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February 2016

Caw of the Wild

The truth about ravens and crows

Adirondackers who love ravens and crows are cautiously optimistic. For the most part, life is good for “corvids” (members of the family Corvidae) up here in the North Country, and their numbers and ranges have been swelling in recent decades.

After near-extermination from shooting and loss of habitat due to deforestation a century ago, common ravens (Corvus corax)—along with crows—have been protected from unregulated hunting under the federal Migratory Bird Treaty Act since 1972 and have been repopulating regenerated forests in much of the Northeast. Nowadays you can hear the resonant gronking calls of ravens all over the Adirondack Park. Half again as large as a crow with shaggy neck feathers and a heftier bill that is well-suited to carcass-picking, today’s ravens seem to relate to modern humans as their ancestors related to wolves. Once, they scavenged wolf kills; now ravens cruise the highways for roadkill. Smart, agile and adaptable, they avoid oncoming traffic with the skill of toreadors. Here on the Paul Smith’s College campus, ravens are so used to people and vehicles that they sometimes rip the soft rubber from windshield wiper blades—perhaps for nesting material—and I’ve seen one pilfer a sandwich from the back of a pickup truck while the owner was occupied in a nearby office. The willingness of these icons of northern wilderness to treat people like two-legged wolves and share our civilized landscapes may seem surprising, but I prefer to see it as a reminder that we are as much a part of nature as any other species.

Ravens typically select remote cliff ledges for nest sites, but they also use tall trees, the favored nesting sites of crows. Last spring my wife and I watched three fledglings half-fly, half-tumble from their nest in a white pine near the Paul Smith’s horse barn. Their parents kept a close eye on them—and us—from the green screen of forest as the excited youngsters flapped and flopped from branch to branch. The raucous shrieks of the young trio were astonishingly loud, fading only slowly with distance as the woods closed around them.

Ravens are also spreading into new territory, as are crows. Brian McAllister, a naturalist at the Visitor Interpretive Center in Paul Smiths, tells me that bird-watchers were delighted in fall 2014 when a lone raven appeared amid the coastal hawk migration at Cape May, New Jersey. “They were practically doing backflips over it,” he recalled. “It was the first time [the birders] had ever seen one so far south.”

How do coal-colored ravens and crows tell one sex from the other? We can only guess, but their rising populations show that they clearly do so when they are sufficiently protected from hunters and well provisioned with garbage, croplands and car carnage. Slight differences in their posture, personality and feather positions mean a lot more to them than to most of us, especially when viewed up close.

For ravens, highly intelligent, social birds with brain-to-body weight ratios equivalent to those of dolphins and only slightly smaller than our own, subtle behavioral cues can speak volumes. A recent article in Nature described how ravens gesture with their bills to show or offer twigs, moss and other items to their partners as we might draw someone’s attention to an object by gesturing with our hands.

Their vision is also different from ours. We have three kinds of color-sensitive cone cells in our eyes, but corvids have four. Not only can they see into the ultraviolet range that is invisible to us, but they probably also see a richer array of bird-colors within our own visible spectrum of light. Perhaps ravens and crows wear more distinctively patterned plumage than we realize.

While we’re on the subject of vision, it’s worth putting to rest a common misconception that ravens and crows are inordinately fond of shiny objects. Not so, and although corvids do steal and cache food on occasion, they only hoard heaps of car keys and jewelry in people’s imaginations. Real birds are more interested in meals than metals, so unless you leave a gob of leftovers on your silver spoon while having a picnic, your glistening utensil is probably safer around corvids than around certain people.

Light and color on fellow birds, however, might be another matter. Like high-quality anthracite, the black plumage of crows and ravens shimmers with rainbow iridescence when sunlight strikes it just so, which might be attractive to a potential mate. And while we’re speculating here, let’s consider why baby crows have blue-tinted gray eyes that darken in adulthood. The cuteness of animal infants (including juvenile Homo sapiens) is not accidental, but is a highly adaptive mechanism that charms parents into caring for them. This principle suggests that blue might have a special place in the visual palette of crows as a result or cause of the lovable chick phenomenon.

