Grey-headed flying foxes are nectarivores and frugivores. Their principal food is the blossom of eucalypts, melaleucas and banksias, supplemented by native figs and, where forests have been cleared, cultivated fruit. They lap nectar with a brush-tipped tongue and pick up pollen on the fur of face and chest.
The distance is the ecologically important part. Individuals routinely commute 20 to 50 kilometres in a night between a camp and feeding trees, and can shift camps hundreds of kilometres between seasons as flowering moves. Pollen carried that far links forest fragments that would otherwise be genetically isolated, and gut-passed fig seeds are deposited far from the parent tree.
The species is listed as Vulnerable, and camps in urban areas are the usual point of conflict. Two things are commonly misunderstood: the camps in cities largely reflect loss and fragmentation of coastal blossom forest rather than a population increase, and extreme heat events have killed tens of thousands of flying foxes in single days, making temperature a major and growing pressure on the species.