Kitabı oxu: «The Homing Instinct: Meaning and Mystery in Animal Migration»
Meaning and Mystery in Animal Migration
Copyright
William Collins
An imprint of HarperCollinsPublishers
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London SE1 9GF
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This eBook first published in Great Britain by William Collins in 2014.
First published in hardback in the US by Houghton Mifflin Harcourt 2014.
Text and illustrations copyright © Bernd Heinrich 2014
Cover photograph © Antagain / Getty Images
The author asserts his moral right to be identified as the author of this work.
A catalogue record for this book is available from the British Library.
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Source ISBN: 9780007594054
Ebook Edition © August 2014 ISBN: 9780007594061
Version: 2015-04-22
CONTENTS
Cover
Title Page
Copyright
Preface
Introduction
I. HOMING
Cranes Coming Home
Beelining
Getting to a Good Place
By the Sun, Stars, and Magnetic Compass
Smelling Their Way Home
Picking the Spot
II. HOME-MAKING AND MAINTAINING
Architectures of Home
Home-making in Suriname
Home Crashers
Charlotte II: A Home Within a Home
The Communal Home
III. HOMING IMPLICATIONS
The In and Out of Boundaries
Of Trees, Rocks, a Bear, and a Home
On Home Ground
Fire, Hearth, and Home
Homing to the Herd
Epilogue
Further Reading
Index
Acknowledgments
Books by Bernd Heinrich
About the Publisher
PREFACE
ABOUT A DECADE AGO I STARTED PULLING TOGETHER BITS and pieces on the “homing” topic and in 2011 had a book manuscript scheduled for publication. I was then living at “camp” in Maine, where I had done my fieldwork on bumblebees for years; lately my work involved feeding ravens with cow carcasses in the winter, and I then got interested in beetles that bury mouse carcasses in the summer. Soon the topic of recycling of animal carcasses of all sorts seemed more urgent than the scheduled book about getting to and living in a particular place. So, I put writing about homing on hold. By the time I again picked up my pencil, it seemed as though everything I thought of or had an interest in had, in one way or another, started to have a bearing on home and homing. In the meantime I had also been confronting personal issues of “homing,” and they seemed to take on increasingly similar forms to what I was reading about in animals.
I had already left my academic position in Vermont and wanted to return home to live in Maine, possibly in the home to which I had bonded strongly as a child. I had planted a row of trees there about thirty-five years ago. Those trees, now huge, brought back many memories related to them. They reminded me of my father, who had liked them, probably because he had strong feelings for a row of chestnut trees that also lined the way to his old home in the old country that he had often talked about. Because I had written a book about my father, and not also one about my sisters or my mother, I had come into the disfavor of both. There had been parent-offspring conflict before my mother died, and then the house stood empty. So then there was also sibling rivalry over the estate. It seemed like being in a real-life situation of the sociobiology theories, in an almost perfect rendition of a naked mole rat colony where one of the family finds a big tuber, and the others claim it as theirs, and then a vocally assertive member establishes herself as the matriarch. I realized then that the difference between what can happen to a human and to a naked mole rat family is mainly one of terminology. This thus provided the topic of home and homing a much wider perspective.
INTRODUCTION
Our passionate preoccupation with the sky, the stars, and a God somewhere in outer space is a homing impulse. We are drawn to where we came from.
— Eric Hoffer
With all things and in all things, we are relatives.
— Native American (Sioux) proverb
I LEANED ON THE SHIP’S RAILING AT THE STERN, A TEN-YEAR-OLD boy with virtually no notion of where my family might be going. I heard the deep roar of the engines, the whine of the wind, and the rush of the churning water. I felt adrift, as though carried along like a leaf in a storm, feeling the rocking, the spray, and the endlessness and power of the waves. I had no notion that we were among multitudes who had made hard decisions to court the great unknown, or any clear idea of why my family had left the only home I’d known in a forest in Germany. The only picture of what our new home might be was that we might find magical hummingbirds, and fierce native tribes armed with knives, bows and arrows, spears, and tomahawks.
