Mind of the Raven: Investigations and Adventures With Wolf-Birds (32 page)

The wing-tipping behavior is unique to ravens. Anyone who watches free-flying ravens anywhere will eventually see a raven “tumbling out of the sky” and simultaneously tipping (or tucking in) just one wing that tilts the body to the side. In Yellowstone Park in late January, we saw this behavior, especially in ravens flying in pairs. I saw one raven dip its right wing five separate times, each time accompanied by a metallic, two-note gong-like call that may very well have been the call to which the Inuit referred. I have seen the wing-tipping in Maine in birds near a kill, when they were presumably well fed and “feeling their oats.” The three-note gong-like call is also common, although I don’t know its meaning. My friend Glenn Booma, who mimics it perfectly, says it almost invariably attracts nearby ravens. Could it indeed be an attractant call meant for other ravens that is then given to humans with the same intention? Could the wing-tilting and the call logically be connected with prey and with hunters in the Arctic?

Visibility in the Arctic landscape extends for many miles in all directions. There is little that is man- or caribou-size that could remain hidden from the view of a raven flying above the low hills. A hundred or so years ago, and thousands of years before that, the only humans walking on the Arctic landscape would have been hunters after prey, and the raven needed them to survive. Given that situation, a raven would make the connection between humans, caribou, and food in a flash. But could a raven communicate location?

A hungry or starving raven who knows that the proximity of humans with caribou means a meal would likely have felt exuberant on seeing human hunters when caribou were grazing nearby. Knowing that caribou were potential food, it might have learned that caribou in combination with people
is
food. In one plausible scenario in the evolution of communication between ravens and human hunters, one can envision a hungry raven feeling exuberant when flying over humans and seeing a herd of caribou on the horizon at the same time. As do other exuberant ravens, it may have tipped a wing as an expression of its emotion, then continued on toward the caribou to wait for the expected feast. After all, whenever it had seen humans and caribou before, it always later found entrails and other fresh meat.

The hunters could have learned as well. They would have learned that the appearance of a raven or ravens meant that large mammals were near. It would have been a small step for humans to presume that if the signaling raven flew to where they could not see, such as over a hill, that the potential prey would be there also. They would have felt the raven’s signal had been intentional. Subsequently, hunters seeing a raven flying by might wonder if it had seen them, hoping the bird would again guide them. “Tulugaq, tulugaq,” they would shout to get its attention. If it did not see caribou from up high, the raven may have had less cause for jubilation. Perhaps it simply flew on without giving any acknowledgment, and the hunter would not have followed it. Since a raven can live longer than a half century, there may have been specific individual ravens that learned the tricks of the trade of hunting with humans, and vice versa, and they could pass it on to others in a mutually reinforcing cycle that could end up resembling the well-known honeyguide example in Africa, where a bird routinely leads people to beehives full of honey.

What seems less logical to me is that the raven would tip its wing precisely in the direction of the game. It may have been that hunters were directed to game regardless of what direction they thought the raven had tipped its wing. Being alerted, they would start to look harder or perhaps travel farther. Caribou are often spread out in more than one direction. A hunter would have been led to game even if he
went south, for example, over a rise from which he had a vantage point to see caribou towards the east. In either case, the hunter who
believed
would have been more successful than one who did not, and the price he had paid for the magic words would have been worth it. As a hunter myself, I know that conviction promotes action, and only action can produce success.

The practice of following ravens must once have been common, because it has inspired humorous Eskimo tales. I presume any truly humorous tale must have a highly serious antithesis. In “The Raven and the Hunter” tale, a raven tells a hunter who wants to settle near some seal breathing holes he has found precisely where to camp. The hunter foolishly heeds the raven and camps where directed. There in the night he is killed by a boulder falling from the mountain above. The raven then flies down and pecks out the hunter’s eyes, saying, “I don’t know why all these hunters believe my silly stories.”

