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

by Bernd Heinrich

  I saw my friend when I returned, and he felt that he had faithfully carried out his duties as raven feeder, eagerly telling me how “tame” some of the ravens had become. When I entered the aviary, I was shocked. One of the ravens had just died. Others, who seemed “tame” all right, were merely weak from hunger. Then I noticed the calves. Although they had been cut along the belly, most of the meat still remained inaccessible. I hastily cut the calves’ hide to expose more meat, as a predator would, and within two days the rest of the birds had fully recovered their strength.

  The surprising thing, besides how unobservant this caretaker had been, was that the starved raven was “NT,” the undisputed, most dominant bird of the whole group of fifteen. The crow, a very much smaller bird totally subordinate to all the ravens, had remained in full health and vigor. Similarly, the smaller, very low-status ravens were also little affected. The ravens could easily have caught and killed the crow, since they have caught and eaten all sorts of birds—including blue jays, grouse, robins, and a saw-whet-owl—that had entered the aviary through the large meshed wire. They also could have eaten the dead NT.

  Rank has its privileges in ravens. High-status birds can monopolize a carcass if they put in the effort to do so. For example, on April 23, 1995, eight vagrants suddenly showed up at 7:30 A.M. at the calf carcass in back of my house in Vermont. Within minutes, the male of the resident nesting pair arrived. (The female was then brooding on her young and could not come.) He chased one or the other of the eight vagrants without pause. The vagrants flew through the trees but always came back near the calf. A nonstop battle lasted for sixty-two minutes. Finally at 8:32 A.M., the male was victorious—the eight vagrants left without having fed once, but all of his costly efforts likely benefited the pairs’ offspring.

  High-status birds can also bide their time before starting to feed at feared carcasses, thereby reducing risk. In late April 1992, I worked on the ground, watching ravens in the aviary complex, after I had provided them with a carcass. It was not until a full hour had passed that one of the birds approached the carcass and started feeding. Within the next minute, most of the crowd had also fallen upon the calf. All, that is, except White Slash, a very high-status female, and her mate, Blue Diamond, the most dominant bird of the whole group. She continued to nudge up to him and beg in her distinctive, yell-like beg call. Her yells were low, more throaty than the others’. She was the only bird in the whole crowd I saw giving anything resembling the food-indicating yell. All her yelling was directed at him. As she nudged up to him, she often preened him, and was preened in return. It looked as if she were entreating him to go to the calf. He soon did, and they both fed.

  I was surprised at that time that the highest-status birds were not the first to feed, and started to note status interactions more closely. The first pattern I saw during the next three days was that indeed the bird that fed first was always a low-status bird. After feeding started, White Slash and Blue Diamond always rushed in and fed wherever they wanted. They had simply let the others take the risk of approaching the feared carcass, while they took the rewards it had to offer.

  A male peacock advertises its sex and its vigor by carrying around an extravagant tail, the embodiment of Zahavi’s “honest advertisement” in communication. Most of a raven’s interactions with others of its kind take place while feeding at carcasses. How can it advertise its sex and vigor? I’ve already noted various ways. Another occurred to me as I watched my captive group feed in May 1992.

  At a carcass, there would often be one bird perched on top, in what almost seemed a precarious position. I had always assumed the dominant bird held this perch because it was the best feeding spot. When I reviewed in my mind what I had observed of birds I knew as individuals, I realized that I may have had it backwards. There are constant squabbles near a bait. I had interpreted the behavior as fighting over food, but had I really seen any bird excluded? No! Not even wimpy X, whom I suspected had a shotgun pellet lodged in his right breast muscle, because his right wing drooped. There was not a single fight at the carcass in three days of feeding. Usually, ten to fifteen birds fed amicably side by side. Almost all of the numerous jabs were by dominants at near-status birds, apparently causing them to make their fuzzy-headed submissive display. After the submissive birds’ displays, they then fed along with the dominants. There was no evidence that the subordinates got less food than dominants, as I found out in a series of experiments where I captured and weighed the birds immediately after feeding bouts. If anything, the dominants took smaller bites and had to feed longer to get the same amount of food. There was an order at the dining room table. With birds wanting to be at the “head of the table,” not only to eat, but possibly also “to be seen.” The squabbles were less over whether certain birds were going to eat than where they would perch. To perch on top of the carcass was equivalent to sitting at the head of the table, a high-prestige place. It was not necessarily the place where food could be grabbed most easily and quickly.

