"Flying Casanovas"PBS Airdate: December 25, 2001 NARRATOR: In the world of birds, nearly all males rely on their looks to attract a mate. A lyrebird, like so many, uses his feathers. The Count Raggi's bird of paradise has gauzy plumes spouting from beneath his wings. Bare patches of brilliantly colored skin can also prove quite arresting. Many males flaunt their spectacular plumage in dramatic dances, as the Riflebird does. But nature does not endow every male bird with such spectacular good looks. In the art of finding a mate, one family of birds has evolved a much more extraordinary technique, the Bowerbirds. Instead of showing off their bodies, they use inanimate objects that they collect and arrange in special ways. Many of them put their treasures on display in front of special structures, bowers. Bowers come in several different basic shapes. Their treasures vary, too. These days, some birds even collect objects made by human beings. One species, the Tooth Billed Bowerbird, collects particular kinds of leaves and displays them in the simplest of ways, on a specially cleared patch of the forest floor. It's no accident that all of these leaves are pale-side uppermost. The bird clearly prefers them that way and I can easily prove that by turning one of them the other way up. That's better. Leaves of the wrong kind, and other bits and pieces, have to be removed to keep the display looking at its best. But will his collection impress the next passing female? Major funding for NOVA is provided by the Park Foundation, dedicated to education and quality television. Science: It's given us the framework to help make wireless communications clear. Sprint PCS is proud to support NOVA. This program is funded in part by the Northwestern Mutual Foundation. Some people already know Northwestern Mutual can help plan for your children's education. Are you there yet? Northwestern Mutual Financial Network. And by the Corporation for Public Broadcasting, and by contributions to your PBS station from viewers like you. Thank you. NARRATOR: Australia is home to eight different species of Bowerbird. This one, the Tooth Billed, is continuing to arrange his collection of upturned leaves in a way he hopes will impress any female that comes by. No other male animal woos his mates by displaying inanimate objects in this way, except, of course, us. He's also using music to help him set the mood. [Bird calls] A rival with a bower nearby listens and answers. One mimics the other. [Bird calls] A female has arrived. [Bird calls] Down he comes to his display ground. And there, he hides behind a tree trunk. He is only allowing her little glimpses, as though he were trying to make her curious as to where this strange clicking sound of his is coming from. She seems interested. He steps up his display with a little fancy footwork and a gargling call. [Bird calls] It's a somewhat alarming way of demonstrating his charms, but it must presumably be the sort of thing that turns on a female. But not this time. So he goes back to singing. The Tooth Billed's treasures are the most modest of any in the Bowerbird family. But nonetheless, they are the key to his breeding success. But the effect can be ruined by careless uncomprehending neighbors. This Brush Turkey is looking for seeds and grubs and worms by overturning the leaves and pays no regard to the Bowerbird's careful arrangements. But there is another threat lurking in the forest. This is not the owner of the bower. This is a neighbor, a rival, and he's not dropping by for a friendly visit. He's here to steal the leaves from this display to use them for his own. Thievery, as it turns out, is a way of life among the Bowerbirds. Farther to the south, in a more arid region of Australia, there lives another member of the Bowerbird family with tastes that are markedly different. Instead of leaves, these are the treasures this male uses to attract a mate. And behind them is something extra, a strange two-walled construction of twigs. This is not a nest; it's an art gallery, or perhaps a treasury. And these are the jewels that it's been built to show off, bones, snail shells, pebbles. And they have one thing in common. They're all white because the artist that built this has a passion for white. And if I retreat and have a little patience, he may well appear. This is him, the Western Bowerbird. His bower is the key to his success and it dominates his life. If it's sufficiently impressive, then female after female, after inspecting it, will mate with him. Each will then go away and rear her family entirely by herself while he stays here, doing what he can to improve his bower's appearance, re-arranging and adding to the treasures it contains and hoping for yet another mating. This is a female who's touring in the neighborhood, seeing what's around. How does this bower compare with others that she's seen? He watches closely to see what her reactions are. Maybe he can add a little spice with a dance. He nods to show that pink tuft on his head. Off they go together, and another male arrives. He has not come to steal. He's here to destroy. He works fast. The owner may be back any minute and if he's caught, there could be trouble. Hours of work destroyed in a few minutes. If a female comes by before the owner of this bower can rebuild it, the vandal with an undamaged, even if inferior bower nearby will have the