By David Cronenwett
If you stare out a window, nearly any window anywhere in North America and wait long enough, you will likely see an American crow (Corvus brachyrhynchos). From the most remote wildland to the densest urban landscape, the many crow species are ubiquitous and recognizable across cultures. A member of the Corvidae genus, which contains over 120 species of ravens, magpies, jays and crows worldwide, the American crow’s ancestors begin to show in the fossil record from 17 million years ago. The bird is unmistakable; large, all black with a stout bill and often found in the cacophonous company of others. They have a unique flying style that relies on measured, steady wing beats with little reliance on gliding. Crows are similar in many ways to their cousins, the common raven, but are smaller and far more social. Winter congregations can consist of hundreds or thousands of individuals in a small area. Generally considered a “trash” bird and pest, the American crow may be among the only wildlife people confined to urban areas regularly see.
The corvids are well-studied birds that demonstrate almost uncanny intelligence; try a YouTube search under “crows playing” or “crow intelligence” to see for yourself. The American crow has a brain-to-body ratio only slightly less than that of human beings and perhaps unsurprisingly, share many of the same characteristics as us. Crows live in complex societies where relationships between individuals must be maintained and remembered over time. Extended families assist monogamous pairs in raising the young, who receive from two to five years of direct care. This sort of refined social behavior is found in very few species worldwide and is by definition a measure of substantial intelligence. Only corvids and humans are known to live in such intricate societies.
Some crow species have been observed using tools in complex ways and have not only the ability to employ them for various tasks, but will use tools to acquire or help make other tools. This “meta-tool use” was previously thought to be the exclusive realm of humans. The corvids have long and deep evolutionary connections with us. Many cross-cultural archetypes exist for ravens and crows, depicting them as alternately clever, devious, wise, tender, or harbingers of death. Crows followed and sometimes led bands of our Pleistocene hunter ancestors to potential prey, as they are known to do with other predators. The mutualistic part of that relationship came as we butchered our kills; despite impressive bills, crows have no ability to break the skin of even a small mammal. Whatever we left behind was always happily consumed by the corvids. Like us, they are highly omnivorous and species that eat a wide variety of plant and animal foods have an ability to recognize and remember each type over long periods of time. This may be one reason that crows easily coexist with civilization; our constant stream of garbage, roadkill and other edible effluvia is precisely what an opportunistic omnivore prefers.
American crows produce more than 250 known vocalizations and two distinct dialects; a loud one used only for communication with the larger community and a quiet one of soft clucks and chortles for more intimate family use. Research over the past few years has demonstrated an astonishing ability of crows to think and remember. Through observation of food storage (caching) behavior, it is now believed that these birds possess a “theory of mind”; that is, an ability to recognize the intelligence and intention of other creatures, which may differ from their own. Individual crows will observe others hiding food, and sometimes steal it. Since crows know this about each other (and about other species too), they will often make a “false cache” to deceive a potential pilferer who has been watching them. This suggests not only an awareness of self and others, but the ability to remember negative experiences over time.
Our understanding of corvid memory and observational acuity has grown substantially in recent years. The work of biologist John Marzluff at the University of Washington has demonstrated that American crows can remember individual human faces for a very long time. Using rubber masks, teams of researchers trapped crows (a negative/traumatic event), banded them, and returned them to the wild after several days of captivity. When the same mask was worn in the presence of previously trapped crows, even in a crowd of people, the birds would dive-bomb and loudly scold that person, something that could be repeated for years. An even more fascinating finding is that adult crows will communicate this information to their young, so subsequent generations will remember and scold a person wearing the same mask. These are behaviors that can only be defined as “cultural” in nature; information is attached to an event, communicated, received and remembered by birds that had no direct exposure to the negative experience of their parents.
It is interesting and a bit ironic that a species close enough to us as to be virtually invisible has helped dramatically illuminate nature’s complexity as well as our kinship with it. Part of the crow’s adaptability and obvious success as a species has to do with its intensely social nature and the ability to observe, communicate and remember. While we have only recently begun to study the American crow and other corvids, I have a feeling they have been studying us for a very long time indeed.