Death of the Bogong – another of Nature’s icons bites the dust

And this time it’s personal

By David Salt

“Don’t it always seem to go, that you don’t know what you’ve got till it’s gone.”

So opined Jodi Mitchell back in 1970 when she protested against the paving of paradise to put up a parking lot, an anthemic reflection on the price of progress.

But the line seems particularly apposite today, fifty years on, as we consider the latest victim of ‘progress’, the seemingly ubiquitous Bogong moth. The IUCN (the international body that monitors planetary biodiversity), has just placed the Bogong moth on its Red List of Threatened Species, not a list any organism wants to join.

Of course, the Bogong is a migratory moth so it’s not actually ubiquitous. For much of the year you never saw them but come migration time in and around Canberra, where I live, they suddenly appeared everywhere; in your cupboards, around your lights, behind pictures, everywhere.

They were once so common that their swarms were said to “block out the moon”. Twenty years ago, hundreds of thousands of them disrupted the Sydney Olympics when they were attracted to stadium floodlights; and many times they’ve invaded Parliament House in Canberra where “they land in your tea, your hair, your handbag and litter office ceilings, walls and windows.” This account, I’m sad to say, was only eight years ago.

From boom to bust

It’s believed Bogong moths have been migrating to the Australia’s snowy mountains every year for thousands of years. They do this around Christmas to escape summer’s baking heat by aggregating in cool mountain caves, literally coating the rocky cave walls like the scales of a fish.

The moths provided a rich source of food for other animals like the Critically Endangered mountain pygmy possum. They are also eaten by humans. First Nations people used to come together from all over the region to feast on the moths. It was a time of celebration, to have a big eat up and strengthen relationships. These ceremonies stopped with European colonisation; though the moths still continued their yearly journey in their billions.

Since the 1980s, however, scientists have detected steady declines in numbers of bogong moths. Then, in 2017 and 2018, their numbers crashed. Ecologists visiting caves at Mount Gingera in 2018 near Canberra reported that this site that had been known to house millions of the moths (17,000 moths per square metre), now only contained three moths! Not three thousand or three million, just three moths. Searches of another 50 known sites have turned up similar catastrophic absences.

Of course, if you look back through the environmental records for this time (and you don’t have to look far, it was only a few years ago) you’ll discover the Great Barrier Reef was undergoing another mass bleaching event, kelp forests were disappearing along with mangroves, and the nation was suffering an unprecedented drought (which gave us our Black Summer in 2019/20).

The decline of the Bogong moth is being connected to extreme drought (associated with climate change), pesticides and changes in agricultural practices. Last summer (2020), numbers were a bit better however, at best, they are only at 5% of what they used to be.

A connection severed

With their loss, we lose a tangible cultural connection to the history of our First Nations people. With their loss it’s likely we will also see the demise of the mountain pygmy possum which depended on the moths as a primary food source. Checks on the pygmy possum, which exist only in Australia’s alpine regions, have revealed dead litters in the pouches of females.

And while we found the Bogong moth a bit of a pest when they invaded our homes, stadiums and gathering places, they have become a creature of our own folklore; their presence signalling one of nature’s miracles in progress. I’ve never thought of them as beautiful (or cuddly) but their existence and behaviour filled me with a sense of awe and joy for the ineffable wonder of the natural world.

In 2018, scientists revealed one more facet of the amazing story of the Bogongs. Apparently they use the Earth’s magnetic field to help them navigate from the grasslands in northern New South Wales and southern Queensland to reach the mountains – sometimes at distances of 1,000km. Their use of magnetic fields for migratory navigation is believed to be a first for insects. Ironic, isn’t it. A miracle partially understood just at the species itself appears to be moving into the twilight of extinction.

Again and again

This is not the first time a populous species that we thought would be with us forever has disappeared. In the 1800s the passenger pigeon in North America formed flocks that darkened the skies for several days at a time. With a population in the billions, no-one believed it could be at risk. But it was hunted in large numbers and its forest habitat was cleared. Its population collapsed over a few decades. Even when it was realised the species was in decline, 250,000 birds – the last big flock – were shot on a single day in 1896! The last individual passenger pigeon, a female named Martha, died in Cincinnati Zoo in 1914.

The large grasshopper (Melanoplus spretus) from the western US suffered the same fate. It went from a population of several trillion to zero in a few decades, when farmers destroyed its breeding grounds.

In Norway and across the whole of the North Atlantic, the great auk (Pinguinus impennis) died out after people harvested them in large numbers.

We took all these species for granted and now they are gone – forever.

You don’t know what you’ve got

The loss of species and ecosystems is accelerating. It is not just the Bogong moth that has been added to the IUCN Red List. A number of other Australian species have gone on including the Grey-headed flying fox and the Arcadia velvet gecko.

Scientists have given us multiple warnings about the parlous and worsening state of biodiversity on planet Earth. Many believe it is a problem even more serious than climate change though the two issues are strongly interlinked. As with climate change, the collapse of biodiversity never seems to be a high priority with any government. It’s framed as a problem for tomorrow.

I grieve at this ongoing loss, but the demise of the Bogong is especially poignant. I have trekked up into nearby mountains to witness their summer cave refuges. I have seen them in their abundance, marvelled at their ancient life cycle and enjoyed eating a few cooked in the ashes of a camp fire (they taste like crunchy pine nuts). I have always looked forward to the yearly return of these large, ponderous brown moths. These simple experiences, however, are now no longer available.

What’s more, these experiences are unlikely to ever be available to my children or their children.

The idea that we will see Bogongs no more is an assault to our very identity.

‘You don’t know what you’ve got till it’s gone.’ What does it take for our political leaders to acknowledge this loss and do something before its irreversible?

Banner image: Around Canberra there are several works of art celebrating the Bogong moth and its significance to our past and present. The one pictured here can be found on the grounds of the Crawford School at the Australian National University. I used it as a prop when lecturing to overseas students in an introduction to the Australian environment.

The bitter irony in the images shown here is that even as I was discussing this amazing insect with students (in 2017), ecologists were struggling to find any moths in the adjacent mountain range; a place they had over-summered in massive numbers since time immemorial.

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