Security for me was the memory of where we had come from, specifically a little cabin in the woods and a cozy arbor of green leaves that enclosed me like a cocoon where I could see out but nobody could see in. It meant a feeling of kinship with the tiny brown wren with an upright stubby tail that sang so exuberantly near its snug feather-lined nest of green moss hidden under the upturned roots of a tree in a dark forest. I had in idle moments in my mind inhabited that nest. I found, too, the nest of an equally tiny long-tailed tit. This little bird’s home was almost invisible to the eye because it was camouflaged with lichens that matched those on the thick fork of a tall alder tree where it was placed.
The ocean all around was a spooky void. But then, after several days at sea, a huge white bird with a black back appeared as if out of nowhere, and it followed us closely. I saw its dark expressionless eyes scanning us. It was an albatross. It skimmed close over the waves and sometimes lifted above them, circled back, and then picked up momentum to again skim alongside our boat. It followed us for hours, maybe even days.
The albatross was big and flew without beating its wings. Years later I wondered if, even in the featureless open ocean where so much looked the same every hour and every day, it may have known where it was all along. How do we find our home and recognize it when we find it? These questions were inchoate then, but given the examples of other animals, they put many ideas of home and homing in context.
Later, as a graduate student, I read that pigeons could return home to their loft even when released in unfamiliar territory, and that some other birds could navigate continental distances using the sun and the stars. There were few answers to how they did it. But I read about researchers at Cornell University who attached magnets to the heads of pigeons and got them all confused. Donald Griffin, my scientific hero (who had discovered how bats can snatch silent moths out of the air in a totally dark room that had wires strung all over the place), was releasing seagulls over forest where they could never have been before and then tracking the birds’ flight paths by following them in an airplane. Most of his birds turned in circles before some of them flew straight, although why was not clear. Searching for a thesis problem to work on, I wrote to ask him if birds passing through clouds might keep in a straight line by listening to the calls flocks make while migrating. He replied in a long, thoughtful letter to let me know that this idea was too simplistic, and that one should not discount much more complicated mechanisms. That was excellent advice. I did not then have the means to solve any of these puzzles, but over the years I have kept in touch with the evolving field of animal navigation and its relevance to the need for a home.
For other animals and for us, home is a “nest” where we live, where our young are reared. It is also the surrounding territory that supports us. “Homing” is migrating to and identifying a suitable area for living and reproducing and making it fit our needs, and the orienting and ability to return to our own good place if we are displaced from it. Homing is highly specific for each species, yet similarly relevant to most animals. And the exceptions are illuminated by the rule.
The image of that albatross took on more meaning decades later, after I learned that the species mates for life and returns to the same pinpoint of its home, on some island shore where it was born, perhaps fifteen hundred kilometers distant. During the years when it grows to adulthood it may never be in sight of land. Seven to ten years after having left its home, it returns there to nest. It chooses to go there because of its bond. When a pair eventually have a chick in a nest of their own, each parent may travel over fifteen hundred kilometers of ocean to find a single big meal of squid, and after gathering up a full crop, it then flies home in a direct line; it knows where it is at all times.
The broad topic of homing subsumes many biological disciplines. In order to show the connections among all animals and us, I have interpreted the traditional use of an animal’s “territory,” or “home territory,” simply as “home.” We think of “home” primarily as a dwelling, but in order to be inclusive with other animals, I here consider their dwellings to be their homes as well. My application of the same terms to different species is deliberate for the sake of scientific rigor and objectivity, to acknowledge the continuity between our lives and those of the rest of life. I realize that this smacks to some of anthropomorphism, a pejorative term that has been used for the purpose of separating us from the rest of life. The behaviors involved in homing include drives, emotions, and to some extent also reason.
A home makes many animals’ lives possible: home is life-giving and sought after with a passion to have and hold. We humans are not thinking much about “home” for animals when we confine them in cages devoid of almost everything they need except air, food, and water in a dispenser, or when we destroy the habitat that contains the essentials of home for many species. So I begin our exploration of home and its implications with the example of the common loons, Gavia immer, birds that may live for decades. The collaborative study by three biologists, Walter Piper, Jay Mager, and Charles Walcott, reveals how important home can be — enough for fights to the death.
