Date of Thesis



The study of Old World fruit bats (Order: Chiroptera, Family: Pteropodidae) is increasingly important from both conservation and epidemiological points of views. Chiropteran biodiversity is threatened by myriad factors such as habitat loss (from both natural occurrences and anthropogenic changes) and the killing of bats for food or as pest control. Furthermore, as bat and human interactions increase, there is greater risk for potentially critical zoonotic spillover events (e.g., Marburg virus, Nipah and Hendra viruses). Often times, bat reservoir hosts are seemingly unaffected by their pathogens, which is in stark contrast to the morbidity and mortality the pathogens cause in novel primary and secondary host species. Knowledge of the immunological and physiological processes, costs, and trade-offs within bats is crucial to understanding the host-pathogen system and disease transmission. There is a general paucity of data regarding basic immunological function in bat species, however, which motivated this study to characterize multiple immunological parameters of healthy male and female captive Old World fruit bats (four species: Pteropus vampyrus, P. pumilus, P. hypomelanus, and Rousettus aegyptiacus (males only)) at four timepoints throughout a year. Significant differences in complement hemolysis ability were found between species, but not sex, at all timepoints tested. Neutrophil to lymphocyte ratio (N:L) also varied by species with markedly higher values in P. vampyrus, and was significantly higher in male versus female Pteropus species in September and December. With few exceptions, higher values of N:L ratio coincided with increased total glucocorticoid levels, and these were often seen in September. Relative total antibody within species also was evaluated; P. vampyrus and R. aegyptiacus males and P. pumilus males and females exhibited significant increases in total antibodies in September and/or December. Taken together and in context of species life histories (such as September breeding season), data collected characterize significant shifts in immune parameters throughout a year. This study will help inform future research of ecological immunology and disease ecology in Old World fruit bats.

Access Type

Masters Thesis (Bucknell Access Only)

Degree Type

Master of Science


Animal Behavior

First Advisor

DeeAnn Reeder