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

by Bernd Heinrich

  I had on numerous occasions seen ravens make false caches—bury food and then immediately recover it to bury it elsewhere—i.e., they lied. However, I had not necessarily interpreted that as conscious lying. As an ecologist, it seemed simplest for me to assume that proximally the birds were only playing or being fussy about their cache sites, with no conscious deception involved. Making false caches can function to deceive, since false caches are sometimes checked by others; but as much as I believed the birds were aware in some ways, I did not think this behavior, by itself, proved awareness. Maybe they always act as if they are being watched without having any conscious knowledge of their actions. Maybe making a false cache is beneficial and costs little to do, and they evolved complex programming to do it unconsciously.

  In a complex animal, the results of any one experiment almost always encompass several realities or perspectives. To see the proverbial “elephant” described by several blind men who touch it in different places, especially one as huge as consciousness, it must be examined simultaneously at many points, and from many perspectives. The jury is still out, but nevertheless the details of the ravens’ behavior indicate to me that the birds predict and anticipate the behavior of their conspecifics. That may be as close to exhibiting consciousness as it gets. To react flexibly and in an anticipatory fashion to a wide range of actions (as opposed to a few specific ones) before they have occurred makes the hypothesis that the animal knows what it is doing increasingly more plausible, and the idea that all of their behavior is unconscious, unlikely.

  A much-discussed current idea that holds promise in understanding the evolution of consciousness is that the most challenging problem faced by individuals is dealing with their companions. The theory of “Machiavellian Intelligence,” or selection for social expertise, is the current front-runner as an explanation for the evolution of high intelligence in the hominid line. As the caching behavior suggests, the same rationale could apply to ravens.

  The “gang of four” feeding amicably together.

  TWENTY-THREE

  Morality, Tolerance, and Cooperation

  AS BEHAVIORAL ECOLOGISTS, WE try to reveal rules of behavior as though we were discovering truths. In reality, the word “rule” as applied to animal behavior is a verbal shortcut. A “rule” means nothing more than a consistency of response. It is not adherence to dictum. Animals adhere no more to rules than we do by showing up at the beach when it’s 110 degrees but not when it’s 30 degrees. Rules are the sum of decisions made by individuals that are then exhibited by crowds, not vice versa. Rules are thus a result. They are the average behavior that we and many animals are programmed with, learn, or make up as we go along.

  Animals exhibit consistency of response only where it serves their individual interest. The necessity for consistent response with respect to treatment of others is obvious among social animals, to whom others of their group are as much a part of the environment as is temperature and other factors. In social animals, it seems almost proper to talk of rules in the sense of dictums, since certain responses are not only evolved but also sometimes enforced.

  Whether or not an animal’s behavior is acceptable can depend on whether it is directed to members of its own social unit versus others. Sanctions and punishments are often applied by the group to enforce its “morals,” which are the reflections of its interests. In humans, morals are even used as a weapon, especially in the political and religious arenas, to help enforce the interests of specific groups or party lines. Through extensive work spanning many years, we have discovered some “rules” of raven behavior relating to groups. We have found, for example, that on average, vagrants disperse widely and individually, forming ad hoc gangs to overpower resident pairs who defend their food.

  Groups of four to a dozen birds sometimes associate in what appear to be social partnerships. Goliath and Whitefeather even tolerated juvenile vagrants at a calf carcass near their nest site in winter. I’ve seen six to eight birds arriving suddenly at a bait when there was only a pair for weeks before. Do ravens have groups within which, as with other animals, enforced rules of behavior are observed? What rules of behavior apply? To find out, I needed an established group that could be observed for extended periods of time. Since the foursome of Goliath, Fuzz, Lefty, and Houdi had been kept together for months and had long since stopped fighting among themselves, they were an ideal group to observe.

  Whitefeather, in the Maine aviary.

  Goliath preening Whitefeather while she holds her head still for him.

  Fuzz and Houdi, allopreening and bill-holding.

  Shed in the aviary where first wild pair (now nesting near Weld village) and then Goliath and Whitefeather nested. Goliath is perched just outside the aviary. Picture below shows the four (standing) young of Fuzz and Houdi, and the two younger young (reclining) of Goliath and Whitefeather.

  Matt and Munster, a pair of male siblings who bonded, built a nest, and who tried to mate and then had vicious fights (but they later made up).

  The white nictitating eye membrane is used for communication and it also serves to protect the eye.

  Many of the raven’s feather bases are white. Note brown eye of this fully adult bird. (Baby’s eyes are blue.)

  Two baby ravens about a week old, and two unhatched eggs.

  Regurgitated raven pellets look much like owl pellets. The indigestible remains of these pellets found under a raven roost contain fur, bones, eggshells, and insect exoskeletons.

  Female knocking display. Note dark mouth color of an adult.

  Wild ravens at a carcass near my house in Vermont. Female is at the left, and male to the right. Note her lanceolate long throat feathers during her bow, when both wings are elevated and her tail is flared.