Loons spend winters in the open ocean, but a pair migrate from it and across the land back to their home, a specific northern pond or lake, to nest along its shore in the spring and raise one or two chicks out on the water. Starting almost immediately after ice-out and almost until freeze-up, camp owners along a lake routinely see “their” pair of loons year after year. It had long been assumed that the same individuals return each year and live as monogamous pairs on their strongly defended home territory. Huge surprises were in store after 1992, when techniques (using a boat, a strong light, and a net) were developed to capture loons and mark them with colored leg bands to identify individuals. In a long-term study of a population of loons in Wisconsin in a cluster of about a hundred lakes, it turned out that a pair of loons indeed returned year after year to their home. However, they were not always the same birds. As expected, given their longevity and reproductive potential, there were many “floaters,” those still without a home, and some of them routinely replaced members of a pair.
The floaters regularly visited different pairs at home at their respective lakes, and spirited vocal meetings resulted. These seldom led to fights, but they were not just friendly visits. These floaters were at first thought to invade others’ home grounds in order to make “extra-pair parenting” attempts (which in males refers to extra-pair copulations and in females to egg dumping into the others’ nests). However, DNA fingerprinting of the young loons from four dozen families produced not a single incident of extra-pair parenting. Instead, the visits by floaters were of an entirely different nature. They had an almost literally “deadly” purpose. The floaters were scouting — making assessments of both the worthiness of the others’ real estate and the defensive capabilities of the resident males — to gauge the possibility for future takeovers.
Loons nest on the ground along shorelines, if islands are not available. Shorelines, if low, are risky nesting places, not only because of potential flooding in early spring, but also because they are within easy reach of raccoons, skunks, and other predators. Most birds test what is a “good home” by direct experience — success in raising a brood there. Or, like the loons, they assess the experience of others: whether or not chicks have been raised there. So, if the territory does yield young, a floater, who apparently finds this out through scouting, may risk a fight in an attempted takeover to remove the defending male (if he achieves takeover, he automatically gets to keep the female who remains on her home). But the floater can risk an attack only when he is about four or five years old. When he is in prime physical condition and has much to gain — namely, a potential lifetime of home ownership — it makes sense to risk the battle. The older territory owner might then fight to the death, presumably because he has much to lose, and almost no chance to gain another home.
Loons may seem extreme in the lengths to which they go to secure a home, as do other birds that risk the hazards of migrating thousands of kilometers. Yet, in the movie I watched with rapt attention on board ship on the way to America at age ten, people on ponies shot arrows at others on a wagon train. All were emotionally charged, because each was fighting for something sacred, and therefore each was willing to risk his life, for defending or wanting a home.
We have learned much about thousands of animal species that twice annually risk their lives to migrate to an exact pinpoint, such as an oceanic island in the case of the albatross or a pond in the vastness of a continent in the loon’s. They open a window with a broad view onto our unending quest into the mysterious minds of animals, and in the process they illuminate our own. How does one tie the vastness that includes other animals, and so much that affects us personally and socially, together into a story?
Writing this book reminded me of when, after riding more or less unconscious in the slipstream of history for over fifty years, I started putting down stones chosen from a vast array of differently shaped fieldstones to build a house foundation. I couldn’t chop them to size or knock the edges off so that they would fit into the inevitable empty spaces to make neat connections. Nor did I want to shape them, like bricks, to make a tidy but artificial structure. The stones found in nature, like facts, are endlessly numerous, wild, and complex. As the famous British geneticist and evolutionary biologist J.B.S. Haldane quipped, “My own suspicion is that the universe is not only queerer than we suppose, but queerer than we can suppose.” I hope to give here a view of some of the “stones” of homing, and their origins, and how they apply in real life.
Homing is central to many aspects of our and other animals’ lives. To understand the meaning of home, like any other phenomenon, it helps to step back and see from another’s world. Animals give more than just clues to the why and the how of homing. They show what is possible, what has been tested, and what has worked over millions of years of evolution.
In this book I cannot hope to provide an in-depth treatment of any issue. My viewpoint is wide, and admittedly personal. Thousands of scientific references are possible for any one topic, and I am not an expert on any topic. Those references I cite are in no way meant to be the specific last word on the topic. They tend to be those I am most familiar with. I apologize for all of the amazing stories and all the details that I have left out. I have tried to speculate freely, and I hope that this will open discussion, not close it.
