A quantum flight for bogong moths

At times, Australia swarms with brown bogong moths. These fat moths spend their winters in Queensland but migrate 1000 kilometres or more south to spend their summers resting in cool mountain caves in Victoria or Tasmania. Six months later they return to Queensland, great clouds of them flying by night over Canberra.

Bogong moths were long a delicacy with Aboriginals, who ate them raw or cooked. They are today sometimes served at adventurous Australian restaurants fried with spiced breadcrumbs.

A team of mainly European scientists, keen to find out how bogongs navigate so accurately over long migrations at night, has just reported on their experiments in the journal Current Biology.

The team tested the moths’ ability to read the lines of the Earth’s magnetic force by tethering bogongs in a round enclosure or flight simulator surrounded by strong magnets.

The powerful magnets overrode the Earth’s magnetic lines and replaced them with fake magnetic compass readings.

It didn’t work. The scientists found that bogongs couldn’t navigate ‘‘on instruments alone’’ and needed something else to find their way about.

The research team found that, in addition to the magnetic compass, the moths need to see big landmarks or they become lost.

So, they provided them with fake mountain silhouettes and concluded that bogongs use both their magnetic sense and topographic landmarks to navigate long distances.

There’s more to animal navigation than that. Experiments with migratory birds in Europe reveal that they use quantum physics to read the Earth’s lines of magnetism.

Tiny subatomic events trigger a cascade of other events that enable these birds to sense the Earth’s magnetism.

It is supposed that long-distance migratory fish, turtles, whales and bogongs probably exploit the same quantum physics.

Meanwhile, in strong westerly winds or during big bushfires, plenty of Australian moths are blown off course and many end up in New Zealand.

In the 1970s, a Dr Fox set traps on an oil rig 40km off the Taranaki coast.

He caught 36 species of Australian moths, including the speckled footman, the spangled green, the meadow argus, the greasy cutworm, a hawk moth, and bogongs.

In addition to the magnetic compass, the moths need to see big landmarks or they become lost.