  Here the wild bird (perch at left) is watching one of the four hiding food, and it then dug in the snow (inset) to retrieve and steal the cache. Inside aviary in Maine.

  Planning by a raven. The bird had made a groove, cutting off the tip of the bread-loaf-sized chunk of suet. Then it cut a groove to cut off an even larger piece. Note peck marks in groove and small suet chips it had left next to groove, as it concentrated on the later, larger, reward.

  Young raven testing the reaction of a dog.

  On February 2, 1995, I released a single wild raven into their aviary—a female in her first year. She had mottled mouth color and brown-tinged tail and wing primaries. Goliath and Houdi, then the most dominant male and female, respectively, both gave violent chase. Goliath cornered the stranger in the shed, put on his macho display—ears, erect posture, bill up—and crowded in upon her. Occasionally, he yanked her wing and tail feathers, to which she objected vociferously but without challenge. Fuzz, the subordinate male, at no time approached her. In contrast to Goliath, Houdi pursued the new female relentlessly. She crowded up to her and pulled her wing and tail feathers. The newcomer sometimes tried to ward Houdi off by reaching out with her foot, but kept retreating, all the while making rasping protests as she was being physically abused. The question of dominance and sex having been established, the four birds then ignored her completely, quite in contrast to similar human situations I was aware of.

  Feeding rights were another matter. When I placed food onto the snow and all the others fed at it, the stranger was always attacked if she came close. Perching by herself and watching them feed, she then erupted in a temper tantrum. She violently hammered her perch and the walls of the shed where she was hiding. Whenever she watched the other birds feeding, she resumed her outburst. She vented her anger only when the others were at the food that she was prevented from reaching. Hours later, when they were not at the food, she ventured out of the shed and down to the ground to try to feed, but the four violently jumped at her whenever she came close to the food pile. When they jumped at her, she crouched in a submissive display with her neck pulled in, wings lowered, and tail vibrating. This is the raven’s extreme entreating display saying, “Please…” (“…let me feed,” “…let me mate,�
� “…don’t pick on me,” depending on context). The gang of four didn’t relent. Theirs was an extraordinarily high degree of cohesiveness or cooperation in a group of ravens.

  The wild bird eventually became even more afraid of her four conspecifics than she was of me. She perched calmly within fifteen feet of me, instead, concentrating on the others, especially when they buried caches of food in the snow. She flew down repeatedly to try to dig out these caches, but attempted the thefts only when the cacher had its back turned or was preoccupied with feeding. At first, she tried to raid a cache immediately after the cacher had finished making it and had flown back to the food pile. Each of the four cachers were soon wise to her ways, leaving the food pile to come back and chase her if she as much as flew near their latest cache site. After a few false starts, she raided earlier caches to which the cachers were less attentive. By this strategy of deception, she sometimes succeeded in recovering the others’ food and getting a bite to eat before being caught raiding.

  Within a couple of days, Houdi’s aggression toward the new wild female subsided somewhat. Nevertheless, all four still chased her from any food pile I provided, and she still fed herself exclusively from their cached food. I presumed that in a few more days she would be tolerated at the carcass itself, and all would be well, given a superabundance of food. When I had to leave to go back to Vermont, I made sure the aviary was well stocked with food, including two large calf carcasses. Given the abundance of food, I expected tolerance to blossom, because it normally does within groups.

  When I came back, I found, to my great shock and surprise, the stranger lying dead on the snow. There was congealed blood on her breast feathers, skin was torn from both her legs and wings, and there were peck and puncture wounds with hematomas all over her head and the base of her bill. She had bled, and only live animals bleed. Ravens regularly peck out the eyes of animals they intend to eat, and they have a strong social inhibition, or “rule,” that prevents them from pecking the eyes of other ravens, yet this raven’s eyes were punctured. In short, there was no doubt whatsoever that my four friends had killed her. She had died trying to defend herself, lying on her back in the snow, using her feet in defense. They had not eaten any of her flesh.

  Perhaps my gang of four, being confined together for an unnaturally long period, had become an “exclusive club,” and this had reduced their tolerance of strangers. But that was not the cause of the murder. It was only an ingredient that led to it.

  The raven’s murder seemed extraordinary because I had previously seen that even starving ravens do not kill the weakest of the group. Ravens routinely threaten or mildly attack others who are in the process of robbing their caches. I had also seen several birds unite to attack another individual for reasons that were not clear to me. But this killing was a severe punishment. It went far beyond the usual behavior aimed at repelling a competitor from a cache or for showing displeasure over a mild infraction. This was censure of the severest kind.

  The murder was probably punishment for repeated infractions. Feelings of outrage that are used to justify cruelty are reminiscent of our own behavior, and have been a major source of human suffering the world over. We cannot expect more from ravens.

  Retaliatory acts are known among birds. Many birds harass those they have seen raid their nests. At the University of Groningen in the Netherlands, which I once visited, a pair of magpies built a nest next to the biophysics building, while a pair of carrion crows had a nest nearby across the parking lot. Soon there were frequent magpie-versus-crow battles. In the escalating battles, the crows finally killed one of the magpies. From the crows’ perspective, justice was served; from the magpies’, injustice.