PART I
Homing
A skull I have lying on my desk is as big around as a somewhat flattened coffee mug, but it comes to a point at the front and has two large eye sockets. The bone on the top of the head is sculpted in ridges and furrows and looks like weathered stone. Seen from the back, the skull has a backward-opening hole on each side. The holes anchored the animal’s powerful jaw muscles. Between them is a much smaller hole. I am looking through this hole (foramen magnum) for the brain cavity, but this large head contains scarcely any brain at all, just an extension of the dorsal nerve cord that runs up from the neck.
It’s the skull of a snapping turtle, a female who met her end as she was crossing the road to dig a hole in the gravel to lay her clutch of eggs. As in previous years, she had come from her bog a mere hundred meters away.
The local snapping turtle is no great wanderer. But two sea turtles — the green turtle, Chelonia mydas, and the leatherback, Dermochelys coriacea — are renowned for migrations spanning entire oceans. The leatherback as an adult feeds in northern cold waters but nests on tropical beaches. It can weigh up to a ton, and although the skull of one that I had the opportunity to examine was as big as a basketball, the cavity holding its brain was, like the snapping turtle’s, only a slight expansion at the end of the vertebral column. It could barely have held a walnut. The green’s could have held two hazelnuts. Their skulls hardly differ from that of any turtle, whether of a species alive now or one that lived 215 million years ago, at a time at least three times more distant than that of the last dinosaurs.
The minute dimensions of some animals’ brains are as astounding as the homing capacity of some of their owners. Like albatrosses, sea turtles of various species lay their eggs in colonies with others of their kind on specific ocean beaches. After the young hatch from the eggs buried in the sand, they head for the water and spend years at sea. They may travel thousands of kilometers, and then, a decade or two later when they are ready to lay their eggs, they return to their birthplace. They mate in the water nearby, and the females then come ashore to dig their nest holes in the sand and to drop in their eggs. How are they able to find their old home after years of wandering in the vastness of the oceans, when we, if taken blindfolded to and then released in unfamiliar woods, would, despite our highly sophisticated massive brains, be as likely to head off in a wrong as a right direction? To get around in unknown territory most of us need a map with which to find at least one known fixed feature that we can both see on the ground and locate on that map, and a compass.
What knowledge and what kind of urges does it take for some birds to fly nonstop for nearly ten thousand kilometers, spending all day and night on the wing, until their body weight halves as they not only burn up all of their body’s food stores but even sacrifice muscle, digestive tract, and other entrails — almost everything except their brains?
CRANES COMING HOME
If feeling fails you, vain will be your course.
— Johann Wolfgang von Goethe, Faust
MILLIE AND ROY ARE A PAIR OF SANDHILL CRANES THAT STAY for most of the year in Texas or Mexico but travel north in April and have for at least fifteen years nested and raised their one or two offspring, known as colts, in a small bog in the Goldstream Valley near Fairbanks, Alaska. Their home is adjacent to the home of my friends George Happ and his wife, Christy Yuncker. George was an insect physiologist and chairman of the Zoology Department at the University of Vermont where I was hired in 1980, and he later moved to the University of Alaska and the land of the Iditarod, where the two built their home in the wild land near Fairbanks. They invited me to visit them and “their” cranes, and I was eager to do it.
The thousands of square kilometers of central Alaska’s permafrost-covered taiga consist of stunted blue-green spruce and white birch, with a groundcover of green-yellow moss and twiggy Labrador tea whose evergreen leaves curl at the edges and have a soft beige fuzz on their undersides. Chalky lichen and small shiny cranberry leaves decorate a thin black soil overlying the permafrost that can extend thirty meters down. In this expanse, there are many bogs or pingos, which are the result of an ice dome (groundwater that freezes into an upwardly bulging ice lens) that has melted and created a depression where a pond or a lake is then formed. After a few centuries, a floating mat of vegetation grows in from the edges to create a floating bog. Such pingo bogs have become the favorite home sites of sandhill cranes.
