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The Intoxicating Birds of New Guinea
by John Tidwell

It all began with an accident. In the summer of 1989, Jack Dumbacher was a graduate student from the University of Chicago conducting fieldwork on the ecology of Raggiana birds of paradise (Paradisaea raggiana) in Papua New Guinea’s lush Varirata National Park. Dumbacher was one of a handful of graduate students on the National Geographic-sponsored team, and part of his research involved catching and examining these exotic orange-yellow birds in fine mist nets set throughout the forest. Sometimes other birds would also get caught, and Dumbacher spent a lot of time freeing unwanted species like the hooded pitohui (Pitohui dichrous), a jay-sized endemic New Guinean songbird with striking black and orange coloration.

For these young researchers, pitohuis (pronounced PIT-oh-wheez) were all too familiar: They were everywhere, they fought and scratched when being disentangled from the nets, and they had a pungent odor that stayed on researchers’ hands for days—the local people called them “rubbish birds.” One day Dumbacher was freeing yet another hooded pitohui from his nets when its sharp beak and claws scratched his hand. Dumbacher put his hand in his mouth and got a strange numbing sensation that he recognized as the effect of some toxin. At first he thought nothing of it, because he occasionally brushed against poisonous plants in the forest. It never occurred to him to suspect the bird. But then a few weeks later another member of the team mentioned the same odd sensation when he put his injured finger in his mouth. Again the culprit was a hooded pitohui. Dumbacher’s interest was piqued, so the next year he returned to New Guinea determined to examine some of these rubbish birds more closely.

“The next time we caught a hooded pitohui,” he remembers, “I just plucked one of the feathers and tasted it: Whammo! Whatever it was, it was definitely in the feathers.”

There were only a few weeks before the arrival of the research team’s leader, Bruce Beehler, then Scientific Assistant to the former Smithsonian Institution Secretary, S. Dillon Ripley. Dumbacher wanted to be as sure as he could that these birds were producing some kind of chemical in their feathers. So he and his three assistants sampled the feathers of several other hooded pitohuis, all with the same tongue-tingling results. As he was driving Beehler up to Varirata from the airport, Dumbacher suggested that the find might make an interesting field note in New Guinea’s local bird journal. But Beehler, the man who literally wrote the book on New Guinea birds, was thunderstruck.

“Bruce looked at me and said ‘Are you telling me you’ve found a poisonous bird?’” recalls Dumbacher, his dark eyes gleaming behind small wire-rimmed glasses. “Then he said, ‘This should be on the cover of Science! Turn the car around! We’re going back to town to get permission to study this bird!’”



In the eight years since Jack Dumbacher—now a research associate at the National Zoo’s Conservation and Research Center in Front Royal, Virginia—first published his controversial discovery in Science, one of the world’s most prestigious scientific journals, his life and work have been largely overtaken by this small, spunky bird. Dumbacher’s research has not only shown that some birds may use toxins for defense, but changed the way people think about the biology of New Guinea. It also launched a scientific quest over several continents to find answers to the hooded pitohui’s noxious mysteries. What is staggering to Beehler and many other scientists about this discovery is that pitohuis have been known to science for more than 100 years and live only a few miles from New Guinea’s bustling capital, Port Moresby.

“It was right there under our noses,” Beehler admits, as he relaxes in his office at Conservation International, where he is a senior representative for Melanesia. “Pitohuis are New Guinea’s most common, widespread bird. They’ve been collected by scores of expeditions. Museums around the world are filled with pitohuis. And yet nobody knew they were toxic. That really says how much we don’t know about what’s going on out there.”

Unraveling the pitohuis’ strange biology has been as difficult and frustrating for Dumbacher as freeing them from his nets. When he first returned to the U.S. in 1990 with the bird’s spicy feathers in hand, Dumbacher searched for a skilled chemist who could help him identify what kind of toxins the feathers carried. But few took the young grad student seriously: No one really believed that poisonous birds might exist. As months passed, Dumbacher began losing hope of ever finding the answer to the pitohuis’ riddle.

One day his luck finally changed. A herpetologist referred Dumbacher to John Daly, a pioneer in pharmacology at the National Institutes of Health (NIH) who had done groundbreaking research on South American dart-poison frogs. It proved to be a fateful introduction. During the 1960s and 1970s, Daly spent years in both the lab and the tropical forests of South America studying the tiny, brilliantly colored frogs that the Choco Indians of western Colombia used to poison the darts of their blowguns. After years of research Daly and his colleagues showed that these frogs secreted a powerful collection of neurotoxins from glands on their backs. These deadly species, including a bright yellow frog the researchers aptly named Phyllobates terribilis, were armed with three unique steroidal alkaloids, called batrachotoxins (BTX), in concentrations so powerful that an amount equivalent to a few grains of salt would be lethal to a person who ate it.

