Years ago I went to Auckland Zoo when they held a free entry day.
I vividly remember arriving at the gibbon enclosure to see a gibbon who was clutching at the cage, screaming at everyone going past. His distress was clear to see and afterwards I felt tremendously guilty that I had contributed to his upset, which must have been compounded by the sheer number of visitors that day.
Now I realise that he was Iwani, a male siamang gibbon who has just been euthanised due to being "severely depressed", as reported in the Herald.
It's well known that animals can suffer from depression - pigs on factory farms trapped for weeks on end in sow and farrowing crates are often in utter despair from the constant confinement. Indeed it was this knowledge that first got former pork board PR man Mike King to come over to the animals' side.
Zoos are little different. The animals may have more room, but life in a cage or enclosure doesn't come close to the wide open space and range of stimuli provided by the animals' natural environment.
It's no secret that animals in zoos can suffer from excruciating boredom, social frustration and loneliness. Many are denied their most basic needs - freedom to move freely, hunt, mate and choose their companions - everything that makes their lives meaningful. Even the best zoo doesn't compare to the natural ecosystems where wild animals belong. No wonder some end up depressed.
We're often told that zoos are essential for conservation but, despite claims to the contrary, most zoo conservation programmes have poor results for the individual animals, and rarely reintroduce the animals to the wild. Most animal species in zoos are not endangered so are merely kept for public entertainment and zoo profit.
Even for those that are endangered, returning captive-bred animals to the wild is difficult, inefficient and costly. Most zoos don't even attempt it. Conservationist Damian Aspinall says, "Zoos say they are in the business of conservation. In my opinion, that's a lie. They are in the conservation of business."
The lure of zoos is clear. Taking kids to see an elephant or a gibbon close up sounds like a great day out, and educational. But it's truly not a great day for the animals. Gawping at them in captivity doesn't educate - it gives us a skewed picture of their true behaviour and visitors leave without having learned anything significant. Animals in zoos are not representative of their species. Lions in the wild do not spend half of their time pacing, bears in the wild do not have their food handed to them, and gibbons do not scream for hours.
Auckland Zoo is currently hoping to import elephants from Sri Lanka. I hope they will not succeed in this endeavour - there really is nothing inspiring about seeing magnificent wild animals living a life of depression and deprivation in captivity. It's time to re-evaluate the role of zoos.
Mandy Carter is head of campaigns at animal advocacy organisation Safe.