In the heart of one of Earth’s most pristine rainforests, researchers have made a startling discovery: more species of poisonous birds. These rare creatures, found in the jungles of New Guinea, have long been a source of fascination for scientists and the public alike.
“We managed to identify two new species of poisonous birds on our most recent trip. These birds contain a neurotoxin that they can both tolerate and store in their feathers,” explained Knud Jønsson of the Natural History Museum of Denmark.
Jønsson and his colleague, Kasun Bodawatta from the University of Copenhagen, embarked on an adventurous research expedition, braving the dangers of warring tribes and the rich biodiversity of New Guinea’s rainforest. It was here that they captured two new bird species, each displaying a remarkable ability to consume toxic food and convert it into a potent poison.
The researchers identified the regent whistler (Pachycephala schlegelii) and the rufous-naped bellbird (Aleadryas rufinucha) as the newly discovered poisonous species. The regent whistler belongs to a family of birds known for their widespread distribution and distinctive songs, which can be heard throughout the Indo-Pacific region.
“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,” said Jønsson.
This fascinating find not only adds to the scientific understanding of poisonous birds but also highlights the incredible biodiversity that exists in the world’s most remote corners.
The iconic poison dart frogs of South and Central America, particularly the golden poison frog, are well-known for their lethal toxins. Recently, scientists discovered two new poisonous bird species in New Guinea that carry the same type of toxin in their skin and feathers, revealing that this potent neurotoxin is more widespread than previously thought.
The toxin present in the birds’ bodies and plumage, called Batrachotoxin, is incredibly powerful and can cause muscle cramps and cardiac arrest upon contact.
“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,” explained Kasun Bodawatta, a researcher on the project.
While South America’s poison dart frogs use their toxins to deter predators, the adaptive significance of this toxin in New Guinea’s birds is still uncertain. Nonetheless, it may serve a defensive purpose, even though the level of toxicity is less lethal than that found in the frogs.
During their fieldwork, the researchers experienced the toxin’s effects firsthand. “Knud [Jønsson] 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 a Pitohui, one of the most poisonous birds on the planet,” said Bodawatta.
“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.”
Jønsson said the local people avoid eating these birds because their meat “burns in the mouth like chili.” He said the toxin even 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 them as a deterrence of those who would want to eat them to some degree.” This discovery of new poisonous bird species provides valuable insights into the complex defensive mechanisms found in the animal kingdom.
In the realm of biology, there exists a distinction between animals that produce toxins internally and those that absorb them from their surroundings. Like poison dart frogs, the newly discovered poisonous birds in New Guinea belong to the latter category. Both species are thought to acquire toxins from their diet, with toxin-containing beetles found in some of the birds’ stomachs. However, the exact source of the toxin remains undetermined.
How can these birds carry toxins in their bodies without suffering harm themselves? The research team, inspired by the poison dart frogs’ genetic mutations that prevent toxins from affecting their sodium channels, explored this question.
“So, it was natural to investigate whether the birds had mutations in the same genes. Interestingly enough, the answer is yes and no. 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,” said Bodawatta.
“Finding these mutations that can reduce the binding affinity of Batrachotoxin 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.”
Consequently, these findings demonstrate that, despite similarities in their neurotoxins, the birds developed their resistance independently of the frogs—an example of convergent evolution.
Primarily, this research contributes to a better understanding of New Guinea’s birds and how various animal species not only develop resistance to toxins but also employ them as defense mechanisms. Moreover, the study has potential implications for human health, as the toxin the birds have adapted to is closely related to other toxins, such as those responsible for shellfish poisoning.
Knud Jønsson acknowledges the potential impact of their findings, stating: “Obviously, we are in no position to claim that this research has uncovered the holy grail of shellfish poisoning or similar poisonings, but as far as basic research, it is a small piece of a puzzle that can help explain how these toxins work in cells and in the body. And, how the bodies of certain animals have evolved to tolerate them.”
Apart from the regent whistler (Pachycephala schlegelii) and the rufous-naped bellbird (Aleadryas rufinucha) mentioned earlier, the two most well-known species of poisonous birds are the hooded pitohui (Pitohui dichrous) and the variable pitohui (Pitohui kirhocephalus), both native to Papua New Guinea. These birds sequester batrachotoxins in their skin and feathers, which they acquire from their diet, primarily through consuming beetles from the genus Choresine.
Another species of poisonous bird, the blue-capped ifrit (Ifrita kowaldi), also found in New Guinea, contains batrachotoxins in its skin and feathers as well. Similar to the pitohuis, the blue-capped ifrit acquires the toxins through its diet.
It is important to note that the term “poisonous” refers to animals that are toxic when ingested or touched, while “venomous” animals inject toxins through a bite or sting. The mentioned species are considered poisonous, not venomous.
The research is published in the journal Molecular Ecology.
Image Credit: Ian Shriner
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