Table of Contents
Title Page
Table of Contents
Copyright
Introduction
SMALL TO LARGE
Beetles That Bury Mice
Sendoff for a Deer
The Ultimate Recycler: Remaking the World
NORTH TO SOUTH
Northern Winter: For the Birds
The Vulture Crowd
PLANT UNDERTAKERS
Trees of Life
Dung Eaters
WATERY DEATHS
Salmon Death-into-Life
Other Worlds
CHANGES
Metamorphosis into a New Life and Lives
Beliefs, Burials, and Life Everlasting
Postscript
Acknowledgments
Further Reading
Index
About the Author
First Mariner Books edition 2013
Text and illustrations copyright © 2012 by Bernd Heinrich
All rights reserved
For information about permission to reproduce selections from this book, write to Permissions, Houghton Mifflin Harcourt Publishing Company, 215 Park Avenue South, New York, New York 10003.
www.hmhbooks.com
The Library of Congress has cataloged the print edition as follows:
Heinrich, Bernd, date
Life everlasting: the animal way of death / Bernd Heinrich.
p. cm.
ISBN 978-0-547-75266-2 (hardback)
ISBN 978-0-544-00226-5 (pbk.)
1. Animal ecology. 2. Animal life cycles. 3. Animals—Psychological aspects. 4. Animal behavior. 5. Animal communication. I. Title.
QH541.13.H45 2012
591.7—dc23
2012010583
eISBN 978-0-547-75269-3
v2.0513
Introduction
If you would know the secret of death you must seek it in the heart of life.
—Kahlil Gibran, The Prophet
....Earth’s the right place for love; I don’t know where it’s likely to go better.
—Robert Frost, “Birches”
Yo, Bernd—
I’ve been diagnosed with a severe illness and am trying to get my final disposition arranged in case I drop sooner than I hoped. I want a green burial—not any burial at all—because human burial is today an alien approach to death.
Like any good ecologist, I regard death as changing into other kinds of life. Death is, among other things, also a wild celebration of renewal, with our substance hosting the party. In the wild, animals lie where they die, thus placing them into the scavenger loop. The upshot is that the highly concentrated animal nutrients get spread over the land, by the exodus of flies, beetles, etc. Burial, on the other hand, seals you in a hole. To deprive the natural world of human nutrient, given a population of 6.5 billion, is to starve the Earth, which is the consequence of casket burial, an internment. Cremation is not an option, given the buildup of greenhouse gases, and considering the amount of fuel it takes for the three-hour process of burning a body. Anyhow, the upshot is, one of the options is burial on private property. You can probably guess what’s coming . . . What are your thoughts on having an old friend as a permanent resident at the camp? I feel great at the moment, never better in my life in fact. But it’s always later than you think.
This letter from a friend and colleague compelled me toward a subject I have long found fascinating: the web of life and death and our relationship to it. At the same time, the letter made me think about our human role in the scheme of nature on both the global and the local level. The “camp” referred to is on forest land I own in the mountains of western Maine. My friend had visited me there some years earlier to write an article on my research, which was then mostly with insects, especially bumblebees but also caterpillars, moths, butterflies, and in the last three decades, ravens. I think it was my studies of ravens, sometimes referred to as the “northern vultures,” that may have motivated him to write me. The ravens around my camp scavenged and recycled hundreds of animal carcasses that friends, colleagues, and I provided for them there.
My friend knows we share a vision of our mortal remains continuing “on the wing.” We like to imagine our afterlives riding through the skies on the wings of birds such as ravens and vultures, who are some of the more charismatic of nature’s undertakers. The dead animals they disassemble and spread around are then reconstituted into all sorts of other amazing life throughout the ecosystem. This physical reality of nature is for both of us not only a romantic ideal but also a real link to a place that has personal meaning. Ecologically speaking, this vision also involves plants, which makes our human role in nature global as well.
The science of ecology/biology links us to the web of life. We are a literal part of the creation, not some afterthought—a revelation no less powerful than the Ten Commandments thrust upon Moses. According to strict biblical interpretations, we are “dust [that shall] return to the earth as it was: and the spirit shall return unto God who gave it” (Ecclesiastes 12:7); “thou return unto the ground; for out of it thou wast taken; for dust thou art and unto dust shalt thou return” (Genesis 3:19).
The ancient Hebrews were not ecologists, however. If the famous lines from Genesis and Ecclesiastes had been stated with scientific precision, they would not have been understood for two thousand years; not one reader would have been ready for the concept. “Dust” was a metaphor for matter, earth, or soil. But in our minds the word “dust” suggests mere dirt. We came from and return to just dirt. No wonder early Christians belittled our physical existence and sought separation from it.
But in fact we do not come from dust, nor do we return to dust. We come from life, and we are the conduit into other life. We come from and return to incomparably amazing plants and animals. Even while we are alive, our wastes are recycled directly into beetles, grass, and trees, which are recycled further into bees and butterflies and on to flycatchers, finches, and hawks, and back into grass and on into deer, cows, goats, and us.
