Mind of the Raven: Investigations and Adventures With Wolf-Birds (22 page)

Contrary to what I had presumed from the first tests, the ravens did not provide one shred of evidence that they use scent to locate food. Nor did they appear to smell skunk’s effluvium, much less mind it. What I did learn, though, is that ravens are very alert to subtle visual cues. Reacting to subtle cues is admittedly not intelligence, but it is a prerequisite for many kinds of intelligent behavior.

Mostly I learned that one never really knows what might be relevant to them. One can’t predict what they perceive, what cues they use, or how they will react. There are always surprises. I suspected ever more that what they
do
has less to do with what they perceive than with how they process information in their minds.

I
F A NUMBER OF RAVENS WERE LINED
up in a row, most of us could not distinguish one from another. I know I can’t, and I’ve had lots of opportunity. I could no more distinguish them as individuals than identify individual peas out of the same pod. I may see a smudge on a wing feather here, a blemish on a tail feather there, but all of these markings are temporary. I see differences in behavior, but I can’t assume behavior is constant, especially if that is what I’m interested in studying.

The birds appear to treat many of their own kind as individuals. One hint of individual recognition can be seen in the evening at communal roosts. Some of the birds’ most vehemently vociferous and sustained squabbles relate to who sleeps with whom. Pairs and preening partners always sit close to each other, and they repeatedly chase off specific individuals while allowing others to perch nearby. Each bird responds to every other bird differently, as if it knows each bird individually. I have
observed, for instance, that while the most dominant birds chase any and all other birds to try to induce them to drop the food they are carrying, those lower in the dominance hierarchy chase only those still lower until they drop their food. I have seen many hundreds of such chases, and I have never seen a low-ranking bird take off to try to chase a high-ranking bird. Obviously, it would not be successful in taking its food, but the important point is that it never takes a mistake for them to find out.

Unfortunately, I had no proof of individual recognition, and I was anxious to devise a study to see if my hunch was right. But what might I use for criteria that could be statistically evaluated? What kind of data would a hypothetical raven scientist gather in order to prove whether or not even humans, who we know recognize each other as individuals, actually do? As Paul Sherman, Hudson Reeve, and David Pfennis have pointed out in a recent review, the only objective measure of individual recognition is a demonstration of differential treatment. If we discriminate individuals one from another, we must first recognize them. That is probably a conservative approach, because even though we may recognize each other, we might still treat each other democratically.

In January 1998, when my group of six ravens were eight months out of the nest, I weighed them and also determined their dominance hierarchy. The latter is easier to do than the first. When the birds feed together at a carcass, there is a constant shuffling as the birds try to feed next to specific individuals and make aggressive jabs and jumps at other specific individuals. I can score who feeds next to whom and who yields to whom, and in a couple of hours know who is top and who is bottom raven, and who likes to be next to whom. In that case, after only 155 interactions the hierarchy was clear. Blue made seventy-eight challenges, and never backed down from any bird. He was top raven. White, his sister, made no challenges but was challenged a total of fifty-three times by all birds, and she backed off to all of them. She was bottom raven. The other numbers also fell into place to reveal a dominance hierarchy from top to bottom, of: Blue, Orange, Green, Yellow, Red, White. Of this group, only Blue and Orange were males, and they were the largest birds.

In August, eight months later, I reexamined the dominance hierarchy of the same six birds, who had been kept together during the
intervening time. One thing had changed; Blue and Red had become friends (they would probably attempt to nest in two years) and regularly fed together, played together, and preened each other. For a week and a half, I brought the birds a frozen calf haunch each day and tabulated 678 dominance interactions. Blue was still the undisputed top bird, dishing out 366 aggressive interactions but never once being challenged. White was still the under-raven, being at the receiving end of 382 of the 678 interactions and never once challenging any other bird. It was with the four ravens in between that relationships got interesting. Orange, the next dominant bird, was still second. He was challenged only by Blue, but he now
rarely
challenged any bird, although before he had challenged Red. Blue’s friend, Red, had risen one rung in the hierarchy. She registered fifty-six aggressions against Yellow and seventy-five against White, but received none from them in return. Furthermore, Orange and Green, the other two birds above her, hardly touched her—I scored a total of only ten aggressions against her. That is, Red was now dishing it out to two underlings, Yellow and White, and she had become practically immune from the attacks of Orange, Green, and Blue. The reason was easily apparent: She fed under the protective umbrella of her dominant mate, Blue. I couldn’t wait to see what would happen when I removed Blue from the group.

