Photos of a mammoth spider devouring a bird in a Queensland backyard are sweeping email inboxes — and according to experts, it's all real.

The photos — which are reported to have been taken this week in Atherton, west of Cairns — show the spider clenching its legs around a lifeless bird trapped in a web.

Head spider keeper at the Australian Reptile Park at Gosford on NSW central coast, Joel Shakespeare, said the spider was a Golden Orb Weaver.

"Normally they prey on large insects… it's unusual to see one eating a bird," he told ninemsn.

Mr Shakepeare said he had seen Golden Orb Weaver spiders as big as a human hand but the northern species in tropical areas were known to grow larger.

Queensland Museum identified the bird as a native finch called the Chestnut–breasted Mannikin.

The bird, which appears frozen in an angel-like pose, most likely flew into the web and got caught, according to Mr Shakepeare.

"It wouldn't eat the whole bird," he said.

But the spider would probably prepare a liquid soup with the finch — as it does with insects — and discard of what it doesn't need.

"It uses its venom to break down the bird for eating and what it leaves is a food parcel," he said.

Greg Czechura from Queensland Museum said cases of the Golden Orb Weaver eating small birds were "well known but rare".

"It builds a very strong web," he said.

But he said the spider would not have attacked until the bird weakened.

"They blunder into [the webs] and their feathers get entangled," he said.

"The more they struggle, the more tangled up and exhausted they get and they go into stress."

The Golden Orb Weaver spins a strong web high in protein because it depends on it to capture large insects for food, unlike funnel web and wolf spiders that actively hunt their prey.

Another species called the bird-eating spider does not actually eat birds.
"If a spider gets a bird, it's a very lucky spider," Mr Czechura said.