  One could watch the birds for days on end, even in the confines of the aviary, and have no idea of the status of one bird relative to another; but as soon as they begin feeding, anyone can pick out the alpha bird in thirty seconds. The alpha bird is positioned on top of the bait. While feeding there, its shoulders are spread, making them seem broader, which results in the wing-tips being crossed over the tail rather than lying parallel to it. The tail also tends to be slightly elevated, rather than straight out or slightly drooping.

  The top-bird position is evident in other contexts as well. In my aviary complex, there is one large dead beech tree with a top stub that seemed to be a favorite perch for Green 67, the most dominant bird in a later group of wild-caught birds I held. This bird, unlike all the others of his group, was restless in mid-April as though wanting to leave. He flew laps round the aviary, always returning to the same stub. When he flew at the stub while another happened to be perched there already, he simply knocked the other bird off. It would flutter off or fall down into the brambles. Since Green 67 always faced in the same westerly direction from that stub, I presumed he had a destination in mind, and the stub was a convenient place for him to face in that direction. (I had captured him four miles from the aviary in that direction, and when later I released him there, he circled and indeed flew off continuing in that direction.) Meanwhile, after Green 67 was removed from the aviary, Blue 110 became dominant and took the same perch. There was no shortage of perches to choose from. When he wasn’t on it then NV, the next in line, perched there. Finally, when I let Goliath in with these birds, he assumed the new dominant position, and the perch became his.

  I concluded that status is central to many aspects of raven behavior. High status is costly to show and to maintain. In ravens, it is based on large size, and large body size requires much food. High status is shown by displays, and displays invite challenge. Nevertheless, the benefits of high status are many. Only high-status birds can consistently reveal their sex, and thus only they can be sexy to potential mates. They become good providers because they can defend food bonanzas when it is critical to do so. Status determines who may feed first at prized food, and also who can afford to allow others to act as a shield by “testing” dangerous food.

  Young ravens have a strong innate tendency to “challenge” dogs, testing their reactions, and then they quickly become used to the dogs, and vice versa.

  EIGHTEEN

  Ravens’ Fears

  THE RAVENS’ FEARS WERE MOST PECULIAR to me. Ravens, I learned, not only were reticent to go into traps baited with carcasses, they also acted impressively shy of carcasses alone. They would fly over repeatedly, not landing at all. When they eventually did land hours or maybe even days later, it was usually more than ten yards away, and then they approached cautiously, stopping often and looking all around, and preferably in a crowd. Finally, when within a yard of the carcass, they would jump up and back, flapping their wings as if startled. They would approach again, repeating the jum
ping jack maneuver, eventually giving the carcass a jab with their bills before retreating, and then approaching a little quicker the next time. It always took a long time before feeding began. I did not know why they were so cautious. For ravens to fear carcasses seemed almost as bizarre as for rabbits to be afraid of carrots. A friend and colleague, Paul Sherman at Cornell University, suggested to me that ravens were perhaps not afraid of carcasses as such, but of ground predators that might be nearby waiting to catch them. This idea seemed plausible, so I dragged a calf up into a tree. To my surprise, the ravens appeared even more afraid to go near it than before. I have friends who place the remains of deer and moose carcasses on trees to feed woodpeckers, jays, and chickadees, and they told me that ravens regularly come at dawn and call, but never touch this food. I was back to square one.

  Another hypothesis might have accounted for the birds’ fear. Instead of innately fearing carcasses, they might have learned individually to associate carcasses with traps and then passed the fear on to others. If fear was learned, then ravens who were never subjected to danger near a carcass should not fear carcasses as adults. On the other hand, if fear of carcasses is innate, they would. I wanted to raise nestlings by hand and examine their reactions to carcasses to distinguish these hypotheses.

