Sir David Attenborough has opened up on the circumstances in which he believes zoos and similar institutions can be "justified".
It comes as the naturalist is voicing a brand new nature documentary series, A Perfect Planet, that will air on BBC One in the New Year.
The new five-part programme explores the forces of nature that support and enable life on earth, including volcanoes, sunlight, weather and oceans while the final episode in the series is all about the dramatic impact human beings have had on the planet.
In a Q&A ahead of the programme's launch, Attenborough, 94, reflected on his own views on humans keeping animals in captivity in zoos and aquariums.
"If you're talking about animals that have been reduced to less than 100 and the reason they've done that is that something has happened in their environment which has made it impossible for them to survive then you can either sit back and say 'well they can look after themselves' or you can to do something active,” he said.
“The Arabian oryx was extinct in the wild and it was only because people realised that zoos in America and Europe as well as private collectors had got these animals and they brought them all together and they created a breeding stock and they grew in numbers and now they re-release them in the wild," Attenborough went on.
He added while the Arabian onyx it was an "extreme case" there are instances of "real urgency" that give reason to animals living in captivity but that it was "impossible" to generalise about animals due to their differing needs and habits.
"There are some animals that thrive in captivity and some animals don't. It depends how big they are, what their habits are. Eagles should not be kept in zoos. But there are monkeys for example - or squirrels - which do perfectly well and aquaria of course do very well indeed.
"It's important that the public at large should be aware of the reality of these things and get close to them, see what they smell like, what they sound like what the reality of the thing is.
"I justify zoos providing they are scientific, providing they are selective about what they keep and provided they keep them to the highest possible standards. That's okay by me," he concluded.
Earlier this year, the broadcasting veteran backed an appeal to help save London Zoo and Whipsnade Zoo from closing down.
He lent his voice to a TV campaign appealing for money to be raised for the Zoological Society of London, as it owns both zoos.
A Perfect Planet will air on BBC One in 2021.
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