Widely considered one of the most deadly toxins, BTX stops all electrical impulses in muscles and nerves, causing cardiac arrest almost immediately. The poison had never been found before in any organism, and for decades Daly toiled over this phenomenon, trying to figure out how the frogs were producing it, and why. But in the mid-1980s Colombia’s political climate shifted, and foreign scientists found it nearly impossible to get permission to work in its forests. As a result, all further field research into the origin of the Colombian frog’s poison became impossible.

But then Dumbacher’s hooded pitohui feathers floated across Daly’s lab desk. Initially the grizzled scientist was skeptical. He performed some routine tests, making a crude extract of the feather’s chemical and injecting it into a mouse. Within minutes the animal was dead.

“I got this call from him, and he was really excited,” Dumbacher remembers. “He said, ‘Jack! You’ve got to send me more of those feathers! There is something extremely toxic in there!’” Daly analyzed the pitohui’s feathers, skin, and internal organs, using chromatography to identify extracts of the chemical. The tests detected the presence of batrachotoxins—the exact same compounds that Daly had found in the frogs.

“It was totally unexpected,” says Daly. “It’s just very fortunate Jack sent the samples to us, because anybody else might have struggled over it for years.”

But what was a bird in New Guinea doing with lethal poisons only found—so far as we know—in frogs from the other side of the world? And why wasn’t Jack Dumbacher dead from tasting them?


New Guinea rises out of the sea about 100 miles north of Australia, with jagged, tree-covered mountains that disappear thousands of feet up into a nearly perpetual mist. Millions of years ago it separated from the mainland; and native animals, like birds of paradise [see sidebar on Birds of Paradise] and pitohuis, followed their own evolutionary paths. To foreigners, the island can seem ancient and magical, like a world lost in time. But to Jack Dumbacher and his team, it’s a wonderland of biological mysteries.

Soon after Dumbacher’s discovery was published, he trekked back into New Guinea’s interior forests to find why hooded pitohuis were poisonous. From the start it was obvious something complex was going on. Hooded pitohuis from some regions of the island were found to be much less poisonous than those from other regions. Tests on three other pitohui species—the rusty (Pitohui ferrugineus), the black (P. nigrescens), and the variable (P. kirhocephalus)—showed that they too were toxic, but not at the levels of the hooded pitohui. In Varirata National Park alone, Dumbacher found hooded pitohuis so full of BTX that simply holding them made him sneeze and his eyes water.  But, a few miles to the north, the same species were almost non-toxic. To the biologists this indicated that the bird’s poisons were not inherited, but rather acquired, or sequestered, probably from something they were eating. But proving this hypothesis has been daunting.

“It’s like looking for a needle in a haystack,” Beehler explains. “New Guinea has about 700,000 species of insects and maybe 15,000 plant species. The toxin source may only be from one organism, at one particular time of year.”

Years before, John Daly had brought some dart-poison frogs back to his NIH lab in Bethesda, Maryland, for study. He fed them a lab diet of non-toxic termites, and to his amazement, the next generation of frogs hatched in the lab was completely non-toxic. When the frogs matured, Daly fed them small amounts of BTX. In no time the toxin began accumulating in their skin, strongly indicating that the source of the frog’s poison came from an unnamed insect living deep in the Colombian rainforest.

Dumbacher wants to do a similar experiment with the hooded pitohuis, and has a tentative agreement with the government of New Guinea to bring several birds to the National Zoo this year. If the pitohuis lose their poison it will be hard evidence that they have a very toxic diet back home. But what? Dumbacher and his team suspect some kind of insect is making the birds poisonous, and they have been examining every bug pitohuis are known to eat. But so far none has come up positive for BTX.

In fact, the idea that an insect either produces or sequesters BTX at all is controversial. Many scientists think that insects aren’t the only suspects in this biological detective story. Some have suggested pitohuis may get their poisons from bacteria, or that BTX is somehow assembled in their bodies from more than one plant or insect they are eating, each providing a vital chemical component. Todd Capson, an independent ethnobiologist at the Smithsonian Tropical Research Institute in Panama, is heading for New Guinea this year to mount his own search for pitohui poison. For him the evidence points to a complex process in which BTX is transferred from prey to predator up the food chain to pitohuis.

“If I was a betting man, I’d bet that a plant makes it in the beginning,” Capson says, “and that plant is then eaten by an insect, which is then eaten by pitohuis. My personal guess is that the insect is a weevil, because weevils are everywhere and they are known to eat every part of plants.”

Even so, Beehler says looking for the source of pitohui BTX by traditional scientific methods, such as by examining the droppings and stomach contents of these birds and watching what they eat, is not the only—or most efficient—way to find the answer. Native Papuan tribes have been observing nature on the island for possibly 50,000 years or more, and their oral traditions of medicine and magic reveal a vast collection of biological knowledge. When he returns to the New Guinea wilds, Capson plans to seek out local village elders and “wily old men” who may be able to provide clues to which local plants or animals may be poisonous.