  Ravens specialize in feeding on animal carcasses in winter, yet to my amazement, the young ravens that I raised on dog food and chopped roadkill showed fright near any roadkill I presented them. They would hide in their shed and venture out only after a day or so. When they finally did approach, they jumped away from the dead animals. Just to be sure that it wasn’t a fluke, I repeated the experiments with three groups of ravens on all sorts of carcasses and variously shaped objects. One group of birds was raised by John Marzluff, another by Bill Adams, a neighbor and friend since my childhood, and the third by myself. The results were the same. We determined that while feathered and furry things were feared, round, smooth objects were highly attractive. Long, thin food objects were treated with indifference. We were pleased with the consistency of our results, which suggested that fear of carcasses was innate, a counterintuitive and puzzling conclusion.

  When I later got Goliath and the three other young ravens, I saw something else entirely. I raised them by feeding them with the same food in the same way the previous groups had been raised. However, I led them through the woods from the day that they hopped out of the nest. Unlike the other young ravens, these four were not afraid at all. They went out of their way to contact any carcass or anything else I pointed out to them. They rushed up to peck a huge blue water bucket, brown paper bags, or a dead woodchuck. I saw wild ravens behaving the same way, but only toward edible items.

  Those things my ravens had not experienced under my tutelage, they remained afraid of as they got older. Turtles, for example. At just over two years of age, Fuzz and Houdi were ready, I felt, to face a turtle. They had by then contacted most kinds of roadkill, and showed little hesitation to begin feeding on them, although a dead crow was greeted with rasping alarm calls, then never touched at all. On June 6, 1995, just as the painted turtles were leaving ponds to lay their eggs on shore, I secured a mature, 6.5-inch-long specimen, to observe both the turtle’s and the ravens’ responses. When I picked the turtle off the road, it extended its legs and head as if trying to escape from my hand. It did not withdraw into its shell.

  When I put the turtle deep into the aviary, Fuzz and Houdi were curious as well as mildly alarmed. Both made long, deep rasping calls, hers slightly higher in pitch than his. The turtle walked forward tentatively and stopped at a log as both birds flew down and looked closely. Although Fuzz never attacked Houdi at food, he attacked her now. She ceded and became passive and watched as he approached closer.

  The turtle, meanwhile, withdrew into its shell. Twenty-one minutes later, Fuzz still had not touched the immobile turtle, but he did yank away sticks and leaves and other debris from it, all the while continuing to edge closer to it, then jumping back nervously. The turtle did not budge. After thirty-three more minutes, both birds finally lost interest in it. But twenty minutes later, the turtle slowly and cautiously moved six inches closer to some cover of nearby grass. Both birds resumed their rasping caws, and Fuzz again approached it. The turtle pulled back into its shell. This time Fuzz left it alone after only seven minutes. After he left, Houdi again became active, hopping back and forth above the turtle and making rasping caws. After thirty-two minutes, at 7:10 A.M., the turtle again poked its head out, but by this time Fuzz was bored. Finally, when at 7:33 the turtle crawled off, the birds, perched on their tree above it, showed no more interest. I then released a turtle hatchling. In less than a minute, Fuzz flew down, grabbed it, and crushed it in his bill. Knocking, Houdi sidled up to him. He responded with a macho choking display, then cached the hatchling, which she immediately retrieved and ate.

  Nineteen days later, on June 26, I found another adult female painted turtle that had just laid her eggs, and put her into the aviary. Fuzz walked to her and nonchalantly contacted her in less than one minute. Within two minutes, he reached under the turtle with his bill and deliberately lifted her up and heaved her over onto her back in one smooth motion, much the way the ravens of Yellowstone Park flip buffalo patties to find insects. He danced around her, lightly picking at her shell. Then he left her and showed no more interest.

  Normally, a painted turtle rights itself in seconds. In the presence of the ravens, this one played dead. The turtle stayed upside down and immobile for ninety minutes before I removed her and put in a dried cecropia moth instead. The dead moth evoked deep, rasping alarm calls. Fuzz danced around it for at least ten minutes, lunging and retreating, jabbing and pecking like a matador. He clearly was afraid—of a moth! Finally, after a number of tentative pecks at its wings, he grabbed it and ate it. As always, Houdi stayed back and watched intently from a safe distance. Was she learning about this object, the moth, by watching Fuzz?

