Becoming a Tiger: The Education of an Animal Child Page 9

  A tame animal may go further and rush over to the wire to plead for its friend the rehabber to give it a snack. If it’s a bear, this is going to be a big problem after it’s released. It will probably be awkward even if it’s a squirrel.

  An imprinted animal is likely to want to set up housekeeping with, or at least mate with, a human. This is a severe problem, as we shall see. Much as humans may be alarmed by wild animals asking for handouts, they tend to be even more alarmed by wild animals asking them out.

  Cross-fostering and confused cockatoos

  When imprinting works right, which is almost always, it’s invisible. It’s easier to see how it works when there’s a mix-up, as in cross-fostering, when one kind of animal raises another. Many animals will adopt babies of their own species who aren’t related to them. And because the ability to recognize the signs of babyhood—the traits of youth and cuteness—is an ancient and generalized ability, many animals will adopt babies of other species under the right conditions.

  Cross-fostering is common in captivity. It’s not hard to get a mother dog or cat to accept a baby skunk or squirrel or piglet. Sometimes you can hardly keep them away from the strange baby they want to cuddle. In the wild, cross-fostering is rare but not unknown. If it happened often, natural selection would favor the evolution of mechanisms that would prevent it from happening. In one interesting place and time, it happened repeatedly.

  In dry western Australia, Ian Rowley and Graeme Chapman were studying cockatoos. This arid region is blessed or cursed, depending on whether you are a birder or a farmer—let us say, equipped—with six different species of cockatoo. Rowley and Chapman were studying the most glamorous one, Cacatua leadbeateri, also called Major Mitchell’s cockatoo after the first European to paint its picture. They’re called Majors for short. Majors are huge white-and-pink parrots with tall white crests striped with red and yellow, which they raise dramatically at the slightest excuse.

  There Rowley and Chapman were, following and counting Majors, putting wing-tags on them, tallying what they ate, and recording their flock movements, when they noticed an oddity. The various cockatoos form flocks with their own species, and while three or four species may feed in the same area, when they fly off, each flies off with its own kind. A flock of Majors, a flock of corellas, a flock of red-tailed black cockatoos. But in the flocks of Majors, occasionally there was a bird of the wrong species. Each time the odd bird was a common sort of cockatoo, the galah (pronounced guh-LAH). These are smaller, powdery gray-and-pink cockatoos, with small crests.

  These few oddball galahs not only flew around with Majors, but they flew slowly like Majors—flap-flap-glide, flap-flap-glide—instead of flying strongly and swiftly as galahs do. Instead of saying “Chet!” like galahs, they said “Creek-ery-cree!” like Majors.

  That was curious. Then other oddities were noticed. They found several cases where a male Major seemed to be keeping company with a female galah—sometimes the Major was raising fledglings. Other times Rowley and Chapman spotted a trio—male and female Major and female galah—together at the nest tree, day after day. Several times they spotted a pair of Majors with a family of chicks in which one looked an awful lot like a galah.

  At first they thought they were seeing hybrids, birds that were half Major and half galah. Only after several years of research did they piece together the story of the birds they call M-galahs.

  Attracted by new wheat farms in former scrubland, galahs had moved in to nest in areas where they hadn’t nested before, but which had contained Majors all along. The two species had a conflict: both nest in holes in trees, which are in short supply. Sometimes a pair of galahs would begin using a nest hole, laying an egg or two, but not sitting on the eggs until the full clutch was laid. A pair of Majors might come along a few days later and choose the same nest hole as their dream home. Eventually the couples would clash.

  Rowley and Chapman saw one such tussle. “The two birds fell locked together to the ground where they continued to scuffle until the [galah] together with its mate eventually flew off.” So the Majors had driven off the galahs. Yet, a week later, they found a nest lining of fresh green leaves in that same hole—and lining nests with green leaves is a habit of galahs, not Majors. The galahs were sneaking in and decorating.

