“Hey, Mike, look at this.” My friend was peering out her window overlooking the river. “It looks like something out of Hitchcock,” she added.
Coming upriver were hundreds of large black birds. It was dusk and the birds were headed to some common roosting area to spend the night. They formed a long, loose, noisy pack that seemed to stretch back for a mile.
Crows often gather in large flocks during the winter. On this mild November day, we could hear them calling through the open windows. After a few seconds, I realized that most were not the ubiquitous American crow, but their lesser-known relatives, the fish crow (Corvus ossifregas).
The fish crow is a large, stocky bird with a stout bill. It is uniformly black from head to tail, including its eyes, bill and legs. Both crow species are about 18 inches from bill to tail. On average, the fish crow’s wings are a bit longer, but over-all the American crow is bigger and bulkier.
The black on the wings and body can be glossy and appear blue-purple or green-black. Just before molting, worn feathers can appear dark brown. The sexes look alike.
American and fish crows are nearly indistinguishable by sight alone. The birds’ vocalizations are the key identifier in the field. Even the most casual bird watcher can identify the American crow’s harshly barked “CAW-CAW.” If you hear a higher-pitched, more nasal “ca-hah,” you are listening to a fish crow. The second syllable has a slightly downward inflection, like that in the informal human word of disagreement, “huh-uh.”
Both fish and American crows are members of the corvid family, which also includes ravens, jays and magpies. Among other traits, these birds are known for their intelligence, acceptance of close contact with humans and loud vocalizations.
Fish crows are found exclusively in the Eastern United States. They are typically found along bodies of water, ranging from the Atlantic Ocean to estuaries, marshes, rivers and lakes. Because they are tolerant of humans, they might also be seen in parks, parking lots and similar locales.
Fish crows were hit hard by the West Nile virus in the early 2000s, but they have recovered quickly. In fact, they are slowly expanding their range north, approaching Canada along the Atlantic Coast, and west and inland, up the river valleys. They are permanent residents within their range.
The generally more common American crow can be found throughout the United States and well into Canada during breeding season. Close to water in the Chesapeake region, though, the crows we see are as likely to be fish crows as American.
Fish crows, like their cousins, are social birds. This trait is most obvious in the fall and winter.
Nests are constructed exclusively by the female in the spring and measure about 1.5 feet in diameter. They produce one brood each summer and build new nests every year.
After nestlings have fledged, fish crows begin to form larger groups. By winter, the flocks, which often include other species, can easily number in the hundreds, even the thousands. This was our friend’s first winter in their new home, and her first exposure to the massive flocks that crows can sometimes form. To those unfamiliar with crow behavior, the first sight can indeed be Hitchcockian.
Fish crows are extreme generalists when it comes to food. They eat everything from fruits and berries to carrion and the nestlings of other birds. They may store food in caches, sometimes drawing on their food banks during their chicks’ incubation and nestling phases.
Although they are generally ground foragers, fish crows are notorious nest robbers. They eat the eggs or nestlings of songbirds and waterbirds alike.
They also steal food from one another, as well as from other species, including gulls. In landfills, the birds seem to spend as much time trying to steal food as they do looking for their own.
I watched the river of crows flying up the Potomac and realized that we often notice crows in an off-hand way. We see them scavenging with gulls in a parking lot or see one or two flying across a highway. We tend to give them little thought. Only when they appear in large numbers do they demand attention.
On the afternoon of this fine November day, I realized these birds are a lot like the public works employees who empty our trash cans, the housekeepers who clean our hotel rooms, or the nurse’s aides who empty the bedpans. They perform vital functions, but we tend not to notice them unless they take collective action.
A closer look at fish crows reveals intelligence and complex social networks.
If we are clever enough, we might even see what an essential role they play.