I led Blue into the adjoining aviary, separating him from the group by a wall of wire screening. When I fed the group, he did not come to the wire as if trying to get through. Instead, he kept his back to the feeding group and showed his anger by making long rasping calls. After I had tabulated 863 aggressive interactions within the group without Blue, I saw significant changes. First, Orange went from his previous 4 percent of the aggressive interactions to 33 percent. A quarter of his attacks were now directed against Red, whom previously he had not touched. Red had sunk in status, and the dominance hierarchy was back to what it had been in January 1998. Red was being “hit” much more, not only by Orange but also by Green. Curiously, even White, the most subordinate bird, who had previously backed away from all in thousands of interactions, scored five “hits”
against Red. That doesn’t seem like many, especially since Red hit White 184 times, but White had not once before hit any bird.

After these experiments, I opened the door to let Blue back in, having first put down a hunk of meat in one spot and another equally large piece about three yards away. Blue rushed to one meat pile and started to feed. His partner, Red, rushed up to feed alongside him, and he tolerated her. All four of the other birds went to the other feeding spot to avoid him. But Blue, greedy as always, wanted both meat piles. He had trouble having both at the same time. In the one hour that I watched, he switched back and forth seventeen times between the two. Red accompanied him, tagging along behind him. Usually, the instant he left a meat pile the others rushed to it, even with Red still there, to grab bits of meat. As soon as he came back, they rushed off to return to the second piece. Red was still an underbird at the meat pile where Blue was
not
feeding. She went near only those individuals that would tolerate her, pointedly distancing herself from Orange and Green.

The birds left their piece of meat when Blue came, not because they had just been hit by him, but before they might be hit. They left when he came within about a yard or two of them, and none went to the other piece if Blue was already there. That is, the birds appeared to
recognize
each other from at least two yards away, and this ability allowed them to stay clear of aggressive individuals as well as to seek out and stay with tolerant ones.

The experiments also showed that the female, Red, benefited from her partnership with Blue. He tolerated her, and she followed him. Under the conditions of the aviary, it seemed like a one-sided relationship, because Red provided nothing to Blue. However, you will recall that in the field (see Chapter 10), teamwork is advantageous in capturing food and/or taking it from powerful adversaries, so the partnerships would be reciprocal.

If the birds recognized each other, as my observations suggested, the next question was: What is the basis for that recognition? We use faces, voice, gestures, gait, and clothes. We can distinguish one individual from any other, even though our facial expressions can vary
tremendously, and even though those expressions communicate a great range of other information besides identity. Ravens also vary their “facial” (head) expressions enormously. Their skin is hidden by feathers, but the head feathers can be rearranged by muscles in the skin to convey a wide range of moods, emotions, and intents. Body language does the same. I can see at a glance if a raven feels afraid, self-assertive, attentive, angry, or contented. Behavior changes as well. When Goliath, in the presence of Fuzz, fell from a dominant to a submissive status, his head feather patterns, body postures, and vocalizations all changed dramatically. But the mates still recognized each other, showing that specific status, as such, is not the one critical feature that serves as an identity tag. Had these birds not been banded, I would, without a shadow of doubt, have thought Fuzz was Goliath and I would have missed an important behavioral event.

What accounts for the ravens’ individuals recognition? Positive individual identification of ravens for us humans must necessarily rely on markers. The best markers are, of course, those already on the bird. I have seen two birds that had white wing feathers, and one with a partially white wing feather. One, Stumpy, had a missing foot. One had a missing right eye. Another had useless curled toes on one foot, and several had unusual bill shapes. For the most part, I have had to mark the ravens in order to ID them. At first, I attached commercially available colored plastic leg rings, but these wore off after about two years. I tried freeze-branding. Freezing kills pigment-producing melanocytes; in mammals, hair that regrows at a once-frozen site is white. Marking domestic animals with a very cold branding instrument to cause regrowth of white hair is a well-known marking technique (Farrell and Johnson, 1973). Lacking a branding instrument, I tried dry ice, which maintains a temperature of minus 57 degrees Celsius. I tried to brand different feather tracts of four young ravens by holding a chunk of dry ice to them for five to ten seconds. I had tried the same technique on myself, pressing the chunk of dry ice to my scalp for thirty seconds. I felt no pain. Unfortunately, when the young ravens feathered out, they stayed totally black, and my hair remained as brown as before. (I later learned that in order to get regrowth of
white hair, one first needs extensive damage to the skin.) As for the white wing feathers on individual ravens, they had all grown where I had previously attached a wing marker with a metal rivet. All the birds molted and regrew black feathers by the third year.