  Ultimately the Majors won. “Possession may be nine points of the law, but when the contender is 20 percent bigger and has a bill like wire cutters and muscles to match, the battle is apt to be one-sided,” writes Rowley. The Majors would toss out an egg they didn’t think was theirs, but since galah and Major eggs look alike, mistakes were made.

  Baby galahs and baby Majors beg their parents for food in the same way, except that baby galahs are noisier. The squeaky nestling gets the grease, and so a young galah in a nest of Majors, though smaller, was in no danger of being underfed. Thus an M-galah was created, genetically 100 percent galah, but culturally a Major.

  Young galahs leave the nest at seven weeks, while young Majors wait till eight weeks. At a mixed nest, there would be a week during which the young M-galah would have left the nest and would be hanging around in the tree, shrieking for food and attention, while the young Majors were still tucked in the nest. The little M-galah would utter classic galah begging calls, “being-fed” calls, and “distant contact” calls, calls it was born knowing. Passing adult galahs would spot the lone fledgling issuing demands and fly down in a helpful spirit. But the little bird would turn away, never having seen galahs, and not liking the look of them.

  By the time a young M-galah joined a larger flock, it had learned a lot about how to act. Instead of giving the galah calls they gave as fledglings, M-galahs had learned the triple call of the Major: Creek-ery-cree! Instead of flying fast, they adopted the majestic flap and glide of Majors, who avoid long flights.

  Sometimes the M-galahs would slip up. They’d get carried away with their flying ability and speed ahead of the flock. Then they’d notice that they were alone out front, quickly circle back, join the ranks, and resume the flap-flap-glide. Or, when startled, they’d let out a galah alarm call.

  Rowley and Chapman write: “Through a combination of imprinting and subsequent learning the innate patterns of [galah] behaviour were largely eclipsed so that M-galahs were accepted by Majors and allowed to feed, fly, and roost in their flocks, whereas normally the two species remained apart.”

  But that was as far as things went, usually. “To some extent such individuals were shunned by both species and appeared to find it very difficult to overcome the barrier of Individual Distance even though both species are very much Contact animals.”

  Parrots want to love and be loved, to preen and be preened. In captivity, parrots generally follow the philosophy that if you can’t be with the one you love, oh well, love the one you’re with. So if an M-galah had been locked up with a Major, they might have paired off. But when choice was free, the Majors didn’t like the M-galahs. Maybe they looked or sounded wrong. They did say “Creek-ery-cree,” but their voices were too squeaky.

  Whether the M-galahs could have been accepted by galahs isn’t clear, because the M-galahs weren’t interested in galahs. They didn’t even like each other particularly: AB and NO were two male M-galahs born the same year, raised in different Major families. Though they were often in the same flock of Majors, they weren’t friendly. For these birds it seems to be inevitable that nobody they like ever likes them back, and yet they don’t like anybody that likes them.

  What about those pairs and trios that included M-galahs? Rowley and Chapman unraveled the stories of several of these matches. Majors mate for life in the sense that pairs usually stay together as long as they both shall live. But life in the wild is hazardous, so many cockatoos are widowed and marry again. Several M-galahs hung around widowed Majors, following them night and day but never helping with the kids. If the widow or widower found a new mate, the M-galah might persist with its attentions, creating a trio.

  Maybe the love of an M-galah is
sometimes returned. Rarely, hybrid cockatoos, half galah and half Major, have been found. Rowley and Chapman suspect that such pairings might occur in the wild if the galah partner is an M-galah who manages to woo the Major into overlooking certain personal quirks. Perhaps a Major who was raised with an M-galah sibling would be less close-minded about a mate with a squeaky voice and a stubby crest who’s always in a hurry.

  It’s not hard to figure out why the M-galahs liked to be with Majors and tried to form romantic attachments with Majors. As for why they chose to fly like Majors, that seems inevitable if they wanted to be in the haven of the flock. If they flew too fast they’d be alone. But why did they stop uttering the galah “Chet” call and say “Creek-ery-cree” like the Majors? Was it only to make themselves understood, or was it also a matter of how they identified themselves?

