My friend Keith and I were driving north for some birding in the Duluth area. We had just passed Pine City when a large black bird crossed the road a fair distance ahead. "There's our first raven of the trip," Keith said.
"I don't think so," I said. "It looked too small, probably a crow."
"Well, we are far enough north," argued Keith.
Thus began another day of quintessential bird identification debates. Seeking a middle ground, I offered, "So if we can't agree, let's call it a craven."
After a pause, Keith had the last word: "Definitely not descriptive of either bird."
What distinguishes these two species from each other? Or are these birds more alike than unlike?
American crows and common ravens are members of the Corvidae family. In Minnesota that also includes the blue jay, the gray jay, and the black-billed magpie. Both the crow (Corvus brachyrhynchos) and the raven (Corvus corax) are robust birds with black feathers, sturdy legs, and large bills. Yet each species also has distinctive physical differences. The common raven is larger, at least twice the weight of the crow. Most birders rely on two diagnostic keys to separate these birds in the field. First, the crow usually heralds its presence with a sharp, high-pitched caaw, while the raven's call is a hoarse, deep krronk or qurock. The next clue is the shape of the tail in flight. The raven's tail is wedge-shaped, while the crow's is more squared-off or slightly rounded. Other features, more obvious at close range, are the raven's longer bill, shaggy throat feathers, and extensive nose bristles, which the crow lacks.
Where the Crow Flies.
Crows can be found year-round throughout most of the state. Common city dwellers, crows show up in parks, woodlots, and other open landscapes. Creatures of wilderness, ravens reside in the state's forested northern half. Driving north of the Twin Cities on Interstate 35, we usually don't count on seeing ravens until we reach Pine County. Roadsides along Highway 61 from Duluth to Grand Marias often offer clear views of both species scavenging roadkill. If you are fortunate enough to see them side by side, you will have no trouble identifying each species, though males and females are difficult to tell apart.
Ravens are pretty much homebodies, seldom venturing far from where they were born. Ravens will roost communally in winter in northern Minnesota, but 20 birds in one roost would be a large number.
Crows that breed in Canada move southerly for winter. Some northern Minnesota crows may drift southward, but only far enough to find food, usually corn. In fall and winter, crows can form huge congregations that may stagger the imagination and conjure up old memories of Alfred Hitchcock. A few years ago, on a November evening, my wife and I ate at a downtown Minneapolis restaurant across from Loring Park. In the setting sun, tree branches were silhouetted against the fading light. Looking out the window, we saw a small raft of crows descending into the trees. Then more … and more … and still more. Within 15 minutes the stark, leafless branches were so thick with crows that the crowns of the trees looked as if they might collapse from their weight. We estimated that more than 500 crows came to roost that evening.
This winter roosting strategy is common among these social creatures, according to Lori Naumann of the Department of Natural Resources Nongame Wildlife Program. Communal roosting provides warmth and many watchful eyes to search for predators. In winter, urban areas offer the advantage of a "heat island" effect. Congregations break up in March as crows' interest shifts to mate selection for spring breeding.
Another behavior, more common among crows than ravens, is what birders refer to as "mobbing." Crows have different calls and the mobbing call is the most frantic, a rapidly repeated cawing. It's a call to arms to defend against predators.
When I hear mobbing crows, it is a good bet that their attention is riveted on a great horned owl or a large hawk, the primary predators that crows have to fear.
Both birds build large, sturdy nests: first large sticks, then smaller twigs, and finally a soft, cozy interior of leaves and grass. Ravens become territorial during nesting season. When they roost in a group or colony, their nests are evenly dispersed. Crows tend to be secretive and silent in their nest building.
Both species lay a clutch of three to seven eggs. Ravens take four to seven weeks to fledge. Crows fledge in five to six weeks. For both birds, brood success is generally high, due to dual parental care and family bonding. Often, in crow families, year-old birds remain with parents and may help tend and feed newly hatched chicks. Monogamy for both species is normal, and this reinforcing bond contributes to family cohesion and brood success.
Adults of both species are omnivorous, opportunistic feeders—not at all fussy about eating whatever they find, including fruits, vegetables, French fries, nestling songbirds, and stream-plucked trout. In winter they rely more on scavenging. Any roadkill is fair game. I have seen both crows and ravens feeding on the remainders of deer carcasses. They may have to compete with bald eagles, foxes, or wolves. While crows will raise a ruckus to dissuade competitors, a raven may pull at a wolf's tail or an eagle's feathers—always staying just out of harm's way.
Longevity and Cognition.
Corvids are long-lived birds. While warblers and other small songbirds seldom survive past their second or third year, crows and ravens have been documented living to nearly 15 years in the wild. Their curiosity and intelligence contribute to their longevity. Young ravens explore, investigate, and pick at just about anything new to them. And they learn behaviors, like caching food for later use, from adults. More learning facilitates a longer life. Interestingly, older birds exhibit much more caution and actually seem to fear new objects in their environment.
Stories abound regarding the problem-solving abilities of both species. Crows have been observed breaking off twigs and using them as tools to reach inside cavities and gather grubs. In Mind of the Raven, Bernd Heinrich relates how ravens managed to retrieve food on the end of a long string tied to a branch. The birds sat on the branch and pulled up the string with the beak, clamped it to the branch with the foot, and continued to pull up the string until the food was in reach. The public television show Nature included a scene where a raven uses the same beak-over-foot method to rob an inattentive ice fisherman of a trout.
Part of Corvidae brain prowess is related to their social nature and especially family bonding. The young learn from their elders, a cultural behavior we once thought restricted to primates. Another indication of complex cognition is the nature of play in both species. Perhaps you have watched crows sporting in the wind, flying upside down, doing 180-degree flip-flops. Ravens have been observed taking turns sliding down a snowy roof into a pile of snow. People have seen them passing sticks back and forth in flight.
In recent decades the scientific community has done some serious work verifying play in a number of animals. Crows and ravens are at the top of their list because of the birds' high intelligence. Spontaneous play may lead to new tactics for locating food in scarce times or avoiding danger from raptors and other predators. The very fact that both crows and ravens have time to engage in play indicates they have sufficiently mastered basic survival skills.
Ravens and crows have the ability to recognize individual human beings. Crows have long-term memory of individuals who did them harm. Their response is to mob the foe. Crows may also recall a friendly gesture. According to a BBC news story, 8-year-old Gabi Mann of Seattle has a habit of feeding a few local crows. The crows now routinely leave small trinkets—buttons, paper clips, Lego pieces—on the feeding tray.
Sometimes ravens give voice to their memories. Because of the physical structure of their multiple larynxes, ravens and crows are capable of wide-ranging vocalizations. A raven residing in a national park campground learned to imitate the gurgling sound of a flushing toilet, much to the consternation of visiting campers. Naturalist David Barash was studying marmots in Olympic National Park in an area where some blasting excavation had taken place three weeks earlier. One day he clearly heard a voice calling out, "Three, two, one," followed by the sound of a small explosion. He nervously called out, "Who's there?" Then he spotted the noisemaker—a raven in a nearby tree.
In literature, and in some native cultures, crows and ravens are often seen as symbols of death, or the dark side, and are feared. With their intelligence, curiosity, and social nature, I believe they deserve a better profile. Among many northwest American Indian tribes, including the Tlingit, Haida, and Kwakiutl, the raven is not berated or feared, but revered. He is the bringer of light. Yes, he is usually "the trickster" and playful, but in Northwest tribe creation stories the raven brings light to humans living in a darkened world. Harbinger of death or bringer of light? I'll cast my vote with the Tlingit.