The method of choice for making ravens individually recognizable seemed to be to attach onto the wings plastic tags of different colors with numbers on them. These lasted up to ten years, after which the birds melted back into the anonymous crowd. I also attached numbered aluminum Fish and Wildlife rings onto birds’ legs, but these can generally be read only when the bird is in the hand.

I had been able to recognize some individuals among twenty-two wild-caught ravens in my aviary complex in the winter of 1992, after I associated with them every day, even when I didn’t see their markers. I had at first presumed they would all be anonymous, were it not for their colored rings and wing tags. Thanks to these markers, I could eventually recognize some individuals even without seeing their identity tags, and I started forming attachments and having favorites among those “characters” that stood out.

For a while, my favorite was C48, a big, dominant bird who had always been the first to investigate anything new, as well as being first at the food I’d bring. Gradually, Yellow O stood out, too. She was uncommonly tame for a wild-caught bird, and she appeared to make a point of perching in front of me, as if to place herself between me and the rest of the crowd. The others tried to keep their distance instead, except when I brought food, but Yellow O came to perch near me even if I didn’t bring food. She sat, calm and composed, with partially fluffed out feathers, indicating her relaxed state of mind. She watched me. I wondered why.

Eventually, Red Dot became my favorite bird of this group. I nicknamed him “Hook” because his bill, which was conspicuously longer than any of the others’ and had a prominent hawklike curve at the tip. Unlike Yellow O, Hook never perched near me. Whenever food was near me, he showed no hesitation in walking up to it, keeping his head tilted so that his bill was pointed slightly up. He walked slowly, deliberately planting each foot one at a time, and his pant
feathers and breast feathers seemed unusually long and flowing because they were not pulled up tight against his belly. His head feathers were often slightly raised, giving his head a fuzzy appearance. In contrast, the other dominant males usually maintained sleek head feathers. Unless displaying, they showed no pants and walked with a quicker stride. Although feather posture often varied radically between individuals, it could hardly contain the key information for individual identification by the ravens themselves, because it often changed from moment to moment.

Individually identified ravens have always been special to people, and other methods of color-coding them have been possibly even stranger than mine. The Athabascan Indians have a myth about why the raven is black and the world imperfect. They say that in the time before man, when the world was young, Raven (an individual) was white as snow. He was the creator of mountains and a lover of life whose soul was filled with light and beauty. All of this goodness made his evil black twin brother jealous, and the evil twin killed the white one with an ax. Ever since, the world has been imperfect and the raven black. In other early American cultures, Raven also was originally white, later turning black and becoming numerous and anonymous. The Tlingit say he was transformed by smoke.

Color is the most superficial of possible characteristics used to identified ravens, if only mythical ones. We tend to see all ravens as stereotypically black, although from up close they have a greenish, blue, and purple sheen. We do not distinguish one individual from another; and until we do, we will see their behavior as stereotyped and programmed.

There are rare ravens in the wild that are identifiable by their color. I received a photo of a young white raven from Josina Davis of the Queen Charlotte Islands in the late summer of 1997. The bird was white as snow except for its pink eyes, feet, and bill. An albino. Davis wrote, “He is hanging around in town {Port Clements} and I have never seen him harassed by others of his own kind. I saw him by the post office and rushed home for my bags of bread and dog food. He didn’t call to other ravens. He picked up the largest pieces of bread—
he chased away two crows—he cached bread and dog food in an empty lot nearby. When he came back, four crows were eating the food I’d put down, and he made no attempt to chase them. The ‘caution white raven’ signs are up.”