Local Papuans provided vital insights for Jack Dumbacher almost from the beginning of his adventure with the pitohuis. In 1990 when he first realized pitohui feathers might be toxic, a co-worker mentioned that she had read about these birds being bitter to the taste in an old book. Dumbacher looked up the book, Birds of My Kalam Country, which was a compilation of local Kalam tribal wisdom on highland birds, written in 1977 by the New Zealand anthropologist Ralph Bulmer and his Kalam colleague Ian Saem Majnep. In the book, Dumbacher discovered a description of the wobob (the hooded pitohui) that reported, “...some men say the skin is bitter and puckers the mouth....”

The book also gave a similarly tantalizing account of the blue-capped ifrita (Ifrita kowaldi), an apparently unrelated bird half the size of a pitohui that lives in the high mountains. Its Kalam name, slek-yakt, literally means “bitter bird,” the authors write, “because if it is not skinned before eating some men find that it burns their mouths, making their lips sore and puckered.”

In 1993 Dumbacher traveled by light plane up into the highlands to the Kaironk Valley, a remote region in the southwestern corner of Mandang Province where Saem Majnep and his Kalam people still live. Majnep had little formal Western education, but among his people he was regarded as a man deeply learned in traditional wisdom. His knowledge of the plants and animals of the highlands had impressed Bulmer so much that he asked Majnep to collaborate on his book on Kalam bird lore. In their paragraph on the pitohui, Majnep also included Papuan folklore about how the wobob bird was often evoked in Kalam war-magic spells because it dodges around like a man avoiding arrows, and how the word wobob itself refers to a kind of skin disease that is uncomfortable and itchy. While such descriptions may at first seem more like myth than science, Dumbacher points out that if one listens carefully, one may discover valuable information.

“The Bonua people of Central Province told me they knew the pitohuis were poisonous, but that if you kill one and want to eat it, what you have to do is mourn for it,” he recalls. “If you mourn for it long enough and sincerely enough, then you can eat it and it won’t make you sick. But they said they usually don’t eat the birds because you never know if you’ve mourned enough.”

What stories like this reveal, says Dumbacher, is that the Bonua knew that some pitohuis are more toxic than others, but that in general they should be avoided. Todd Capson also found important biochemical information about pitohuis from listening to local hunters. They told him that the only way to eat a pitohui is to strip off its feathers and skin and then smear charcoal all over its meat before roasting it.

“To most people this sounds weird,” says Capson, “but to an organic chemist what they are doing is removing the toxin, because charcoal is well known for its ability to adsorb, or adhere to, organic compounds like homobatrachotoxin.” This process would render the bird safe to eat.

Majnep gave Dumbacher vital clues about the blue-capped ifrita as well, and had his hunters collect some specimens. Small and brown with a bright blue crest, the ifrita behaves like a nuthatch, foraging for insects among the trees of the highland cloud forests more than 12,000 feet above sea level. Everything about it is different from a pitohui, except for one thing.

“We were with the local guys,” Dumbacher remembers. “I was examining an ifrita and was about to taste one of its feathers, when the locals started shouting ‘No!!! Don’t do that!!’ They were absolutely convinced I would die if I tasted it.”

When the results came back from NIH on the ifrita’s skin and feathers, they showed nearly identical profiles of BTX alkaloids for both birds. Dumbacher also found ifrita farther to the east, in the Finisterre mountain range of the Huon Peninsula. In the Kaironk Valley, ifrita were loaded with BTX, but here they appeared uniformly non-toxic. Clearly this bird was also getting its poisons from a food source. Now Dumbacher had an even bigger mystery: two apparently unrelated birds, living in two very different regions of New Guinea, yet both using the same spectrum of toxins. This indicated that the use of BTX among the island’s birds was more than a single freak event of evolution. Something much more complex was at work in these forests.


In 1941 British ornithologist Hugh Cott was on military leave in the Egyptian city of Beni Suef, doing what he enjoyed most: studying birds. He was preparing some specimens for mounting and had left the skinned carcasses of a palm dove (Streptopelia senegalensis aegyptica) and a pied kingfisher (Ceryle rudis rudis) lying nearby on the grass. Then Cott noticed something odd: Hornets, which love fresh meat, were feasting energetically on the dove, but had left the kingfisher conspicuously untouched. Intrigued, Cott decided to test the palatability of kingfishers and other birds’ flesh, first on hornets and then on cats and humans. Cott’s research eventually led him to conduct extensive  studies that not only showed that some bird species tasted bad, but also a possible reason why.

