On the edge of a thin strip of roadside vegetation, a man in the far end of his 80s peers up into the canopy of a bulloak tree.
A minute speck flashes high above him. “Here’s a Bulloak Jewel! It’s a male, you got it?” he calls out.
He wears no glasses or binoculars, but the eyes of legendary lepidopterist Dr Don Sands are undiminished. So is his enthusiasm.
His research assistant, ecologist Matthew Head, tracks the speck, eyes darting. He wields a hefty 600mm lens. “Look at the size of that monstrous subtropical butterfly,” he mutters drily.
It is hardly bigger than a thumbnail. “C’mon mate … Ah no, don’t go over there!” Eventually it perches, high and vigilant.
We are at Ellangowan Nature Refuge, a 1.5km stretch of road near the one-pub town of Leyburn, on the Darling Downs of south-east Queensland.
This tiny, unprepossessing patch of scrub is home to one of Australia’s most endangered insects. Even here, it is incredibly vulnerable.
Between the 50 metres that separate the road and private property, gnarled, burnt-orange angophora trees predate the arrival of Europeans by centuries. There hasn’t been a fire here for a long time. But the trees are scarred by old lightning strikes, leaving hollows and stumps that have been colonised by a very special ant on which the butterfly depends.
After three years of La Niña, the bulloaks – a type of she-oak with long, needle-like leaves – are alight with brilliant pink sprigs of flowering mistletoes. It’s a highly complex ecosystem that has all but disappeared. On the other side of the fence, every tree has been felled. Piles of lumber lie in the paddocks.
But the abundance of mistletoe means the jewel, by Sands’ estimation, is having its best season in 20 years. In early 2019, before the long drought detonated into the black summer, he saw barely half a dozen butterflies in three months. Today we are treated to twice that number in a single afternoon.
Female Bulloak Jewel, Ellangowan Nature Reserve 1 March 2023
Nonetheless, numerically at least, it remains arguably Australia’s rarest butterfly (allowing for the possible extinction of the Australian Fritillary, last observed in 2015).
And it has Sands agitating for a difficult cause: the protection of similar remnants of roadside vegetation. For many invertebrates like the jewel, it’s the only habitat they have left.
“There’s a lot of threatened species of insects and plants living by the side of the road, and they’ve got no formal protection at all,” Sands says. “I’m using the Bulloak Jewel as an emblem of the need to conserve road reserves as corridors for other fauna and flora.” He stops and calls out: “Another one up here, Matt!”
Previously, Ellangowan was managed jointly by the Queensland departments of Environment and Science, and Transport and Main Roads (TMR). The agreement lapsed a decade ago, and its stewardship – including weeding, monitoring and surveying – has now fallen entirely to Main Roads, a situation that infuriates Sands.
The Department of Environment and Science says TMR “has agreed to ensure any activities carried out on the land does not impact the population of the Piceatus [Bulloak] Jewel butterfly, other butterfly species, and invertebrate species”.
It was Sands who formally described the Bulloak Jewel in the late 1960s, along with a medical scientist, Dr John Kerr, and a local farmer, Jack Macqueen, who collected the first specimens in this same patch of woodland. The jewels are well-named: their underwings are marked by a series of crimson bands, etched with black and glittering turquoise.
What took a lot longer to describe was the relationship between the jewel and an ant that, until two years ago, didn’t even have its own name. Sands eventually helped describe that, too: Anonychomyrma inclinata. It’s an entirely arboreal species that, were you to squish one, emits an acrid odour that tells you you’re on the jewel’s trail.
Because the ant refuses to come to ground, it uses fallen timber to navigate between trees. Sands does his bit to help, dragging branches into place. “No species stands on its own, interactions are the basis of life on earth,” he says. “If we lose a lot of insects, we’re going to lose the flow-on effects of food for vertebrates and the interactions for plants as well.”
A Bulloak Jewel flies for around two weeks, with two generations annually being produced in spring and summer. Females lay their eggs on the bulloak needles. The eggs hatch as larvae, which exude a sweet secretion that attracts and provides energy for the ants. And every day, to protect them from the heat, the ants physically carry the caterpillars to their nests.
The cool hollows used by the ant colonies become literal caterpillar creches. By night, the caterpillars are borne back out to munch on the needles. But while the butterflies have evolved to depend on the ants, the reverse is not true. “We’ve got more than 30 ant [inclinata] colonies that I know of where there are no butterflies,” Sands says.
The reason why, he surmises, is fire. The ants, insulated in their hollows, are fire-resistant. But the butterflies depend on the nectar of mistletoe. “If you get a fire through here, every mistletoe will drop out for years until they’re brought back by the birds that carry the seeds, and it could be 30, 50 or even 100 years before you get recolonisation.”
For a species as restricted as the Bulloak Jewel, with less than a handful of remnant colonies between Leyburn and Goondiwindi – and without enough connective tissue in the landscape – a hot fire here would be disastrous. For this reason, and with unnervingly mathematical precision, scientists recently rated the jewel a 37 percent probability of extinction by 2040.
Head gestures southwards, back towards town. “Just down the road here there was a fire that went through here recently, and it would have been a hot fire, not a planned burn – probably a cigarette – and you can see trees of that height, they just cooked to the roof,” he says. “The trees might come back, but nothing’s living there now, mistletoe or anything else.”
Sands says the threat of fire comes down to three factors: season, scale and frequency. “The more you burn the bush, the more you select the survival of fire-adapted and flammable plants, and the more you get rid of the fire-sensitive plants,” he says. “For invertebrates, we’ve got to use a new set of methods for managing fire if we don’t want to lose the lot.”
Another, more remote threat is butterfly collectors, who have been seen in the reserve, but Sands is less worried about them than their habitat. Amateur enthusiasts – “leppers”, the butterfly equivalent of birdwatchers – are coming here too, toting camera gear that is revolutionising survey methods. Sands nods to Head.
“I, with my long-pole net, couldn’t get anywhere near high enough to collect the specimens, but he’d just go click-click-click and immediately we’d get a picture,” he says. “With invertebrates, we had always had a policy – don’t take any notice of people’s reports, because not only do you get untruths, but you get misidentifications.”
When he originally described the jewel, Sands separated it from similar species on the basis of microstructures: specifically, he dissected its genitalia. Happily, that’s no longer necessary, at least not for identification purposes: “We’re now saying, for the first time, that we can confirm identifications using that quality of photography.”
First published in the Guardian, 12 March 2023