  Individuals of the same species can also be singled out. Once in the winter woods in Vermont, I saw a very excited group of ravens make a concerted effort to pin down and attack one individual. I and others have observed crows doing the same thing. To me it had at first seemed logical to assume that the birds were attacking the other simply because it was a stranger, rather than because it had done something they disapproved of, or because it has harmed only one of its attackers. To admit to the possibility that it had harmed one and the others felt outraged would be to go beyond the angry raven to the potentially moral one with standards of behavior that it expects others to follow.

  Most birds attack others that come near their nests, mates, food, or territories. The attacked birds are punished for presumed intentions. Few would interpret this behavior as moral—the birds are simply protecting their self-interests. We tend to think of morality as behavior that promotes not just our own direct interests, but those of the group. The distinction is not as clear as it may appear, however. For example, a crow defending its nest from a raven may in fact endanger itself and assist its mate and its helpers at the nest. Colonial breeders defend the whole colony as well as their own interests. A bird that has once caught a certain nest raider in the act will remember that species, and even that individual. For instance, at Cornell University where Kevin McGowan climbs crow nests to band the young, he is singled out among all the students and professors for attack by crows when he walks across campus. He is attacked first by the parents of the nest he is nearest, but then the neighbors join in, helping to defend the first pair’s nest.

  Ravens would remember an individual that consistently raided their caches, if they caught him in the act almost every time. This is possible in the confines of an aviary, where the thief cannot escape vigilant eyes. Violators are remembered, and apparently, violators are attacked. That’s primitive justice in their system and ours. In such a system, the “others”—those that are identified for one reason or another, or that identify themselves as “others”—are often automatically excluded.

  I presume that the murdered wild raven in the experiment above had raided the caches of all four captive ravens. All four may simply have been defending their individual interests. If so, their behavior was not moral, in the sense we use the term. On the other hand, if one of the four birds did not see any of its own caches being raided, but still lustily joined in the murder because the others’ caches were raided, then academically speaking, it was a moral raven seeking the human equivalent of justice, because it defended the group’s interest at a potential cost to itself.

  Two subsequent experiments confirmed that group interests can drive individual volition. In one of these I introduced three yearling ravens (who had grown up together) to my group of six who had been together for two years. The six attacked these three instantly, even though none had raided caches. More tellingly, though, when one of my six attacked one of the three, its five group-mates jumped in to help in the attack. In the second case, when one pair got ready to nest, one of the mated birds at times became aggressive to one of the four other birds in the aviary. Interestingly, whenever one of the pair started an attack, first its mate and then all of the other birds also helped in attacking the same victim. These observations show that outrage is exerted, and apparently felt, along “party lines,” obliterating the birds’ original individual tolerances. Futhermore, the gang attacks are instigated by leaders; there are clear followers. The extreme case, the murder, was thus a social—and hence moral—act.

  Intolerance is something for which ravens are well known. I previously discussed (Chapter 7) mutual intolerance as a mechanism that likely keeps nests dispersed. Yet, in our radio-tracking studies of Number 8130 (Chapter 8), the resident bird easily traversed back and forth over the territories of seven local pairs, even in the breeding season, when territorial birds are most intolerant of others of their kind. In the winter at the beginning of the breeding season, I had also sometimes seen several pairs of ravens come to feed at the same carcass, and I often had seen Goliath and Whitefeather socialize with neighboring pairs in the air. I received other intriguing reports, suggesting that ravens could be tolerant of others even at their nests.

  Hans Christensen and Thomas Grünkorn, in following about 800 broods of ravens in the
Schleswig-Holstein area of northern Germany from 1985 to 1996, on five different occasions (1991, 1992, 1994, 1995, and 1996) found a nest defended by three adults. The pair’s helper, likely a female judging from its size, contributed to feeding the young. In Switzerland, Markus Ehrengruber and Hans-Rudolf Aeschbacher saw a third raven, likely a male, feeding an incubating female at a nest, and this “helper” was sporadically at or near the nest, but this nest and young were eventually destroyed. The cause was unknown. Lorenzo Russo, studying ravens on the island of Stromboli in Italy, told me of being mobbed by a pair of ravens at a nest as he was climbing. The pair left briefly to come back with three helpers, who joined the first two against him. Chris Walsh noted the same behavior in May near a raven nest on Raven Rock just west of the village of Moretown, Vermont. Chris and a companion were being chastised by the resident pair, who sometimes came as close as twenty feet over their heads. Chris wrote, “The display was mesmerizing, and we stayed.” But “soon the pair departed, flying south down the valley until out of sight. To our amazement, some minutes later, a group of eight ravens appeared from the same direction, making a direct beeline for us. They resumed, as a group, to make the same type of agitated displays the pair had made.” Similar mobbing by ravens of a golden eagle preying on a raven has been reported (Dawson, 1982).