“What he found was that the more vulnerable a bird was, the nastier it tasted,” says Harvard anthropologist Richard Wrangham. “He defined ‘vulnerability’ as being brightly colored or slow moving or the like. He also found that across Europe, Africa, and North America black birds generally taste bad as well. So the old refrain about ‘eating crow’ holds true.”

Recent studies have suggested that many birds may be using some kind of chemical weaponry as defense, much like insects and amphibians. Ocean-going fulmars spit noxious stomach oils to drive away predators, some species of grackle give off a terrible odor when threatened, and many passerine birds, of which pitohuis and ifrita are members, have been known to smear their feathers with ants, apparently to repel parasites. Some birds, like the Eurasian quail (Coturnix coturnix cortunix), the spur-winged goose (Plectropterus gambensis) and the African olive-pigeon (Columba arquatrix), are suspected of being toxic as a result of eating poisonous insects and plants [see “Quailing from Quail”]. Two species of Australian bronzewing (Phaps sp.) may even be sequestering the lethal toxin fluroacetate, more commonly known as “1080,” a poison that occurs naturally in their diet of heartleaf (Gastrolobium bilobum). But no one knew exactly which chemicals were being used.

“The pitohuis and the ifrita are the first examples of birds that use an identified toxin as part of their defense strategy,” says Cornell chemical ecologist Thomas Eisner. “That discovery changed everything about how we think about birds.”

Where Papuan birds and Colombian frogs diverge, Eisner says, is in the way they use their poisons. The tiny frogs store highly concentrated BTX alkaloids in glands on their backs, so that when they are threatened they secrete almost pure toxin. The pitohui and the ifrita, on the other hand, seem to have BTX in their dander, which diffuses all over their bodies, making the birds poisonous but not necessarily lethal. In fact, Dumbacher noticed that the greatest levels of BTX were found on the birds’ breasts and underside, suggesting that their eggs and nests may also be infused with BTX. This would be a particularly effective defense against snakes, which Dumbacher sees as a likely pitohui predator. Snakes hunt birds in their nests at night, and tend to taste with their tongues before striking. One quick flick of a serpent’s tongue might instantly tell it that pitohuis and ifrita were too risky to eat. Dumbacher thinks BTX might even act as a natural bug repellant, driving off hungry lice and mosquitoes.

Critics of Dumbacher’s ideas say that his team is placing too much emphasis on the fact that these birds are toxic, not noticing the possible cocktail of other repellant chemicals at play in both species. Todd Capson disagrees.

“There is a real advantage to being able to use and sequester homobatrachotoxin,” he explains. “Not only is it very effective at protecting these birds against predators, but it also guarantees them an exclusive food source because they can eat bugs with this toxin that nothing else can.”

In many cases predators wouldn’t have to get close enough to taste these birds, or get a whiff of their distinctive smell. Like monarch butterflies and gila monsters, pitohuis are bright orange and black, a color-coded warning that tells predators they are poisonous. Pitohuis of both sexes are equally toxic and colorful, a signal that may play a larger role in the New Guinea ecosystem. According to University of California at Los Angeles writer, physiologist, and naturalist Jared Diamond, large flocks of several brown and black bird species are known to forage together in the island’s swampy lowlands. Usually these flocks are led by members of at least three of the toxic pitohui species, suggesting a highly complex social defense system among New Guinea’s birds. Writing in the British journal Nature shortly after Dumbacher’s initial discovery, Diamond even proposed that birds of paradise might also be distasteful.

“At least 15 species of birds of paradise join the pitohui flocks,” he says, “and the taste of birds of paradise has been reported as: ‘the most shocking flesh I have ever eaten…bitter as gall…truly abominable.’ So interactions with poisonous brown and black birds may have a long-standing selective force on birds of paradise.”

Right now, however, the only thing that has been shown about pitohuis and ifrita is that they use BTX, and that it appears to repel some of their parasites. Whether the birds use BTX for defense, where it comes from, and how they are able to withstand its effects are questions that remain tantalizingly unanswered. Jack Dumbacher and his team plan to return to New Guinea’s Varirata National Park to continue the search, looking for pitohui nests, fitting birds with radio collars to track their feeding habits, and sending new batches of suspicious bugs back to Daly at NIH for analysis. Coupled with information from Capson and Majnep, Dumbacher hopes that his project will answer some of the questions his research has raised. But the process could take years. For scientists like Jack Dumbacher, that’s all part of the allure of New Guinea’s biological terra incognita.

“Almost nothing has been studied there,” says Dumbacher, “so you can stumble across tree kangaroos and poisonous birds—all kinds of weird things. I’ve always tried to let the animals tell me where to look and what to study. In a place like New Guinea, nature is way ahead of our imagination.”

John Tidwell, a freelance writer and independent television producer, last wrote about parrot smuggling in the November/December 2000 ZooGoer.

ZooGoer 30(2) 2001. Copyright 2001 Friends of the National Zoo. All rights reserved.

 
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