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Standing on a West Berkeley sidewalk, I watched three young barn owls jostling around in an Atlas cedar near the palm tree where they had hatched. The light was fading, but you could still see their ghostly shapes among the branches. And you couldn’t miss their incessant “feed me” calls—a vocalization described by ornithologists as the “snore.” The parents were nowhere in sight; maybe out hunting, more likely roosting nearby, away from the racket. 

When dinner eventually arrived, it would be some kind of small mammal. Barn owls in rural locations prey heavily on voles and shrews; in urban settings, the mix would include house mice and young rats (adult rats would be too much for the owls to handle). 

With their silent flight and hyperacute sense of hearing, the birds are consummate hunters. They can locate their quarry in total darkness, dispatching it with a bite through the back of the skull. 

I had been thinking about predation since a couple of days earlier, when I had an unexpected encounter in the Lakes Basin region of the Sierra. At Sand Pond, near Sardine Lake, there’s a nature trail that winds through a patch of forest flooded by beavers, full of dead snags where woodpeckers and other birds nest. A pair of hairy woodpeckers, joined by a mixed posse of neighbors—a flicker, a warbling vireo, a couple of mountain chickadees—were harassing what I first took to be a squirrel poking its head into a nest cavity. But it wasn’t a squirrel; it was larger, with an elongated body and a semi-bushy tail. When it pulled back from the hole and turned toward me, I realized it was a marten—an arboreal member of the weasel family, a creature I’d never seen before. 

The marten went back to the hole and pulled out an almost-fledged woodpecker, already in its black-and-white plumage. It ran down the snag to cache its prey somewhere at the base, then back up. In a frenzy, it began gnawing at the rim of the nest cavity; I could see chips flying. Then it managed to cram its entire body into the hole. 

Exiting rump first, the marten brought out a second woodpecker. Back down, back up, into the cavity again, and out with the third and last nestling. The birds continued to call and swoop, but the show was over. 

I had stood speechless through the whole sequence; it never occurred to me to try to scare off the predator as it cleaned out the woodpeckers’ nest. A bad day for the woodpeckers, of course; it may have been too late for them to begin a new brood, making their nesting season a complete bust. The marten might have been a female with a litter of hungry kits, which I believe is what you would call young martens. It might have been an opportunistic male, killing more than it immediately needed (as weasels are prone to do). In any case, it was fascinating to watch the predator at work. 

The woodpeckers were predators in their own right, of course, although we tend not to think of them that way. Like most birds, they are voracious consumers of insects, beetle grubs and the like. And the gopher snake I’d seen earlier this spring being dismembered by a parent red-shouldered hawk had done in its own share of rodents. Predation is inescapable: part of life in the food chain. It’s also a large part of our perception of nature. Spend some time watching Animal Planet or PBS and you’ll see a significant body count.  

This bothers some people on a philosophical level. The naturalist Alexander Skutch, who died earlier this year (around the same time as the great evolutionary theorist Ernst Mayr and the eccentric but splendid Dame Miriam Rothschild), considered it life’s fundamental evil, and enforced a zero-tolerance policy for predators at his Costa Rican ranch. Although he loved birds, he detested hawks, snakes and other nest-robbers. For Skutch, the moment the first single-celled organism made a meal of one of its neighbors was a kind of evolutionary Original Sin. It was all downhill from there; better we should have gone the route of photosynthesis. (Skutch was willing to give some slack to scavengers that eat what something else has killed.) 

Skutch’s is definitely a minority view, though. Others see predation as the force that drove the diversification of life. I’m wary of reading progress into the evolutionary record, but I’ll buy Richard Dawkins’ argument (in his recent The Ancestor’s Tale) that arms races between predators and prey have ratcheted up adaptations on both sides: “Arms races are deeply and inescapably progressive in a way that, for example, evolutionary accommodation to the weather is not.” As Robinson Jeffers put it: “What but the wolf’s tooth whittled so fine/ The fleet limbs of the antelope?” And the antelope helped shape the wolf, too, as the moth shaped the bat and the vole shaped the barn owl. 

The case can be made (as in Donna Hart and Robert Sussman’s Man the Hunted) that the human brain is one more product of the prey-predator dynamic. Modern primates are subject to heavy predation pressure by cats, raptors and snakes. Instead of cryptic coloration or defensive armor, they have evolved social and communications skills (like the African monkeys with specific alarm calls for leopards, pythons and eagles). Long before crude weapons made our ancestors effective predators, they must have been prey as well—and their responses to that role were part of the long path to humanity. 

A world without predation might be a kinder one, but I suspect it would be a whole lot less interesting. (I’ll admit, though, that I might view the issue with less equanimity if a local great horned owl happened to mistake my associate Matt the Cat—a semiretired predator himself—for a tasty skunk).›