Mind of the Raven: Investigations and Adventures With Wolf-Birds (5 page)

It was 6:45
A.M.
, the anticipated magic arrival time. Nothing. 6:50…6:55…7:00. Still nothing. It was fully light now, and I was sure the crowd would not appear all day. The birds’ decision about where to go had been made last night, or at the latest before daylight. It probably had been just a coincidence that the swirling crowd had flown in the direction of this bait—they had been flying to some other destination, possibly ten to twenty miles farther on. I knew all of this, and it was barely light. I still had a whole day ahead of me of sitting immobile in my blind.

I lay down on my deerskin in the semidarkness and scratched notes on folded sheets of paper, kept dry in my back pocket. After twenty minutes, the cold was already creeping in, due to my inactivity. When the body suffers in this cold, the mind does not work very well either. There was nothing exciting to look forward to. There were no birds to be seen, and there was no assurance that any would come. I had no idea—not the foggiest notion, when I might be the beneficiary of a pleasurable reward. It could be days from now, or weeks, or months.

Indeed, the territorial pair were unpredictable in their arrivals. They came at 7:10
A.M.
that day, then stayed in the vicinity much longer than previously. I heard their aggressive interactions with other ravens until about 9:00
A.M.
Presumably, these were not only against Number 837, but also yesterday’s newcomers. Number 837 did not get to feed until much later than usual. Her descent near 8:00 was her only opportunity to feed. The two other vagrants of yesterday edged close to the food only when she was feeding there. She paid no attention to them, again confirming that she was not defending her find of this food bonanza. They needed each other’s company as a shield from the adults who might come at any second.

At 1:20
P.M.
, a bird I could not see in the woods made sounds that could pass for someone hitting a metal stake into the ground with a metal hammer. The metallic
thud
was repeated several times, then the raven came out of the woods to perch near the bait. Other sounds now: a soft
growl-pop-grr
sequence, repeated at intervals, followed by a rasping series—
rraap, rraap
—to be followed by several soft hooting calls. Then the caller left. What was that all about? What was the bird signaling? And to whom? Why so many different calls in rapid succession?

A little while later, I heard the more familiar rapid series of percussion sounds, each followed by a
pop
. Also, there were regular repeated
quork
s. What strange goings-on I was observing! I felt a certain snugness in my blind. In the woods, a human is almost always seen by the other creatures first. Here, it was the opposite. They could hardly know I existed. Repeatedly, ravens had landed almost on the blind or beside it. They could not see into it, but I could see out.

I liked being invisible among them. What’s more, I possessed an almost supernatural power—I could identify some as individuals, and with the radios on, I could find out where they slept and thus find their roosts without actually seeing them at all. Unfortunately, ravens do not form one tight group that can be followed within a certain area. The population wanders over many thousands of square miles. After a bird is marked, it will not stay. Once a bird finishes feeding at a bonanza, it may be in another state the next day. I might complain about this habit of ravens, but to some extent, it is why I study them. What is easy is exhausted quickly.

When I came back down the road to meet John in the evening, I climbed up into the spruce as usual to join him until it got fully dark and all the ravens had returned to their roosts. This evening, there were no ravens at the usual roost. John had indeed read the display correctly. Here the roosts were temporary. They really were “traveling information centers,” as we titled a joint research paper in the journal
Animal Behaviour
. This roost had traveled on.

I had long been racking my brain how it could be possible that dozens, hundreds, even thousands (as one report from California indicated) of ravens can use a roost for days, or weeks, and after wandering
independently all day, suddenly one evening,
not one bird comes back!
It would be easy enough to explain if the birds always traveled in a group, but they don’t. In the early morning, they might travel together to one or several food sites. After feeding, they are more or less independent for the rest of the day, only gathering up from all directions at the roost at night. Even when all feed on
one
carcass, they still come and go from it independently throughout the day. Some may feed only for a few minutes in the morning, and then spend the rest of the day flying many tens of miles over the countryside (to look for a possible next food bonanza?) primarily alone. Was there some agreed-upon signal the night before, like the social soaring that informs them of the next stop?

As I dozed off to sleep that night, I mulled over what to do the next day. We knew a raven crowd would come eventually. Here in Maine they always do, sometime—maybe tomorrow, December 21, the next day, or two months from then if the meat lasted.

Our experimental protocol called for keeping tabs on everything until the crowd arrived, but there invariably comes a time when you say: “Enough. It’s time to do something else.” It seemed that time had come. It was time to release the next bird. After that, we would have only sixteen more to go. I hoped with more releases, we would begin to see a pattern.

The site chosen for our next release was about six miles (as the raven flies) from the previous one. I built another blind and lugged in five fifty-pound garbage bags full of meat and suet, just to make sure there was enough for a raven to share.

It was 3:00
P.M.
John was positioned up in his usual spruce, and I had been settled in my blind for half an hour. Our new bird, a dominant one, radio frequency 843, should be calm and ready to be released. Slowly, ever so slowly, I pulled the string on the door. Would the hungry bird welcome its freedom by rushing out to partake of the feast in front of him?

