Natural Acts

by David Quammen

  Most likely it runs in their genes, along with the black plumage and the talent for vocal mimicry. Crows belong to a remarkable family of birds known as the Corvidae, also including ravens, magpies, jackdaws, and jays, and the case file on this entire clan is so full of prodigious and quirky behavior that it cries out for interpretation not by an ornithologist but by a psychiatrist. Or, failing that, some ignoramus with a supple theory. Theoretical ecologists adept at computer modeling can give us those fancy equations depicting the whole course of a creature’s life history in terms of energy allotment to every physical need, with variables for fertility and senility and hunger and motherly love, but they haven’t yet programmed in a variable for boredom. No wonder the Corvidae dossier is still packed with unanswered questions.

  At first glance, though, all is normal. Crows and their corvid relatives seem to lead an exemplary birdlike existence. The home life is stable and protective. Monogamy is the rule, and most mated pairs stay together until death. Courtship is elaborate, even rather tender, with the male doing a good bit of bowing and dancing and jiving, not to mention supplying his intended with food; eventually he offers the first scrap of nesting material as a sly hint that they get on with it. While she incubates a clutch of four to six eggs, he continues to furnish the groceries and stands watch nearby at night. Then, for a month after hatching, both parents dote on the young. Despite strenuous care, mortality among fledglings is routinely high, sometimes as high as 70 percent, but all this crib death is counterbalanced by the longevity of the adults. Twenty-year-old crows are not unusual, and one raven in captivity survived to age twenty-nine. Anyway, corvids show no inclination toward breeding themselves up to huge numbers, filling the countryside with their kind (like the late passenger pigeon or an infesting variety of insect) until conditions shift for the worse and a vast population collapses. Instead, crows and their relatives reproduce at roughly the same stringent rate through periods of bounty and austerity, maintaining levels of population that are modest but consistent and that can be supported throughout any foreseeable hard times. In this sense they are astute pessimists. One consequence of such modesty of demographic ambition is to leave them with excess time, and energy, not desperately required for survival.

  The other thing they possess in excess is brain power. They have the largest cerebral hemispheres, relative to body size, of any avian family. On various intelligence tests—to measure learning facility, clock-reading skills, the ability to count—they have made other birds look doltish. One British authority, Sylvia Bruce Wilmore, pronounces them “quicker on the uptake” than certain well-thoughtof mammals like the cat and the monkey, and admits that her own tamed crow so effectively dominated the other animals in her household that this bird “would even pick up the spaniel’s leash and lead him around the garden!” Wilmore also adds cryptically: “Scientists at the University of Mississippi have been successful in getting the cooperation of Crows.” But she fails to make clear whether that was as test subjects or on a consultative basis.

  From other crow experts come the same sorts of anecdote. Crows hiding food in all manner of unlikely spots and relying on their uncanny memories, like adepts at the game of Concentration, to find the caches again later. Crows using twenty-three distinct forms of call to communicate various kinds of information to one another. Crows in flight dropping clams or walnuts on highway pavement, to break open the shells so the meats can be eaten. Then there’s the one about the hooded crow, a species whose range includes Finland: “In this land Hoodies show great initiative during winter when men fish through holes in the ice. Fishermen leave baited lines in the water to catch fish and on their return they have found a Hoodie pulling in the line with its bill, and walking away from the hole, then putting down the line and walking back on it to stop it sliding, and pulling it again until [the crow] catches the fish on the end of the line.” These birds are bright.

  And probably—according to my theory—they are too bright for their own good. You know the pattern. Time on their hands. Underemployed and overqualified. Large amounts of potential just lying fallow. Peck up a little corn, knock back a few grasshoppers, carry a beakful of dead rabbit home for the kids, then fly over to sit on a fence rail with eight or ten cronies and watch some poor farmer sweat at the wheel of his tractor. An easy enough life, but is this it? Is this all?

  If you don’t believe me, just take my word for it: Crows are bored.

  And so there arise, as recorded in the case file, these…—no, symptoms is too strong. Call them, rather, patterns of gratuitous behavior.

  For example, they play a lot.

  Animal play is a reasonably common phenomenon, at least among certain mammals, especially in the young of those species. Play activities, by definition, are any that serve no immediate biological function and that therefore do not directly improve the animal’s prospects for survival and reproduction. The corvids, according to expert testimony, are irrepressibly playful. In fact, they show the most complex play known in birds. Ravens play toss with themselves in the air, dropping and catching again a small twig. They lie on their backs and juggle objects (in one recorded case, a rubber ball) between beak and feet. They jostle one another sociably in a version of king of the mountain with no real territorial stakes. Crows are equally frivolous. They play a brand of rugby, wherein one crow picks up a pebble or a bit of shell and flies from tree to tree, taking a friendly bashing from his buddies until he drops the token. And they have a comedy-acrobatic routine: allowing themselves to tip backward dizzily from a wire perch, holding a loose grip so as to hang upside down; spreading out both wings, then daringly letting go with one foot; finally, switching feet to let go with the other. Such shameless hotdogging is usually performed for a small audience of other crows.

