From Nov/Dec 2005   Zoogoer

In the Company of Crows and Ravens. John M. Marzluff and Tony Angell. 2005. Yale University Press, New Haven and London. 384 pp., hardbound. $30.

Until West Nile virus swept through in 2002 and killed it, a murder of crows had dominated the skies around my home in northwest Washington, D.C., for more than 15 years. Their preferred roost was the roof of a house kitty-corner across the alley from my backyard. Next door, a pair of mockingbirds invariably nested in a pear tree. And every summer, at least once or twice, I watched a crow sally into the pear tree, snatch an egg or nestling from the mockingbird nest, and carry it back to the roof, seemingly oblivious to the mockingbirds' frantic distress. The parents fearlessly mobbed the cradle robber, but to no avail. Some people might have found these scenes distasteful*mockingbirds, after all, are much cuter than crows*but I miss seeing such wild displays of nature red in tooth and claw in my tame urban habitat.

While urbanization has dealt a death blow to many bird species, American crows (Corvus brachyrhynchos) thrive on it. So do several of the other 45 species of birds in the widespread genus Corvus, which includes ravens, jackdaws, and the rook. (For simplicity, I'll refer to them all collectively as crows unless a distinction is in order.) At the same time, some other crow species have suffered mightily from human actions. Two species of crows that once lived in Hawaii were wiped out by the Polynesian settlers of these islands, while the third, of which a small number now exists only in captivity, was the victim of more recent habitat loss and introduced diseases. For better or worse, though, relationships between crows and people are ancient and intricate, so much so, the authors of In the Company of Crows and Ravens argue, that people influence the evolution and culture of crows and, most intriguingly, vice versa.

Consider the following novel (at least to me) scenario for the origins of our cooperative lifestyle. Crows and ravens lived in the same African habitats where humans evolved. These scavengers would have been constant competitors for meat, but even a little teamwork would have been enough to keep the birds at bay. This then set the stage for ancestral people to evolve cooperative strategies for warding off more formidable competitors like lions and hyenas.

Marzluff and Angell bolster this argument with research findings on how wolves and ravens interact. Whenever wolves make a kill, ravens quickly gather to steal meat. Wolves may lose from five to 45 pounds of food per day to ravens, with larger wolf packs losing less than smaller ones. "Pleistocene humans and wolves faced ravens together, first in Europe and then in North America. As ravens molded human sociality, perhaps they also favored . . . domestication. The wolf, our first domestic species, may have joined ancient families, in part, to chase away ravens."

Apart from these speculations, In the Company of Crows and Ravens is replete with fascinating and well-documented stories about crows, many of which highlight their remarkable intelligence and ability to evolve culturally mediated behavior patterns. After parrots, crows are considered the brainiest of birds. As the authors put it, "Mentally, crows and ravens are more like flying monkeys than they are like other birds."

For instance, crows of many species learn to drop nuts and other hard food items like clams from just the right height over just the right hard substrate to break them open. But carrion crows living near a driving school in Japan learned to use cars to do the work for them. These crows wait for traffic to stop at an intersection, fly down and place the nuts in front of the tires of the stopped vehicles, then retrieve the nutmeats from the nuts cracked open when the cars ran over them. Over the last 20 years, this behavior gradually spread beyond the immediate vicinity of the school*and people have begun to help the crows by deliberately running over the nuts on the road!

Marzluff and Angell also recount the diverse and ever-changing place of crows in human affections. At different times and in different places, crows have been revered, respected, feared, and reviled. In 15th- and 16th-century England, crows were appreciated and protected because their catholic tastes in food, which include putrid meat and other spoiled food, helped keep the streets clean. Later, however, when crows in numbers feasted on the corpses of Londoners killed in the great fire of 1666, they were viewed with revulsion and bounties were placed on their heads. (Crows' propensity for feeding on human corpses may explain why a group of crows is called a "murder.") In the Company of Crows and Ravens further explores the myriad ways crows have inspired human legends, literature, art, and language*you'll learn, for instance, the origins of such expressions as "eating crow" and "crow's feet."

Finally, after describing the complex, flexible social behaviors and communications of these adaptable birds, Marzluff and Angell suggest how nearly everyone can conduct observational research on whatever crow species happens to live in their vicinity. After reading this book, I'm looking forward more than ever to crows returning to my backyard*although when they do, I'd like to be able to warn those mockingbirds about the perils of nesting in a pear tree so close to a murder of crows.

*Susan Lumpkin

ZooGoer 34(6) 2005. Copyright 2005 Friends of the National Zoo. All rights reserved