Echidnas at Taronga Zoo have recently been taking part in a strange breeding ritual known as "trailing", leading keepers to hope for a rare puggle, as the babies are known.
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A great deal of mystery surrounds the species' unique mating ritual.
At breeding time, the female echidna releases a pheromone that attracts males, who start trailing behind her in a line.
Echidnas can trail for up to 10 hours a day over several days.
In the wild, up to 10 males can follow a female at a time.
"It's a mystery why echidna females find their mate by taking them on an arduous journey through the bush," Taronga's echidna keeper, Brett Finlayson, said.
"They're a bit of an enigma.
"One theory is that the males trail the female until she eventually grows tired and stops walking. She will then accept the first male in line as a mate.
"Another thought is that the female recognises the compatibility of the male through smell.
"It's possible that she is waiting for the right male to be directly behind her.
"It's not necessarily the strongest but the smartest who wins the opportunity to breed," he said.
Taronga has four females and five males involved in a breeding program.
Last month, up to four males were seen trailing behind one of the females, which has zoo staff excited as no puggles have been born at Taronga since 1987.
"It is notoriously hard to breed echidna offspring in human care," Finlayson said.
Only about 25 echidnas have ever been bred in captivity, and nearly all of those were in the past 10 years, he said.
Echidnas are not endangered in the wild, although loss of habitat has led to a reduction in their distribution in Australia.
Taronga says it is important to continue to try to breed echidnas in case numbers in the wild fall to critical lows.