Mesilla Valley Audubon Society Bird of the Month: American Crow

American Crow photo courtesy Robert Shantz.
American Crow photo courtesy Robert Shantz.
This is the first of a three-part series on a trio of birds found in southern New Mexico; the American Crow (Corvus brachyrhynchos), the Chihuahuan Raven (Corvus cryptoleucus), and the Common Raven (Corvus corax). They all belong to the Corvus genus in the family that includes crows, jays, magpies and ravens — the Corvids.

Crows and ravens are some of the most intelligent — and maligned — birds on the planet. They’re also some of the most widely recognized worldwide. After all, most of them are large, jet black birds with similar voices, habits, and appearance.

You might be unaware that three species of crows (American, Fish, and Northwestern Crows) live in the U.S. A fourth, the Tamaulipas Crow, a very rare Mexican visitor to extreme south Texas, looks and sounds much like them. Only one, though, the American Crow, is in our area. In fact, the worldwide birding database eBird, shows no confirmed sightings of any of the other species of crows in Doña Ana County from 1900 to the present.

From the point of view of a birder — your author — who often has fits distinguishing very similar species from one another, that is just fine. With the American as the only crow likely to be seen here, it means one less difficult identification to make.

American Crows are medium to medium large (40 – 50 centimeters or 16 – 20 inches in length, sometimes up to almost half of it tail) birds with jet black iridescent feathers with an average wingspan of 85.34 centimeters to 1.6 meters (about 34.5 to almost 43 inches). On average, they can weigh from 11.2 to 22.4 ounces (317.4 to slightly more than 635 grams).

The only other birds in southern New Mexico with which one could reasonably confuse them are the two North American raven species (the next two birds in this series, which like the crow also have black eyes, bills, legs and feet) and American Crows are smaller than both. A large American Crow can look the same size, or maybe even a bit larger than a small Chihuahuan Raven, though, so size alone is not enough to differentiate between the two.

Another distinguishing feature between American Crows and ravens (both Chihuahuan and Common) is bill shape and size. The American Crow’s scientific name is from the Latin and translates into English as “shortbilled (-beaked/-nosed) Crow”. Indeed, it has the shortest bill of all three; crow beaks aren’t as heavy, and they’re straighter than those of ravens. By comparison, raven bills are massive bludgeoning cleavers with a classic “Roman nose” shape.

Flight profile and voice are the two final diagnostic characteristics to help you distinguish between crows and ravens. A crow’s tail, unless it’s fanned out, is squared off at the end, and even then, it will be shorter than a raven’s. A crow’s wingbeats are also much more labored than a raven’s; it looks almost like they’re rowing through Jell-o, or as if they’d tumble out of the sky if they skipped a single wingbeat. Ravens also frequently soar and glide; crows almost never do either.

The “caw-caw-caw” of crows is one of the most widely recognized bird calls in North America. Ravens, on the other hand, possess a repertoire of croaks, gurgles and “cronks”. All three are expert mimics, too, but all raven vocalizations are distinctly more guttural and croaky than their smaller cousin’s calls are.

During the winter, there are vast flocks, or murders, of crows in the Mesilla Valley. This is a recent phenomenon. The upsurge in crow population is directly correlated to the increase in pecan acreage dating to about the early 1960s.

Pecan growers generally aren’t fond of crows, as they see the flocks descending on their orchards in winter as voracious marauders and fight back. Yet, the crows thrive. This is a microcosm of the relations between crows/ravens and humans for millennia. The birds of the genus Corvus are among the most intelligent in the world, with some having a brain to overall body mass ratio comparable to humans and the higher apes. So, despite human efforts to exterminate them, including dynamite, poison and other means of wholesale slaughter, they thrive.

Indeed, the American Crow and Chihuahuan Raven are supremely adept at adapting to our presence in and modification of their environment. In areas where they both occur (such as southern New Mexico in winter) mixed flocks of these two Corvids foraging in dumpsters, fast food parking lots, agricultural fields — in fact, anywhere where human activity offers them an opportunity to scavenge for food — are a common sight.

All crows are omnivorous and opportunistic in their diet. Fruit, vegetables, grain, berries, nuts, other birds’ eggs and young, small reptiles, amphibians, mammals, road kill, garbage, carrion all go down the hatch. Being as intelligent as they are, these opportunists are also proficient tool users. Crows living in coastal areas frequently drop clams and mussels onto rocks to smash the shells open, much as gulls do.

So, the next time you see a large, broad-winged, short-tailed allblack bird, or a flock of them, stop and take a closer look. See if you can spot the American Crows in the group. When you do, remember Henry Ward Beecher’s comment: “If men had wings and wore black feathers, few of them would be clever enough to be crows.”

The Bird of the Month feature is brought to you by the Mesilla Valley Audubon Society, the local chapter of the National Audubon Society. To learn about MVAS and its activities, including monthly fieldtrips and beginner bird walks, visit new-mexico-birds.com/