When we think of poisonous creatures, birds are not the first thing that comes to our minds. Frogs, toads, puffer fish, and various insects are more common examples, but despite their rarity, poisonous birds do exist, and they have recently been identified, studied, and documented by scientists.
The journey to identifying these birds begins in the summer of 1989, when then-University of Chicago graduate student Jack Dombacher made his first trip to the lush rainforests of Papua New Guinea.
Dumbacher aimed to study the mating behavior of “birds of paradise,” the majority of whose species live on this tropical island nation in the southwestern Pacific Ocean near Australia, home to some of the most magnificent and venomous birds in the world.
One humid afternoon, he noticed an unusual bird with a bright orange body like sunlight, and a head, wings and tail covered in black, stuck in one of the fine misty nets he had set up between the trees to catch birds of paradise, but as he was trying to free it from the net, the bird scratched him.
“The wounds were very painful, but we had so many nets to take care of, we didn’t have time to stop, put bandages on the wound, and run to the next net,” says Dumbacher, who is now curator of birds and mammals at the California Academy of Sciences.
He added in his interview with Al Jazeera Net, “I instinctively placed the wound in my mouth to relieve the pain, and immediately I began to feel tingling, numbness, burning, and even numbness, and this feeling continued for several hours, and even an entire night.”
When Dumbacher asked his local field guides what they knew about these birds that seemed to him to be poisonous, they nodded that they knew how poisonous they were, told him how they were avoided by hunters and villagers who called them “garbage birds,” and said, “They’re no use, you can’t even eat them.”
The venomous nature of these birds aroused the curiosity of the young trainee ornithologist, and he immediately began studying them and the type of poison they used. He spent the next year collecting specimens of these birds and enlisting the help of a natural poison chemist in his native country who could determine the source of these strange sensations.
Three years later, in 1992, Dombacher and his colleagues announced their amazing discoveries in… study Published by the magazine “Science”, they found that these birds, which were called “bitahoe”, carry a poison that belongs to a group of highly effective compounds called “batrachotoxin.”
This poison turned out to be more lethal than cyanide, a well-known defense mechanism, and among the deadliest substances in the animal world.
“It is one of the most toxic natural substances known,” says Dumbacher. “It can initially cause tingling, tears, sneezing, and numbness, and ingestion of high doses can lead to paralysis, cardiac arrest, and even death.”
But 35 years after Dombacher discovered these birds by chance, a lot of mystery still surrounds the birds, starting from their environment to how they use poisons to defend themselves, and where they get them from.
Searching for the origin of the deadly poison
Speaking to Al Jazeera Net, evolutionary biologist and community ecology researcher Kasun Budawata from the University of Copenhagen says, “Until recently, bird toxicity was not known as a trait, and studies have only begun to explore this topic during the past two decades.”
He added, “I believe that most of the mystery surrounding venomous birds is due to the lack of field research, and the scarcity of venomous birds, which makes them less susceptible to study among different categories of birds, and it is also difficult to reach many places to conduct field work in New Guinea.”
Before the discovery of batrachotoxin in the bodies of pethoi birds, it was thought to be present only in some species of poison dart frogs (also known as golden poison dart frogs) widespread in the Southern Hemisphere, hence the name of these toxins: “batrachos,” which is an ancient Greek word meaning “frog.”
However, the majority of these birds carry this poison, and they are all endemic to the forests of New Guinea, including at least 5 other species of pethoi.
These birds differ in their toxicity, with the highest concentration of these toxins found in… Skin and feathers, especially chest, leg and abdominal feathers, and in much lower concentrations in other tissues such as internal organs and bones.
Of the many venomous birds, the Masked Pitohoe is thought to be the most venomous, and the Variable Pitohoe, which resembles the Masked Pitohoe, carries homobatrachotoxin (a toxin similar to batrachotoxin, but less potent) in its feathers and skin.
Scientists believe that the bright colors of male and female pethawi, just like the poison dart frog, may serve as a warning to predators, as their feathers call out to predators “I am poisonous, do not come closer!”, sending the message that eating me will be a bad and disgusting experience.
There appears to be another common denominator between frogs and frogs, which is that their toxic chemicals are derived from their food.
It is interesting that arrow frogs are not born poisonous, and do not produce toxins themselves, but rather acquire them from eating insects and other arthropods that they hunt among the remains of tree leaves, and their effectiveness varies depending on their species.
In fact, the arrow frog’s toxicity disappears completely when given a more suitable food, such as fruit flies. In a previous scientific experiment, they put him on a diet of cockroaches, and then he became less toxic, or not toxic at all.
“It is believed that the toxicity of pethoy birds is not an inherited trait, but rather developed over time,” says Bodawata, who continues Dombacher’s research. “We hypothesize that the source of the stored neurotoxin comes from foods that contain high levels of batrachotoxin, which makes them taste unpleasant.”
