Mind of the Raven: Investigations and Adventures With Wolf-Birds

by Bernd Heinrich

  Vision is important in recognition, but I have no clue what they look for or see in another raven. They recognize me—I am the only individual who can regularly walk up to them to within one yard while they are feeding. If any other person comes within fifteen yards, they fly up in fright. I have experimented with them by giving or withholding clues about my identity, to see what cues were important to them. When my young ravens were less than a year old, they showed fright if I wore different clothes. They were startled and flew away from me when I wore a hideous Halloween face mask. Perhaps they used clothes and faces to identify different humans.

  Tests with my four tame birds after they were two years old showed that more was by then involved. In one experiment, I came into the cage after having been absent for a week, wearing my blue jacket, snow pants, and snow boots, but I had pulled a knitted green stocking cap they knew well completely over my head, with tiny peepholes for my eyes. As I entered the aviary “faceless” on this and other occasions of the test, I was careful not to say a word to them, because I didn’t want acoustic cues to override all others. It was clear that my face was not the sole criterion they used to identify me; the birds were quite at ease, although they appeared to look me over more carefully than usual. In my next trial, I showed my face but wore new clothes that I had never worn near them before. The birds were still quite at ease. On the other hand, when I came dressed up in a bear suit they were quite alarmed, especially when I did the “bear walk” on all fours.

  Ann, a neighbor, obliged me by taking part in the next experiment. As I expected, the same birds were wild with fright when she walked into the aviary. So far so good. We left, exchanged clothes, and came back. I wore Ann’s blue shirt, and she wore my boots, jacket, and snowsuit, and pulled the green stocking hat with the one peepholes in it over her head. Then she walked into the aviary again. She was masked and dressed exactly as I had been when the birds were quite nonchalant. The birds flew about in their cage in fright with open bills, although not quite as wildly as when she had come in dressed in her own clothes. Next, I walked in wearing Ann’s blue shirt and the ski mask. The birds were not fully at ease, as they had been when I wore my own clothes and a mask, but neither were they wildly afraid. They were just moderately uneasy. When I pulled off my mask, they became totally at ease.

  I next tested the responses of another group of birds that were wild-caught but had become tame after a year. I had on four previous occasions chased and caught these birds using a long-handled smelt net. I had tried to conceal my identity by wearing a black mask and wig during the chases so that they would later allow me to come close to them for my behavioral observations. When I came near the birds at other times, I had worn my “good” hat, the orange one that left my face bare. They always flew away from afar when they saw me coming either with the smelt net or wearing the black mask with wig. Did they know just the smelt net, or me, or my mask? Wearing my “good” orange wool hat, I entered the aviary and threw down a handful of oatmeal. They gathered around me like chickens. Okay, they were not afraid of me and the orange hat. As soon as I pulled the black mask out of my pocket, they all flew off. So they feared the mask. I asked Chelsea, one of my Winter Ecology students, to enter the aviary while wearing my orange hat. Results were clear: As soon as she entered the aviary, the birds left the main aviary, flying off into the side aviaries. She spread the oatmeal, and they all stayed away. When she came out of the aviary, the birds streamed back in to eat the oatmeal. I reentered and they stayed fully relaxed, feeding all around me. It was clear that the birds identified individual humans, regardless of what they wore or carried. However, one’s trappings can themselves be frightening to them, especially if they were associated with fearful situations.

  The hiding of my face had not frightened one group of my tame birds, but I wondered if perhaps they had identifed me by my clothes. What about a strange face? I put on a grotesque face by crossing my eyes and rolling them up. It made no difference. I could still walk to within a yard of the feeding crowd (a later group). With dark sunglasses, I got to three yards. Apparently, my eyes didn’t contain the important clue of my identity of them. I tried limping in to them. That also got me almost equally close, but when I hopped on one leg they flew up at seven yards already. So they at least noticed my gait, but my walk was either not the one deciding characteristic that held my “signature” for them, or else they knew very well it was me, and they were uneasy merely because of my weird behavior.

  Some things, though, scared them at the same distance as strangers did: carrying a gun, wearing a long dress, and carrying a broom. The birds were then one and a half years old and no longer afraid of my regular clothes. Perhaps they recognized my consistent style or fashion. But a kimono? When I wore that, they flew up at fifteen yards, but it didn’t fool them for long. After my thirteenth approach in the kimono, they again allowed me to get next to them. They never allowed me to get close if I was carrying a broom, even though I had never chased or hit them with one.

  I had not pinpointed any precise cues they used to identify me, or that they might use to identify each other. A big complication was that whenever I took away one cue I was really adding another. I could not just remove my face. I could only substitute. I concluded that the ravens recognize me without seeing my face and without identifying my clothes, although both cues are used when they are available and relevant. Presumably, the cues they use to identify each other are also multiple.

  Vocal signatures are surely important in individual recognition, such as at a distance or when pairs make barely audible whispering-wimpering calls to each other when they are being intimate with each other. Males and females and dominants and subordinates have displays and vocalizations signifying sex and status, but none of that explains how they distinguish one another while they are engaged in the business of feeding, when, as the previous experiments indicated, they discriminate each other at a glance.

