On 11 Dec. 2013, a vast flock of the Little Red Flying-fox (Pteropus scapulatus) abruptly arrived in my home town and established a day-time roost along the small river that runs through town. A small roost, of perhaps a few hundred individuals, had been present for a week or so prior, but from 11 Dec. the roost contained at least 10,000 individuals but perhaps twice that many. The flying-foxes (AKA fruit-bats) roost in more than 300 trees, the roost extending continuously along about 550 m of the river.

At dusk the flying-foxes form a great swirling cloud more than 1 km long before dispersing to feed overnight. The attraction appears to be a mass-flowering of the Inland White Mahogany (Eucalyptus mediocris), from which the flying-foxes obtain nectar or possibly pollen. This tree is abundant for perhaps several hundred square kilometres on the hills surrounding the town, and almost every tree is flowering. This mass-flowering only happens about once every ten years. How the flying-foxes knew about or discovered the flowering is an intriguing mystery.

However, we can stab a guess at where they’ve come from. The propensity of flying-foxes in Australia to establish roosts in and around towns does not always make them popular; some object to the smell, and they do bring with them some risk of disease that can effect horses and humans badly, though the risks appear to be exaggerated. A large roost had worried the townsfolk of Charters Towers, 300 km to the south of here, and they finally got permission to scare them off – this happened in the very week that they arrived here.

Thus far, my local townsfolk have remained tolerant and some are even enjoying the event. I hope that tolerance will continue, we can appreciate one of nature’s marvels, and the Mahogany trees can be pollinated.

At the time of writing (31 Dec. 2013) the flying-foxes are still there and appear even to have increased in numbers.

Update: in late Febuary or early March, numbers began to wane as the food supply diminished, and by late March the last of the flying-foxes had departed for roosts and foraging grounds further afield.