  Many people have had the sensation of not fitting into a group we wanted to belong to, even felt that we naturally did belong to. But the experience of the M-galahs goes beyond this, for galahs and Majors are different species.

  To compare the cockatoo case with a human case more directly, if I were to break into a house that some French people were moving into, and kicked them out and stole their baby and raised it as my own,* so that the poor thing walked like me and talked like me—if, then, you suddenly came up behind this formerly French baby when it was all grown up and grabbed it, it would not instinctively shriek “Mon dieu!” before turning and striking you. Because—unlike those crazy cockatoos—we’re all the same species.

  More cross-fostering confusion

  Researchers messing with the minds of zebra finches by cross-fostering them into the nests of Bengalese finches, or of mixed pairs with one zebra and one Bengalese finch, managed to come up with birds they called “dithers” because they couldn’t make up their mind which species was more attractive to them. Apparently they were “double-imprinted.” However, even finches that were firmly imprinted on a foster species could change their views based on experience. In such male birds, it is proposed, sexual imprinting has two stages. In the first, or sensory, stage before the bird is 40 days old, it learns what “the sexual object” should look like, but since it is only a child the question is academic. In the second, or verification, stage the male bird courts females and establishes a bond with one. “The initial preference is either consolidated if the female is the same species as the rearing parents, or it is modified if it is a different species.” I call this the First Girlfriend Effect.

  The black robin and the Chatham Island tit

  Researchers in New Zealand were desperate to save the black robin. At one point there were no more than five of these friendly, bouncy, little birds, who are solid black from head to foot. They survived on one tiny island, on which the vegetation was in terrible shape. Researchers moved the birds to another, slightly less tiny, island on which the vegetation was in slightly better shape. To increase the number of chicks hatched, the researchers began stealing the first set of eggs the black robins laid and putting them in the nests of other birds to raise. Meanwhile the black robins would lay another clutch of eggs. In this way the researchers could double (and sometimes triple, if they did it again) the number of chicks produced in a season.

  First they tried putting black robin eggs in the nests of warblers, but the nestlings didn’t survive. Then they tried putting the black robin eggs in the nests of closely related Chatham Island tits, a species which, though rare, wasn’t as rare as the black robin. That worked better, and the tits raised clutch after clutch of black robins. The black robins raised by robins stayed with their parents longer, for about six weeks after fledging, whereas tit foster parents only kept the kids around for four weeks, but this didn’t cause problems.

  But imprinting turned out to be a problem. At first the project members thought they’d gotten away with it, when Mertie, a male black robin raised by tits, paired off with the black robin Ngaio.

  But robins who’d been raised by tits were giving tit calls and singing tit songs. Alarmed researchers saw one of the black robins, Marion, encouraging the advances of a male tit, accepting gifts of insects from him. Worse, she built a nest with him, and laid an egg in it (which the researchers promptly switched with a plastic egg).

  Marion wasn’t the only one. The black robins raised by robins were mating and breeding, but those raised by tits were not. The exception was Mertie, but Mertie had been moved from the island where he was raised to Mangere Island, from which all the tits had been moved. In other words, Mertie may have mated with a robin, when he would have preferred to mate with a tit, only because there were no tits to be found. They began moving other malimprinted black robins to Mangere. They moved Marion, for example, and she soon took up with Mertie (Ngaio having vanished). After a while Mertie, who had previously sung a tit song, began singing a robin song. Gonzo, another male raised by tits, compromised and spent his days singing “two bars of robin calls followed by full tit song.” Tiger, a male robin raised by tits, was disruptive on Mangere because he didn’t respect robin territories. He was a tit, he felt, and didn’t have to respect robin rules. But male black robins who saw Tiger wandering through their territories took a different view, seeing him as a wicked trespasser robin who must be resisted. They failed to understand that Tiger was merely looking for a female Chatham Island tit.