Not at all. From inside, he pecked at the fully open door. He leaned out and shoveled snow with his bill just in front of the cage
entrance for three-quarters of a hour! Will he ever leave his cage? I wondered, as my left leg fell asleep after holding stock-still for so long. Finally he walked out, shook vigorously as if after a long bath, and continued to peck at the snow, still ignoring the meat. He walked thirty feet west, returned, and paraded right in front of my blind. Then he flew up above me, perched in a tree, and preened for another half hour. He remained silent. Finally, he disappeared into the dense fog of the forest as it was getting dark and starting to rain hard. Our bird stayed close by for the night.

It poured all night. As I lay in a warm bed under a watertight roof back at my camp, I savored my warmth and dryness, and I thought of the raven I had released that morning. He had not eaten anything for three days, and must now be burning off calories at a tremendous rate just to keep warm.

As I settled into the spruce blind the next morning in the pitchblack, I was even more uncomfortable than usual. The driving rain had stopped, but a drizzle persisted in the heavy fog. Water settled on the branches, eventually causing a steady dripping. Lying down in the blind on my raincoat to avoid soaking up ice water from the snow, I experienced a new torture, custom-made for raven maniacs—drips of ice water hitting my face at random intervals in random places (right in the eye is the worst). Luckily, John relieved me after four hours, during which time our released bird had flown by only once. Totally unlike the previously released bird, which had alternately fed and then sat tight on some tree in the nearby forest, this one was a mover and seemed interested in joining other birds. First, he flew to visit the twenty birds at our giant aviary on the hill a mile to the north, then he also visited the second aviary with six birds to the west. Often he was out of radio contact. Do males recruit and females not? Was this just an annoying individual variation, which seem so prevalent in these birds, that would necessitate our enlarging our sample size before we would see a pattern emerge?

Next morning was foggy and cold. Eventually, I began to make out the shapes of the territorial raven pair, dueting in low grunting
honks
. Half an hour later, I heard a long series of
knock-knock, knock
knock
, like a stick hitting a hollow log. The rest of the day brought no surprises.

As on the day before, Number 843 flew over the bait several times, but showed not the slightest intention of landing. Instead, he frequently wandered out of radio contact, possibly visiting other nearby ravens. At least twice, he visited the birds in the aviary a mile away.

Near 10:00
A.M.
, the drifting fog was swirling through the trees, driven by a steady wind. It was as dark as evening, and then it poured rain. I left the blind. It was a good time to unload the 1,200-pound cow that filled the entire back of my pickup truck. I attached a chain to the cow and a nearby tree, drove forward ten feet, and presto, the raven bait was just where I wanted it. I cut the carcass open, then covered it with brush and snow, hiding it until later, when I would reveal it to the raven world for our next experiment. Before climbing the tree that would be my observation post, I rechecked the two baits. There were tracks at the first bait, and as expected, no tracks at the second bait; but Number 843’s beeps sounded close.

Suddenly, a series of quick rasping
quork
s came closer and closer from the direction of the lake, where I had put the first bait. Then a pair of ravens came into view—coal black, with powerfully stroking wings. John had seen them come from the same direction for the past three days. They were probably the pair that had intermittently been harassing my released bird, Number 837. They came by me, flying close over the treetops and steering a straight course to the pine grove to the north, where I suspected they might build their nest next spring.

Ten minutes later, a lone raven flew by, a white shoulder patch shining brightly against each dark wing. It was an adult we’d marked in a previous winter. That was a rare occurrence. We’d seen few of the 463 birds we had marked. With the exception of those residents near the cabin, I would eventually get reports of only eight marked ravens from an area of approximately 240,000 square miles stretching from Quebec, New Brunswick to Nova Scotia, Canada; and northern Maine to near Boston and western New York.

Then I noticed moving black specks against the sky. Hooking one arm around the tree I had climbed, I lifted the binoculars to my eyes
and observed ravens gamboling. What a sight! Soaring, diving, climbing, and spiraling down again, pairs and small groups and singles flew in close formation, separated, regrouped, over and over again. Gradually, they drifted over, covering a wide swath of sky in a big semicircle. They flew for miles, making air currents work for them, sailing in a sea. I was thrilled. I could have watched them all day. After about ten minutes, they banked down, folded their wings, and came shooting like so many black falling stars into the pines to the north. Was this the gang that would be led by Number 843 to the so-far-untouched meat pile?

Ultimately, after all our time and effort, we ended up proving what I already deduced from other data from previous years; namely, that ravens who are knowledgeable about food can recruit others from communal roosts. The idea of recruitment is an old one that had been endlessly bandied about in the scientific literature. We were the first to provide sufficient proof that it does indeed occur.

We had ascertained that knowledgeable birds are followed by naive birds, and that both leaders and followers eventually benefit from their behavior. The result is an inordinately simple, beautiful, and elegant system of sharing that relies on mutualism rather then reciprocity.

Our field studies provided a solid and much-needed conceptual framework in a context of behavior ecology. The studies addressed evolved adaptive patterns of behavior. Within that context, the individual variation that is so prevalent in ravens is more of a hindrance than a help in elucidating patterns within the population that we hoped to unravel. These studies could not tell us what was going on in the birds’ minds, however, because they were not fine-grained enough. They gave no indication of what was innate, learned, or due to insight. Individual variation might do that. Perhaps the best chance of seeing the involvement of mind would be by embracing individual variation and using it as a tool in future experiments.