advantage. Thievery and vandalism are, sadly, the inevitable consequences of rivalry among any creatures that place great value on inanimate material things. The only other country in the world where Bowerbirds exist is in the gigantic thousand-mile-long island of New Guinea, just across the narrow arm of the sea to the north. Its thick, rain-drenched forests were once continuous with those in tropical Australia. So it's not surprising to find members of the family up here too. Travel in New Guinea is not easy. It rains almost every day, so everything in the forest is permanently wet. And over great areas there are no roads, only thin tracks. So the only way to get around is on your own two feet. But it's a journey worth making for here there are species that build the most extraordinary bowers, including one that uses the Tooth Billed's technique of decorating the ground but drapes the branches above as well. In this forest, where every tree is hung with moss, you might walk straight past this bower; unless, that is, you noticed that there were blue berries pounced on this branch and then behind you, dried orchid stems hung round the sapling like tinsel on a Christmas tree. And they go 12 feet up and extend 20 feet beyond me. And then, as you walk into the heart of this path, there is really conclusive evidence of what it is. Here, lots and lots of wing cases of beetles, and most extraordinary and conclusive of all, three of the amazing head plumes of the King Saxony Bird of Paradise. They could never have fallen into this position naturally. The Bowerbird must have deliberately put them there. And this is the proprietor, Archibald's Bowerbird, until very recently the least known member of the whole family. That yellow crest shows that this is the male. He's picked up a beetle's wing cover. Clearly he thinks it would look better in a slightly different position. This bird doesn't have that yellow crest. It must be a visiting female. Her arrival is the cue for him to display. He seems to be playing hide and seek, like the male Tooth Billed. It's a way of drawing her attention to the wonders he's laid out on the ground. And when the female comes down to inspect them, he chases her in a ritualized way, back and forth across the floor of the bower. But whether he is successful or not, who knows? No ornithologist has ever seen the mating of Archibald's Bowerbird. Walking through this forest, you have to keep your eyes skinned. If you stop for any length of time, leeches are likely to start looping across the ground toward you. And you also ought to keep a lookout for berries balanced on branches as a sign of a nearby Archibald's bower. But there's one kind of bower here that is so extraordinary that you can't fail to spot it. It's easy to imagine how baffled early European travelers must have been when they found something like this in the depths of the forest. It's based around the stem of a tree fern. These aren't tree fern roots. They are separate twigs, each individually placed. On the ends of many of them, there are pendants made of caterpillar droppings. This is a rim around the corridor made of impacted moss. And on the top of it little black objects. They're actually fungus, but rare fungus. It's very hard to find these if you look in the forest here. And here is the owner, McGregors Bowerbird. Fungus, clearly, in any well-appointed properly tended bower should never be found in the runway round the base of the maypole. Keeping the bower smart requires such continuous attention that the male has little time for other things. So when he does manage to get away to forage, he brings back as much food as he can carry and stores it nearby. That way he won't have to leave the bower when he wants a snack. His reproductive success will depend on his having, in the eyes of the females, the most impressive bower around. So one can never have too many caterpillar droppings hanging on one's maypole. And suspending them is not easy. What next? Another twig, that could look good on the very top of the maypole. We know that the females tour all the bowers in the neighborhood, assessing them and presumably making a choice between them. And there must be fifteen or twenty within a mile of where I'm sitting now. So on what basis do they choose? Well, they aren't judging as to whether the bird is going to be a good father in the sense of helping in the nest, because these male Bowerbirds have no part in either building the nest or feeding the young. So the females, presumably, are judging on the way that this bower has been built, how it's been decorated and how he dances within it. And that means that the females must have some kind of aesthetic sense, artistic sense. And the interesting thing is that in recent years, European sculptors have also thought that there is great aesthetic power in constructions like this. Andy Goldsworthy is a highly regarded artist who creates what has become known as land or environmental art. ANDY GOLDSWORTHY (Environmental artist): My art is unmistakably recognizable as a touch of a person. I am not a bird and I do not mimic the things that I see that birds and animals make. However, there are parallels to be made. The sculptures are a response to place, light, atmosphere, the daytime. But it starts with the material. That's the beginning, and if there are a lot of branches that have curves in them, then that takes