Portrait of Millie and Roy
George and Christy’s pingo in the Goldstream Valley is, like others, clear of trees but surrounded by stunted black spruces. It is the home site not only for the crane pair but also for Bonaparte’s and mew gulls, pintail and mallard ducks, and sometimes horned grebes. I intended to arrive several days in advance of the cranes’ anticipated return, to try to watch their homecoming. Surely this return during the first week in May would be a big event in their lives, and I wanted to see their reactions to their old home.
Millie and Roy had last been seen as they left the bog in the previous year, on September 11, 2008, for their southward migration. They had been delayed from their normal end-of-August departure date because Oblio, their colt, had a leg injury that prevented him from being ready in time for the family flight to western Texas. Waiting for him saved his life; we know that young cranes, as well as geese and swans, learn the route between wintering and breeding homes from their parents. The proof and the implications of the necessity of the young to be able to follow their parents, or alloparents, in order to migrate were perhaps most convincingly demonstrated by William Lishman after he first played parent to hand-raised geese that he later led as a flock with an ultralight aircraft. He also led sandhills in this way. Finally he led a flock of whooping cranes from their breeding grounds in Wisconsin to establish new homes for them in Florida. However, nobody as far as I know has been able to follow wild birds, and my chances of seeing Millie and Roy touch down for the first time on their arrival this year might be slim. But I felt it was worth a try.
Cranes, like other large birds, grow slowly. It takes them thirty to thirty-two days to incubate their two eggs, and another fifty-five days for their (usually one) colt to be able to fly well enough to migrate. This far north there is only a narrow window of time for cranes to breed successfully, especially for those that fly even farther to breed, as some of those wintering in Mexico do, in Siberia. If late in arriving, they waste their effort of migrating the thousands of kilometers north. If they are too early, snow and ice cover all food sources. This year had been a winter of heavy snows in central Alaska. Even the boreal owls were starving from their inability to reach the voles under the snow. By late April, when I arrived, the woods around Millie and Roy’s home bog were still under at least half a meter of snow, and the cranes had not yet shown up.
I would have liked to fly with the cranes on their homeward journey, but the best I could do, apart from trying to beat them to their destination, was to see a piece of their flight path. My transcontinental flight of 3,872 kilometers from JFK Airport in New York was followed by a direct flight on April 23 from Seattle to Fairbanks, and I spent most of the three and a half hours of the 2,467-kilometer flight from Seattle north in the Boeing 737–800 with my face pressed to the window, trying to see like a crane. How did the cranes navigate and negotiate their five-thousand-kilometer journey from Texas or Mexico to come home to their own pingo out of thousands of others scattered throughout the vast and seemingly unending Alaskan taiga?
The cranes arrive lean at their main staging area, at the Platte River in Nebraska, and stay three weeks to gather reserves for their continuing journey north. When ready, they gather with thousands of others and wheel high in the sky into giant “chimneys,” to travel together on their common journey. Once in Alaska, they take separate paths to their individual homes, and a third of them fly beyond, to their homes in Siberia.
We had scarcely lifted off in Seattle when we passed over white-capped mountains with knife-edged ridges, dark forested valleys, and peninsulas surrounded by blue-gray water. An hour later, cruising at about eight hundred kilometers per hour at eleven thousand meters, there was ever more of the same — white mountains as far as the eye could see. Another hour — it was still the same. To me, barely a feature stood out from the jumble of endless peaks that melded into each other, and the vast mountain scape was broken only by frozen lakes glinting in the evening light. And so it continued for yet another hour. When we started our descent to Fairbanks, I saw oxbows of meandering rivers, and finally the thin thread of a road.
Cranes, swans, and geese travel south in the fall as family groups. On their way, the young learn the route they will later take north in the spring, to come back to try to settle near where they were born. What they see and remember seems astounding. I might, with intense concentration, memorize a tiny portion of the way, perhaps around this or over that mountain. But these cranes come not from my point of departure, the state of Washington, but from considerably farther south. (Four cranes from the Coldstream Valley that the Alaska Department of Fish and Game had equipped with radio transmitters ended up in various parts of Texas in the winter.) I could never retrace even my own much shorter flight route from Seattle, even if I were to return the day after having flown over it, much less a half-year later. What are the cognitive mechanisms that allow the birds to do this?
