• social play
• affiliation
• grooming
• drills
• Mandrillus leucophaeus
• drilli
• gioco sociale
• celebrazione del cibo
• food celebration
• aggressive behaviours
• self-directed behaviours
• frequency
• presence
• comportamenti aggressivi
• comportamenti autodiretti
• frequenza
• presenza

Drills (Mandrillus leucophaeus) are Old World monkeys found in Africa, from South-Est Nigeria to Cameroon and Bioko Island, where they occupy the bottom layer of tropical primary forests. They are diurnal terrestrial monkeys that live in groups (up to 25 individuals), organized around the figure of a dominant male. Alongside the mandrill (Mandrillus sphinx), they are the only remaining species present in the genus Mandrillus, and they are listed in IUCN Red List as Endangered. The present study is a pilot study on the drill social behaviour, due to the scarcity of information on that species in the scientific literature. Specifically, my analysis will be focused on social play in drills. The individuals included in the analysis are animals hosted at the Dvur Kralove Zoo (Czech Republic). They are a group of 14 individuals, including 4 post-pubertals (2 males and 2 females), 7 juveniles (4 males and 3 females), and two infants. The animals were filmed for two months (August-September 2020). A distance of 10-15 meters was adopted by the operators to avoid disturbing animals as much as possible. They were recorded every day (5 days per week), both in the morning and afternoon. The animals were filmed both in the outside and inside areas of the enclosure. The operators both collected focal and all-occurrences videos. The first ones are centered on each subject to code its interactions closely, while the all-occurrence on the whole group was used to keep track of the behavioural states of the animals (i.e., proximity, contact, grooming, play) that can be useful to evaluate their social relationships. Both types of videos will be analysed, and the patterns observed will be used to create an Excel-sheets. My analysis will be focused on social play in drills. The overarching goal of the study is to verify the presence of the so-called “celebration of food” in drills, already described for the ape species. Specifically, I will investigate if/how social play varies in frequency and modality according to the different conditions such as pre-feeding, feeding, post-feeding. Generally, during the pre-feeding period, the arousal tends to increase in primates and animals need to cope with this new behavioural mood by engaging in social behaviour such as social play and grooming. I will expand my analysis by evaluating which type of play and which play modality animals tend to prefer during periods of social tension.