  There is also an element of the practical jokester. Of the Indian house crow, Wilmore writes that “this Crow has a sense of humor, and revels in the discomfort caused by its playful tweaking at the tails of other birds, and at the ears of sleeping cows and dogs; it also pecks the toes of flying foxes as they hang sleeping in their roosts.” This crow is a laff riot. Another of Wilmore’s favorite species amuses itself, she says, by “dropping down on sleeping rabbits and rapping them over the skull or settling on drowsy cattle and startling them.” What we have here is actually a distinct subcategory of playfulness known, where I come from at least, as cruisin’ for a bruisin’. It has been clinically linked to boredom.

  Further evidence: Crows are known to indulge in sunbathing. “When sunning at fairly high intensity,” writes another British corvidist, “the bird usually positions itself sideways on to the sun and erects its feathers, especially those on head, belly, flanks and rump.” So the truth is out: Under those sleek ebony feathers, they are tan. And of course sunbathing (like ice fishing, come to think of it) constitutes prima facie proof of a state of paralytic ennui.

  But the final and most conclusive bit of data comes from a monograph by K.E.L. Simmons that appeared in the Journal of Zoology, published in London. (Perhaps it’s for deep reasons of national character that the British lead the world in the study of crows; in England, boredom has great cachet.) Simmons’s paper is curiously titled “Anting and the Problem of Self-Stimulation.” Anting as used here is simply the verb (or, to be more precise, participial) form of the insect. In ornithological parlance, it means that a bird—for reasons that remain mysterious—has taken to rubbing itself with mouthfuls of squashed ants. Simmons writes: “True anting consists of highly stereotyped movements whereby the birds apply ants to their feathers or expose their plumage to the ants.” Besides direct application, done with the beak, there is also a variant called passive anting: The bird intentionally squats on a disturbed anthill, inviting hundreds of ants to swarm over its body.

  Altogether strange behavior, this antic anting—and especially notorious for it are the corvids. Crows avidly rub their bodies with squashed ants. They wallow amid busy ant colonies and let themselves become acrawl. They rev
el in formication.

  Why? One theory is that the formic acid produced (as a defense chemical) by some ants is useful for conditioning feathers and ridding the birds of external parasites. But Simmons cites several other researchers who have independently reached a different conclusion. One of these scientists declared that the purpose of anting “is the stimulation and soothing of the body,” and that the general effect “is similar to that gained by humanity from the use of external stimulants, soothing ointments, counter-irritants (including formic acid) and perhaps also smoking.” Another compared anting to “the human habits of smoking and drug-taking” and maintained that “it has no biological purpose but is indulged in for its own sake, for the feeling of well-being and ecstasy it induces.”

  You know the pattern. High intelligence, large promise. Early success without great effort. Then a certain loss of purposefulness. Manifestations of detachment and cruel humor. Boredom. Goofing off. Anomie. And finally…the dangerous spiral into drug abuse.

  But maybe it’s not too late for the corvids. Keep that in mind next time you run into a raven, or a magpie, or a crow. Look the bird in the eye. Consider its frustrations. Try to say something stimulating.

  The Widow Knows

  HERE’S A CHEERFUL THOUGHT: Some knowledgeable people believe that black widow spiders, like locusts and jackrabbits, come in plagues.

  No one, of course, has kept a precise running count on our total supply. Since the black widow spider is by nature shy, almost fanatically discreet, the intermittent explosions of black widow populations are gauged by extrapolation from the number of bites suffered by humans. At certain historical junctures of place and time, those widow bites have reached what are called “epidemic” levels. Spain had such an epidemic in 1830. Eastern Russia had another in 1838–39. France endured a peak forty years after Russia, Uruguay in 1910, and then, in 1926, black widows terrorized Yugoslavia. These outbreaks of spider bite and spider fear were all presumably caused by members of the genus Latrodectus, not precisely the same species as our American black widow but closely related. The last major episode of notoriety for Latrodectus mactans, our domestic version, occurred a half-century ago. In the autumn of 1934, with Huey Long gamboling in the Senate and John Dillinger freshly slain on the streets of Chicago, Americans were suddenly worried about black widow spiders.

  The widow boom that year was no doubt a combined result of climatic conditions, ecological cycles, and publicity. Through the mild winter and dry summer of 1933, more black widows had been surviving, raising larger broods, biting more humans, and getting more journalistic attention for doing so. The Associated Press carried continuing reports on the condition of two unfortunate men, one in Alabama and one in Idaho, both dangerously ill from black widow bites. Local newspapers ran stories about barbarous mortal battles staged between black widows and scorpions, black widows and tarantulas, even black widows and snakes. With a peculiar repulsive fashionableness, black widows were in. Then Scientific American fanned the coals with an article announcing in careful detail why Latrodectus mactans should rightly be feared, and in November the sober journal Science published a note entitled “On the Great Abundance of the Black Widow Spider.”

