The National Zoo and Aquarium in Canberra has announced two new lions have been added to their pride, with the goal of welcoming some new cubs.
Mlinzi, an adult male, and lioness Nairibi were carefully chosen and imported from other zoos, after experts determined they made a good genetic match.
If they do succeed in breeding, their courtship will produce the first lion cubs at the Canberra zoo in more than 19 years.
And, as lion habitat across the African continent continues to be threatened, their arrival could mean more than simply some cute additions for zoo visitors to enjoy.
'Signs are really good' the couple will breed
A decision to import Mlinzi and Nairibi came after the zoo's two veteran lions — who have been among their attractions for the last 19 years — were retired.
The zoo's general manager of wildlife and operations, Paul Whitehorn, said the elderly pair were no longer suited to being on display and were now in a more-private part of the zoo, where they could see out their final years napping quietly in the sun.
Two further white lions are also residents, but are brother and sister and, as a result, are not part of the breeding program.
Mr Whitehorn said that organising for the arrival of the new breeding pair was a complicated and meticulous process.
"We make sure that we have space available for the animals, and we have space available for offspring and to hold them for a certain period of time," he said.
"And then recommendations are made through our breeding program, through the species coordinator and the stud bookkeeper, as to the best pairings that are available.
"Then we go into negotiations with the zoos, where those animals are currently housed, and we do the big swapsies, move around everybody and end up with a pair that are genetically important to the region, and then, hopefully, nature takes its course."
There are roughly 2,000 lions in captivity around the world.
Mr Whitehorn said it was important for the zoo to contribute to the global population of lions, which are listed as a vulnerable species.
"There's potential down to the track to be the 'ark'," he said.
"If something was to wipe out lions in the wild — some major disease outbreak — then we are at least in a position where we have animals that would potentially be released back into the wild."
Zoo staff are optimistic that the new couple will produce offspring after a period of getting to know one another.
"The signs are really good," Mr Whitehorn said.
"She's definitely the boss, which is a good start, so she's got him well and truly worked out.
"A lot of the work we're doing is to make her feel comfortable."
He described the process as similar to an "arranged marriage".
"You do hope that you've got animals that are compatible in that way," he said.
"And then, once the female starts cycling, and the male does what he needs to do, we then need to make sure that mum's comfortable, she's got somewhere where she can have the cubs where she doesn't feel threatened."
Zoos now playing an important role
Conservationists have not always viewed zoos as the ideal environment for different species but, over time, they have played more and more of a role in preservation.
Australian National University conservation biologist Rob Heinsohn said lion habitats in Africa were shrinking.
"Lions are getting into real trouble in Africa," Professor Heinsohn said.
"They were thought to be pretty secure and then, with the growing human population, they've been squeezed out of their natural habitat, and they're really retracting to what they consider to be about five main areas where they think they can conserve them on the ground.
"It's getting to the point where we're losing the battles in Africa, and these programs — where we take animals into captivity and try to build up an insurance population in captivity — is worth it."
While zoos once functioned primarily to entertain, today they also contribute to breeding programs, and educate the public about the importance of conservation.
Professor Heinsohn said lions generally adapted well to captivity.
"A lot of species just don't do well in captivity, and it's a real nightmare trying to get them happy and to the point where they're breeding … and where they're actually good to take back to the wild," he said.
"Lions are better than many, because they're not particularly wide-ranging — they only go as far as they have to to get food."
What it takes to breed healthy lions
The key is for zoos to ensure their lion populations are both well-fed — including with meat on the bone to maintain jaw strength — and that they have a social group to spend time with.
"Lions are really interesting because they're the only cat that is truly social," Professor Heinsohn said.
"And they simply have to have other lions around them, they live in prides.
"As long as zoos manage them so that they're happy socially, then they tend to get on OK, and the lions that you see in captivity are, on the whole, pretty happy and healthy."
In the case of Mlinzi and Nairibi, the hope is that future cubs will build up the pride and provide much-needed social contact for years to come.
Because males tend to become aggressive towards one another as they reach adulthood, a male cubs will likely be moved on from the zoo, while females are likely to stay on.
Professor Heinsohn said the zoo's approach to importing lions was critical to ensuring populations remained healthy.
"That's the number one reason for moving the animals around — it's to keep the genetic health of the population as [strong] as possible."
He said that, to ensure the couple bred, Nairibi would need to feel comfortable with Mlinzi.
"Females are naturally really wary of the males and that goes back to the wild behaviour," he said.
In the wild, males come and go from a pride, which is made up mostly of females.
When males fight and take over a pride from each other, they often kill any cubs already there to ensure females are ready to mate again with their own young as soon as possible.
"[Females] do accept their losses and they do come back into oestrus quite quickly and then they'll have a new batch of cubs to the new males and life goes on," Professor Heinsohn said.
"But they do lose a lot of cubs along the way. So, in captivity, there's always going to be some initial tension."
What's in a roar
Time will tell whether romance blossoms between this new pair, but experts agree there's one clear sign that a lion is happy in its habitat.
"The one thing that tells me that the lions are doing quite well in captivity is the fact that they roar, and if they weren't happy and settled, they wouldn't roar," Professor Heinsohn said.
Roaring is a sign from lions that, not only they are content, but also a territorial warning to others.
Lions are able to count, Professor Heinsohn said, and use roaring as a way to assess how many others are in the area.
"The roaring is one of the fantastic things that people can experience," he said.
"However many animals are there, they'll all roar together, and that's basically saying, 'This is our territory. Keep out'.
"And, in the wild, there'd be another territory a kilometre or two away and the lions over there would hear the roaring and they'd know that they were at home, they're occupying their territory, 'No point going there or they will get beaten up'."
Mr Whitehorn said the lions at Canberra's zoo roared "regularly".
"It's basically telling everybody, 'Hey guys, this is where we are, we're happy here'."
