximately 10 seconds between an adult male and presumed adult female during peak flood season (April 18, 2023, river level 63.15m), and (2) brief facial investigation lasting 3–4 seconds between an adult male and subadult male during rising water period (February 22, 2023, river level 62.6m). Both interactions, documented photographically, occurred in non-agonistic contexts characterized by relaxed postures and absence of aggression. The April event occurred during apparent pre-copulatory interaction, while the February event followed group foraging and may represent social mediation or status assessment. These observations represent previously unknown components of C. calvus social behavioral repertoire and the first formal description of oro-facial contact in any Pitheciidae species. The distinctive morphological specializations of C. calvus—including hairless red facial skin and polymorphic color vision enabling fine discrimination of facial coloration nuances—likely facilitate these close-range communicative interactions. This field note highlights the importance of detailed behavioral documentation for understanding the full social complexity of specialized neotropical primates.Q Science (General)QL Zoology2026-09-09WileyArticle

For work being deposited by its own author: In self-archiving this collection of files and associated bibliographic metadata, I grant Greenwich Academic Literature Archive the right to store them and to make them permanently available publicly for free on-line. I declare that this material is my own intellectual property and I understand that Greenwich Academic Literature Archive does not assume any responsibility if there is any breach of copyright in distributing these files or metadata. (All authors are urged to prominently assert their copyright on the title page of their work.)

For work being deposited by someone other than its author: I hereby declare that the collection of files and associated bibliographic metadata that I am archiving at Greenwich Academic Literature Archive is in the public domain. If this is not the case, I accept full responsibility for any breach of copyright that distributing these files or metadata may entail.

Clicking on the Deposit Item Now button indicates your agreement to these terms.