Respiratory Disease Risk of Zoo-Housed Bonobos Is Associated with Sex and Betweenness Centrality in the Proximity Network

SIMPLE SUMMARY: One of the basic conditions of animal welfare is good health. While social behaviors have many benefits for group-living animals, they also play a role in disease transmission. This is especially true in primate species, like bonobos, who have complex social dynamics, which can facilitate disease transmission. Bonobos are also more susceptible to human disease variants due to their close genetic relatedness and are therefore at higher risk of infection in captivity due to closer proximity to humans. Therefore, investigation whether an individual’s characteristics, like sex, age, or social-network position increase disease risk provides information that can be used for future management decisions to improve general animal welfare. To do so, we monitored the occurrence of respiratory disease symptoms during one winter season in a relatively large group of 20 zoo-housed bonobos. We found that individuals that were more central in the social network had higher chances of contracting respiratory disease and that males were more likely to get infected than females. These results indicate that for bonobos, social behavior and sex influence the risk of contracting respiratory disease, two factors that can be taken into account when managing fission-fusion dynamics during disease outbreaks in this zoo-housed species. ABSTRACT: Infectious diseases can be considered a threat to animal welfare and are commonly spread through both direct and indirect social interactions with conspecifics. This is especially true for species with complex social lives, like primates. While several studies have investigated the impact of sociality on disease risk in primates, only a handful have focused on respiratory disease, despite it being a major cause of morbidity and mortality in both wild and captive populations and thus an important threat to primate welfare. Therefore, we examined the role of social-network position on the occurrence of respiratory disease symptoms during one winter season in a relatively large group of 20 zoo-housed bonobos with managed fission-fusion dynamics. We found that within the proximity network, symptoms were more likely to occur in individuals with higher betweenness centrality, which are individuals that form bridges between different parts of the network. Symptoms were also more likely to occur in males than in females, independent of their social-network position. Taken together, these results highlight a combined role of close proximity and sex in increased risk of attracting respiratory disease, two factors that can be taken into account for further welfare management of the species.