The grey-headed flying-fox faces several threats to survival including human culling of roosts to protect fruit orchards, competition with other species of flying-foxes for food and roost resources, climate change, and natural habitat loss (Welbergen, n.d.).  Flying-foxes are often culled for human convenience.  Fujita and Tuttle (1991) note that because flying-foxes are often seen as pests and are targeted for eating farmers’ crops, the populations of flying-foxes has declined significantly.

Deforestation throughout Australia has caused flying-foxes to lose natural habitat (van der Ree et al., 2006) which increases the competition within flying-fox species for natural resources (Welbergen, n.d.).  Climate change has also affected the range of flying-foxes.  Increased rainfall and temperature has driven the grey-headed flying-fox southward.  van der Ree et al. (2006) reports an average temperature increase of 1.13°C over the past 20 years in Melbourne, which is a very significant increase. 

Welbergen et al. (2008) examined the effects of extreme temperatures on a colony of flying-foxes in Sydney, Australia.  During 2002, New South Wales experienced an extreme heat wave of temperatures above 42 degrees Celsius.  Due to the flying-fox roosting behavior of roosting in the upper canopies of trees, they were extremely affected by this particular heat wave.  Welbergen et al. observed several heat-reducing behaviors by the flying-foxes including wing-fanning, shade-seeking, panting, and saliva-spreading.  Once individuals became over-heated, however, they fell from the trees and usually died within 10 to 20 minutes (Welbergen et al., 2008).  Due to their susceptibility to high temperatures, climate changes could also be detrimental for the flying-fox population.

Because of the adverse affects of the aforementioned factors, both the grey-headed flying-fox and the spectacled flying-fox maintain the status of “threatened” in the Commonwealth Environment Protection and Biodiversity Conservation Act of 1999 (DSE, 2008). 

Photo by University of Sydney Courtesy of Scientific Frontline

Ecological Importance of the Flying-Fox

Not only would the loss of flying-fox species be detrimental by itself, it would also be detrimental to many plant species in the region, as flying-foxes play critical roles in seed dispersal and pollination of plants (DSE, 2008; Parry-Jones & Augee, 2001).  Because flying-foxes feed primarily on fruit and travel great distances while foraging, they are able to spread the seeds of those fruit species while defecating in flight (Tuttle & Fujita, 1991).

Fujita and Tuttle (1991) examined the role several species flying-foxes play in essential ecological processes and provide a compelling argument for flying-fox conservation.  There are more than 200 species of pteropodid bats around the world, and each species helps with seed dispersal and pollination of a wide variety of plant species.  It is believed that 289 plant species rely in varying levels on bats for regeneration (Fujita & Tuttle, 1991).  It is therefore important to consider the conservation of flying-foxes a priority.