Matthew Hayward said the cost of adequate conservation action in Australia would be equal to the cost of one submarine.
Subscribe now for unlimited access.
$0/
(min cost $0)
or signup to continue reading
By latest estimates, that's about $19 billion.
Associate Professor Hayward, a University of Newcastle conservation specialist who has been researching leopards in Botswana, said humanity was at "an important juncture".
"Many countries have the wealth to adequately address the biodiversity crisis, but we need the political will to do so," he said.
"Australia's bushfires reinforced this point - so many species are hanging over a precipice of mankind's making."
Unless conservation action was adequately funded, future generations "will look very dimly at those of us who failed to preserve their natural heritage".
"Rich countries need to support poor countries in developing their economies without devastating their environments," he said.
Dr Hayward describes leopards as "supreme predators".
"They hunt entirely alone and can bring down prey as large as a giraffe calf or eland.
"They can then drag the carcasses up a tree to avoid losing any of it to scavenging hyenas or lions."
Dr Hayward said leopards and other large predators "illustrate to humans that we are not the toughest kid on the block".
"On foot in the African bush, there are a multitude of animals that would comfortably kill us," he said.
"Out there, we are as close to our ancestors as we can get - where one mistake could be our last."
He said the existence of leopards "links to our primal instincts".
"Watching them hunt and live illustrates the beauty and brutality of nature - red in tooth and claw," he said.
Leopards are agile, stealthy creatures.
"We had a radio collar on a male leopard in Addo Elephant National Park," he said.
"The leopard climbed over an electrified fence in a single day. The fence had kept lions housed for three months.
"We would get his signal and drive in to see where he was, but we never saw him because he kept moving."
The leopard kept itself inconspicuous in bush, beyond where its human observers could see.
Leopards are listed as a vulnerable species. Loss of habitat is the key threat, along with persecution.
"They are not particularly compatible with pastoralism, although there are options that can minimise their impact like livestock guardian dogs," Dr Hayward said.
Dr Hayward's work on leopards has recently appeared in two academic papers.
These included a study into how leopards avoid encounters with apex predators.
"There's lots of research that has looked at how smaller [meso] predators can co-exist alongside larger [apex] predators," he said.
Examples include wolves and coyotes or dingoes and foxes.
"In simple ecosystems with one apex predator and one or two mesopredators, there is some evidence that apex predators limit mesopredators - although that is weakening by the day.
"We were interested to see how a smaller, subordinate predator like the leopard could co-exist alongside much larger and more dangerous predators like lions."
The research found that radio-collared leopards encountered radio-collared predators "pretty equally among the species we studied [lions, wild dogs and cheetahs]."
The leopards were more likely to "bump into lions when the information they had to assess risk was limited (such as thick vegetation)".
"If they had perfect information on where lions were, they would do more to avoid them," he said.
"But then, leopards are pretty good at scaling trees at the first sign of trouble."
Further research examined how leopards conduct scent-marking with urination and defecation.
The aim was to determine if they try to "conceal the information these marks confer to competitors and predators".
"It turns out that leopards prioritise marking on the periphery of their home ranges," he said.
In these areas, encounters with other territory-invading leopards - rather than lions - were more likely.
"They also used roads far more frequently than we'd expect," he said.
This suggested that roads act as "important conduits" through a landscape that all predators were likely to use.
Understanding how a complex group of carnivores can co-exist gives researchers an understanding of "what to expect in simpler systems like Australia".
"It also helps us understand the mechanisms these species use to avoid costly encounters with potentially dangerous prey," he said.
"If a leopard can co-exist in Africa alongside lions, hyenas, cheetahs and wild dogs, surely a fox can do so in Australia alongside dingoes."
Dr Hayward said large, effectively protected areas were "critical to the conservation of large predators".
"Leopards are somewhat lucky in that they can co-exist with people to a certain extent," he said.
"If we can improve our livestock-husbandry practices, then we could improve the likelihood of leopards persisting in the wider landscape - beyond protected areas."