I do not claim originality in examining the key role of the specialized undertakers that ease all organisms to their resurrection into others’ lives. I do believe, however, that many readers are willing to examine taboos and to bring this topic into the open as something relevant to our own species. Our role as hominids evolving from largely herbivorous animals to hunting and scavenging carnivores is especially relevant to this topic; our imprint has changed the world.
The truism that life comes from other life and that individual death is a necessity for continuing life hides or detracts from the ways in which these transformations happen. The devil, as they say, is in the details.
Recycling is perhaps most visible—as well as dramatic and spectacular—in large animals, but far more of it occurs in plants, where the most biomass is concentrated. Plants get their nutrients from the soil and the air in the form of chemicals—all bodies are built of carbons linked together, later to be disassembled and released as carbon dioxide—but nevertheless they are still “living off” other life. The carbon dioxide that plants take up to build their bodies is made available through the agency of bacteria and fungi and is sucked up massively and imperceptibly from the enormous pool of past and present life. The carbon building blocks that make a daisy or a tree come from millions of sources: a decaying elephant in Africa a week ago, an extinct cycad of the Carboniferous age, an Arctic poppy returning to the earth a month ago. Even if those molecules were released into the air the previous day, they came from plants and animals that lived millions of years ago. All of life is linked through a physical exchange on the cellular level. The net effect of this exchange created the atmosphere as we know it and also affects our climate now.
Ca
rbon dioxide, as well as oxygen, nitrogen, and the other molecular building blocks of life, are exchanged freely from one to all and all to one daily on a global scale, wafted and stirred throughout the atmosphere by the trade winds, by hurricanes and breezes. Molecules that have long been sequestered in soil may be exchanged within the local community over a long time. Plants are made from building blocks derived from centipedes, gorgeous moths and butterflies, birds and mice, and many other mammals, including humans. The “ingestion” of carbon by plants is really a kind of microscopic scavenging that happens after intermediaries have disassembled other organisms into their molecular parts. The process differs in method from that of a raven eating a deer or a salmon, whose meat is then spread through the forest in large and not yet fully disassembled packets of nitrogen, but it does not differ in concept.
DNA, on the other hand, though made mainly of carbon and nitrogen, is precisely organized and passed on directly from one individual plant or animal to the next through a fabulous copying mechanism that has operated since the dawn of life. Organisms inherit specific DNA molecules, which are copied and passed from one individual to another, and so it has continued over billions of years of ever-conservative descent, which has branched through innovation into trees, birds-of-paradise, elephants, mice, and men.
WE THINK OF the animals that do the important work of redistributing the stuff of life as scavengers, and we may admire and appreciate them for providing their necessary “service” as nature’s undertakers. We think of them as life-giving links that keep nature’s systems humming along smoothly. We tend to distinguish scavengers from predators, who provide the same service, but by killing, which we associate with destruction. But as I began to think about nature’s undertakers, the distinction between predators and scavengers became blurred and almost arbitrary in my mind. A “pure” scavenger lives on only dead organisms, and a pure predator on only what it kills. But very few animals are strictly one or the other. Ravens and magpies may be pure scavengers in the winter, but in the fall they are herbivores eating berries, and in the summer they are predators living on insects and mice and anything else they can kill. Certain specialists, however, some with unique abilities, spend most of their time finding food in one way. Polar bears usually catch seals at their breathing holes in the ice, but on occasion they will find and eat a dead one. A grizzly bear will relish a dead caribou as well as one it has killed, but most of the time it grazes on plants. A peregrine falcon is a swift flyer that captures flying prey, while a vulture would not as a rule be able to capture an uninjured live bird, so it has to rely on large, already dead prey. Indeed, vultures, ravens, lions, and almost all of the animals we typically typecast as “predators” just as readily take the ailing and half-dead and the (preferably fresh) dead; they will not enter a fight for life with another animal unless they have to. Herbivores too take those organisms that are least able to defend themselves. Deer and squirrels, for instance, munch on clover and nuts but will gladly eat any baby birds that they find in a nest. Strictly speaking, herbivores take the most lives; an elephant kills many bushes every day, while a python may ingest but one wart hog a year.
The potential ramifications of recycling are almost as varied as the number of species. I hope to provide a wide view, and I give examples from personal experiences everywhere from my camp in Maine to the African bush.
I
SMALL TO LARGE
Size is an important aspect of the way an organism can live and the form it can have. It determines the kind and proportions of body support systems that are needed to fight gravity. An organism’s size determines the diffusion rates of gases and nutrients, which set the maximum metabolic rate, the amount of food required, the kinds of places used to hide in, and the defenses needed. Size matters in how a body is disposed of, who the disposers are, and how they do it. Burial, part of what we associate with “undertaking,” is seldom part of disposal, but when it is, it is not to get rid of bodies but to keep them for a purpose.
