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How do echidnas make love?
Carefully… of course! No truly – that’s a direct quote from the scientist behind the latest discovery about Australia’s favourite spiky mammal’s love life. Dr Christine Cooper and her team have just released the first published recordings of echidnas “talking”. Her research not only proves that echidnas can vocalise, given that the sounds have only been heard in breeding season, it raises the question; is this the echidnas’ secret love language?
“It’s not very loud,” she tells me. “Quite soft – that might be why it hasn’t been recorded before. I have heard some members of the public who’ve contacted me since the paper was released describe it as a purring sound. But to me it sounds like a dove cooing.”
Cooper is based at Curtin University’s School of Molecular and Life Sciences in Western Australia. One day, more than a decade ago, while working with a PhD student at their main echidna field site in the Dryandra National Park near Narrogin, 200km south west of the capital, Perth, they heard a weird sound.
“We just sort of looked at each other and went, ‘Did you hear that? Was that the echidna?’” she remembers. “To be honest, if I’d been there by myself I’d probably have thought I was imagining it!”
The reason for her incredulity is that echidnas weren’t supposed to talk. Smell is their major form of communication. “We went back through the literature and there was no reference to them vocalising. The only thing we could find was an honours thesis from 50 years ago which mentions this sound, but the study was never published.”
Astonishingly, it was to be another 15 years before Cooper heard the sounds again. Only this time, they had smart phones.
If I’d been there by myself I’d probably have thought I was imagining it!
Dr Christine Cooper
“So we were able to record them. It was just luck.” Over the next month, she and her team heard the mysterious calls 5 times and managed to make 3 recordings. But what exactly were the echidnas trying to say?
“The truth is we don’t really know what they mean by it,” Cooper confesses. “But the first time we heard it was a male in a mating train. So we suspected it was to do with breeding.”
(At this point, I interrupt briefly, curious whether his purry-coo made this echidna the standout out suitor, but the unsatisfying answer is the scientists don’t know who the successful mate was.)
All the coos were heard during August, which is peak breeding season for West Australian echidnas, which does strongly point to a reproductive purpose. It also might explain why the sounds are so rarely heard. Confounding the translation though, some purry-coos were made by males in a mating train, others by males on their own, and yet others came from solitary individuals of indeterminate sex. So it’s still uncertain whether females also make the sound.
And while the coo-purr certainly sounds gentle to this possibly biased reporter, and rather “flirty” (similar to the coos used by doves in courtship, or the cat’s contented purr), it could mean the opposite.
“One of the hypotheses put forward is that it’s actually for males in conflict,” says Cooper.
In other words, a sort of back off sound – similar to the growl of the platypus. If so, it has to be one of the least aggressive-sounding warn-offs in the animal kingdom.
Much about the echidna’s love life is gently confounding. Take the already mentioned mating trains – perhaps one of the most visible quirks of echidna behaviour. A group of males follow around a female in an orderly fashion; politely single file with the occasional and not terribly boisterous attempt to overtake. Cooper has seen these trains take days, with regular clock offs of an evening for everyone to go to bed, before resumption of the slow pursuit around 9 the next morning. This continues until the female is ready to mate.
Which brings us to the thorny – literally – issue of how echidnas make love. Once Cooper and I have stopped giggling at the obvious answer, she expands. “The few matings I’ve seen, he tips her on her side. He tries to get his paw underneath her, underneath the spines, and flips her over. And they mate in that position.”
“Are echidnas affectionate?” I ask, still wondering if the purr-coos could be flirtatious? “That’s a really interesting question,” says Cooper, “because they’re supposed to be solitary, and they certainly forage on their own, but we’ve actually observed a lot of our animals in groups.
“For example, we have some echidnas in captivity in a large area with lots of nice nesting spots but they tend to all pile into the same one. Often it’s a different one each night so it’s not like they’re all just choosing the best site. So I suspect echidnas are a lot more social than people think.”
It could just be that these echidnas are West Australian. Echidnas are found across Australia, but their behaviour from region to region varies greatly; and that includes their love life. Dr Stewart Nicol, Associate Professor of Biology at the University of Tasmania, is one of Australia’s pre-eminent echidna biologists. He has painstakingly observed Tasmanian echidnas over many decades.
“If there’s one thing I’ve learned,” he tells me, “it’s that you can never say ‘echidnas do this’. You can only say ‘echidnas in this region do this.’” And one regional factor that dominates the Tasmanian echidna’s love life is that winters are colder than in WA – cold enough for echidnas to hibernate.
Echidnas are one of only a few Australian mammals with true hibernation (others include pygmy possums, feathertail gliders and some bats). And that has fostered a curious hibernation inter-sex arms race.
“The males come out of hibernation well before the females,” Nicol tells me. “They use olfactory cues to go round mapping the location of all the females. And they can tell her condition – they’ll ignore her if she’s not fat enough to breed successfully.”
“Do they do it while she’s asleep?” I ask, innocently. “They’re not so ungentlemanly about it,” explains the professor. “She has to warm up first.”
In the torpor of hibernation, the female echidna’s body temperature can drop to 4°C; her body too immobile for the “act of love”. Like its fellow monotreme, the platypus, the male echidna has a gland on its hind leg which swells in breeding season, producing a venom. In the echidna, Nicol thinks it’s this venom which, as he describes it, may chemically help “put her in the mood.”
“We’ve seen the males dragging their back foot with the spurs across her back. So one of the functions of this venom, we think, may be to stimulate ovulation.”
One of the functions of this venom, we think, may be to stimulate ovulation.
Dr Stewart Nicol
In the matings Nicol has observed, it’s a more traditional position with the male climbing carefully on the females back, then tipping his tail under her cloaca to complete the fertilisation.
Mating can occur early in winter, when not enough food is available to produce sufficient milk for her young. So, remarkably, the female echidna can then take herself and her developing egg and embryo back into hibernation. The only trouble is, if she is too frequently woken by males, she can lose the baby.
These animals are pretty much loners. Nicol has never heard a Tasmanian echidna make the mysterious coo-purr sound.
“Our WA animals are completely different,” confirms Cooper. “Our echidnas don’t hibernate. We see big male trains and they don’t. Ours are much more social. And much harder to pick up! Ours are more spiny and they curl up into an impenetrable ball. You can pick up a Tassie echidna with ordinary gardening gloves. We have to use welding gloves!”
Which may explain why WA lovemaking echidnas are extra careful…
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