rusty, like rusty pitohuis; and why some 

 have color patterns that differ from those 

 of the first two. 



Now we have a clue: "Miillerian mim- 

 icry," the phenomenon, well known in 

 tropical butterflies, whereby several poi- 

 sonous species share the same bold pat- 

 tern. As a result of this mutual mimicry, 

 each species benefits by the other's poi- 

 son, because a predator that tastes and 

 spits out one species thereby learns to 

 avoid the other species as well. In the two 

 parts of New Guinea where I collected 

 pitohuis, however, not only did I smell and 

 taste nothing after handling the birds my- 

 self, but the local New Guinea tribesmen 

 working with me also stuffed and ate them 

 with no ill effect and volunteered no sto- 

 ries about their being "rubbish birds." Per- 

 haps the presence of poison varies geo- 

 graphically in New Guinea pitohuis, and 

 the variable pitohuis resemble the hooded 

 pitohui, rusty pitohui, or neither, depend- 

 ing on which species is locally poisonous. 



But the pitohui story has still bigger im- 

 plications. All three pitohui species are 

 leaders of wandering flocks, composed of 

 several dozen different species belonging 

 to at least seven different families. All 

 members of the flocks are various shades 

 and combinations of rust and black. And 

 several flock members also mimic other 

 member species' calls. Why? 



When I published an article on the 

 flocks six years ago, I advanced the usual 

 two explanations that ornithologists have 

 invoked to explain convergence in oflier 

 flocks of unrelated species: the mimicry 

 may make it hard for a would-be predator 

 to concentrate on foUowing any single po- 

 tential victim and easy for each flock 

 member to stay with die group. Now, as a 

 result of the discoveries by Dumbacher 

 and his colleagues, I have to wonder 

 whether the flock members are also simul- 

 taneously signaling or pretending to be 

 poisonous. 



And yet another big question arises. In 

 the rusty-and-black flocks are individuals 

 (mostly females) of at least fifteen species 

 of New Guinea's most famous birds, the 

 birds of paradise. Male birds of paradise 

 have attracted much scientific attention 

 because they evolved through sexual se- 

 lection to have the world's most bizarre 

 plumage. Females have drawn much less 

 interest, their rusty-and-black plumage 

 being much more conservative. But note a 

 comment of feather collector A. E. Pratt, 

 reduced by starvation nearly a century ago 

 to eating a bird of paradise. He wrote of 

 his dinner: "The most shocking flesh I 



have ever eaten. . .as bitter as gall. . .it was 

 truly abominable, and after the first spoon- 

 ful we got no further." While ornitholo- 

 gists have been concentrating on the 

 gaudy bird of paradise males and ignoring 

 the females, could they have been missing 

 another story of poison and Miillerian 

 mimicry on a grand scale? 



Thus, behind one sentence in the ethno- 

 biological literature lurked a cascade of 

 major discoveries and questions: the first 

 proven examples of poisonous birds; a 

 case of convergent evolution at the molec- 

 ular level; a case of Miillerian mimicry; a 

 possible explanation for geographic varia- 

 tion in plumage; a force behind mixed- 

 species flocking; and a major selective 

 force on birds of paradise. In retrospect, 

 one might ask why none of the biologists 

 who had read Majnep's and Bulmer's 

 book beat Dumbacher to his discovery of 

 poisonous birds. Undoubtedly, the main 

 reason is that Majnep's clue was no more 

 than a single, qualified sentence in a long 

 book. Dumbacher discovered the bitter 

 skin for himself and came across Majnep's 

 sentence afterward. But there is also an- 

 other reason: chemists aren't yet accus- 

 tomed to asking New Guinea villagers for 

 suggestions about promising research pro- 

 jects. Here's one hint to chemists who may 

 now be starting to regret their past over- 

 sight: also buried in Majnep's book is a 

 paragraph about the bitter, mouth-pucker- 

 ing taste of the blue-capped ifrita, a New 

 Guinea bird quite unlike pitohuis. 



In the case of the pitohuis, we now 

 know that local folk knowledge was scien- 

 tifically valid. Next, let's consider the 

 "Case of the Stinking Birds." 



The case began one morning in July 

 1967, when a group of New Guineans and 

 I were sitting in a tent in the jungle, skin- 

 ning some bird specimens that we had just 

 caught. A Fore tribesman named Esa was 

 working on a mound builder, a large bird 

 famous for incubating its eggs with the 

 heat of scraped-together mounds of rotting 

 vegetation. Esa complained of feeling sick 

 from the carcass's stink; then he abruptly 

 vomited. This surprised me because the 

 bird had been shot only that morning, it 

 had had little time to rot, and the tempera- 

 ture was cool. None of my field assistants 

 had vomited over a carcass before, and, in 

 fact, they had struck me as notably unfas- 

 tidious in their wilUngness to eat birds that 

 had been kiUed the day before. 



Another New Guinean present, who 

 was more famiUar with mound builders 

 than Esa or I, explained that they were dis- 

 tinctive in stinking much sooner after 



death than other bird species. When I later 

 traveled to the Solomon Islands, where 

 mound builders are abundant, I was given 

 the same information. My Solomon Island 

 friend Alisasa Bisili told me the following 

 traditional story of how his people hunt 

 mound builders (called e-yo in Alisasa's 

 Roviana language): 



If you want to eat an e-yo, here's what you 

 have to do to cook it before it can start stink- 

 ing. During the day, go into the jungle and 

 look for a low branch with a white stain on 

 it. That stain is the e-yo's droppings. The 

 stain tells you that that's the branch on 

 which an e-yo roosts at night. Then go back 

 there after sunset with a pot of water and a 

 bow and arrow. When you spot the e-yo 

 sleeping on the branch, light a small fire on 

 the ground directly under it, and set the pot 

 on the fire. When the water reaches boiling, 

 shoot the e-yo with your bow and arrow, so 

 that it falls straight into the pot of boiling 

 water. That's the only way that we can kill 

 an e-yo and cook it soon enough that it 

 won't start to stink! 



Mound builders aren't the only stinking 

 New Guinea bird, as I learned in 1966 

 when I took the Tudawe fiibesman Omwai 

 to Utai village in the Sepik Basin. An Utai 

 villager named Uteno had earned 

 Omwai's dislike by threatening to poison 

 him and by nevertheless coming to our hut 

 every morning to cadge bu-d carcasses and 

 tobacco. On this particular occasion, I saw 

 Omwai give Uteno the skinned carcass of 

 a giant cuckoo known as Menbek's cou- 

 cal, and named pini in Omwai's Tudawhe 

 language. I asked Omwai with surprise 

 why he had given so much meat to a man 

 whom he despised. Omwai explained — 

 and I confirmed with my own nose the 

 next time we shot a pini — that the pini is 

 the only other bird that starts to stink as 

 quickly as does a mound builder The gift 

 of the pini was Omwai's revenge against 

 Uteno. 



We all know that dead animals smell 

 bad, but we rarely pause to reflect on the 

 smell's possible function. Think of any 

 dead body as a potential battleground be- 

 tween hyenas, beeties, other animal scav- 

 engers, and many species of microbes, all 

 seeking to digest the carcass for them- 

 selves. If a hyena swallows the carcass, it 

 thereby becomes unavailable to bacteria. 

 Biologically synthesized poisons, bad- 

 tasting substances, and evil-smelling 

 gases are weapons of chemical warfare by 

 which a microbe attempts to drive other 

 microbe species and scavenging animals 

 off the battlefield. The best-known such 

 weapon is peniciUin, a potent chemical se- 

 creted by a mold to kill bacteria (and now 



8 Natural History 2/94 



