Simple SummaryCallimico are a small primate species of conservation concern. While commonly found in zoos there is little published research relating to their captive behaviours and space use. Observational research was undertaken to address this knowledge gap by examining differences in the type and amount of behaviours in five different UK collections, and how different vertical zones of their exhibits were used. We found that there were differences in levels of behaviours between collections, including locomotion and foraging. The height use reflects their natural ecology as their behaviours were linked with the different heights within their enclosures. These findings offer evidence to support the importance of foraging enrichment such as whole foods and floor substrate to extend foraging and feeding time as well as validating EAZA’s recommendations for enclosure height for this species. The results allow a better understanding of suitable furnishing for callimico and create a springboard for further research to enhance optimum captive care for both callimico and the wider callitrichid family.AbstractProvision of optimal captive care should be supported by species-specific evidence. Callimico (Callimico goeldii) is a small South American callitrichid primate. This study sought to address gaps in species-specific knowledge and captive management research by examining differences in callimico behaviour across multiple collections, investigating vertical enclosure use and a possible association between specific behaviours and vertical zones. Observational research was conducted at five European Association of Zoos and Aquaria (EAZA) organisations, in exhibits that were visually divided into four vertical zones. Instantaneous scan sampling was used to record behaviour and location of callimico over a six-day period at each collection, exceeding 160 observational hours. Significant differences were observed in foraging between collections and were much lower than the recommendations in Best Practice Guidelines, although near-wild levels were recorded in one enclosure. At an average height of 2 m, callimico utilized a similar vertical space across very different enclosures, regardless of overall available height, reflective of their natural ecology. The association between whole food items and increased foraging time, horizontal branches and locomotion and deep substrate and diversity of behaviours, offers further species-specific evidence of how the callimico use their captive environment. Our findings complement current EAZA guidelines to support species appropriate care for callimico and makes specific recommendations for further research.