A kiwi is watched by a cat outside a predator-proof fence at Orokonui Ecosanctuary, near Dunedin.

A photo of a cat eyeing up a kiwi inside a Dunedin ecosanctuary highlights the need for wildlife protection, a senior manager says.

The photo was taken on a trail camera by student Jemima Gardiner-Rodden and uploaded to the sanctuary's Facebook page.

Orokonui Ecosanctuary conservation manager Elton Smith said the photo and caption had prompted the biggest response on the page.

"We have had so many comments ... it is a real talking point. It has been a real eye-opener."

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In an online post, Smith wrote if a "picture is worth a thousand words, so then what does this photo say".

"Clearly that the fence is a good idea. It is said, that along with stoats, cats kill 70 per cent of wild-born kiwi chicks before they reach 6 months of age."

While cats and conservation were "contentious", he said people should not shy away from the subject. Smith believed the cat controlling the reserve's perimeter fence was someone's pet.

The trap line around the fence trapped all introduced mammals, but not cats. Those 414 traps had caught five ferrets, 30 stoats, 11 weasels, 153 rats, 547 mice, 35 hedgehogs and 49 rabbits.

"At this point in time it is too politically difficult for us to target cats and we certainly don't want to be killing someone's pet," he wrote.

"However, we also want to fully protect the spill over of our wildlife such as robins, kaka, fernbird and lizards. All of course, are potential cat food. So what should we do?"