EXPLORING THE MISSISSIPPI River with his hunting dog, Dash, some time in the early 1800s, artist and ornithologist John James Audubon decided to perform a little experiment.
According to the native Americans and some scattered literary references, the beautiful green and gold Carolina parakeets that once littered the south-eastern United States were deadly toxic, and John had to know for sure.
So he caught some by the side of the river, boiled them up and fed them to his dog to see what happened.
Was Dash okay? No one knows, but all mention of her in John’s well-kept diary stops dead at this Mississippi meal, so perhaps her fate was sealed when she fed on what could have been the only species of toxic bird in the world.
Sadly, the Carolina parakeet has been extinct for almost a century, but another toxic bird lives on. In 1989, Jack Dumbacher from the California Academy of Sciences travelled to the Papua New Guinea bush in search of birds of paradise.
He strung up a number of delicate nets between the trees, and one day found several striking songbirds tangled in them. They were hooded pitohuis (Pitohui dichrous), little black and orange passerines with powerful beaks and dark red eyes.
As Jack struggled to free the pitohuis from his nets, they scratched his hands and the cuts hurt more than they should have. He put his fingers in his mouth to dull the pain, but that only made his tongue tingle and burn.
When Jack asked the locals if hey knew anything about this peculiar effect, they knew all too well to stay away from the hooded pitohui – “a rubbish bird”, they said; no good for eating.
Jack flew some pitohui feathers back to the United States for further testing, and showed them to chemist John Daly at the National Institute of Health. Years earlier, Daly had identified the presence of batrachotoxins – extremely potent neurotoxic steroidal alkaloids that in high doses can lead to paralysis, cardiac arrest and death – in the tiny poison dart frogs of South America.
Gram for gram, it is one of the most toxic natural substances known to science. In 1992, Daly found that exact same toxin in the feather fibres of the hooded pitohui.
Twelve years later, with the help of the Papua New Guinea locals, Jack discovered that the pitohuis were getting their batrachotoxins from the small melyrid beetles they fed on.
It was a mystery solved, but what drove these birds to pick the highly toxic melyrids as their primary food source? Why the hooded pitohui ended up toxic is anyone’s guess.