Natural History or Behavioural Note | In&Vertebrates Most et al., 2024; Peer Reviewed In&Vertebrates | https://doi.org/10.52732/GOVP5115 Intertroop kidnapping of a young infant in wild olive baboons (Papio anubis) Corinna A. Most 1,2 , Florence Landry 3 , Iulia Bădescu 3 and Monica L. Wakefield 2,4 1 Department of Ecology, Evolution, and Organismal Biology, Iowa State University, Ames, Iowa, U.S.A. 2 Uaso Ngiro Baboon Project, Laikipia, Kenya 3 Department of Anthropology, Université De Montréal, Montréal, QC, Canada 4 Department of Sociology, Anthropology & Philosophy, Northern Kentucky University, Highland Heights, KY, United States https://doi.org/10.52732/GOVP51155 ABSTRACT On June 16, 2023, a juvenile female olive baboon (Papio anubis) from the study troop at the Uaso Ngiro Baboon Project grabbed a ~3-week-old infant from another troop and released him near a high-ranking adult female in her own troop. This adult female, who was already pregnant, took the infant and treated him as her own, allowing him nipple access. The infant survived for over a month, which suggests the female produced some milk, at least initially, but he eventually died on July 24. Here, we describe the behaviours of all individuals involved in this rare event, and present possible proximate mechanisms and ultimate explanations for the behaviours observed. Rare events can reveal a species’ behavioural and physiological flexibility, and this one sheds light on the potential for reproductive stacking in baboons and the use of infants as a commodity within the social market of the troop. Keywords: Primates, olive baboons, social behaviour, intertroop interactions, infants, alloparental care, kidnapping. Behaviour described Common name Scientific name Conditions Location Intertroop kidnapping Olive baboons Papio anubis Natural observation over the course of several days, daylight, open shrub savannah Laikipia, Kenya (0.417633, 37.041619) This article is part of the Special Issue ‘Undocumented animal behaviours – reviving natural history’ Peer Reviews: The peer review reports are published alongside the article. Received 13 Mar 2024 Revised 14 Oct 2024 Published 24 Oct 2024 (v3) This article is distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use and redistribution provided that the original author and source are credited.