Assessing the sociability of former pet and entertainment chimpanzees by using multiplex networks

Abstract

Advances in the field of social network analysis facilitate the creation of multiplex networks where several interaction types can be analysed simultaneously. In order to test the potential benefits of this approach, we investigated the sociability of atypically raised chimpanzees by constructing and analysing 4-layered multiplex networks of two groups of former pet and entertainment chimpanzees (Pan troglodytes). These networks are based on four social interaction types (stationary vicinity, affiliative behaviour, allogrooming, passive close proximity) representing low- to high-level interaction types in terms of sociability. Using the tools provided by the MuxViz software, we could assess and compare the similarity and information gain of each these social interaction types. We found some social interaction types to be more similar than other ones. However, each social interaction type imparted different information. We also tested for a possible impact of the chimpanzees’ biographical background on the social interaction types and found affiliative behaviour as well as allogrooming to be affected by adverse early life experiences. We conclude that this multiplex approach provides a more realistic framework giving detailed insight into the sociability of these chimpanzees and can function as a tool to support captive care management decisions.

Early Trauma Leaves No Social Signature in Sanctuary-Housed Chimpanzees (Pan troglodytes)

“…Similarly, the social network metrics, which reflect the chimpanzees' social embeddedness in their groups, did not show any obvious differences between the two groups either. If the early social trauma suffered by the orphaned chimpanzees would have had lingering effects, as has been observed in other groups of chimpanzees (e.g., [9]), we may have observed a signature in their social behaviour one way or another, be it in their tendencies to isolate themselves from the group (i.e., smaller party sizes) or in their refraining from seeking bodily closeness or contact with group members (i.e., close proximity and grooming) [8,29]. In other words, the strength of these findings lies in the consistency of an absence of differences, especially given our fairly large sample size.…”

“…In fact, we do not even have data on the extent to which the respective chimpanzees suffered by the loss of their motherinstead, we work under the assumption that chimpanzees suffer when becoming orphaned and that a certain rehabilitation process is needed to re-socialize them. Support for this assumption is relatively abundant, both from ethnographic descriptions of chimpanzee life in the wild [33] as well as detailed studies of the effect of trauma on social behaviour such as grooming, abnormal behaviour such as coprophagy, sexual behaviour and activity levels of chimpanzees in zoo-settings [8][9][10]28,29]. In zoo-settings, typically, the signatures of early trauma on chimpanzees' social behaviour remain detectable in later life, even into adulthood.…”

“…Furthermore, chimpanzees with relatively little exposure to conspecifics in the first 4 years of their lives were found to exhibit lower frequencies of grooming and sexual behaviours later in life: two essential social activities within chimpanzee communities [10]. Similarly, chimpanzees who were orphaned within the first two years of their lives experienced problems with socialising as adults-in particular, they held back from social grooming, an interaction which is vital for establishing and maintaining social relationships ( [8] also see [29]). Lastly, it was observed that ex-laboratory and early long-term maternally deprived zoo chimpanzees were more restricted in their grooming associations compared to non-deprived zoo chimpanzees, leading the authors to conclude that "early maternal loss has lifelong effects on the social integration of chimpanzees" [9].…”

Neighbors Matter: An Investigation into Intergroup Interactions Affecting the Social Networks of Adjacent Chimpanzee Groups

“…SNA is an extremely useful tool, which allows researchers to describe, quantify and statistically compare the social relationships of individuals, thereby increasing our capacity to analyze and understand even highly complex social structures [34,35]. Regarding the analysis of social behavior patterns in animals, it has been used in a wide range of animal taxa, including insects [36], fish [37], cetaceans [38], and mammals [39] including a large number of studies of non-human primates [40][41][42][43][44][45][46][47]. It has been used in chimpanzees to advance our understanding regarding social learning [48], cooperation [49], effectiveness in the transmission of information [50], spread of diseases [51,52], the establishment of hierarchies [53] and to assess group cohesion and stability [11,54].…”

“…Although inter-community interactions in wild chimpanzee groups are well documented [55], to date, the vast majority of SNA studies have focused on social interactions in captive chimpanzees, and therefore consider only relationships and interactions between members of the same group, and hence only within closed social systems [46,56,57]. To the best of our knowledge there are only two studies of captive chimpanzees to analyze the impact of neighboring captive groups in relation to one another [58,59].…”