Art of the Wild
The Mating Game
Bernd Heinrich’s latest book explores why birds pair up and parent in various ways.
The Nesting Season: Cuckoos, Cuckolds, and the Invention of Monogamy
By Bernd Heinrich, The Belknap Press of Harvard University Press, 337 pages, $29.95
Mating behavior has preoccupied us from the time we first diverged from apes and stood erect on the broad African plain. From our first gatherings around the communal fire, mating behavior has drawn the attention of shamans, tribal elders, priests, Talmudic sages, matchmakers, anthropologists, sociologists, sexologists, psychologists, courtesans, and presidents.
It is also a hot topic in biology, because it is one of the best examples of problem solving by evolution. Evolution, in its sublime indifference, confers selection advantages only on those behaviors that best perpetuate all species, from the simplest to the most complex. In his newest book, The Nesting Season, renowned naturalist Bernd Heinrich draws heavily on his personal observations as he explores this most compelling topic in birds.
Heinrich’s father was a field biologist. His parents deposited him and his sister in a school for disadvantaged kids so they could go off to Africa and Mexico to collect specimens. Having inherited his father’s passion for biology, Heinrich has devoted his life to drawing, photographing, collecting, keeping journals, and teaching and writing. He is professor emeritus in the biology department at the University of Vermont and author of more than a dozen books on a broad array of subjects, including winter survival strategies, animal intelligence, bumblebee economics, and long-distance running. (At 70, he still runs ultramarathons.)
When it comes to choosing a mate, males typically pursue and persist, but females ultimately get to decide. They make their choice, Heinrich explains, based on traits that serve as a sign of health and vigor. Depending on the species, selection might be based on an elaborate vocal repertoire. Showy behavior, colorful plumage, or architectural genius also come into play. Female song sparrows, for instance, opt for males that sing a variety of songs—some have up to 15. And in the case of the penduline tit, the male’s intricate, pear-shaped nest is the sexual magnet. “A female inspecting nests compares males indirectly,” Heinrich writes. “She chooses for herself a resource she needs for reproduction and also indirectly assesses the male’s potential vigor and industry.”
The core of The Nesting Season is Heinrich’s exploration of those mating strategies that work, how they work, and how conditions determine what works and what doesn’t. Since humans find monogamy to be an attractive trait in birds, Heinrich explores it early in the book. “Pairwise parenting is rare in mammals, insects, crustaceans, fish, reptiles, and amphibians, although it occurs sporadically in all of them,” he writes. “It is common only in birds. Birds routinely team up into one-on-one male-female partnerships, and such pairs are so obvious and conspicuous that we take monogamy almost for granted.” Yet monogamy, like all mating strategies, incorporates a rich palate of behaviors and rarely results in complete lifetime sexual fidelity to a single mate. It’s advantageous only when nesting and parenting responsibilities demand an extraordinary investment of energy by both parents. In fact many birds that we “know” to be monogamous are like other animals (including humans) in that they frequently engage in extra-pair copulations as conditions allow.
What good is monogamy anyway? The answers depend on conditions. Heinrich cites the example of screech owls, which are typically monogamous throughout their lifetimes. But when food is plentiful and nest density is high, males can easily provision more than one nest, so they become polygynous. And when food is readily available, females need less parenting investment from males. On the other hand, when food is widely scattered, so are nests and females. In these instances, females benefit most from increased help in parenting, which means males can maximize their reproductive success only by devoting themselves to a single mate and a single nest.
Although polygyny appears to be a kind of captain’s paradise, having more than one mate, like all behaviors, has its pluses and minuses. Heinrich recounts the discovery by Swedish biologists that the primary female mates in certain populations of reed warblers suffered three times more nest predation than did the secondary females. The team devised an experiment to determine why and discovered that the secondary females were the culprits. They were destroying the eggs of the primary females, presumably to obtain increased parenting help from their male partners for their own offspring.