  In the meantime, the researchers instituted a new plan in which they stole black robin eggs, gave them to tits to raise, and then snatched the baby robins back just before they fledged, and put them back in robin nests, on the theory that fledging is the time when imprinting takes place in this species. This meant that some robins, after laying their usual two eggs, losing them to light-fingered researchers, laying two more eggs and hatching them out successfully, would return to their nest one day and find that instead of having two chicks they had four, and not all the same ages. Fortunately the robins coped, and the babies imprinted on the robin parents, not the tit foster parents. This kept the researchers extremely busy shuttling robin eggs, tit eggs, plastic eggs, robin chicks, and tit chicks back and forth. When they weren’t doing that, they were steam-cleaning nests to get rid of feather mites.

  In one case, however, researchers gave a pair of tits a robin egg, which they successfully hatched and began rearing. When the researchers took it back and gave it to robins to finish rearing, the bereaved tit foster parents managed to track down their stolen darling “and were competing for the right to care for it.” The researchers were forced to step in and transfer the tits to another island.

  The strategy was so successful that after a few years they were able to reintroduce the Chatham Island tits to Mangere Island. By this time most of the robins who had become imprinted on tits had broken down out of sheer loneliness, accepted robins as mates, and were singing robin songs. Even Tiger took up with a black robin.

  Maggie was the last of the black robins imprinted on tits. She was rather secretive, and the researchers had a hard time keeping tabs on her. They spotted her accepting insects from a courting tit, but then they saw no more of him. Later, seeing a male robin near her nest, they assumed he was her mate, but when it was time to band her chick, they were shocked to find that “the unthinkable had occurred,” and the baby, Tobin, was a hybrid, half black robin, half tit.

  The heart wants what?

  An ill-suited dream lover is found in the case Konrad Lorenz relates of a white peacock, the sole survivor of a clutch killed by an early cold spell at the Schönbrunn Zoo in Vienna. To save the last chick, the keeper put it in the warmest place at the zoo, the reptile house. He was put in with the giant tortoises, perhaps because they could be trusted not to eat a chick. “For the rest of his life this unfortunate bird saw only in those huge reptiles the object of his desire and remained unresponsive to the charms of the prettiest peahens.”

  Imprinting seems to have spoiled a promising plan to protect endangered whooping cranes by duping greater sandhill cranes into raising them. By placing whooper eggs
in the nests of sandhill cranes at Grays Lake National Wildlife Preserve in Idaho, the wildlife services of the United States and Canada hoped to establish a new migration pattern for whoopers. If they followed their sandhill parents from Grays Lake to their wintering grounds in New Mexico, a whole new population of whoopers could be established, increasing their numbers and reducing the chance that a single catastrophe (storm, disease, etc.) could wipe out the world’s remaining wild whooping cranes. It worked to a point. The sandhill cranes were good parents to the whooper chicks, and the whooper chicks respected their parents and learned the migration route from them. But when the whoopers matured they did not breed, apparently since they had imprinted on sandhill cranes and only wished to breed with sandhill cranes. The scheme was abandoned in 1989. A few years later one of the cross-fostered whooping cranes successfully romanced a female sandhill crane. While this is nice for him, it does not lead to species survival.

  On the other hand, whooping cranes who were hand-reared by humans at Patuxent Wildlife Research Center—but by humans dressed in crane suits—and then released in Florida, fell in love with whoopers and raised children.

  Nice outfit, Mom. Excellent wig, Dad.

  If you were raised by birds dressed as human, would you be fooled? How dumb would you have to be to be fooled? But perhaps the foster children aren’t always as fooled as some might think.

  Captive-reared condors were entirely too casual around people and their dwellings. Keepers had tried to keep from habituating the condor chicks to humans by serving their food via condor hand puppets, but the condors weren’t really duped. “It is not clear the nestlings are truly ‘deceived’ by the puppets or deceived for very long. As realistic as the puppets seem, there is no way for them to be perfect mimics of adult condors in behavior,” write Noel Snyder and Helen Snyder. On the other hand, the condors don’t seem to imprint on beings they don’t see.