he had just glimpsed, high above our 

 heads in the jungle, a small bird known lo- 

 cally as mawe. Looking through my 

 binoculars, I identified it as Lorentz's 

 whistler and objected that Robert had al- 

 ready applied that name to another bird, 

 which I knew as the regent whistler. 

 Robert then gave me a short lecture (in the 

 Indonesian language that we shared) on 

 the distinctions. "Yes, we use the name 

 'mawe' for two different birds. This one 

 lives high on the mountain, and the male 

 and female have identical plumage. The 

 other one lives lower on the mountain, has 

 a different song, and the male differs in its 

 black crown and yellow nape." I was flab- 

 bergasted, because both sexes of Lorentz's 

 whistler are so similar to female regent 

 whistlers that even ornithologists poring 

 over stuffed specimens didn't recognize 

 them as distinct species until 1939. 



While Robert was demonstrably right 

 about the whistlers, he also described to 

 me some bird lore that sounded wildly im- 

 plausible — stories of birds that stink and 

 birds that act as living flytraps. But those 

 stories, too, may be true; an equally wild 

 tale, told by other New Guineans about 

 supposedly poisonous birds, has just been 

 confirmed by scientists. Such confirma- 

 tion illustrates that major scientific discov- 

 eries, perhaps of great economic value, 

 await teams of chemical ecologists and 

 ethnobiologists. The stories also carry a 

 larger message about the tragedy of 

 shrinking human knowledge. 



The recent "Case of the Poisonous 

 Birds" has to do with three common, con- 



spicuous, and very noisy species of jay- 

 sized New Guinea birds called pitohuis, 

 which have been known to scientists since 

 1827. Thousands of specimens are in the 

 world's museums, and hundreds of tourists 

 visiting New Guinea observe them in the 

 jungle every year. I have caught hundreds 

 of pitohuis in nets, watched and tape- 

 recorded thousands, and published two pa- 

 pers on their behavior. None of us "profes- 

 sional" scientists suspected poison. The 

 sole hint was a single sentence in a long 

 book published in 1977 by the Kalam vil- 

 lager Ian Saem Majnep, in collaboration 

 with New Zealand ethnobiologist Ralph 

 Bulmer. Detailing what Kalam villagers 

 knew about each of 137 bird species living 

 in their valley, Majnep wrote of the 

 hooded pitohui, "Some men say that the 

 skin is bitter and puckers the mouth." 



Pitohuis in general, and that sentence in 

 particular, were far from the mind of 

 American graduate student Jack Dum- 

 bacher in 1989, when he set up nets in the 

 New Guinea jungle to trap birds of par- 

 adise. Hooded pitohuis got caught in the 

 nets and had to be removed. In the process, 

 the birds scratched Dumbacher's hands 

 with their claws and bills, and he noticed 

 that the birds had a strong, sour smell. 

 When he licked off his wounds, his lips 

 and mouth began to tingle and bum and 

 then went numb for several hours. His 

 New Guinea field assistants later told him 

 that the hooded pitohui was "good for 

 nothing, a rubbish bird" and was not to be 

 eaten unless carefully skinned. 



The explanation began to emerge when 



New Guinea's rusty pitohui: common, noisy — and poisonous. 



Brian J. Coates; Bruce Coleman, Inc. 



Dumbacher sent dead specimens of 

 hooded pitohuis to National Institutes of 

 Health scientists for chemical testing. In- 

 jection of pitohui skin or feather extracts 

 into mice caused the mice to develop hind- 

 leg prostration and paralysis, leading to 

 convulsions and death in as Uttle as fifteen 

 minutes. Dumbacher's belated discovery 

 came as a real surprise. Although many 

 other animals, such as monarch butterflies, 

 were known to accumulate or synthesize 

 poisons to make themselves unappetizing 

 to predators, this was the first well-docu- 

 mented example among birds. Presumably 

 such would-be predators as snakes and 

 possums would be driven off after one bit- 

 ter, mouth-puckering lick of the pitohui's 

 feathers, and the bird's sour smell and 

 bold, orange-and-black coloration would 

 help them remember the experience. 



Another surprise emerged when the 

 hooded pitohui's poison was extracted, pu- 

 rified, and chemically identified. It proved 

 to be the nerve and muscle poison homo- 

 batrachotoxin — a substance otherwise 

 known only from a different continent and 

 different vertebrate class — in South and 

 Central American poison-dart frogs, so 

 called because Indians use the animals' 

 skins to poison blowgun darts. Homoba- 

 trachotoxin is one of the most poisonous 

 substances known, hundreds of times 

 more powerful than strychnine. One 

 hooded pitohui contains enough of the 

 poison to kill more than 500 mice. How 

 the pitohui's nerves and muscles resist its 

 own poison is not known. 



The appearance of the same toxin in 

 frogs and birds exemplifies, astonishingly, 

 the phenomenon of convergent evolution 

 at the molecular level. Just as birds, bats, 

 and pterodactyls independently evolved 

 wings, pitohuis and poison-dart frogs have 

 converged on each other by evolving ho- 

 mobatrachotoxin. The poison itself has no 

 odor, so pitohuis seem also to have 

 evolved some as-yet-unidentified, sour- 

 smelling chemical to warn off predators 

 before they can take a bite. 



Dumbacher and his colleagues identi- 

 fied homobatrachotoxin not only in 

 hooded pitohuis but also (albeit at lower 

 concentrations) in two related species, the 

 variable pitohui and the rusty pitohui. As 

 its name implies, the variable pitohui 

 shows far greater geographic variation in 

 plumage than any other New Guinea bird 

 species. Until now, no ornithologist had 

 the faintest idea why two populations of 

 variable pitohui, from opposite ends of 

 New Guinea, are orange and black like 

 hooded pitohuis; why some are uniformly 



6 Natural History 2/94 



