In New Guinea, researchers uncover birds with neurotoxin-laden feathers.

Two new species of poisonous birds have been found by researchers from the University of Copenhagen during an expedition into the New Guinean jungle. These birds are now able to transport a potent neurotoxin thanks to genetic changes.

One of Earth’s most pristine rainforests, which is as exotic as any other place in the world, is home to poisonous birds. Most people’s eyes will be opened when they hear the words poisonous and bird together. However, there are actually poisonous birds. More species are currently being found in New Guinea’s jungles.

“On our most recent trip, we were successful in identifying two new species of poisonous birds. The neurotoxin in these birds is something they can tolerate and store in their feathers, according to Knud Jnsson of the Natural History Museum of Denmark.

“On our most recent trip, we were able to identify two new kinds of toxic birds. These birds have a neurotoxic in their feathers that they can tolerate and store.”

Knud Jønsson of the Natural History Museum of Denmark.

Jönsson and fellow UCPH researcher Kasun Bodawatta have been on an Indiana Jones-like research expedition, risking life and limb to interact with frequently fighting tribespeople and ex-cannibals in the midst of the rainforest’s astounding biodiversity. Here, they managed to capture two new bird species, each of which has evolved the capacity to ingest poisonous food and transform it into its own poison.

One of the newly discovered poisonous birds is the rufous-naped bellbird (Aleadryas rufinucha). Credit: University of Copenhagen

The two birds that the researchers found to be poisonous are the rufous-naped bellbird (Aleadryas rufinucha) and the regent whistler (Pachycephala schlegelii), both of which are members of a family of birds with widespread distribution and easily recognizable songs.

Since there haven’t been any new poisonous bird species discovered in more than 20 years, we were very surprised to learn that these birds are lethal. Particularly considering how prevalent these two bird species are in this region of the world,” claims Knud Jnsson.

Muscle spasms are brought on by neurotoxins.
The recognizable poison dart frogs of South and Central America are well-known to most people, particularly the golden poison frog. Even a light touch from one of these tiny, vividly colored amphibians can be fatal to a person. The discovery of two new poisonous bird species in New Guinea, which have the same kind of toxin in their skin and feathers, shows that the frog toxin is more common than previously thought.

Bactrachotoxin is the name of the toxin found in the bodies and feathers of these birds. It is an incredibly strong neurotoxin that, in higher concentrations, like those found in the skin of golden poison frogs, causes cramping in the muscles and cardiac arrest almost immediately after contact.

According to Kasun Bodawatta, “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.”

Similar to chopping onions, but with a nerve agent.
The poisonous dart frogs of South America use it to defend themselves against predators. Although the New Guinean birds’ level of toxicity is less lethal, it may still serve a defensive function; however, the significance of the birds’ ability to adapt is still unknown.

“When they discovered me with a runny nose and tears in my eyes, Knud assumed I was depressed and having a difficult time on the trip. In fact, I had been observing a Pitohui, one of the most lethal birds on the planet, while collecting feather samples. It’s not bad to remove birds from the net, but when samples must be taken in a small space, you can feel something in your eyes and nose. Kasun Bodawatta chuckles, “I guess it’s kind of like cutting onions with a nerve agent.

Because they believe that the meat from these birds burns in the mouth like chili, the locals, who dislike spicy food, avoid them. In fact, it was through research that they were first discovered. Holding onto one of them causes the toxin to be felt. Holding on to one for too long isn’t an appealing option, and it feels somewhat unpleasant. This could indicate that the poison serves them as a deterrent to those who would want to eat them to some degree,” explains Jnsson.

A race for evolutionary advantage.
The researchers contend that nature’s ongoing evolutionary arms race is represented by the poisonous birds. With beetles, insects, and other invertebrates at the bottom of the food chain, it begins. Some of these eventually become toxic in order to prevent consumption. They might also develop a certain coloration that could act as a warning. They were then able to emerge from their caves beneath rocks and logs.

Then a predator responds, making it so that any species of bird can eat them. A mutation that provides resistance to the toxin is also acquired by the predator. As a result, the bird gains an advantage over rival species in the ecosystem and gains access to a brand-new food source. The beetles will have to crawl back under that rock until they have developed their next move a few million years later, as there is obviously an arms race going on, says Jnsson.

The birds that have developed the ability to consume toxic food will subsequently become toxic themselves and may be able to defend themselves against predators higher up the food chain. And so, the race continues up the chain. In evolution, anything is possible, but it frequently takes a very long time,” the researcher claims.

Making the poison their own.
Biology distinguishes between the two ways that animals use poison. Animals that are poisonous can either produce toxins on their own or take toxins from their surroundings. The birds fall into this second category, just like frogs. According to theory, both pick up toxins from their diets. Some of the birds’ stomachs have been found to contain beetles that contained the toxin. But the source of the toxin itself has yet to be determined.