  Can they recognize themselves in a mirror? We think of self-recognition as a higher mental faculty. It is not a faculty demonstrated in any bird. To the contrary, birds routinely and convincingly demonstrate their incapacity for self-recognition, by battering themselves aggressively against a mirroring surface, quite often until they bleed, in apparent attempts to dominate a rival. In North America, almost everyone with a window to a dark cellar has had the experience of seeing a male robin or song sparrow bash himself against such a mirroring window every morning, sometimes for hours and many days in succession, during the breeding season. There is no evidence whatsoever that the unfortunate birds ever catch on to their misguided behavior, despite the repeated daily brutal punishment they give themselves.

  Not even crows are immune to attacking themselves in the mirror. The May 12, 1996, Western Australia Sunday Times shows a picture of an Australian raven presumably “caught in the act” of vandalizing a car, although to me the bird appears to be attacking its reflection in the car window. Wondering how a dominant northern raven, Corvus corax, who always vigorously challenged every other dominant raven that he met would react to his image in a mirror, I planned to videotape Fuzz, the super-male, when he met his unyielding and identical match.

  It was June 25, 1995, and for three days I had been involved in the very frustrating process of trying to videotape the raven’s reaction to itself in a 17" × 36" frameless mirror that a glass vendor had kindly donated expressly for this project. I had set up the mirror, but hid it behind a plywood panel of equal size. A dead chipmunk was tied to a stick in front of it. It took a full day before Fuzz, the boldest raven, ventured to yank at the chipmunk in front of the plywood hiding the mirror.

  I presumed I could then pull the board away to reveal the mirror and stand back to film the show. Fuzz would want not only to impress any rival in the aviary, but also to repel any competitor daring to try to take his choicest food. What happened? As soon as I removed the plywood panel and the reflecting surface became visible, all the birds went bonkers. They retreated
into their loft. After a few hours, they started begging piteously. They were hungry for chipmunk, yet they did not dare to come down to feed.

  I tried again on July 5, and the results were almost an exact repeat of the previous week. I left the mirror set up with the plywood covering. The birds fed every day in front of the plywood, and were thoroughly habituated to feeding at that spot.

  On September 20 at 7:02 A.M., I provided Fuzz, Goliath, Whitefeather, and Houdi with delicacies—chopped squirrel—at the usual place, but this time I exposed the mirror surface. The meat was within inches of the polished and unscratched mirror, and it was situated so that any bird walking up to it could see the “other” raven approaching from the opposite direction.

  The birds looked down from their perches. They hopped back and forth nervously. At last, after fourteen minutes, Goliath descended to the ground, walked cautiously to the mirror, and took a piece of meat. Fuzz instantly chased him until he dropped the meat, but it happened to fall back in front of the mirror.

  After four more minutes, Fuzz went to the front of the mirror and grabbed a piece of meat. Goliath then followed and got one, too. Next, the two females begged and received their food from their respective male partners. Curiously, neither male acted as though he saw what was in the mirror when he approached it.

  On September 23, I again revealed the mirror, and they went to the food placed two inches from it within two minutes. They acted only slightly nervous. Even though all four birds stayed feeding directly in front of the mirror, they at no time overtly acknowledged anything they might have seen in the mirror. I was somewhat puzzled by these results. I could conclude that they didn’t attack the mirror reflections as they would if they saw strangers, but I didn’t think I could conclude they recognized themselves because they didn’t attack.

  I tested another group of ravens at the same mirror on October 25. As before, when I first brought the mirror into the aviary and set it in front of plywood, the birds were afraid of it. I turned the reflective surface away to let them first get used to the mirror as a strange object. When I finally reversed the mirror after a week, to expose its reflective surface, they were again afraid, staying away from food placed in front of it. The next dawn, they came up to the mirror and took the food, appearing to ignore the images of themselves, as the other group had done; but then two of the six birds ambled back to mildly interact with the mirror. These two each peered into the mirror intently, bill to reflected bill, then both repeatedly reached up with their feet as if trying to grab their reflected images. They were silent and they didn’t seem aggressive. These birds had been born that spring, whereas the first birds in the experiment were over two years old. I’m not claiming that age is relevant. I suspect it isn’t. It is just the only difference that seems tangible enough to mention.

  Soon after I had made these observations, I received a call from a man in northern Maine named Matt Libby, who told me about a peculiar raven problem. For about a hundred years, his family had rented out wilderness camps, and there had never been any raven problem “until three or four years ago.” The problem was that one or two ravens perched on his camp porch railings, leaving considerable white deposits, tearing up his cedar wood chairs, hacking window framing to bits, and dirtying up the windows under the shaded porch. Ravens had always been around, he said, but they had never been a problem before. I asked if there was anything different now. There wasn’t, he said. Then he thought a bit and came up with one tiny detail: “Only that I’ve now got thermopane windows rather than single glazed panes.” I checked with glass merchants and learned that most thermopane sold these days is “very low reflective,” called “Low E.” It has a coating on the outside that allows heat waves in and then reflects them inside, so that less heat leaks out as radiation. Did that have something to do with the ravens under the dark porch attacking or being attracted to their reflected images in the camp windows? My data do not answer the questions with which I started, but they point to interesting studies that would be fun to do, not only with mirrors but with television screens. For the time being, I had to be—and was—content to observe ravens in the field, where they routinely make other, perhaps even more vital, identifications.

