"I don't need a marker as it's always easy to find", remarks Eric, a Professor at the Department of Biology at the University of Lund in Sweden, pointing to a large flock of seemingly well-fed ravens perched atop a cluster of boulders.

"At this time of year, wherever there are Little ravens there are moths - the ravens love to feast on them".

The moths Eric is referring to, are, of course Bogong moths, and Eric is leading me to a secret cave where he has been monitoring the mysterious insects for more than a decade.

Much to the bewilderment of a young family pushing a stroller along the summit path, Eric leaves the track and like a mountain goat cavorts several hundred metres down the steep slope. I follow, but soon find it's easier to traverse the steeper sections on my posterior, using my hands as rudders. No dignity here. Anyway, now out of view of the path, it's only the ravens who can see me.

It's one of those delightful early autumn blue sky days and to the west is one rugged range stacked up against another for as far as the eye can see. But the vista isn't all rosy; I pause to reflect on the patchwork of black scars from the summer's fires which, from below the treeline, extend like a giant cancer in just about every direction. It's a view I hope to never see again.

Eventually, I catch up to Eric at the entrance to a cave created by a jumble of boulders, it's only about the size of a small car. We peek in and see thousands of moths. But there should be more. "In a good year, there'd be millions [of moths] just in this cave," remarks Eric. "The drought seems to have knocked them around in recent years".

Thankfully, the fires don't seem to have affected the moths is this particular cave. "There are about the same numbers [of moths] here as there were in December before the fires", says Eric. "Other caves that were below the treeline where the fires burned were not as lucky.

"It could be potentially devastating on those populations of bogongs because they aren't very tolerant to heat nor smoke."

But Eric hasn't brought me here to explain the effect of fires, nor the drought on the moths. No, Eric, also a Visiting Fellow at ANU, is about to reveal exclusively to your akubra-clad columnist the initial findings of his ground-breaking research which unlocks a mystery that has puzzled scientist for years. And what better place to tell all, but this secret cave on the roof of Australia.

It's well known that the bogong moths migrate in spring from their breeding grounds in the hot and arid plains of Queensland, NSW and Victoria to the cool of the Snowy Mountains and then return all the way back to their birthplace in autumn to start the life cycle all over again. However, until now it has been a mystery as to how an insect with a brain smaller than a pea can pull off this amazing migration.

Several years ago Eric and his colleagues partly discovered the answer when they determined that bogongs, in a similar way to sea turtles and some nocturnal songbirds, are able to use the Earth's magnetic field as a compass.

However, that research showed that the bogong was also using visual cues to help navigate.

"It's akin to a bushwalker using a compass to find a direction, then looking for a visual cue, such as a hill in the desired direction to walk towards, thereby allowing them to put the compass back in their pocket," explains Eric. "But whether these visual cues for moths were terrestrial, celestial or a combination was a mystery."

As the moths migrated at night, Eric decided to first look at celestial cues - such as the moon and the stars. And he hit the jackpot.

"We now have some very promising evidence that indicates bogongs are able to use the Milky Way as a true compass," he reveals.

"We'd known from our previous research that African Ball Rolling Dung Beetles use the night sky for keeping a straight line rolling dung at night, so thought we'd test it on the bogongs," explains Eric.

To test his hypothesis, Eric captured live bogongs during their migration south from Queensland to the Snowy Mountains, tethered them to hooks and then, in his specially-designed moth flight simulator, subjected them to a series of tests that involved projected starry skies. "This was all undertaken in a magnetic vacuum so they couldn't use the magnetic field to navigate," explains Eric.

"We discovered that in spring if we turned the projected night sky by 180 degrees, the moths would also turn 180 degrees and fly in the opposite direction - north," explains Eric. "Likewise, in autumn when they'd usually fly north, if we turned the projected night sky by 180 degrees, they would fly south instead." Amazing.

Eric, who bemoans that the bogong is a much maligned insect, hopes his research will "help people realise just how amazing these little creatures are and how important they are to the ecology of the mountains".

We have so much still to learn about the bogong, but it's heartening to know that dedicated scientists like Eric are on the case.

Bogong Moths: To escape the heat every year, bogong moths migrate to caves and crevices of the Australians country where they aestivate - a state of dormancy similar to hibernation characterised by inactivity and a lower metabolic rate, but which takes place in summer rather than winter.

Spectacular site: Although the aestivating moths lay dormant during daylight hours, at dusk, significant numbers leave the caves en masse, returning later in the night. "We are not sure why they do this, or what percentage of moths fly out every night," says Eric Warrant. "It's another mystery that needs to be solved. Garry McDougal, who camps regularly in mountains, reports that "in a good year on dusk, the sky is black, filled with moths, it's an incredible site not many get to see".

Main predators: Apart from ravens, the main predators of the bogongs are Mountain pygmy-possums. These mouse-size nocturnal marsupials which live amongst boulder fields in Australia's high country heavily depend on bogongs as their main food source.

Did You Know? The Monarch butterfly is another Australian insect that completes a long and deliberate migration. However, instead of the night sky, it uses the rising sun as a compass.

Timeless treasure: Among the highly productive pastures of the 1200-hectare Uriarra Station is an area of exposed granite about 30 metres long by 10 metres wide. But for the fact Dr Tony and Helen Griffin, current custodians of the historic farm, have the stone fenced off, you wouldn't look twice at it. However, the "Uriarra moth stone" as it is often referred, is a significant site where Indigenous people historically feasted on bogong moths, a delicacy they would travel from far afield to collect. "We've been told the women would heat up the stone while the men trekked high into the hills each summer to collect the moths," explain the Griffins.

CONTACT TIM: Email: timtheyowieman@bigpond.com or Twitter: @TimYowie or write c/- The Canberra Times, 9 Pirie St, Fyshwick.

Cryptic Clue: Well, it is getting close to St Patrick's Day.

Degree of difficulty: Hard

Last week: Congratulations to Judy Sillis of Carwoola who was first to correctly identify the location of last week's photo as a vantage point from the upstairs balcony of the building at the Bermagui Fishermens Wharf, looking out towards the entrance of Bermagui Harbour. Judy just beat 10-year-old Mahalia Plant, Peter Kercher of Holt, and Greg Royle of Red Hill to the prize. Let's hope Bermagui, like other South Coast towns, is buzzing with Canberra visitors this long weekend.

The clue of ''divine intervention'' related to the 2001 film The Man Who Sued God, starring Billy Connolly, some of which was filmed in and around Bermagui Harbour.

How to enter: Email your guess along with your name and address to timtheyowieman@bigpond.com. The first email sent after 10am, Saturday, March 7, 2020 will win a double pass to DENDY - THE HOME OF QUALITY CINEMA.

While it is well-known that mountain pygmy possums and ravens like to feast on Bogong moths, photographic evidence recently captured by Peter Caley, a CSIRO senior research scientist, suggests that the moth may also be on the menu of feral pigs. These photos show pigs eating moths at the entrance to a cave in the Brindabellas.

While recently fossicking along the Molonglo River near Coombs, prolific geocacher Thomas Schulze was shocked to see this face peering back at him. Is it an out-of-place Pac-Man? Or a ghost with teeth?