Day after day for almost eight months now there had been no crane at the pingo. For most of that time the ground had been under a deep layer of snow that locked any food out of reach. What would happen if, after their long-distance flying, the pair were to arrive at their home and find the bog still under snow and ice with no cranberries to be found and no voles to catch? How much can cranes afford to gamble in order to try to come on time, or even early?
It was only in the last week of April, after another snowstorm, that the weather suddenly warmed, and just then, on the 24th of April, on my first morning, we heard a crane in the distance. Still, no cranes landed on the pingo on the 25th, 26th, 27th. But the next morning at dawn I awoke to the loud and penetrating trumpeting calls of a single crane. These metallic sounds are unearthly; as Aldo Leopold wrote in his “Marshland Elegy,” they evoke “wildness incarnate.” On and on this bird shattered the dawn’s stillness, and I ran out to look. But the bird was then distant, and the sound kept shifting position, so I presumed it was flying around in great circles, possibly looking for a patch of cleared ground; the mossy floor of the nearby stunted spruce forest was still covered in deep snow.
That evening we sat down to supper by the window facing the wide-open panorama of the pingo in front of us. The sun was still high. We were just polishing off the last of our freshly grilled salmon when we looked up to see a crane with spread wings gliding down for a landing. Its long thin legs touched down gently on the still-thick ice of the pond. It bugled and sprang up half a meter or so, unfurling its long neck with beak held skyward and with extended wings at the apogee of its graceful leap as if to catch itself in the air to prolong this moment. It looked like a physical embodiment of joy and excitement. The crane kept leaping, all the while continuing its stirring bugling. Cranes don’t do this every time they land; this was indeed a special landing. Finishing its dance, the crane started to walk in a contrastingly slow and deliberate manner, thrusting its head forward and up with each step, and at the same time opening its bill and making a very different, trilling, call.
The crane walked and leaped in several more repetitions of its dance before eventually lifting off with even wing beats to sail off in the same direction from which it had come, its haunting cries growing faint in the distance. Two hours later the (same?) crane came again, but this time it circled the bog only once before leaving, continuing its calling. It had given the impression that it was glad to be back but was at the same time agitated and looking for something; a mate? In previous years Millie and Roy had always returned as a couple, George and Christy told me, so lacking positive identification, we were skeptical that this was either of them.
I had barely gone to bed that night when I heard another one or possibly two cranes calling excitedly, while a third seemed to answer from the distance. I jumped up and rushed outside to look: a pair were walking from one end of the bog to the other. George and Christy were up also, and for the next hour, until it got dark at 11:15 p.m., we watched. One of the cranes stood tall and extended his head and neck forward and up, reminding me of the dominance display of a male raven. This was Roy. The second one, whom I would soon identify by her walk and talk and narrower white face patch, held her neck and head in a more downward curve like a heron’s, projecting her head slightly forward with each step. She started to pick up cattail fronds and grasses and then to deposit them, sitting down briefly on the materials. Was she encouraging her mate by suggesting to him that it was time to start nesting at one or another of these potential nest sites? I could hardly wait to see what would happen next.
Crane pair coming home
Another clamor awoke me in the early dawn, around 4:00 a.m. There had been a heavy overnight frost and the two cranes were standing on the ice in the middle of the bog. Both Millie and Roy tossed their heads up in a quick motion, their bills opening wide during each call. We heard what sounded like a hammer hitting a metal bell or drum, as he opened his bill once to make each call and she chimed in at the same time but called and opened her bill twice to make two short similar cries of a higher pitch. It was a composite call made by both together; a duet. A third, distant crane responded. The distant calls, and the pair’s duet, were repeated back and forth, often and loudly.
The vigor of the pair’s unison calling was still palpable, even when the first morning light lit the sky and silhouetted the black spruces, and when I thought about the enormous effort they had invested to get here, I realized what was at stake: home ownership. The pair’s loud clanging calls attracted no others flying in from the distance; instead, the calls are a vocal “no trespassing” sign, one leaving no doubt that any potential challenger would be facing not just one bird, but a united, cooperating pair.