E
VEN A PARTIALLY EATEN MOOSE OR
elk carcass is a huge food bonanza for a raven, but that is not a guarantee for a continuous food supply. The bird may then face days or weeks without food, since any one carcass is usually ephemeral due to competitors ranging from bacteria to carnivores. There is great advantage to hoarding food for future use. Food caching by animals often looks as if it involves conscious planning, though it need not be conscious behavior. For example, bees make and store honey for use months in advance, even building elaborate receptacles of wax for this food. But these are largely programmed, inflexible responses.

What might a raven’s caching behavior look like if the bird
were
consciously aware? Overall, a conscious bird should take into account various consequences of its behavior in a continually changing scenario, not just proceed according to a script. For example, it might respond to
others’ activity. If it found competitors at a carcass, the cognizant raven would hurry its pace. It would decide whether to feed and then cache, or cache and then feed. It would decide whether to fly off with each piece of food that it removed from the larger chunk, or to wait until several chunks were removed that could be carried all at once. With the latter strategy, there would be the question of putting pieces temporarily to the side to be picked up later before departing. This option would only be taken if no other ravens that would take it were near. If others were near, the cacher would leave immediately after tearing off a large chunk, or collect small chunks and store them safely in the gular sac of its throat. When ready to depart with the meat, the conscious bird would already have picked a general destination. If many birds were near, it would fly far away. If it saw others nearby who were uninterested in food, it could simply walk a few paces and then hide the food. If others
were
interested in its food, which it would determine from watching their behavior, then it would fly far out of their sight before caching. If after flying far away, it found another raven, it would fly off again and try to find another secluded place. After caching its packet of food, it might return to the carcass and see another bird caching. It would watch intently from hiding and wait until the cacher flew away, then fly over to that site. Before it recovered the others’ cache, the original cacher (who saw the presumptive cache thief fly in the direction of its cache) would fly at the cache-robber and chase it off, provided the cache-robber was a weak bird.

What does the raven’s actual, as opposed to hypothetical, caching behavior look like? Take Goliath. Like most other ravens, he would cache surplus food if he had recently experienced a shortage. But caching, to him, involved much more than just hoarding. During one observation, I saw him grab two pieces of meat and fly into the side aviary behind a big rock. He put down both pieces of meat, dug a hole in the dirt, then shoved one piece of meat in, walked a few steps to pick up leaves, and brought them back to cover the meat. He then picked up the second piece of meat, flew to another spot, and repeated the process. Meanwhile, Fuzz had been perched quietly on the dead beech stump in the other aviary some one hundred feet distant,
intently watching Goliath through the wire screening. A few seconds after Goliath returned to beg for more meat from me, Fuzz rushed into the side aviary and found both pieces of Goliath’s hidden meat. He ate one on the spot and recached the other for future use. That was not an isolated incident.

On February 6, 1998, my six nine-month-old birds were all around my feet, feeding on scraps of meat. Blue, the largest male, got the biggest piece and hopped off with it to bury it deep in the snow. Then he hopped right back to get more meat. All continued to feed. Minutes later, Orange, the next-largest bird, walked toward Blue’s cache, but Blue flew over to intercept, and Orange aborted his attempted theft. Blue and Orange next both flew into the other aviary, out of sight of the other birds. White, a small female, immediately walked toward the site of Blue’s cached meat. She dug at the precise spot in the snow where Blue had cached the chunk of meat, pulled it out, and cached it elsewhere. A minute or so later, Orange came back, leaving Blue in the other aviary. With Blue safely out of sight, he went to Blue’s cache a second time. He dug. Of course, he found nothing because White had already raided it. I have never seen a bird go back to a site from which it had removed food or seen another remove its food. It was comical to watch Orange. He looked again and again at the other’s empty cache site, much as I had done looking for a radio transmitter (see Chapter 6), as if in genuine disbelief to find that Blue’s food was gone when he knew Blue could not have taken it. He didn’t realize that White had taken it instead.