Since predation is often the main limiting factor to reproductive success, birds must develop strategies to reduce its toll. One approach is to hide the nest and develop behaviors to avoid tipping off possible predators to its location. Another is to build nests in colonies, where there are many neighbors to ward off predators. One of the seemingly strangest is to build a nest in or very near the nest of a raptor. Heinrich cites examples of house wrens and common grackles that build theirs in the interstices of active osprey nests, and of kingbirds that build theirs in active golden eagle nests. A raptor nest would seem like perilous digs for a songbird, but all birds, it turns out, have an innate reticence to attack or destroy anything in or nearby their own nests—a reticence probably stemming from a protective behavior that keeps birds from devouring their own offspring. As with all real estate, the three most important things in determining value are location, location, and location. Build your nest as far as possible from a raptor, and risk having raptors and other birds snack on your eggs or chicks. But build your nest in a raptor nest, and you will be assured of formidable guardians that are very good at keeping undesirables out of the neighborhood.
Reproductive success depends on a huge suite of behaviors and strategies that must change as conditions demand. This book is a rich and detailed account, and as with Heinrich’s other works, it’s illustrated with the author’s own drawings and photographs. The Nesting Season is one to read and read again.
Wayne Mones has written about binoculars and spotting scopes for the magazine. Read more from him on The Perch.
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Shooting in the Wild: An Insider’s Account of Making Movies in the Animal Kingdom
By Chris Palmer
Sierra Club Books, 223 pages, $24.95
“We strongly recommend that Chris Palmer be fired [from Audubon].” So begins wildlife documentarian Chris Palmer’s new book, Shooting in the Wild: An Insider’s Account of Making Movies in the Animal Kingdom. It’s a bold opening for a book that is, in part, a career memoir, but one that aptly captures Palmer’s nerve and resolve at the dawn of his professional life. A National Audubon Society energy lobbyist in the 1970s, Palmer became disillusioned with the prospects for inciting change through government channels. So instead he lobbied his superiors to fund a documentary about energy conservation. His termination was all but certain until media mogul Ted Turner backed his vision for a sexier genre of wildlife programming that drew on popular celebrities. Thirty years and more than 300 hours of documentaries later, Palmer is disenchanted once again—this time with the “ethically challenged” environmental film industry. Palmer keeps early chapters on the process of wildlife filmmaking juicy by marinating them with his own adventures—like the time he, his crew, and celebrity host Alicia Silverstone righted a fallen elephant on the shores of Lake Zimbabwe with only their hands—before launching into his beef: “Filmmakers, producers, and broadcasters have given in to the temptation to exploit animals for profit.” He slams such dubious practices as depicting domesticated animals raised on game farms as wild, or the harassment of wildlife on such shows as the Discovery Channel’s Man vs. Wild. The solution, he concludes in Shooting in the Wild, is partnering with reputable scientists, developing an ethics ranking system, employing greener leave-no-trace filmmaking practices, and educating the public to recognize abuse on the screen. “Now more than ever, we in the wildlife filmmaking business have to put on our thinking hats,” Palmer writes, “and find exciting ways to tell wildlife stories, while using sound principles that will engage, entertain, and educate audiences.”—Nathan Ehrlich
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ART OF THE WILD
Seashells, the skeletal overcoats of certain mollusks, scatter shorelines for miles. Pick one up to study its contours, and a bit of history unfolds. Shells grow in layers, archiving invertebrate life from the larval stage to death. But how fast they grow and the shape they take depend on the type of mollusk inside. The Book of Shells: A Life-size Guide to Identifying and Classifying Six Hundred Seashells (M.G. Harasewych & Fabio Moretzsohn, $55) is a primer on a handful of the 100,000 mollusk species. Sorted into groups, such as gastropods, each animal’s shell is photographed life-size on a simple white background, accompanied by delicate range maps and succinct species descriptions. The diversity is stunning. Contrast the cock’s comb oyster shell, whose jagged edges interlock like gnashing fangs (the better to remain anchored to rocks to avoid predators), with the ribbed, symmetrically curved halves of Cyrtopleura costata, a bivalve the color of porcelain (no wonder its common name is angel wing). With this book, beachcombers will find more natural treasures to dig for in the sand.—Julie Leibach
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