Mind of the Raven: Investigations and Adventures With Wolf-Birds Page 3

  My four, which I had secured from two different nests, consisted of two males and two females.

  Even before they were out of the nest, the males were larger than the females. I called one of them “Goliath.” One of the females with a broken toenail on her left foot became “Lefty.” The other female was eventually dubbed “Houdi,” for the great magician and escape artist Harry Houdini, because she escaped from my aviary several times.

  By May 10, as the woods leafed out almost overnight, the ravens were hopping onto the rim of the nest I had made for them in the apple tree next to my cabin. They now constantly “talked” to me in husky, throaty voices.

  A week later, they were still unable to fly, but they frequently flapped their wings vigorously. The birds now had velvety black heads and body (contour) feathers, and shiny tail and wing feathers. They had lost the tufts of baby down attached to the ends of some of the head feathers, except for one male who had two tufts of down remaining on the top of his head. He became “Fuzz.”

  On May 17, I let them all down onto the ground. All four made little grr comfort sounds in apparent excitement. They enthusiastically beat their wings and hopped about, picking at leaves, twigs, and grass. They were fearless of a big white husky dog a friend brought. When one of the wild ravens that nest nearby at Hills Pond flew over making kek-kek-kek alarm calls at them, they froze, became silent, and made themselves look thin, pitiably shaking in fright as if shivering in a cold breeze, although the sun was shining. I told them, “Relaaax—it’s okay,” as soothingly as I could, and they did immediately relax. They fluffed out again, stopped shaking, and resumed begging for food.

  The young ravens were genuinely endearing, but gave the impression of not being very bright. They appeared to try to cache pieces of meat by tucking them into crevices, but made no attempt to cover them. They often immediately picked up the meat again to repeat the process a couple more times.

  When they were only a few days out of the nest, they could fly well, but were very reluctant to do so. Instead, they begged forlornly to be fed when I could not reach them in a tree. Eventually screwing up their courage, they would launch themselves off a branch and generally end up even higher in the next tree. Hopping always onto the branch nearest to their eyes, they kept going higher, still farther away from food.

  From the time the birds left the nest, the two males, Goliath and Fuzz, were the most dominant, and the females, Lefty and Houdi, were considerably less confident. Unlike most dominance hierarchies, this one was not static. In the next few months, there were two main power struggles, one between Goliath and Fuzz, and another between Lefty and Houdi. Goliath remained top bird for the first several months. Suddenly, inexplicably, on August 27, Fuzz assumed top-bird position. Thereafter, he was always the first at most food, and he attacked all his nestmates. At larger or feared food piles or carcasses, he allowed subordinates to go first, then chased them off. Right after Goliath’s reversal of status, I wrote in my journal that he “now has funny-looking eyes. It is as if the lower lids are drooping, exposing the whites, giving him a strange bug-eyed look. He has stopped flying onto my arm, when he had been the only one of the four birds to do so. He seems psychologically disturbed and his voice, unlike the others’, has now taken on a sharper edge. He also refuses to take food out of my hand. He has changed overnight from being the tamest to becoming the shyest of the four birds.”

  Young ravens, eyes just opening.

  Goliath was unique in another way. Shortly after he was out of the nest on June 17, he began submissively crouching to me, drooping his wings and vibrating his tail. He did this routinely to me for more than a year, while none of the other birds ever did it at all. I had felt closest to Goliath since he was a fledgling. I even had the impression that he routinely and deliberately tried to make eye contact with me. Perhaps it was reciprocal.

  By September 9, Goliath was no longer bug-eyed. He had regained his former status as the top bird, but his reactions to me remained unchanged. At that time, his dominance was expressed in the number of wins during interactions with others (twenty-seven versus nine for Fuzz at one count) and in the position he took on carcasses. Before the status flip-flop, he had seventeen top-bird positions on carcasses versus fifteen for Fuzz (and four for Lefty and one for Houdi). After he became dominant again, he held the top-bird position thirty-four times versus three for Fuzz, none for Lefty, and one for Houdi.

  Throughout the winter, Goliath clearly remained the dominant bird, regularly showing erect “ear” feathers and flaring his feather “pants,” the trapping of high raven status. Fuzz displayed rarely, and the females never. Most of the fights and chases were between the two females, who had a long dominance battle. In most of these interactions (twenty-one versus three), Lefty prevailed over Houdi.

  Goliath’s dominance display became even more pronounced by late February. Whenever I brought in a piece of food that he was anxious to have, he immediately flashed his ears, flared his “baggy pants,” then slowly swaggered up to the food and took it. The others always hung back with smoothed-down head feathers, then bowed down and fluffed their head feathers whenever they came near him. His dominance was no longer tentative. It was palpable, demonstrable, unquestioned, and unchallenged. Fuzz, in contrast, responded to my bringing food by begging like a baby bird.

  At two years of age, Fuzz was still doing the baby bird wing-flutter and uttering high-toned begs whenever I came near him, although the other three birds had not done either since November in their first year. Doting father that I was, I had begun to see them as characters, and I would soon be observing what had never been possible in the field. One of them would end up taking a wild bird as a mate, and nest in the wild by my cabin.

