Two species of poisonous bird have been discovered living deep in the jungles of Papua New Guinea.
The birds carry a powerful neurotoxin in their feathers also found in the deadly dart frogs of South America.
Danish researchers risked life and limb to carry out their study amongst regularly warring tribespeople and ex-cannibals in the New Guinean rainforest.
The two birds are the regent whistler and the rufous-naped bellbird who eat poisonous food and turn it into venom of their own.
The poison is Batrachotoxin, one of the most powerful known neurotoxins and 250 times more toxic than strychnine.
In higher concentrations, such as those found in the skin of golden poison frogs, it leads to muscle cramps and cardiac arrest nearly immediately after contact.
Although in these birds it is not concentrated enough to kill people, the toxins give humans a runny nose and teary eyes, a bit like cutting onions, if the birds are handled.
Locals avoid eating them as they say they have a ‘burning’ taste in the mouth like chili.
Associate Profesor Knud Jønsson of the Natural History Museum of Denmark and University of Copenhagen (UCPH) said: “We managed to identify two new species of poisonous birds on our most recent trip.
Two new poisonous bird species: The regent whistler and the rufous-naped bellbird.
“These birds contain a neurotoxin that they can both tolerate and store in their feathers.
“The locals aren’t fond of spicy food and steer clear of these birds, because, according to them, their meat burns in the mouth like chili.
“In fact that’s how researchers first became aware of them. And the toxin can be felt when holding onto one of them.
“It feels kind of unpleasant, and hanging on to one for long isn’t an appealing option.
“This could indicate that the poison serves as a deterrence for those who would want to eat them to some degree.
“We were really surprised to find these birds to be poisonous as no new poisonous bird species has been discovered in over two decades, particularly, because these two bird species are so common in this part of the world.”
Fellow author at UCPH Dr. Kasun Bodawatta added: “The bird’s toxin is the same type as that found in frogs, which is a neurotoxin that, by forcing sodium channels in skeletal muscle tissue to remain open, can cause violent convulsions and ultimately death.
“Knud thought I was sad and having a rough time on the trip when they found me with a runny nose and tears in my eyes.
“In fact, I was just sitting there taking feather samples from one of the most poisonous birds on the planet.
“Removing birds from the net isn’t bad, but when samples need to be taken in a confined environment, you can feel something in your eyes and nose.
“It’s a bit like cutting onions – but with a nerve agent, I guess.”
The toxicity level of the New Guinean birds is less lethal than dart frogs but may still serve a defensive purpose, though the adaptive significance for the birds is yet uncertain.
Venomous animals either produce their own poison or ingest it and use it themselves.
Beetles containing the toxin have been found in the stomachs of some of the birds but the source of the toxin itself has yet to be determined.
Dr. Bodawatta said that the birds could tolerate the toxin due to genetic mutations.
He said: “The birds have mutations in the area that regulates sodium channels, and which we expect gives them this ability to tolerate the toxin, but not in the exact same places as the frogs.
“Finding these mutations that can reduce the binding affinity of Batrathotoxin in poisonous birds in similar places as in poison dart frogs, is quite cool.
“And it showed that in order to adapt to this Batrachotoxin lifestyle, you need some sort of adaptation in these sodium channels.”
While their neurotoxin is similar to that of the South American poison dart frogs, the birds developed their resistance and ability to carry it in their bodies independently of the frogs. This is an example of what biologists refer to as convergent evolution.
Prof Jønsson said it is all part of nature’s arms race.
He said: “Over time, some beetles develop toxicity to avoid being eaten. Perhaps they also acquire a particular coloration that may serve as a warning. This in turn allows them to venture from their hideouts beneath logs and rocks.
“Then, a predator counters and suddenly, a bird species can eat them regardless. The predator too acquires a mutation that offers resistance to the toxin.
“This gives the bird an advantage and opens up a whole new food source that isn’t available to its ecosystem competitors.
“So, there is clearly an arms race going on and the beetles will need to crawl back under that rock again until they’ve developed their next move a few million years later.
“Subsequently, the birds that have evolved the ability to eat toxic food, themselves become toxic and may be able to defend themselves against predators further up the food chain.
“And so, the race continues up the chain. It’s evolution – anything can happen, but it often takes a long time.”
Since the Papua New Guinean government does not own the forest land, it was crucial to contact, negotiate and come to an agreement with the people who live in the Saruwaged Range, where the study took place.
The team landed in a tiny plane and then took local guides who hacked their way through the forest before they set up camp and put up bird nets to catch the birds alive.
Prof Jønsson added: “Life as a bird researcher in New Guinea is not exactly comfortable. It is hot, wet and even comes with a bit of anxiety from time to time.
“If you aren’t prepared and haven’t made agreements with the locals, going in cold can be downright dangerous.
“On a previous trip, we experienced ten men from a neighboring village suddenly standing in the camp with machetes – they can be and regularly are equally well used on vegetation and humans.
“They were angry and had a completely different perception of where the village boundaries were than the leaders of the tribal village with whom we had made the agreement.”
Produced in association with SWNS Talker