Living Sanibel: American crow and fish crow can live to be 14 years old
The only place where the American crow is uncommon is along the coast, where it is often replaced by the fish crow, a slightly smaller, but similar species. On the mainland and near-coastal regions the American crow can be found just about anywhere. It is commonly found along highways where it feeds on roadkill, from deer to dragonflies. It is a regular at garbage dumps, dumpsters, and residential garbage cans where it pick through our refuse looking for scraps of food, potato chips, and everything in between.
The crow is extremely opportunistic and intelligent. It has been observed not only using tools, but also fabricating them. For example, the crow has been seen pulling the leaves off of small twigs, then inserting these stripped twigs into holes in fence posts in search of termites and ants. It knows which day the trash is put out and shows up accordingly. Native Americans held crows in high esteem. They recognized this bird’s intelligence and based many of their myths and tales on the crow.
Once considered an agricultural pest, the crow is now widely seen as mitigating some crop damage by eating the insects that destroy the wheat and corn fields.
The crow is similar to the Florida scrub jay in that it is a cooperative breeder. The fledglings remain with their extended families for several years to help raise future broods. Flocks of crows, called murders, have been known to reach 2 million birds. When these extended families chance upon a resting great horned owl, or a perching hawk, they exhibit another interesting behavior called “mobbing,” harassing the owl, or raptor until it leaves the area. Birders can be alerted to a well-hidden roosting owl by paying attention to this avian behavior.
Recently the American crow population has been decimated by the West Nile virus. The crow appears to be the most vulnerable species to this form of encephalitis. To date, more then 45 percent of the North American crow population has died from this pathogen. That’s more than 25 million birds. For the moment this pandemic appears to be subsiding, but there are regions in the U.S. where the crow has virtually vanished from the landscape.
The adult crow has quite a few predators, including owls and Cooper’s and red-shouldered hawks. Its nests are often raided by raccoons and squirrels. No crow-on-crow predation has ever been observed. In past decades bounties placed on killing crows by state and local governments accounted for considerable mortality in crows, but most of these have been repealed or discontinued.
The fish crow, although slightly smaller, is all but impossible to discern from the American crow. The American crow is almost never found along the coastline, however, so the chances are that any crow you see along the coast is a fish crow. One distinctive difference between the two birds is the call; the fish crow is famous for its nearly constant cah, uh-uh.
The fish crow is unique in that it is one of very few birds endemic to North America. It does not have the range of the American crow, extending only as far north as Rhode Island, while the American crow’s range extends all the way to the Northwest Territories. The American crow far outnumbers the fish crow. Unlike its cousin, however, the fish crow does not appear to be as vulnerable to the West Nile virus, which in some regions has decimated American crow populations.
A highly adaptable bird, the fish crow feeds on garbage, eggs, insects, carrion, ticks from livestock, various berries, and some fruit. Like all crows, jays, and ravens, the fish crow appears to be capable of learned behaviors. The fish crow, for example, has learned to pick up a mollusk, fly high above a rock pile or highway and release it, breaking the shellfish open so the bird can feed on it. While not quite at the same level as the tool-using green heron, it is a fascinating example of avian intelligence.
Huge flocks of fish crows, called murders, roost on islands in and around St. Petersburg and Tampa where they number in the thousands. The fish crow has adapted well to the habits of Homo sapiens and because of that is expanding its range throughout the southeast.
This is an excerpt from The Living Gulf Coast – A Nature Guide to Southwest Florida by Charles Sobczak. The book is available at all the Island bookstores, Baileys, Jerry’s and your favorite online sites.