me in a certain direction. It allows me to work with the material in particular ways that I cannot with a straight branch. NARRATOR: Both Bowerbirds and human art lovers must find something rewarding in constructions which carry, in Andy Goldsworthy's words, "the touch of a person." And just as every human artist has his or her individuality, so does every male Bowerbird. So, if this is a work of art, as it certainly is in the opinion of many critics, why is this not? It's certainly constructed with great care, and when you watch a male at work, it's quite clear that he's giving great consideration to the placing every one of its decorations. There may be over five hundred of them distributed around the maypole. Sometimes he will change the placing of a new acquisition several times before he is satisfied it can be seen to its best effect. Time for a refreshment. He takes a snack from his larder in the nearby saplings. And now he backs up the effect of his sculpture with an intimate murmuring song. A female has appeared. [Bird calls] He uses the standard family technique of trying to arouse her curiosity by hiding. [Bird calls] She flies off to one side and he dodges to the other, to keep out of her sight behind his maypole. But she's going to look elsewhere. Had she been more impressed, she would have flown down into the runaway, and then he would have launched into his full display. That is a very rare site indeed, for the females are extremely choosy. But the owner of this bower has struck lucky. The final revelation, the full display of the crest, that until now he has kept hidden, though he still now only gives her glimpses of it. Less than one in ten male Bowerbirds manages to persuade a female to reach this stage and then copulate with him in the forest nearby. But those few successful males will mate with the majority of the females. All bower builders try to be polygamists. Five of the eighteen species in the family build their bowers on the maypole plan and each does so in its own particular way. In the Australian rainforest there's another. This is a rather more complex bower. It is similar in many ways to the maypole but instead of having one maypole, it has two. Here's one around this sapling and here, not quite so big, is another. Every single twig has been brought in and on this kind of bower you nearly always find that they have been glued together with a kind of fungus. And between the two maypoles there is a horizontal branch and it's there that the jewels are placed by the birds. There are lots of these translucent seedpods but mostly it's this yellow lichen. And if I put this on there I don't think he'll like it. That might bring him in and I will go and wait over there to see if we are in luck. [Bird calls] The forest is full of sound. [Bird calls] That is him. That is his scolding call. The trouble with this forest it is full of mosquitoes. I daren't flap my hands too much. That's the Whip bird. It is very typical in sound to this Queensland rainforest. That is the Whip bird again. And he's coming down to the bower. There's the Bowerbird. That's one of his approach posts. He often perches here. Here he comes. [Bird calls] No, he certainly doesn't like that bit of lichen where I put it. Back again. This time he has brought a Jasmine flower, one of his favorite decorations. There must be a female nearby. He is playing peek-a-boo like the MacGregors, only this time he is not using a sapling but a very substantial tree trunk. That's her. She's come down to the bower. That's him again. Here he comes. But he is behaving very strangely. He is not rearranging his decorations. He is throwing them away. This must be a neighbor, a rival, intent on damaging this bower, in order to make his, nearby, seem better. [Bird calls] Sometimes you find one of these twin maypole saddle-backed kind of bowers quite high up in the trees, like this one. This is its creator. He belongs to just the same species. He's a golden Bowerbird. But why should he build in such different positions? It may well be that all the bowers of the golden birds start this way, and they're used for so long, generation after generation, that the vine on which they're built increases in length so much that eventually it nears the ground. And it's these bowers that we usually find. Just as some building sites in the city are more valuable than others, so it is with the sites of bowers in a forest. [Bird calls] The longer a bower has been established, the more valuable its site becomes. And that is for two reasons. First of all, all the females in the neighborhood would know where it is and where to come to look for a mate. Secondly, the owner of the bower has been depositing his droppings in the neighborhood, very necessarily containing the seeds of the fruits on which he feeds. So, if the site has been occupied for a long time, there will be an unusual concentration of food drops there. This particular site has been occupied for at least twenty-two years. Two years ago disaster struck. A tree fell and smashed the bower. But did the male abandon his property? No, he did not. It was far too valuable. He simply moved a few yards and built another construction. And one, if anything, that is even more spectacular than the earlier one. And he is back within seconds to keep it so. The mountains of New Guinea, away to the north, are much higher and much wetter