Or not. Perhaps the colors that a crow actually sees in its mate’s feathers and its offspring’s baby blues are unlike anything that we perceive with our inferior retinas, concealing secrets that are known only to them.

It can also be difficult to tell one species from another at a distance. Both ravens and crows are acrobatic fliers, although some would argue that the former outclass the latter in terms of agility and creativity. Both perform aerial courtship displays, barrel-rolling and looping and sometimes flying upside down beneath their sweethearts to briefly clasp claws before breaking away. Such talents also come in handy when dive-bombing hawks, owls and other winged enemies, which all corvids do with gusto.

There are, however, more distinctive traits to watch in the field. In keeping with an avian law that states “thou shalt harass larger birds,” a medium-sized corvid loudly chasing a larger corvid is usually a crow mobbing a raven. An expert birder might also tell you to watch for a raven’s uniquely “wedge-shaped” tail, advice that confused me for years until I realized that the imaginary wedge is supposed to be oriented sideways so the tip appears pointed rather than flat. And finally, ravens usually fly in ones or twos, but crows do it alone, in family groups or in mass migrations to nightly roosts. McAllister recently encountered one such roost-flight in the Champlain Valley. “It was like a river of crows,” he said. “My friends and I counted about 3,000 of them in one long stream.”

Perhaps the simplest approach is to listen to them. Ravens honk and holler and croak and gargle while crows mainly settle for variations on the generic caw. And your ears are even more crucial if you’d like to tell American crows (C. brachyrhynchos) apart from their less-numerous cousins, the fish crows (C. ossifragus). In fact, your ears might be your only hope.

You may have seen fish crows without knowing it, most likely along the edge of a river, lake or ocean. I’ve only identified them twice in my life, first as a college student on the coast of Maine when my professor pointed them out, and recently on the west coast of Florida, where a flock of them erupted from a mangrove thicket and let loose a chorus of nasal whining cries that, to my ears, sounded like fledgling American crows begging for food. Fish crows are only slightly smaller and slimmer than American crows, and even though McAllister is an expert birder, he struggled to explain how he recently identified a fish crow near a shopping center in Saranac Lake. “They just look different,” he told me, “but not by much. The calls are your best bet.”

Difficulty in telling these two species apart may help to explain why surprisingly little is known about fish crows. Search the Web and you’ll just find snippets. The species name refers to bone-breaking and the common name refers to fish, but their diet is actually as omnivorous as that of American crows, including everything from bird eggs and bugs to burgers and fries. (The mosquito-borne West Nile Virus, which appeared in North America in 1999, apparently harms fish crows less than American crows, which die of the disease at greater rates than most other North American bird species, but we’re not sure why.) The primary range of fish crows hugs the Atlantic coast from New England to the Gulf states, but in recent decades they have been moving inland along river corridors, possibly because of reduced hunting pressure and a taste for human foods. In New York, fish crow territory is expanding northward along the Hudson-Champlain corridor with isolated outposts in Ithaca and other points inland, and it is anyone’s guess as to when the first nesting colonies will settle the Lake Ontario shoreline.

Simply knowing that a secret species lurks among the hundreds of thousands of crows in the North Country raises more questions. Did fish crows arise through a mutation that turned them into corvid Peter Pans who never fully grow up? Crows are intensely social, visual, and vocal, and I imagine that romantic advances on full-blooded American crows by the first scrawny-looking, immature-sounding fish crow ancestors might have been met with, “Are you kidding me?” Perhaps such reproductive isolation helped to turn former social rejects into a new species of their own. And in light of recent findings that both species occasionally mingle while foraging and can mimic one another’s calls, it’s not clear how many cases of mistaken identity have muddled what we think we know about these birds.

Ah, mystery! Like our ravens and crows, it too is alive and well in the Adirondacks.

Curt Stager is a professor of natural sciences at Paul Smith’s College. Watch him play the song “Blackbird” on his guitar for a music-loving crow.

A version of this article originally appeared in the February 2016 issue of Adirondack Life. Subscribe now to receive eight issues per year.

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