“One possibility centers on soft-winged flower beetles belonging to the genus Choricin, but given the distribution and diversity of venomous birds, there may be many food sources of batrachotoxin,” he added.
In fact, scientists have not confirmed this, and the source of the poison has remained a subject of great debate among them, with Dumbacher, who was the first to rule it out a description In 2004, Batrachotoxin was found in both birds and beetles, and the source of this toxin came from beetles.
“Most information indicates that these small insects cannot produce such toxins,” he says, adding, “It is very likely that these birds obtain it from another source, such as mites, soil mites, or even plants.”
The mystery of toxicity
There is another mystery that still remains, and arouses the curiosity of scientists and bird lovers, which is the exact role of these toxins, and how these birds protect themselves from the deadly poison they carry.
For example, the masked pethoi – the most poisonous bird species – is not lethal when handled or consumed. However, it secretes neurotoxins that are considered some of the most powerful poisons in nature.
Some researchers believe that this contradicts the theory of using poisons as a unique means of deterring predators or subduing prey, as there are 8 species of hawks that feed on peregrine falcons.
“We currently do not know the exact role of toxins, but the most logical explanation for their use throughout his life is that they have a role in deterring animals and warding off potential threats, including humans,” Bodawata says. “The people of New Guinea do not like to eat these birds because of their strange taste.”
Research has indicated that lice, mites, and other external parasites are repulsed by toxins found in the skin and feathers of the pethawi bird, and that insects infected by them lived shorter lives.
Therefore, toxic batrachotoxin compounds may act as an insecticide or repellent for ectoparasites, lice, ticks, and mites, however, they do not appear to affect endoparasites.
As for why these organisms are resistant to toxins, and how to protect themselves from the deadly poison they carry, Bodawata says that there are a few theories proposed about this matter.
Some scholars attribute the reason to: Theory The explanation for how venomous creatures avoid poisoning themselves is that these birds, like poison dart frogs, have mutations in their sodium channels, which prevent the poison from binding to them.
The same toxicity is found in the fugu pufferfish, blue-ringed octopus, and other venomous animals that remain immune to the toxins they carry.
Batrachotoxin, which is secreted by birds of the bathoe family, binds to sodium ion channels in nerve, muscle, and heart cells. The poison disrupts their transport inside and outside cells, which is one of the most important physiological functions in the body, leading to numbness, burning, cramps, and paralysis.
In fact, when Buddawata and his colleagues compared the genomes of six venomous bird species with their non-venomous relatives from the same species, Find out The venomous birds contain multiple mutations in a gene that encodes a specific sodium channel.
However, Budawata says, “We did not find these mutations in all venomous birds, so, there may be other mechanisms of intrinsic resistance to the venom.”
For example, birds may have certain transport proteins that can bind to venom and keep it inactive until it reaches the skin, such as toxic sponge proteins that absorb and eliminate deadly toxins before they can harm the animals.
There’s still more to explore
Dombacher’s last visit to the habitat of these birds was in 2012, and another team of scientists – including Bodawatha – continues the research, and they have already achieved remarkable progress. In 2023, for the first time in nearly two decades, Find out Two new species of birds are venomous in the same way, meaning batrachotoxin is more widespread than previously thought.
To trace the source of batrachotoxin, the researchers plan to collect venomous birds and compare their stomach contents to potential prey — such as insects caught in nearby fisheries — that contain the toxin.
They also collaborated with other chemists to molecularly identify batrachotoxin and similar toxins in samples already collected, and tests showed that the poisonous birds contained a mixture of toxic derivatives that may vary in concentration between individuals and species.
Regarding the reason for continuing his study of these poisonous birds, Dombacher says, “There are two different reasons: First, I think that these toxins are very interesting, have biological activity, and patents have been registered for them in the past.”
“One of the reasons it wasn’t developed and turned into any drugs is because we didn’t have a large enough source of it to do the experiments we needed to understand how to turn it into something usable,” he adds.
Budawata and a team of scientists plan to visit New Guinea annually until 2028, and they hope to answer a pivotal question: Where does this deadly poison come from that makes the Pitohoe bird a wonderful example of nature’s hidden defenses, and the diverse and complex adaptations found in the animal kingdom?
“We are working on a new project to delve deeper into the mechanisms of intrinsic resistance to toxins in venomous birds and trace the source of batracocin, and we hope that in the next two or three years we will be able to improve our insights into venomous birds,” Buddawata says.
Starting this November, researchers will collect as many samples as possible from these birds from various parts of the island, and will examine them for batrachocin toxins. They also plan to sequence the genome of at least one individual for each species to identify sodium channel mutations.