I watched the pair for another hour. She by then occasionally fluffed herself out and, as she had done the day before, continued periodically to squat where she had pulled at or dropped sedge and other potential nesting material.
The pair continued their slow, deliberate steps that morning while meandering from one end of the bog to the other, as though inspecting every square centimeter of it, and at 9:00 p.m. we saw Roy jump high and with outstretched wings dance by himself out on the ice. Millie dashed by him with fluttering wings, to round out a mutual performance. A little later we heard a purring call as she spread her wings to the sides and stood still. Roy, with outstretched neck and elevated bill, jumped onto her back and, balancing himself with a few wing beats, mated. He dismounted after a couple of seconds. Both then bowed to each other and continued their walk. They were home, intended to nest, and had now sealed the deal.
Still, the lone bird that had tried to intrude on their turf did not easily abandon its intended claim. But why would this crane want a claim without a mate to nest with? Was it Oblio, their grown colt from last summer? Was he, now that Millie and Roy were re-nesting, finally being “thrown out of the nest” by his parents, who no longer tolerated company of any sort? I suspect this was the case. The offspring of most birds have a strong attachment to home. This emotion is a biologically relevant drive, because home is where reproduction has proven to be successful. But the young have a lifetime ahead of them, and if for some reason the parents don’t make it back home, the offspring could inherit their territory. If the parents do come back to reclaim their home, at least nearby territory would be more like the old home than the far-off unknown. Even if a bird is without a mate, finding a suitable territory is often a prerequisite to getting one.
Shortly after we had breakfast the next morning, the lone crane flew over once again, and the pair immediately launched their synchronized duet as a vocal challenge. This time, although the lone crane did not land, the pair jumped into the air and chased it until all three were out of our sight and hearing. But the pair returned soon and then again performed several nest-building probes. They again mated in what would become a routine for the next several days: at least once in the morning and once in late afternoon or at night.
When I first saw the cranes the next dawn, each was standing on one leg with its head tucked into its back feathers. Ice had again solidly covered their pond, after having partially melted along the edges the day before. Both Millie and Roy seemed to be asleep, although he, balancing himself on one leg, occasionally reached up with the other to scratch his chin and head with the toes of the foot. But whenever a crane called from the distance, both their heads shot up instantly, and they renewed their spirited in-unison call, she making the two short notes and her mate making one, at a lower pitch.
We had so far not seen them feed. Indeed, it was hard to imagine that there was food available in any case. If lucky, they might by now catch a vole or find a few of last year’s cranberries, but this year that would probably not be likely until days later when the snow would melt. A crane’s large body size requires much more food than a small bird’s, but that same large size is an advantage in tiding them over during lean periods, and thus to return to their homes before the anticipated flush of food becomes available.
As it got lighter on this dawn, the cranes soon had company. A pair of swans and then a small flock of five Canada geese flew by. A robin sang. By about 7:00 a.m., the crane pair became animated as well, walking over the bog while picking here and there, and again mating.
We did not see the pair most of that afternoon. The lone crane, seemingly to take advantage of their absence, again flew in and this time landed, looked around, and repeatedly made a trilling call. But in about fifteen seconds the pair flew in as if out of nowhere, and one of them sped over the ice as if to attack the interloper, which immediately flew off. The pair gave chase, and all three disappeared from sight. In several minutes the single bird returned. Again the pair came and caught up to the lone crane before it had a chance to take off, and this time they attacked it viciously, in a flurry of flailing wings.
The pair had by now, after the third day, won the major part of the battle. Barring accidents, they would within days lay their two eggs and go on to raise their colt. Normally both eggs hatch, but as in some eagles and vultures, usually only one chick survives, probably because one gets fed less and then weakens and eventually starves. Presumably through evolutionary history, for the fast growth required to reach full development and readiness to migrate by August, there has not been enough food to raise two colts at once. One might suppose the cranes could simply lay only one egg, but sometimes an egg does not hatch, and the second is insurance.
