By Ingrid Hipkiss
Researchers from Otago University have discovered that birds that grow up in artificially safe environments can lose their ability to recognise predators.
They studied native robins raised on a pest-free island and found the birds "forgot" to be scared of rats.
Rats have been present on Stewart Island since the 1600s. The clued-up robins that live there know rats are dangerous.
But nearby Ulva Island is rat-free. It turns out the robins born there don't know danger when they see it.
Scientists discovered this by filming the Stewart Island robin. It swoops in for food, but when a rat, in this case a stuffed one, is present, it doesn't land.
The same study of an Ulva Island robin, which hasn't seen a rat before, shows it's oblivious to the danger.
“Intuitively we think that animals such as birds should be able to recognise their enemies,” says associate professor Ian Jamieson. “But our research shows it is more complicated than that.”
Mr Jamieson says the research may explain the variation in survival rates when species are re-introduced to the mainland.
While predator-free islands may not prepare birds for the real world, they're still crucial in ensuring the survival of some of our most endangered birds.
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