than those of Northern Queensland. And it's on their flanks and in the most leech-ridden parts of these forests that you have to go if you want to see the almost unbelievable complexity to which a maypole bower can be brought. And this the work of the master builder among Bowerbirds. I am in the Vogelkop in the far-western tip of New Guinea and this is the bower of the Vogelkop Bowerbird. And what an astonishment it is, surely one of the wonders of the natural world. The bower has been completely roofed over, thatched with these stems of orchids. It has been built around the base of a sapling that has a stout pillar right in the middle and it's got two smaller pillars on the side to support it. The hole of the treasury is five or six yards across and what treasures it contains...or what variety of treasures it contains. On the far side, there are the black stems of tree ferns. Here is the lawn, neatly planted with moss and on it the shiny wing covers are beetles. There are orange fruit. There are these glowing, orange, dead leaves. These are the acorns of the oak trees, the tropical oaks which are common around here. Behind me there are black fruits. This individual nearby, however, has completely different tastes. His bower is just as large and as splendidly thatched but he's taken advantage of this bush coming into bloom and has decided to try to impress the touring females with floral decorations. Like anything else in a bower, flowers, to create the best affect, have to be arranged with great care. Only a few hundred yards away from that, a third bower, and yet another quite different display. This bird is experimenting with brown—brown fungus and brown leaves. Yet another short walk and yet another bower, and another quite different collection: black berries, orange fruit and orange blossoms from a mountain rhododendron. The next bower, the same elements, but this male has arranged them differently and given them a special bold individuality by placing right in the center a huge black mushroom. As well as the ground displays of the Toothed Bill and the maypoles of the Golden and McGregor Bowerbirds, there's yet another basic design for a bower, an avenue. And to see that at its best, you have to go back to Australia. You might think that this is just a rather untidy nest that some reckless bird has put on the ground, but in fact it is not a nest at all. It is another bower. It has two sides to it. It's an avenue bower and at that end of it is a cleared patch and just one or two treasures, nothing spectacular, just a few little green leaves. That, you may say, is not much of a temptation to display to a female but you wait until you see the bird that made it. The Regent Bowerbird has the most spectacular plumage of the entire family. His female once again is very plain. It seems that there's a rule among some Bowerbirds, the more elaborate your bower, the less vivid your plumage. And conversely, as in this case, the simpler the bower, the more colorful the male. And since the male Regent has such brilliant plumage, he understandably attracts the females initially by perching in the topmost sunlit branches where he can be best seen. Having got her attention, he must now lead her down. His bower may not be much but she, nonetheless, has to have a sight of it before she will accept him. And she follows. What will she make of it? Perhaps because his collection is not as huge as some others, he picks up particular gems to show them to her individually, just in case she's missed their finer points. He also makes sure she realizes how splendid he is personally by repeatedly showing her the back of his neck. It seems to be a family habit, shared with those other species that have crests on their napes. She certainly seems interested. And what about this for a real treasure? The molted skin of a cicada. And that may well have done the trick. They go off together into the bushes. In the forests a little farther north, another member of the family builds a rather more substantial avenue, taller walls, more treasures. It's the creation of the Satin Bowerbird. He's certainly very handsome, but he's not quite as splendidly plumaged as the black and yellow Regent bird. So perhaps it's not surprising, in view of what seems to be the rule followed by some Bowerbirds, that he builds a bower that is very much more substantial and impressive than that of the Regent. He gives the walls great solidity by firmly interweaving the sticks. Now he adds the decorations. He has a liking for blue objects, but he's also fond of green, and regularly garlands the bower with leaves. But he does something else. He paints it. He chews up leaves and smears the pulp over the inside walls. One can only assume that the female Satin has a particular liking for interior decoration. When it comes to jewels, blue is undoubtedly his favorite—objects like this berry. Presumably, since Satin females clearly find their males' blue feathers attractive, this is an obvious way of adding to his appeal. But his tastes are wide. He likes a touch of green, curiosities like cicada skins, oddly shaped bones and skulls and skeletonized leaves. Carrying a jewel about is a sign that he knows a female is near. She has landed just behind him. Here she is. Walking into the avenue is a strong hint that she is interested. Good afternoon, madam. We have a particularly impressive