Even the first sunshine of spring is not enough to prevent the lion enclosure at Copenhagen zoo from looking forlorn. One female lion lounges on a branch basking in the rays, while the other lolls on the dusty ground beneath her. Otherwise the pen is empty.
"They're shifting around the pack a little – that's why those females are here alone," explains Martin, a young zookeeper passing by with a tray of fruit. "We have a new male lion in the holding facility and before we can introduce him to our females, they need to get comfortable."
He doesn't volunteer the fact that, as part of this process, the zoo on Monday slaughtered two older lions and two cubs. But when it's brought up, he's unapologetic.
"It's a necessary part of keeping a healthy population," he shrugs. "Because we don't bring in animals from the wild any more, we need to do this."
On Monday, when the zoo announced that it was putting down the four lions, it argued that if it hadn't, the new male would have done the job himself in a much bloodier fashion.
"The new male in the pride would have killed the immature males as soon as he got the chance," the statement read.
That's not all. The two older lions would have fought with the new male, and the older males would have killed any cubs fathered by the new male.
"This may, of course, seem harsh, but in nature it is necessary to ensure a strong pride of lions with the greatest chance of survival," the zoo explained. It said it had tried and failed to find another institution willing to take the animals and this, along with the risk that the elder male might also impregnate his two daughters, left it with little choice.
"The zoo is recognised worldwide for our work with lions," chief executive Steffen Stræde concluded in the statement. "I am proud that one of the zoo's own brood now forms the centre of a new pride of lions."
Since February, when the zoo put down a healthy giraffe called Marius, dissected it in front of children and then fed the carcass to the lions, Stræde and his scientific director, Bengt Holst, have faced intense criticism from animal rights activists.
Online petitions to save the giraffe, sack Holst and even close the zoo have gathered tens of thousands of signatures across the world.
"We have all had some hate mail and death threats and other nastiness," Carsten Grøndahl, one of the zoo's vets, says when he is stopped while riding his bicycle past the llamas. "But that's all emotional, and you can't argue with emotions."
"We have a low profile now," says Mette Nyborg, another zookeeper, when asked about future dissections. "There has been too much bad attention."
In Denmark, however, at least judging by the 10 or so families at the enclosure on Friday, almost everyone seems to support what the zoo has been doing.
"It's totally OK," says Mette Brendstorp, who is visiting with her daughters, aged two and four. "If you talk about what's cruel, it's wanting to go to the zoo and look at all the animals, and then getting hysterical when the zoo takes responsibility to ensure that there is no inbreeding."
She wholeheartedly approves of the zoo's decision to dissect the giraffe.
"I'm a schoolteacher and I wouldn't blink twice about bringing my fifth grade class to see a dissection. They are not seeing it being killed; they are just seeing it being cut open."
Irene Kyhl, who is visiting the zoo with her grandson, argues that the public should trust the experts. "The people in the zoo are in the best position to know what to do," she says.
Even her four-year-old grandson accepts it. "Maybe it's OK if there is going to be a new dad for the lions," he says, shyly.
"The public is very supportive," Martin, the young zookeeper, tells me. "They see that we have good intentions and we generally have very broad acceptance of the work that we do."
Grøndahl himself didn't put down either Marius or the four lions – that job went to his colleague Mads Bertelsen. But he cheerfully admits to having put to death countless antelopes, a "surplus" zebra, and even an elephant.
"It was a really high dose," he says of the elephant, which had been suffering from arthritis. "She weighed three tonnes, so it took a lot of drugs."
Grøndahl believes that the uproar over the zoo's practices, which it had been quietly following without criticism for many years, has come about because people are now too distanced from the natural world.
"It's because we're far from nature now," he says. "I think that people don't realise that the meat they buy in the supermarket was once an animal."
It's clear from the educational material around the enclosures that the zoo wants the public to understand nature's harsher side.
In the Arctic Ring, where from the safety of an underwater tunnel the public can watch hulking polar bears swimming by inches above them, there's a seal-killing game for children.
"Imagine you are the polar bear. Try to catch the seal when it comes up to breathe," read the instructions, next to an image of a hole in the ice.
If you press the button at the very moment when the seal's face appears, it is replaced by a spatter of blood.
In the next-door exhibit, the face of a polar bear dissolves at the press of a button to reveal the skull (presumably a real one) lying in a glass case beneath.
Grøndahl believes that it's good that the zoo is helping to give the public a better understanding.
"You shouldn't Disney-fy everything under the sun, and think that animals do not have a life expectancy," he argues.
The animals living at Copenhagen zoo are, he argues, fortunate in many ways.
"They have a good life," he says of the handful of young male antelopes he puts down every year. "It's not a very long one, but it's good, and in the wild they probably wouldn't live even that long. They have nice surroundings. I think they're happy. And they do not hear the gun go off."
guardian.co.uk © Guardian News and Media 2014