  A group of ravens feeding near one of my observation blinds. This photo was taken with a 400 mm lens from a window of my house in Hinesburg, Vermont.

  TWO

  A Field Experiment

  FOR YEARS, I WONDERED IF RAVENS in the wild who had discovered food were instrumental in bringing in, or “recruiting,” others to the feast.

  In field experiments, you may set up contrived but plausible situations to test responses. This has problems, the main one being that your subjects usually choose not to show up to participate in your plans. Or if they do show up, they are moved by agendas over which you have no control. My usual field approach in the early 1980s was to drag a calf carcass into the woods and then watch from a hiding place, hoping to see something interesting. Eventually, after four years and thousands of hours watching, I determined that various adult ravens lived in pairs near my study, while juveniles seemed vagrant, wandering widely, coming and going. The adults usually defended carcasses I put out, chasing the vagrant juveniles off. At least in late winter, vagrants slept together in large groups and they sometimes recruited their roostmates to bait, arriving in noisy crowds from their sleeping place long before daylight. This crowd then got to feed by overcoming the adult defenders.

  In 1988, John Marzluff, who recently had earned a doctoral degree from the University of Arizona at Flagstaff, joined me to help tackle the next problem: how ravens recruited others from the communal roost. Did they perform a dance, as bees do in a hive? Did the birds have specific “follow me” signals? Did the most knowledgeable birds leave the roost early and purposefully provide a cue that the roost-birds follow the first bird out? Did the dominant or the more subordinate juveniles recruit? Who benefited, and why? What were the costs of recruiting?

  In the field experiments that John and I were about to do in mid-December 1990, we wanted to test for the effect of a vagrant’s status on recruitment, attempting to keep everything else constant. Our idea was to release a bird of known status directly at a calf carcass in the woods and then see which birds, having discovered our offering, would subsequently bring other birds back later.

  We had done other versions of this experiment before. First, long-held captive birds, who could not have had knowledge of any food bonanzas in
the field, joined crowds at roosts without hesitation after we released them near the roosts in the evening. The next dawn, they showed up at the baits where that particular roost crowd was feeding. Control birds released on the same evening without access to a roost did not show up at the bait. This was definitive proof that the communal roost served as an information center.

  This year we would do the reverse experiment of releasing potential recruiters at baits rather than potential recruitees at roost. A huge complication to be expected was that the roost birds were already feeding at other carcasses, and hence uninterested in changing feeding sites. We would try to restrict the number of potentially competing carcasses by removing those we knew about.

  To set up this new experiment, we captured twenty wild birds and maintained them for months in our large aviary in the Maine forest. John watched these birds daily to tabulate who made submissive gestures to whom at food. He found that they were all aligned in a dominance hierarchy, starting with the most dominant bird who challenged all and yielded to none, and to whom all others yielded. We could then pick birds from either end of the dominance spectrum for our recruitment trials in the field. We had twenty radios for this experiment, which we would use to track the birds.

  The result of the first release of the year, at a food pile near the inlet to Lake Webb, was spectacular! Freed at dusk, our radioed bird did not feed, although she had not eaten for two days. Unlike most of the others, she did not bolt away either. Instead, after we opened the door of the cage, she calmly walked to a puddle near the bait and drank. Then she flew onto a tree above the bait and preened vigorously for half an hour. Next, cawing loudly, she flew north in the direction of a roost. Roosts are noisy at night, and perhaps she heard the din. We knew that the birds at that roost had just finished feeding at another bait. All the conditions that one can never control for in the field were miraculously just right. Better still, our radio signals indicated that the bird entered the roost that night. The result the next dawn was stunning: At first light they came—a string of more than thirty ravens, all flying directly from the roost to the bait that they could have known about only from our radioed bird, who was in or near the lead! Results like that convinced us that ravens can and do recruit from the roost.

  For the particular trial I’m about to describe, John picked a bird of low status. Our studies had already shown that the reason only vagrant juveniles recruit to a food bonanza is that it allows them to overpower the territorial adults to gain access to food, although there could be other reasons as well, such as wanting company during feeding at food. We now expected such subordinate juveniles as our present subject to recruit more than dominant juveniles, because subordinates should have the most to fear from the adults. On the other hand, in a crowd of juveniles, they experience less aggression at a carcass or bait, since the dominants fight with each other and are also attacked by the defending adults, thus giving the subordinates more chance to get past the socially distracted dominants to get at the meat.

  John attached a radio transmitter to the bird’s tail. He also attached a large red plastic tag to each wing. Each tag had a large number written on it, enabling us to identify the bird not only by her radio signal but also by sight. He then put her into a pet travel-cage and did not feed her for two days so that she would appreciate the super-bonanza of food we had in store for her. Meanwhile, I drove the two hundred miles from Vermont, in a snowstorm as it happened, to help conduct the experiment. My job was to release this bird at a fresh food bonanza, about 150 pounds of meat scraps, that I had dropped in the woods. The idea was that we would release this bird next to the food; i.e., we would arrange for the bird to discover the food. Would she then find a roost and bring others?