  There is no doubt that the young originally learn from the parents’ example. On June 7 in a later year, 1996, when they were parents, I spread out a gray squirrel, a woodchuck, a calf, and a porcupine at different locations in my clearing by the cabin. Goliath and Whitefeather fed unhesitatingly from one carcass after another, and their six young followed close behind them. The young had never seen any of these animal carcasses. The six of them, unlike all of my hand-reared ravens of this age, did not hesitate to hop right up to the carcass with their parents to be fed at the squirrel, the calf, the woodchuck, and the porcupine, and to peck them themselves. They showed not a flicker of concern. When the parents left, they continued to feed at the different carcasses. Just like that, the young had overcome all fear that would have kept them from feeding without the parents. No wonder that when Goliath had been just out of the nest, he had followed me closely and examined and pecked everything that I touched, quickly feeding on it if it was food. His following behavior ensured he’d learn what not to fear and what was food, from an older individual with experience, a parent, who in his case was me.

  Ten days later, I spread more roadkills around in the field in front of the cabin—two woodchucks, one painted turtle, and one large snapping turtle. Within minutes, the whole crowd of eight made raucous cries and came boiling out of the woods. Goliath was first down to the woodchucks. The young followed and started to pick meat on their own. Goliath then left them and went first to one turtle, then to the other. The young followed and fed unhesitatingly at the turtles also, quickly and effortlessly having learned from him.

  Eight days later, I dropped off another carcass the young had never seen before: a roadkilled cat. At 7:45 A.M., one of the young circled over it and flew on. Goliath and Whitefeather were away that morning. At 9:00 A.M., five of their young were near the cat, perching in a spruce, looking and yelling forlornly. They wanted to feed but were afraid to go near it. Goliath returned at 10:44 A.M., saw the cat immediately, walked to it, pulled at it, rolled it over, and started to feed at the cut-open bell
y. Within seconds, the whole crowd of five young rushed down, crowded around him, and started to feed themselves. (I presumed Whitefeather had left that morning with the sixth young.)

  Wild ravens do not touch a carcass if they know it has been associated with someone they don’t trust, as the following example showed. At the end of October 1992, I had fourteen newly caught wild ravens in the main aviary with thirteen wild-caught veterans of the previous year remaining in a side aviary. Even though the birds were left alone, it took the newcomers three days before they started feeding on a calf they had seen me drag in for them. I had also brought them two calf lungs and a gray squirrel, items the tame ravens would have taken in seconds. These remained untouched even after five days.

  I placed one of the calf lungs directly next to the calf from which the fourteen had started feeding. Would they feed from the lung at the “safe spot,” or avoid it because they had seen me handle it? I soon had the answer. They almost immediately took the one lung I left, not touching the one I had laid next to the calf. Had they forgotten that I had handled it three days before, since they just saw me carry one and not the other? Two days later, nothing was left of the lung but a picked-clean windpipe. They still had totally avoided the other lung that they had seen me carry to the calf from which they continued to feed.

  The most parsimonious explanation of my conflicting experimental and observational results is that ravens go through developmental stages. When they first leave the nest, they are, like human babies, highly curious of all objects. They are fearless and “get into” everything that crosses their paths. At that time, they are accompanied by their parents, who steer them away from dangerous things. Because of this parental protection, the young are free to explore and learn. During these early months, they also learn from their parents’ reaction what is dangerous, what is harmless, and what is a source of food. The parents have experience that might span decades, and that has been passed down partly from their parents in turn, so that in effect the young learn from grandparents as well. The first group of juvenile ravens I examined were afraid of carcasses because they had skipped the tutorial stage during which the young follow their parents. Those young ravens had had to do all of their learning on their own, and so had little guidance in determining what was safe or not. It might take them two days instead of two minutes to begin to feed on an opened raccoon carcass.