Life in the Slow Lane
Believe it or not, most animals seem to spend most of their time doing nothing. But are they really loafing?
Photographer Michio Hoshino didn't have to worry much about an attack. The three white bears ahead of him lounged in the brittle cold last November as somnolently as if they had been baked into sleep by a hot sun.
Quietly, he moved closer along the Hudson Bay waterline, then knelt and centered the viewfinder on a particularly slumberous-looking bruin that lay sprawled on its back against a chunk of ice, gazing with the others out to sea. The sound that came from the slowly heaving chest was like a snore.
"They're just waiting for the bay to freeze," whispered the researcher at his elbow. When the surface could hold their weight, the bears would pad across it to hunt ringed seals. "That particular one hasn't moved 200 yards in two weeks," added the scientist.
Animals, it appears, are capable of just about any adaptation imaginable in order to live the quiet life. Counterintuitive as that notion may seem, biologists have been impressed in the last decade by the discovery that most wildlife spends about two-thirds of the time quiescent. Though cat owners have always been able to attest to their pets' love of languor, for the most part the general phenomenon had previously escaped notice. Perhaps humans simply aren't drawn to an absence of activity. "Even as scientists," says University of Vermont zoologist Joan Herbers, "we've submitted to the human preference for looking most closely at what animals do" when they are active.
Now, in yet a new twist, researchers are learning that the reasons for the down time are as critical as anything animals do when they're more visibly busy. Hoshino's prone polar bear, for one, had achieved a torpor that might be the most efficient mammalian metabolic process yet unraveled by science. Every year, the bears snooze during the autumn months waiting for the big freeze so they can get to where the seals are. Elsewhere, polar bears hitch rides on pack ice to feed on seals that hop aboard. But this group has had to adjust to the geography of Hudson Bay with its own system.
"It's not exactly a walking hibernation," says Canadian government biologist Wendy Calvert of Edmonton. "It's a condition in which the body pretty much tells the brain that it's going to shut down for a while and to wake it up when it's feeding time."
The shutdown kicks in metabolic industriousness through which the bear converts fat to energy, which in turn recycles urea into protein-a process so efficient that the bear ends up with a little more protein and a little less urea. Among fasting animals, "The polar bear is the most efficient we know of," says researcher and physician Ralph Nelson, executive head of medicine at the University of Illinois College of Medicine.
Nelson has found that the bears feed less than 5 percent of the time during the months between late July and early November, when the ice breaks. Yet they remain alert enough to test the thickness of the forming ice now and again, to snarl into action to face a threat and to flip all systems into seal-hunting mode once the November ice will bear their weight.
Some of the other purposes of apparent laziness in the wild are familiar to all of us: The chameleon that would rather blend than run, the hatchling quail that freezes in the sedge at our feet, the alligator that resembles a log. "But now we're learning there's so much more," says Herbers. "We're finding that the reasons for what animals don't do are often just as important as-and even more interesting than-what they do."
Across the continents and across the phyla, more and more researchers are shifting their emphases to nature's quiet side. A sampling of their findings: Mojave Desert sand scorpions that hunt by standing still enough for sensors in their feet to pinpoint the vibrating footfalls of approaching prey, a lizard that holds its breath when a snake is in the neighborhood, hummingbirds that hibernate on a nightly basis to prevent a drain of their precious energy reserves when the temperature dips, snakes that convert their skins to "lungs" so they can hibernate under water.
The notion that animals seem to loaf at all, much less that their loafing is sophisticated, started as an accidental discovery by zoologist Herbers more than a decade ago. In 1980, she was gathering information on animal foraging activity for a study in the relatively new field of time-budget analysis. The data were out there; researchers had recorded the foraging time in thousands of projects.
When she pulled the information together, she says, "I found myself saying, 'Hey, look at the pattern here!' because it was suddenly obvious that all kinds of creatures were spending most of their time apparently doing nothing at all!" She called her discovery "the laziness syndrome." Even the various species of shrews, generally seen as perpetually restless and endlessly hungry, spend only about a fifth of their time foraging and 68 percent of their time at rest.
"The presumption by behaviorists that non-foraging time is spent in other important activities is unwarranted," she wrote in 1981. And she urged further research into animal laziness, which she defined as "the lack of functional significance for idle periods."
For a while, subsequent research did seem to support the theory, which also delighted the popular press. "Busy as a bee? Then who's doing the work?" asked science writer Natalie Angier in The New York Times just two years ago. Laziness, she wrote, "is perfectly natural. Perfectly sensible and shared by nearly every other species on the planet." But even Herbers and Angier acknowledged that there were probably some intriguing reasons for all the apparent indolence. And sure enough, animal behaviorists are finding that what they first perceived as lack of functional importance often has dazzling significance after all.
Take the case of the sand scorpion of the Mojave Desert. A tiny-eyed night hunter that obviously can't see what it is hunting, the sand scorpion seems to emerge from its burrow and just stand around waiting for a meal to happen by. But Oregon State University zoologist Philip Brownell has discovered that the scorpion has receptors on its feet that sense approaching insects from several inches away by detecting minute disturbances of the desert.