  Houdi’s nemesis. The female raven at her cliff nest, about a mile from my house in Vermont. Photograph from a blind in a nearby maple tree.

  FIFTEEN

  Dangerous Neighbors

  RAVENS ARE FLEXIBLE. THEY NEST on pine trees in Maine’s inland wilderness, on tall beech trees in northern Germany, on power lines, on radar towers, on buildings above busy streets, under highway overpasses, in active railroad trestles and abandoned buildings. They’ve nested in the trunk of an abandoned car in the Mojave desert, and on a baseball stadium in Elmira, New York. There is even now an active raven nest under the MJ section of Penn State’s Beaver Stadium.

  Whenever possible, ravens prefer to nest on rock shelves tucked under overhangs on cliffs. These are the same sites also preferred by some of their mortal enemies: golden eagles, gyrfalcons, and great horned owls. Strange as it may seem, raptors and ravens are often coinhabitants of the same cliff, sometimes nesting within yards of each other. Very often, falcons and owls take over an old raven nest because the raptors cannot build their own nests. The ravens, when evicted from their nest, will often build another one nearby. Thus, ravens provide the raptor a nest.

  In the city of Bern, Switzerland, ravens started nesting above the busy public square in the middle of the city on a large government building, the Bundeshaus, in 1988. By 1995, the raven pair had built five nests in different cornices of the building, and at least five pairs of falcons of two different species (Falco tinnunculus and Falco peregrinus) had moved in to use each of the nest places the ravens had constructed. In 1998, they still nested there, bringing off three young, and entertaining the townspeople.

  The associations between nesting ravens and raptors, and between neighboring territorial ravens, are complex and “personal.” Relationships probably change with time as disputes are resolved, antagonisms subside, and truces develop. As one example of a truce among traditional enemies, I once had a tame great horned owl and two tame crows, all of whom lived free in the woods close around my cabin. Crows are one of the owl’s favorite and common prey. Their first encounters were tense, yet owl and crows eventually ignored each other altogether and peace was restored.

  Raven nest on the Bundeshaus in downtown Bern, Switzerland.

  The raven-raptor association is not always one-sided. There is also advantage for ravens to associate with raptors, who often provide kills from which to scavenge. Perhaps even more important, if one fierce species becomes tolerated near the nest, it becomes a “watchdog” for predators of the other, seeing and repelling strangers.

  Most raven nests do not have a “dear enemy” guard, and at least one member of the raven pair stands guard at the nest at all times. In Denali Park in Alaska, I had the privilege of watching a raven nest with several half-grown young for a week at a cliff where I occasionally saw peregrines, gyrfalcons, and golden eagles fly by in the distance. No raptor nested on the cliff itself. One of the raven pair was always on guard to greet me loudly whenever I came near the nest. The second bird, summoned by the first’s commotion, would come immediately and join in the clamor. Then one day, one of the adults disappeared. Since the remaining bird had to leave the nest to forage, the young were sometimes left unprotected. After just one day, the young disappeared from that nest. Only a large raptor could have taken those young, since the nest was inaccessible from the ground.

  Young ravens taking the measure of a turkey in my aviary.

  Ravens also come in contact with numerous other potentially dangerous birds at food. What follows is a set of observations of one raven, several crows, a turkey vulture, and two broad-winged hawks, Buteo platypterus, feeding at the same carcass near my Vermont house in 1994.

  On April 2, I did my part like all the other people who feed birds in the winter. I la
id out bird food. I put a dead, cut-open calf within sight of my bedroom window. The first birds came at dawn: three crows and one raven. The raven was soon feeding and flying off with chunks of meat. The crows alternately perched in the trees and fed when the raven had left. The raven, the male of the pair that nests nearby, had already come to feed on my offerings here for a number of years. The female would now be incubating, and he daily brought her meat from this calf.

  On April 3, one raven along with one crow and one turkey vulture came in the early morning. The vulture fed almost continuously for at least two hours in the presence of either the crow or the raven. As before, crow and raven fed alternately, but both fed alongside the vulture, acting as if it were invisible. The vulture in turn ignored both corvids.

  Eight crows arrived in the early forenoon. As many as five of them fed simultaneously alongside the vulture, but all the crows left the bait whenever the lone raven came back to feed. Crows vigorously chase ravens one-on-one, especially in spring and summer, but sometimes also in the fall and winter. But here, none of the eight ventured onto the ground when the one raven was near. The raven paid no attention to the crows, nor have I ever seen ravens aggressive to crows or try to chase them away from bait.