The pandas failed to breed in 2012 but the zoo is using thermal imaging technology to monitor the pair this time - a world first.

BBC: Edinburgh Zoo encouraged by panda hormone test

The city owns the land and chips in with some public funds, but an independent trust runs the zoo.

ECONOMIST: From zoo cage to modern ark

She said that in her village the bridegroom was expected to take bushmeat to his in-laws as part of his dowry, but the zoo visit had shown her that there could be other alternatives to bushmeat.

BBC: Keeping Cameroon's primates from the pot

The albino condition, caused by a lack of colouring pigments in the skin, can lead to the animal being susceptible to sunburn, but the zoo said its wallaby enclosure had lots of shade and it should lead a "normal life".

BBC: Rare albino wallaby born at Linton Zoo

Some shots in that programme, narrated by Sir David Attenborough, were filmed in a Dutch zoo, but many viewers assumed footage came from the Arctic.

BBC: Sir David Attenborough

The owner of the zoo said Thursday that safety protocols were in place but he would not discuss them because they are a part of the law enforcement investigation.

NPR: Lion Killed Woman As She Was Cleaning Enclosure

But they're endangered, so it's pretty remarkable that the Nashville Zoo successfully bred one in captivity.

CNN: Apparently This Matters: Baby Baird's tapir

Edinburgh Zoo said the wild population was in its healthiest state since before World War II, but remained at serious threat of extinction.

BBC: Aye of the tiger as pair go north

"Sympathetic concern" has also been observed in gorillas, bonobos, dogs and even rooks - but it is the calming effect that it had on the Chester Zoo chimps which is said to be a new observation.

BBC: Hugging benefits fractious chimps