Conservation implications of Chamorro consumption of flying foxes as a possible cause of amyotrophic lateral sclerosis-Parkinsonism dementia complex in Guam

In the Pacific island of Guam, flying fox (Pteropus mariannus and P. tokudae) populations historically persisted for centuries despite subsistence foraging by the indigenous Chamorro people. However, the militarization of Guam in the twentieth century, with an increased emphasis on a cash rather than a subsistence economy, led to two features that had deleterious effects on the flying fox populations: easy access to firearms greatly increased hunter yields and disposable income facilitated commercial traffic in flying foxes. As a result, consumption of flying foxes dramatically increased, leading to the extinction of one indigenous species and near extinction of another. The demise of the flying fox populations was mirrored by a subsequent decrease in the health of the Chamorro people. Amyotrophic lateral sclerosis-Parkinsonism dementia complex (ALS-PDC), a neurological disease with aspects of ALS, Alzheimer's, and Parkinson's disease, became a major cause of adult death in some villages. It has been recently hypothesized that consumption of flying foxes by the Chamorro may have generated sufficiently high cumulative doses of neurotoxins to result in the observed high levels of ALS-PDC among the Chamorros in Guam because flying foxes forage on cycad seeds that are rich in neurotoxins. Commercialization of traffic in wild flying fox populations may have therefore produced grave health consequences for the Chamorro people.