Sick bats stay home alone: fruit bats practice social distancing when faced with an immunological challenge. Issue 1 (19th April 2021)

• Record Type: Journal Article
• Authors: Moreno, Kelsey R.; Weinberg, Maya; Harten, Lee; Salinas Ramos, Valeria B.; Herrera M., L. Gerardo; Czirják, Gábor Á.; Yovel, Yossi
• Is Part Of: Annals of the New York Academy of Sciences. Volume 1505:Issue 1(2021)
• Page Start: 178
• Page End: 190
• Publication Date: 2021-04-19
• Subjects: sickness behavior -- immune response -- social behavior -- foraging -- chiroptera; Medical sciences -- Periodicals; Medicine -- Periodicals; Science -- Periodicals; 610
• DOI: 10.1111/nyas.14600
• Languages: English
• ISSNs: 0077-8923

Abstract

Abstract: Along with its many advantages, social roosting imposes a major risk of pathogen transmission. How social animals reduce this risk is poorly documented. We used lipopolysaccharide challenge to imitate bacterial infection in both a captive and a free‐living colony of an extremely social, long‐lived mammal—the Egyptian fruit bat. We monitored behavioral and physiological responses using an arsenal of methods, including onboard GPS to track foraging, acceleration sensors to monitor movement, infrared video to record social behavior, and blood samples to measure immune markers. Sick‐like (immune‐challenged) bats exhibited an increased immune response, as well as classic illness symptoms, including fever, weight loss, anorexia, and lethargy. Notably, the bats also exhibited behaviors that would reduce pathogen transfer. They perched alone and appeared to voluntarily isolate themselves from the group by leaving the social cluster, which is extremely atypical for this species. The sick‐like individuals in the open colony ceased foraging outdoors for at least two nights, thus reducing transmission to neighboring colonies. Together, these sickness behaviors demonstrate a strong, integrative immune response that promotes recovery of infected individuals while reducing pathogen transmission inside and outside the roost, including spillover events to other species, such as humans. Abstract : We demonstrate that in addition to showing the classical mammalian sickness physiological response, sick‐like Egyptian fruit bats exhibit voluntary, apparently self‐imposed, social distancing. This is the first time that social self‐isolation has been recorded in a mammal, rather than isolation through avoidance by conspecifics or as a byproduct of lethargy. Such isolation behavior stands in stark contrast to the normal behavior in this species, reflecting a temporary shift in the need to prioritize survival.