The pair seemed more animated after their last fight with the lone intruder, and by evening they again mated (for at least the third time that day). In most birds one mating is enough to fertilize the eggs. Perhaps several matings are insurance, but this seemed more than enough for insurance. Perhaps, like their dances, mating is additionally part of their bonding ritual.
A pair of mallards, and then a pair of pintails, arrived in the evening, and the ducks swam next to each other near the cranes at the edge of the pond, where some open water had reappeared during the day. The cranes ignored them and again walked in their stately manner back and forth across the ice of the pond, and now they pecked in the low vegetation being exposed along the edges. They were by now finding overwintered cranberries exposed by the melting snow.
On the evening before I would leave for my journey home, Christy and George hosted a potluck party. Shadows fell on the white frozen middle of the pingo as the western sky turned yellow and orange and the spruces became dark silhouettes. A pair of pintails again landed in the open water along the pond’s edge. The cranes were standing, each on one leg, their heads tucked into their back feathers. People crowded around the spotting scope in the living room, watching them occasionally shift position, lower a leg, poke a head out to look around. Suddenly the person then at the scope erupted with an exclamation: “They are mating!” She had seen the male approach the female with her spread wings, mount, flutter, and jump off. The pair had bowed to each other. Suddenly many people crowded around the scope to watch.
Why, I wondered, would anyone, or almost everyone, want to watch cranes mate? Why was nobody interested in watching the mating activity of the two ducks, or of the numerous redpolls? Could it be, I wondered, because we feel a closer kinship with cranes than with other birds?
Cranes are similar to us in many ways. Some are nearly as tall as a person. They walk on two long legs like us, albeit with a much more graceful and deliberate gait, so that they remind one of a caricature of a gentleman or an elegant woman on a leisurely stroll. The sandhill crane’s red bald pate and sharp yellow eye add to the caricature. Cranes form lifelong pairs and stay together as families, but they are also gregarious and join up into large groups. They form a strong attachment to their home. They not only make music with trumpeting calls that sound like bugles, but they also dance, and do so on various occasions.
All of the fourteen species of the world’s cranes dance. Crane dancing involves running, leaping into the air, flapping the wings, turning in circles, stiff-legged walking, bowing, stopping and starting, pirouetting, and even throwing sticks. Dancing is primarily done by pairs and presumably functions in cementing pair bonds and/or synchronizing reproduction. But it can also be induced at any time, and it stimulates other cranes to dance. Even the young colts perform some of the species’ dance. Possibly it serves as practice and could be motivated by the same basic emotions of joy that are an indicator of health important to mating.
Cranes’ dances often stimulate humans to dance as well and have been mimicked in many cultures all over the world where cranes live. Crane dances were performed by ancient Chinese, Japanese, southern African, and Siberian people. If not emulated, cranes are admired. In the Blackfoot tribe of Native Americans of northern Montana, the last name “Running Crane” is common.
Nerissa Russell, an anthropologist, and Kevin McGowan, an ornithologist from Cornell University, revealed that eighty-five hundred years ago at a Neolithic site in what is now Turkey, people probably performed crane dances using crane wings as props that were laced to the arms. Furthermore, someone of these people apparently hid a single crane wing in a narrow space in the wall of a mud-brick house along with other special objects (a cattle horn, goat horns, a dog head, and a stone mace head). Russell and McGowan also found evidence that vultures may have been hunted for their feathers for presumably a much different costume worn as well for a ceremonial purpose. The authors inferred that the cranes were linked with happiness, vitality, fertility, and renewal (since they arrived in the spring). While the crane dance was one of life and birth, and possibly marriage and rebirth, the vulture dance was associated with death and perhaps return to the afterlife.
Russell and McGowan believe that the crane wing interred in the wall of the house was never intended to be seen. It was a symbolic object related to marriage and construction of a new home and may have been coincident with a particular human marriage and home-making. The associations among dancing, pairing, and raising young and home would have been natural for people who saw cranes return to their home ground, just as I had seen Millie and Roy do. Seeing the close parallels in the biology of the birds with their own lives, and understanding the cranes’ dancing as helping to make or cause the good things that followed, Neolithic people would have been compelled to symbolically emulate the crane dance of homecoming and of new life.
Pulsuz fraqment bitdi.
