The hormonal and behavioral response to the presence and activities of humans in three co-roosting flying fox species (Acerodon jubatus, Pteropus vampyrus and P. hypomelanus) in Boracay and Mambukal in the Philippines

Many species of large flying foxes are endangered, mainly due to habitat loss and hunting. Although hunting and logging are prohibited in many areas in the Old World Tropics, numbers of flying foxes are still decreasing. The best compromise for the welfare of both local residents and flying foxes in many areas would be ecotourism. However, the effect of human activities on the welfare of flying foxes is unknown and needs to be investigated. Using non-invasive methods, stress levels of three species of flying foxes (Pteropus vampyrus, Pteropus hypomelanus and the endangered Acerodon jubatus) in two tourist areas in the Philippines were investigated, Boracay with little human activity, and Mambukal with intense and large variations in human activities. Fecal samples were collected in the most disturbed area, Mambukal, while the flying foxes were out foraging and concentrations of glucocorticoid metabolites (GCM) were measured. Stress-related as well as other types of behavior, environmental conditions and human activities were measured. The results suggest that flying foxes have habituated to the presence of humans. (1) We found no overall differences in behaviors between both study sites, which differed significantly in human numbers and activities, and during days with disturbance and days without disturbance. Flying foxes behaved identical in both study sites. (2) No behavior correlated with measured GCM. (3) Despite the large variation in human activities in the study site, we found no effect of human activities on glucocorticoid metabolite concentrations. However, GCM was lower in the center of the colony than in the periphery. (4) Some environmental factors like disturbance and distance from the colony center had an effect on behavioral factors like 'uneasiness', 'body care' and yawning. If disturbance has no effect on flying fox stress levels, ecotourism would be a good solution to preserve the habitat of endangered flying foxes. However, one has to realize that the influence of human presence on bat behavior might be more complex than outlined in this study which is based on visible bahaviors, and that disturbance should always be kept at a minimum.