The researchers studied this with inspiration from poison dart frogs, whose genetic mutations prevent the toxin from keeping their sodium channels open, thereby preventing cramps, to understand how these birds can have a toxin in their bodies without themselves being harmed.

The regent whistler (Pachycephala schlegelii) is the other newly discovered poisonous bird. Image credit: Ian Shriner

“Therefore, it made sense to look into whether the birds had the same genetic mutations. Interestingly, the response is both yes and no. The birds have mutations in the area that regulates sodium channels, which we expect gives them this ability to tolerate the toxin, but not in the exact same places as the frogs,” says Kasun Bodawatta.

The discovery of these mutations, which can lower batrathotoxin’s binding affinity in poisonous birds in regions similar to those found in poison dart frogs, is interesting, the author continues. And it demonstrated that these sodium channels need some kind of adaptation in order to adapt to this batrachotoxin lifestyle.

These bird studies show that, despite the fact that the neurotoxin they produce is similar to that of the South American poison dart frogs, the birds evolved their resistance and capacity to carry the neurotoxin in their bodies independently of the frogs. This demonstrates convergent evolution, as defined by biologists.

This basic research will primarily contribute to a better understanding of New Guinea’s birds and how different animal species not only acquire a resistance to toxins but also use them as a defense mechanism.

Other aspects of the research may benefit common people. The toxin that the birds overcame over time is connected to other toxins, like the one that causes shellfish poisoning.

“Clearly, we are not in a position to say that this research has found the cure for shellfish poisoning or other poisonings, but from the standpoint of basic research, it is a small piece of a puzzle that can help explain how these toxins function in cells and in the body. Additionally, certain animals’ bodies have developed to tolerate them, according to Knud Jnsson.

The excursion.
In the middle of one of the cleanest, most inaccessible jungles on Earth, ten-meter-long nets are stretched between poles. Alongside the nets, a small camp has been constructed with two tents. A rickety little table made of a few small logs has been hacked with machetes, and underneath a tarpaulin that the researchers brought with them, a few pieces of research equipment are shielded from the rain.

“It’s not exactly easy to live in New Guinea as a bird researcher. It is humid, hot, and occasionally even brings with it a little anxiety. Going into a situation unprepared and without prior arrangements with the locals can be extremely dangerous, according to Knud Jnsson of the Natural History Museum of Denmark.

Prior to their journey, the researchers were granted a government-issued permit to carry out their research. It was essential to get in touch with, bargain with, and come to an agreement with the residents of the Saruwaged Range, where the study was conducted, because the Papua New Guinean government does not own the forest land. The New Guinea Binatang Research Centre, which has solid relationships with numerous villages in northern Papua New Guinea, also assisted in making this work possible.

“We moved forward with machetes, hacking paths through the jungle with a group of local helpers after landing the small propeller plane on a strip of dirt in the middle of the forest and far from much else,” recalls Kasun Bodawatta.

“I like these people. And as long as one respects their ways and takes care not to bother the spirits, they’re really nice. It’s truly amazing how they navigate the forest in bare feet. In our big boots, Kasun and I were just stumbling over roots as we moved around clumsily,” Knud Jnsson chuckles.

Despite their agreement with the nearby tribal village, they had learned from experience to remain vigilant in camp.

“On a previous trip, we saw ten men with machetes from a nearby village suddenly appear in the camp. Machetes can be used on both people and vegetation, and they frequently are. According to Knud Jnsson of the Natural History Museum of Denmark, “They were upset and had a completely different understanding of the village boundaries than the tribal village leaders with whom we had reached an agreement.

For this reason, we constantly involve local collaborators in our work. Multiple objectives underpin their inclusion. They offer practical assistance, and we disseminate knowledge to those who are interested. They also play a crucial role in legitimizing the presence of the researchers, though. Things can go horribly wrong if there are any doubts.

Small settlements inhabited by numerous tribal groups that frequently engage in conflict in the rainforest Such fights fifty years ago involved cannibalism. There have also been instances of “ex-cannibals” breaking the law, despite the fact that Papua New Guinea’s custom of rival tribal groups eating one another was officially abolished 50 years ago.

The government finds it challenging to gain much insight into what occurs in the forest. Of course, that increases the tension for us. It is quite unusual to conduct research in a setting where safety must be prioritized so highly. But even though it can be challenging, being a biologist is everything you’ve ever wanted, according to Knud Jnsson.

The article appears in the journal Molecular Ecology.

More information: Kasun H. Bodawatta et al, Multiple mutations in the Nav1.4 sodium channel of New Guinean toxic birds provide autoresistance to deadly batrachotoxin, Molecular Ecology (2023). DOI: 10.1111/mec.16878

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