Beetles That Bury Mice
I often see flowers from a passing car
That are gone before I can tell what they are.
—Robert Frost, “A Passing Glimpse”
CATS MAY SCRAPE LEAVES AND GRASS OVER DEAD PREY TO conceal it, and some wasps drag drugged but living insects into previously constructed homes so the wasp larvae can safely feed on fresh meat. But to my knowledge, only one group of animals, beetles belonging to the genus Nicrophorus, regularly moves carcasses to a suitable place and then deliberately buries them. Unlike humans, who generally bury only our own species and those pets who have become surrogate humans, these beetles bury a great diversity of birds and mammals but never their own kind. They bury dead animals as a food source for their larvae, and the burying is a central part of their mating and reproductive strategy.
There is much in a name, but sometimes it can be misleading. The genus name, Nicrophorus, comes from the Greek nekros, meaning dead, and philos or philia, meaning loving, or perhaps phoms, meaning to carry. (Nicro was probably a spelling mistake by the person who originally named the species; by scientific convention, the original name has prece dence.) Not that “death-loving” is strictly accurate, either. It might factually have been more appropriate to call the beetles “life-loving,” or viviphorous, because their whole purpose in seeking out dead animals is to create life from those already dead. A mouse carcass, for example, will nourish a dozen or more new beetles.
Burying beetles (also called sexton beetles) are master mouse undertakers. They are strikingly beautiful, colored deep black and adorned with flashy, bright orange markings on the back. Their fascinating life cycle involves monogamy and extensive parental care of their offspring. They are so common and widespread that almost anyone in the north temperate zone of the earth can see them in late summer if they want. I meet them regularly every summer, but only because I give them dead mice and road-killed birds.
The romantic story line of Nicrophorus beetles (of which there are sixty-eight recognized species worldwide, including ten in northeastern North America, where I live) is that a pair is formed after meeting at a carcass. When a male finds a mouse or other suitable carcass, he executes what is essentially a headstand on it and emits scent from a gland at his rear end. The “calling” scent wafts away on a breeze, and if a female detects it she flies upwind to find him and his carcass, and they mate. (On the other hand, if a male comes along, he may be aggressively excluded by the original mouse claimant.) The male and female cooperate in burying the carcass in part to get it away from other possible claimants, which often requires transporting it to soil suitable for digging the burial chamber.
Burying beetles don’t have grasping feet, so the pair transport a carcass by crawling underneath it and lying on their backs with feet up, “walking” on the carcass rather than on the ground. As long as the beetles can partially lift the mouse while their backs stay pressed to the ground, the carcass moves forward. The trick is to get it to move in the desired direction, and indeed these beetles do pick a specific direction and stick to it. The wonder, I think, is that both members of the pair apparently “know” where they are going, because they work the carcass in the same direction rather than at random, which would not be at all effective.
After the beetles have moved the carcass to the selected area, they excavate the soil under the carcass by pushing it out to the sides. Gradually a pit develops and the mouse (or other small animal) carcass, which is by now softening, folds inward and gradually sinks into the soil. After burying it several inches deep, the pair continue to roll the carcass into a ball while at the same time removing its hair (or feathers). They spray it with antibiotic secretions from the anus, which kill bacteria and fungi and thus retard spoilage of this valuable food. The female then lays eggs in soil nearby. The larvae hatch in several days, crawl to the carcass, and settle into a depression at the top. Both parents feed the larvae regurgitated food taken from the carcass until the larvae are able to burr
ow through the skin and into the softening meat.
Like the parents of altricial baby birds (those that hatch naked and helpless), the adult beetles make squeaking noises to announce that they’re ready to feed the young. In response, like baby birds, the grubs raise themselves up and are fed directly, mouth to mouth. As the grubs get older, they feed themselves, but they may still be assembled by the parental dinner call and fed directly. After several days the male usually comes up out of the ground to search for another carcass and start another family. The female usually stays longer with the larvae.
After a week to ten days, the fully grown young burrow into the surrounding soil, where they pupate. In most northern species, they hibernate where they are and emerge as adults the following spring or summer, with the seasonal timing varying among species.
The Nicrophorus life cycle has been studied in ever greater depth and detail for more than a century and is still a source of wonder. Current work has centered on hormonal regulation of the life cycle and on differences between species of burying beetles. For example, one species buries snake eggs rather than animal carcasses. Usually the behaviors follow the pattern described above, as notes from my journal suggest:
11 August, 2009. 5 P.M. The fresh mouse [white-footed, Peromyscus leucopus] I put out this morning is no longer visible; it is almost buried by a Nicrophorus. Only the one beetle on it when I pulled the carcass out of the ground.
12 August, 2009. The mouse is re-buried, when I checked on it at 3 P.M. As expected, there is now a pair on it.
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