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 lov
er 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.”
Others have written to me about seeing a white raven flying in a flock with others. One young emaciated white raven was found in New Brunswick, Canada, and ended up in an animal rehabilitation center. Mary Majka, the raven’s keeper, wrote, “Albie is tremendously shy and scared of his own shadow. We’ve had regular ravens here before, and they were very intelligent, inquisitive, bold individuals. But this bird, although he’s been with us for two years, still displays the same shy behavior.” I wasn’t surprised that Albie had idiosyncratic behavior. Most do, once you get to identify them and to know them.
I was sent a photograph of a chocolate brown raven that an Alaska newspaper article described as “the first off-color raven in Anchorage,” although a dark silvery metallic one had been seen there in the 1970s. The bird is “very noticeable. When the sun hits him he’s almost like a golden raven,” Alaska raven biologist Rick Sinnett wrote. “This bird seems to be a loner that other ravens seem to pick on.” The Anchorage newspaper headline read, “Off-Color Bird Faces Raven Racism.”
The rare off-color ones notwithstanding, ravens must normally distinguish one another by cues other than color. Movement might be one relevant cue. But that is a difficult cue to interpret, except that you know when it is absent.
Given the ravens’ predilection for poultry of all sizes, I provided my birds a recently killed raven that had been shot by a crow hunter. They reacted to this raven with loud, deep, rasping alarm calls. After some hours, they still ignored it. It was not eaten within minutes, unlike other birds I had given them that were pounced on in seconds. It was not eaten at all.
They would easily recognize a live crow. But a dead one? Would they eat that? My curiosity aroused, I had to observe their reaction to a dead crow. I presented a young frozen crow from my stock of roadkill in the freezer to Whitefeather and Goliath. Both birds erupted in harsh, deep, rasping alarm calls, and just as with the dead raven, neither bird fed from the carcass. It eventually rotted in place. They did not even dig for the maggots.
Two months later, I presented another crow, a headless one, to the same two ravens plus Fuzz and Houdi. The reaction was the same. Two days later, on September 18, I again presented the headless frozen crow to observe their reactions more closely. That time, the reactions were weird, to put it mildly. As I entered the aviary with the crow in my hand, Fuzz erupted in the deep, long, rasping alarm calls normally given in response to ground predators. Within seconds, all four birds had joined in. At first, all made only the deep rasping caws. After a few minutes, they also made the rapid rap-rap-rap calls they usually give when a raven comes by. Fuzz then initiated several series of high-pitched, fluting quorks that I had never heard him give before. Whitefeather, the dominant female, suddenly went into an extreme crouching position (often referred to as a precopulatory display) in which she flared her wings widely and rapidly vibrated her tail. She crouched in place like that for minutes, as if glued to her perch. I had seen the same display used in entreaty, as when a subordinate bird was denied access to food or a bath. Then she erupted in knocking calls, the female power display. Houdi, the subordinate female, also did a mild version of the crouching display, but she didn’t knock. Fuzz did a lot of bill-wiping on the perch, a displacement activity common during times of conflicting emotions. I had never seen these behaviors toward other bird carcasses—those that they ate, and they usually ate at once.
After several minutes of intense interest, both Fuzz and Goliath went down to investigate the crow carcass. Only Fuzz, the most dominant male, touched it. He approached it in his macho, erect, male-dominance stance with smooth head feathers, gently touched the dead crow with his bill, and shouted directly at it. He stared at the carcass while doing several series of rapid rap-rap-rap calls normally given when a raven flies by in the distance, a call that I believe says, “Notice, I’m here.” He looked at the carcass for a time, then casually walked off. After that, none of the other birds paid the crow carcass any more visible attention. I next gave them a dead cottontail rabbit, and they began feeding on it in seconds.
Seven days later, I presented the same frozen, headless crow still again. The response was similar to the previous experiment, except that Whitefeather knocked but did not crouch. I left the crow. Two days later, they still had not eaten it. After I skinned it and removed the wings and legs, Fuzz approached it in less than ten seconds and ate it.
Do ravens have inhibitions against cannibalism, and did they mistake the dead crow for a raven? Or are they upset by the black? I gave them a piece of black rubber they had never seen before. They made deep rasping alarm calls, but no rap-rap-rap calls. Then I tried red flagging tape. Same response. When I presented them with an almost pure white bird—a ring-billed gull—they again reacted with deep, rasping alarm calls. They did not eat it right then, either. But when I gave them a second ring-billed gull two months later, Fuzz approached it within several minutes, plucked it, and ate it. When I presented them with the weirdest bird facsimile I could think of, a plastic pink flamingo purchased specifically for them, they made no alarm calls. They ignored it. I then brought them a big, black, battery-operated raven fascimile that gave the speech, “The end is near, the end is near—ha, ha, ha, ha, ha,” when you touched a button. Long before I pushed this button, all four birds flew wildly about with their bills partially open in fright. Even though this fake raven was smaller than any of them, all acted afraid of it. None went near it or displayed to it. The “speech” it made later had little additional effect on them. Goliath, the big male, made deep rasping alarm calls. They apparently saw it as something strange and hence somewhat frightening. After I removed the toy raven from the aviary, both males went to their respective females and made throaty, hiccup-like calls with a downward inflection followed by a musical upward inflection. They showed their ears during these displays, which apparently were to reassure their mates of their strength and power. The ravens showed no alarm when I gave them the carcass of a black chicken. The black feathers didn’t fool them one minute; they went right to it to pluck and eat. I also gave them a dead adult opossum. They had never before seen one, but in less than a minute, Fuzz approached it; then all came and fed. There is no easy explanation for these observations. That is why ravens are so interesting. Nevertheless, I think the experiments do show that body language is important to them for recognition, even to the extent of allowing them to distinguish between a raven and a crow, an otherwise easy task for them in live objects.
I am confident the birds do not identify each other by the markings I put on them, such as leg rings. No bird ever looked dow
n to examine another’s legs before cozying up to it. Goliath never looked over Whitefeather’s shoulder when he approached on her left side, to check for the white wing feather on her right wing. When she molted and lost the white feather, he did not change his behavior towards her. Mutual preening (allopreening) is often accompanied by soft comfort sounds that may have individual characteristics that the birds recognize, but they did not “call” to identify themselves before beginning to allopreen.
Whitefeather’s white feather was mostly black.
The relevant cues they use become more specific with age. Young birds in the first weeks or so of life are blind, and respond to any sudden vibration of the nest by stretching their necks up, begging loudly, and opening their mouths for food. The vibrations are normally caused by the adults’ landing on the nest edge. The young nestlings do not yet identify the parent as such, because their necks are directed straight up, regardless of the parent’s direction. After the youngs’ eyes open, they gape toward almost any moving object. With time, they learn increasingly specific details of their parents. By the time they leave the nest, they have learned to respond to numerous cues and to reliably identify whoever has been feeding them, be it raven parents or human foster-parents. Soon, they follow specific individuals, flying away in fright from strangers, both human and raven.
Mind of the Raven: Investigations and Adventures With Wolf-Birds Page 20