seed that might interest you. Away she goes and so does he, leaving his collection unguarded. And that's reckless, bearing in mind the family's tendency to thievery. Here comes his neighbor. Robbery is certainly widespread among Bowerbirds. But not all visitors to a bower are necessarily thieves. This, in front of me, is the work of the Great Bowerbird, which builds the biggest of all of these avenue type bowers. But it has not been produced by a single male. That is a juvenile, a young lad as it were, and he is one of a group of about half a dozen young immature males, that's apprentices, who are learning their skills by working together on this bower. The techniques of wall construction seem to come just as easily to a Bowerbird as nest building does to other birds. But home decoration is another thing and these youngsters seem to have their own ideas. They have built a bower here in Townsville, in the municipal cemetery. Cemeteries offer special possibilities to an imaginative Bowerbird. Marble chippings, and lots of them, that could be a disadvantage. The thing that impresses a girl about diamonds is that they are rare and, therefore, expensive. You couldn't say that about marble chippings here. Still, they could work. You can vary them a bit—snail shells, a few fragments of beer bottles, a hair band—but marble chips are the favorite. If you can't impress with their rarity, then quantity could be the thing to go for. But shifting marble chips in large numbers is thirsty business. Over on the other side of town, there are other opportunities for a bird with adventurous tastes. There's an army barracks. Camouflaged green is used by the modern army for all sorts of things. And the bird that owns this bower clearly thinks it is just the color with which to dazzle a female because it's assembled a whole collection of green objects here. There are foot powder packets, bits of flecks,but mostly water bottle tops in green. But is he just choosing green because that is what happens to be around? Let's find out. He's back within seconds. I carelessly shifted that bottle. That is the first thing to put right. And then...what's that? That certainly won't do. You might think that there would be quite enough military paraphernalia here for everyone. On the other hand, stealing from your neighbor not only improves your collection but damages his. The owner is back and there must be a female around for he's starting his display. His only bright feathers are in that small pink crest on the back of his neck. That's her. This is the moment to add to his attractions by showing her his crest, but at the same time drawing her attention to one of his choicest possessions. And while he goes through his display rituals, so do his human neighbors. A few miles away there's a school. There are lots of things here for an avant-garde Bowerbird, who wants to impress the opposite sex by showing what imaginative and innovative tastes he has. And indeed there is a bower, a big spectacular one right in the school's grounds. It's been built by another collective of young males practicing their art. All kinds of brightly colored, highly desirable objects are being handed around during outdoor lessons. But there are limits as to how brave even a Bowerbird can be. Until, that is, it's time for the class to go back indoors. The boys move in. There are all kinds of possibilities here. Some test the birds' lifting strength to the limit. So the Bowerbirds have come to town, and like anyone else coming into the big city for the first time, they're discovering all kinds of new visual excitements that they never encountered in their old homes in the country. How many can you carry at one time? Who knows what these extraordinary bird artists will do with such new materials at their disposal in years to come? No other male animal seeks to impress his mate not with his strength, his beauty or his physical skill but with the wealth that he has accumulated through industry, thievery or artistic inspiration, except of course one, us. But in both cases it does seem to work. [Bird calls, doorbell] Bowerbirds and men aren't alone in going all out to attract members of the opposite sex. On NOVA's Web site explore some of the amazing courtship displays of the animal world, on PBS.org or America Online, keyword PBS. To order this show or any other NOVA program for $19.95 plus shipping and handling, call WGBH Boston Video at 1-800-255-9424. Next Time on NOVA: "Standing by for addition. And Pegasus is up and burning." A race to discover a force more powerful than anything ever known before. "It would sort of be like Hiroshima going off all over the world." "Pure energy, e=mc2." "Deathstar." NOVA is a production of WGBH Boston. Major funding for NOVA is provided by the Park Foundation, dedicated to education and quality television. This program is funded in part by the Northwestern Mutual Foundation. Some people already know Northwestern Mutual can help plan for your children's education. Are you there yet? Northwestern Mutual Financial Network. Science: It's given us the framework to help make wireless communications clear. Sprint PCS is proud to support NOVA. And by the Corporation for Public Broadcasting, and by contributions to your PBS station from viewers like you. Thank you. This is PBS. PRODUCTION CREDITSFlying Casanovas
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