  The note’s author speculated about effects of the recent weather, commented that cousins and competitors of the widow seemed to be in eclipse, and concluded, “Possibly L. mactans is beginning to get the upper hand in the great struggle for existence.” But the struggle against whom? To some nervous observers, this upper-handhood seemed ominous in a creature with eight legs, not to mention a pair of poisonous chops, so within months that statement from Science had been translated—now in the less sober pages of Popular Mechanics—into this one: “Aided by favorable climatic conditions, the spider has multiplied so rapidly that it is becoming a real menace to man.” The headline in Popular Mechanics was “Wasps May End Black Widow Spider Menace.” Entomologists were groping about for some spider-eating savior, a natural predator, a nemesis, to turn back those menacing, swelling, surging hordes of Latrodectus mactans.

  Two species of wasp were considered, a mud dauber that kills adult black widows as food for its young and another form that chews its way into the silken egg sac and deposits its own eggs where, after hatching, the wasp larvae can eat the unborn spiders. There was also talk that black widows might be subdued by a species of small parasitic fly, or by alligator lizards allowed to run rampant, or by a certain brave sort of toad, or perhaps by spider-eating spiders of the genus Mimetus. People were desperate.

  Yet these scientists and other widow-watchers needn’t have been quite so concerned.

  The Great Widow Scare of 1934 came and went, like the Kingfish and Dillinger, but no airplanes were ever called out to spray. No frantic eradication campaign or mass deployment of wasps ever took place. The crisis—more accurately, the perception of a crisis—passed away inconclusively, thanks to some form of natural equilibration. Latrodectus mactans continues to be widely distributed, present in every American state and common in many, abundant in most of the warmer ones. Chances are good that wherever you live, during the last year sometime you have sat down within ten feet of a black widow. (If you had occasion to use an old wooden outhouse, among the widow’s favorite habitats, you might even have been cheek-by-jowl with one.) Still, the species has never become a large-scale problem. Being bitten is nothing to take lightly, and if the victim is an old person or a small child, it can be fatal. But this is quite rare. The plague hasn’t happened. The widow hordes, with their eight upper hands in the great struggle for existence, have never come marching like driver ants over the hill into your town or mine. Why not? Partly because, in an ecological sense, the black widow knows its place.

  More specifically, she knows her place. The most efficient natural predator controlling any population of black widow spiders is very likely the female black widow. In that delicate Malthusian balance between vast reproductive potential (many eggs per sac) and limited life-supporting resources (only so many good spots to build a web, and only so much food available to be netted), the female of the species serves a gyroscopic function.

  Concerning the behavior of the female of Latrodectus mactans, one point should be clarified. A black widow spider is not like a mad dog or a vicious human: She doesn’t bite without reason, she doesn’t kill without purpose. She is not necrophilic or otherwise kinky. Yes, sometimes she does lasso her chosen male after copulation, as he makes for the exit, and suck him dry as a roasted chili. But that only happens if she’s hungry.

  The female widow’s hunger, or lack of it, is the standard against which certain life-or-death decisions are made, and those decisions exert a geometrically multiplied impact on overall population levels of the species. When the concentration of widows in any area is high, competition is fierce for good web sites and ambient provender. As a result, each widow tends to be hungrier. The female has an amazing capacity to endure long stretches without food—three or four months, at least, and one widow in captivity went unfed for nine months, then was nursed back to health—which makes it unlikely that the species could ever die out entirely from starvation. But as competition grows keen and food grows scarce, the female widow takes some drastic population-control measures that tip the balance back toward circumstances of lonely affluence. In the process, she also slakes her own hunger. The first of these measures involves mating.

  The male widow, much smaller than the female and more mobile across unfamiliar terrain, takes the romantic initiative. He appears at the edge of the female’s web, sets his feet on a few strands, and, by bobbing his abdomen, causes the whole web to vibrate. This is the mating offer. If the female is not in condition to breed or not in the mood, she will not respond. But if she happens also to be very hungry, she may wait cryptically for him to venture within reach, then grab him, swathe him in silk, and eat him. If she is ready to mate, there is an answering pattern of web vibrations from her. After about two hours of foreplay, during which he wraps her in a loose v
eil of silk, they consummate. That takes about five minutes, but the positions are exotic.

  As they uncouple, the question again arises: Is she hungry? If so, he is snatched back and devoured. If not, he is allowed to leave peaceably, or he may linger in a corner of her web, safely ensconced as mate emeritus, until accelerated senescence kills him a few days later. Whichever of these outcomes occurs, the female has remained in character, neither sentimental nor sadistic but merely practical, all eight of her eyes fixed on the basics of survival. She is the incarnate future of her species, far more so than the male, and in a deeply instinctive way she acts upon that responsibility.

  The same sort of chilly pragmatism governs her maternal behavior. She’s a solicitous mother, but only up to a certain point. Her eggs are laid—anywhere from 25 to 1,000 in a batch, on average about 200—and then wrapped by her in a silken cocoon. This egg sac is watertight and reflective; it shields the eggs from sunlight, rain, and predators and helps keep them warmly incubated. The mother has taken great care over it. She will fight to protect it. She will spend immense effort moving it from one part of the web to another, sunny exposure to shade, for the sake of maintaining its optimal temperature. Then, when the eggs hatch and her young crawl out, if the message of hunger has by now again reached her and the prospects seem meager for black widows, she will eat them.