There is plenty of method to the malingerings of other lie-in-wait predators as well. The polar bear often naps next to a seal's breathing hole with one paw cocked for a lethal swipe. Alligators have floating slumber parties beneath heron rookeries during nesting season, waiting for hapless fledglings and jostled eggs. The female fence lizard, which is "at rest" 98 percent of the time, spends that time in the energizing sun within a tongue's dart of smorgasbord rest stops for passing insects.
The African lion, which University of Minnesota zoologist Anne Pusey says can eat 66 pounds at a sitting and then lie around on its back for several days digesting the meal, is another strategic loafer: It does most of that lying around in the shade, near a waterhole, with one eye open to potential next meals.
So is there anything at all to animal laziness? Do wild creatures ever just plain loaf? Not, says Cornell biologist Paul Sherman, from the point of view of evolutionary biologists. "The basic theory of evolution, the basic message in nature," he says, "is always that every part of an animal's physiology and behavior ought to contribute to its reproduction, to the perpetuation of its genes, and thus its species. An animal at rest or asleep isn't taking a time-out from the process of natural selection. There are no time-outs from natural selection."
If that's true, then what about the red-sided garter snake of northern Manitoba, which spends eight months a year in hibernation, and as much as half its remaining time draped in sunny weeds? "The reasons for what these snakes don't do are like complex clues," says Oregon State University zoologist Bob Mason. "You peel back one subtlety after another." Mason has discovered that in order for the snake to survive the long winters north of Winne-peg, it spends two-thirds of the year snuggled up to 10,000 or so of its kin in limestone caverns far enough below the surface to escape the frozen soil of winter.
"That's amazing enough," he says. But even more astonishing to the researchers is the snake's physiology. For one thing, it can choose the delivery date for its offspring within an 11-year time span. After breeding in April when it wakes up, the female stores the male's sperm. Then, says Mason, "She goes out and tests the year-to see if there are enough frogs and minnows and worms and water around to provide a healthy nursery. If so, she ovulates and delivers live young six weeks later. If not, she keeps her reproductive organs asleep, so to speak, until a good year comes along."
Zoologist Herbers, who readily acknowledges that such discoveries lead to questions "so much more sophisticated than they were ten years ago," still maintains that animals like to loaf. "Sure, there are good excuses for lounging around at a certain time and place-like the lions in the shade at the waterhole, where they can keep cool and jump a warthog at the same time," she says. "But make no mistake; some of these animals are relaxing. They're there because they would prefer to lie around in the shade on a hot day than to work for a living." She is particularly intrigued by rest as a reward for efficiency. "A quick kill," she says, "equals a nice long nap."
Conversely, some animals we tend to think of as slower and even perhaps lazier, actually are among the most active. Whereas the efficient lion is active less than a fourth of the time, migrating caribou are active about 80 percent of the time, and browsing moose about 48 percent. In such cases, says Herbers, "you're looking at animals that might have to eat mega-quantities of food in order to get micro-quantities of nutrients like sodium."
In addition to foraging efficiency and thermoregulatory requirements, dozens of other factors can influence how and why an animal moves or moors. The motionless marmot is often a sentry, not a sluggard. The mayfly basking in sunlight is actually drying its skin, bracing to burst forth into the loveliest and most momentous few hours of its life. The sloth, moving so slowly that its fur is green with the two algae species that live in it, is utilizing the adaptive strategy of camouflage to the extreme.
And among those most studied of animals, the social insects, division of labor determines whether they're on active duty or just standing by. Doctoral candidate Susanne Kuhnholz of Cornell University is almost certain that some bees, for instance, are designated water carriers whose job is to cool or heat the hive and brood as need dictates.
"Most of the time it looks like they're just hanging around the hive," she says. "But if it gets too hot, they become very busy, distributing water. And if it gets too cold, they uncouple their wings from their flight muscles and shiver to generate metabolic heat."
Within those flight muscles is perhaps one of nature's best excuses for occasionally sitting one out: a built-in count down to death. "The worker bee's miles are numbered from the day it is born," says Huang Zhi-Yong, a visiting University of Illinois researcher from China. "Regardless of how much a bee eats, the flight muscles contain a fixed amount of glycogen." When the glycogen supply is exhausted, the bee dies. The end comes at 500 miles-"whether that distance is flown in five days or eight weeks."
For a dozen years, Herbers' theory of the laziness syndrome has not only informed wildlife research, but also has naturally generated much speculation about the neglected role of rest for the human species. After all, on the face of it, we spend more time working than most other animals.
These days, even with the new appreciation of what's really going on during animal loafing, researchers still muse about the message for people. At the Point Defiance Zoo and Aquarium in Tacoma, Washington, the bats observed by biologist Margaret Gaspari use such strategies as long-term storage of sperm and short-term hibernation.
"But I think maybe there's more for us to learn from these animals than about their special abilities," Gaspari says. "They also know when to slow down and when to knock off for awhile. If they need a break, they break. And so many of us humans just don't take care of ourselves that way anymore."
Maybe, as we peel through the subtle layers of physiological clues within bears and bees and bats, we can relearn some of the old connections between ourselves and an Earth chock full of instinctive appreciation for the values of rest and renewal.
Oregon writer Grant Sims plans some restorative loafing of his own later this year after completing a book about Alaska, Leaving Alaska (Atlantic Monthly Press), due out in October.