  This would be our third release. After seventeen more, we might be wiser. At least, that was the idea. I couldn’t wait to get started. We decided to release our bird on the west side of Lake Webb, about a twelve-mile drive from camp. That site was about three miles from a white pine grove where a group of juvenile ravens was then roosting at night. We hoped that our bird would find that roost after she fed. Since ravens are shy, we expected the release to be tricky—the bird could easily flee in panic, paying no attention to the meat and never locating the roost.

  I needed to build a secure blind out of spruce and fir boughs from which to watch and release the bird. I drove out to the release site at 8:00 A.M. The snow was about a foot deep, caked in giant cushions all over the red spruces and balsam firs. Near a small opening about 150 yards in from the road, I found a thicket of firs in which I could construct a blind. Every blow of my ax to one of these trees released refreshing cascades of snow onto my head and neck.

  After two and a half hours, I had built the blind. I could only see a few pinpoints of light through the back of it, but I could peek out through the interlaced evergreen foliage in the front. It was a deluxe model, tall enough to stand up in. After lugging three garbage bags full of meat from my truck through the snow to the site, I felt relaxed and thoroughly warmed. The ice and snow down the neck was almost welcome.

  There was still time to get back to camp once more, so I drove back, jogged up the trail, and made some lunch. After that, I went to John’s place to pick up the bird. I saw her large bill and her eyes through the slats of the cage. She looked calm, much calmer than one might expect a captured wild raven to be. But they are never panicky if you handle them gently. They are often even as calm as a sleeping baby in your hands. I checked her on my radio receiver—on frequency 837 megahertz, her frequency. Yes—beep, beep, beep—she was coming through loud and clear. We would be able to track her movements even in the dark and discover where she went to sleep. We hoped she’d join the nearby roost.

  The sky was dark blue when I got back to the woods by the lake. There was no wind. I pulled the tarpaulin off the meat, making it visible for the first time. I made sure the bird had a good view of it from her cage. I unlatched the door, but kept it shut, and gave her fifteen minutes to see the bait from her cage.

  I retreated into my blind, settled onto the furry deer hide I’d brought, along with binoculars, radio receiver, and note pad, and peered through the latticework of evergreen boughs.

  Within a few minutes, the bird began to hammer the door with her bill. I had attached a fifty-foot-long string to open the cage door, but in three minutes she opened the door herself, without any help from me. Totally silent and with hardly a glance right or left, she walked to the bait and began eating fat. She hacked off gob after gob and swallowed each one, then she walked all over the bait, gently picking here and there as if inspecting details. She picked up a piece of fat and walked directly toward me, stopping at the very edge of my blind to shove the morsel into the snow. Then she covered it with more snow in several back-and-forth bill-swipes. After this first cache, she made another, and another…a total of fifteen, all at different locations and within raven walking distance. She seemed to disdain flight and vocalizations, two things I considered major raven avocations. When there is a crowd of birds at a carcass, their behavior is very different; they never walk to make caches. They always fly long distances, and make a lot of noise near the carcass.

  Suddenly, her single-minded and silent pursuit of fat-caching was interrupted. She froze in her tracks. I heard the heavy swoosh, swoosh, swoosh of wing-beats, followed by the ripping, rasping quorks of a newcomer who was decidedly loud, raucous, and forceful. Round and round he flew, then he perched in a red maple tree. I was disappointed. Since the bait had now been discovered by a second bird, our planned experiment was compromised. I was, of course, still interested in what might happen next.

  The newcomer loudly snapped his bill while his “ears” were erect and his lanceolate throat hackles glistened and bristled in a perfect rendition of the macho male power display. Next, he gave a few high flute-like calls. Through all of this male dominance display, by a bird I presumed was a local adult resident, our female remained stock-still and silent, like a statue,
all the while holding the same piece of fat in her bill. When he finally left a few minutes later, she immediately resumed her feeding and caching.

  About twenty minutes later, two birds arrived, flying directly toward and then over the bait. I think one of them was Mr. Big, swinging by with his mate for another look-see. Our bird, fully gorged and having made even more caches, now disappeared. According to her radio signal, though, she did not go far. Just as it was getting dark, she finally flew out over a clearing near the bait, making a rapid series of alarm calls, the kind the birds make when a predator approaches a nest. But there was no predator here as far as I could tell. Finally, she flew down to the edge of Webb Lake about a half mile away, where, according to my radio signals, she settled in for the night.

  After I left, I stopped by the spruce tree John climbs every night for a view of the roosts and the flying birds’ behavior. That night, John saw more than thirty ravens return to the roost from the direction of Mount Tumbledown. That meant that the birds now sleeping at the nearby roost were already successfully feeding at another site, in a direction where moose are common.

  The previous year, all five of the subordinate birds we had released at baits had quickly flown off without touching the food in front of them. They then had joined the local roosts and headed for those carcasses, a calf and a deer, from which the roost occupants were already feeding, rather than returning to the food we had allowed them to discover.

  This time, we didn’t think we’d see a crowd the next day, because the roost birds wouldn’t leave a productive food site, possibly a moose carcass, until they had finished eating it. If by some chance Number 837 (our subordinate bird) joined this group, she would likely go with them to their feast rather than come alone to our bait.