The chimpanzees showed significantly higher levels of proximity, allogrooming and displace in the outdoor exhibit compared to the indoor one and higher levels of threat and display in the indoor enclosure compared to the outdoor one. It has been found that chimpanzees prefer shade much more than direct sunlight in captive environments. The first period of the study took place in the mornings and afternoons during summer, when the biggest area of the outdoor enclosure was exposed to the sunlight except in a few shelters that offered shade. In this period, the chimpanzees spent much more time in the shade compared to the direct sun. The higher levels of displace recorded in the outdoor exhibit compared to the indoor one can be explained by the fact that the individuals took the physical territory of other individuals outdoors in a higher rate than indoors, to find a shadier and thus, better spot for them to utilize. Furthermore, since they would spend most of the day in the shelters, because of the shade, they would spend much more time closer to each other, in contrast to the indoor enclosure, and thus they would present higher levers of proximity and affiliative behaviours such as allogrooming. Moreover, in this study, higher levels of threat and display, which are aggressive interactions, were found in the inside enclosure compared to the outside one, but no significant difference in play was found between the two environments. This increase in aggression can be explained by the ‘spatial crowding’ hypothesis, which suggests that chimpanzees under crowded conditions display increased conflicts of interest.

 In the absence of enrichment there was an increase in associative and affiliative behaviour compared to when any type of enrichment or food-based enrichment was used. This can be explained by the fact that on days that either any type of enrichment or  food-based enrichment was used, the chimpanzees would spend more time with exploring and manipulating the enrichment, thus they would demonstrate lower levels of associative and affiliative behaviour compared to the absence of enrichment.

Three pairs of individuals: Maggan-Citrus, Marycen-My-Gun and Mariana-Marley were found to have the strongest, most preferred relationships. This makes sense, since the pairs with the strongest associations are the mother-infant ones like is the case with all these pairs. Furthermore, some males (Mango, Claudius, Fred) spent more time closer to Fiffi compared to other individuals. Fiffi was the only female in the group that was in oestrous (sexually attractive to males) for some part of the study, thus these males stayed closer to her possibly for a higher possibility to gain access.

Within the allogrooming network, Fiffi was the recipient with the highest interaction rates. Fiffi was the only female in the group that was in oestrous for some part of our study, thus the increased allogrooming towards her can be explained by the fact that males increase their grooming interactions with females during maximal tumescence (oestrous). Furthermore, in the allogrooming network a significant relative reciprocity was found. Chimpanzees can exchange grooming, as an interchange currency, for itself or for other acts such as agonistic support, tolerance, food and cooperative services in breeding groups.

Within the agonistic network, Claudius was the most frequent actor in aggressive interactions, but never recipient. Agonistic interactions are fundamental in establishing dominance across the group. Claudius was ranked as the most dominant by all three ranking methods, because he directed so much aggression towards other individuals but was never the recipient of aggression, thus the dominance rank analysis regarded him as the most “dominant” because he was “winning” (or acting) in more agonistic interactions than he was “losing” (or receiving). Martin (the male with the bigger size in the group) was the second most dominant individual and Mamba was the least dominant. Furthermore, we observed that individuals of this group exchanged aggression in a reciprocal manner.

In conclusion, with our results, we aim to help the zoo stuff to develop better management practices and improve the chimpanzees’ welfare. This can be achieved by gaining further knowledge about the social behaviour between the individuals and how it is being affected by different factors, such as the type of enclosure, diet, presence of enrichment, type of enrichment etc. Fiffi is the most common recipient of allogrooming interactions and Claudius is the most frequent actor in aggressive interactions. Therefore, these individuals can significantly affect the groups’ stability and aggressive interaction rates. This knowledge can help the zoo stuff to be more prepared in case of attrition of these individuals. In such a case, a temporary separation of individuals that are mostly connected with Claudius and Fiffi could diminish possible increased aggression. Moreover, it should be noted that the use of a randomized enrichment schedule could provide novelty and prevent that the animals get habituated to the enrichment. However, testing specific enrichments only for the study period and not different ones every day could provide us with more detailed information about the effect on the chimpanzees’ interactions with specific enrichment. It might make it possible to identify if they prefer specific types of enrichment and the effect of specific enrichments and not the effect of the presence or type of enrichment on their social interactions. Future research should focus on a systematic selection of different enrichments that are tested in a randomized manner and examine how they would affect the social interactions of the chimpanzees.