As long as I kept giving each bird pieces of meat, there was little reason, or time, for any of them to do much cache-raiding. To see more of what was involved in this intriguing behavior, I needed to provide more motivation for it. I started by cutting two red squirrels into twenty approximately equal pieces, and I allowed only three birds into the experimental aviary: Orange, the next-to-dominant bird of the six, and Red and White, the two most subordinate ones. I showed all the pieces I had in my hands, then I started handing out the pieces one at a time, but only to Orange. Since a raven takes all it can get, especially if that means getting food away from others, he cached each piece as
quickly as he could and instantly came back to me for the next piece. Orange was very dominant over Red and White, so he had less reason than a subordinate bird to hide his caches. He made the first ones in plain sight, as Red and White watched from a perch nearby. Red was brave and flew down to dig the first piece out of the snow, and she managed to get it (or Orange allowed her to get it). But then Orange chased Red twice around the aviary until she dropped the meat. Her cache steals and the subsequent chases occurred several more times, and each time she ended up empty-billed despite her thefts. Finally, whenever Red dug up a cache, she would drop the meat without even bothering to fly off with it when Orange approached. White also ventured to steal a couple of caches and was also violently chased until she dropped the stolen meats.

After Orange had made about a dozen caches, he occasionally stopped to feed. While he was bent over picking on a piece of meat, Red and White unerringly went directly to his buried caches, pulling out his cached meat, and feeding as well. When Orange noticed their thefts, he again gave chase, even while picking up and carrying along the piece he had last been feeding on. Ultimately, he could not hide or control his twenty caches all at once within the confines of the aviary, and both Red and White got to feed.

Next, I threw in new variables. I let in the other half of this raven group, Blue, Green, and Yellow, and I gave them a calf head. Blue was the most dominant bird of the six, and he fed by standing on top of the food, as is the dining etiquette among ravens. Blue focused on trying to extricate the calf’s eye, while all the others except for Orange fed amply on the calf meat. The eye was extremely difficult to dislodge, and Blue worked more than ten minutes at this task. All this time, Orange sat watching at the sidelines, undoubtedly digesting a stomach full of squirrel meat. Being the next in line in the dominance hierarchy just below Blue, Orange was always the main object of Blue’s aggression at food. Orange held back and waited. During the moment that Blue was pulling the eye free, when I (and probably Orange)
knew
he’d fly off to cache it, Orange flew off his perch and landed on the calf head and started tearing at the meat. As Blue spent
more than two minutes walking and looking for a place to cache the eye, Orange had two minutes of feeding time. Having finally cached the eye, Blue returned to resume feeding at the calf head, and Orange left it. Several minutes later, I happened to see White, the most subordinate bird of the group, fly by me into the other aviary, carrying the calf eye in her bill. She had found Blue’s cache.

This anecdote reinforced my impression that the ability of these birds to anticipate the actions of others, coupled with their good memory, are traits that can compensate in competition with larger and more dominant associates. My observations were possible only because I was so closely in their midst. My rearing them from nestlings, and daily association with them for ten months, had won me their trust, which made the expression of their fine-grained unfiltered and hence complex behavior possible in my presence. The aviary also compensated for my inability to fly. I could follow them here, while at the same time provide an experimentally crowded situation that elicited flexible and innovative behaviors that otherwise might occur only rarely in the field where the birds can more easily avoid each other if they choose.

The ravens routinely recovered food they saw me bury in the snow. They also seemed to anticipate the actions of not only other ravens, but other animals as well. Gerald Fitz, a ravenphile from Lowell, Vermont, is convinced that his tame raven quickly figured out his buddy, the Fitz’s beagle. Gerald had rescued the raven as a nestling from a local granite quarry, where a raven’s nest had been destroyed three years in a row by blasting. The raven had grown up with the beagle. The two played with each other, and the raven followed the dog around, apparently enjoying its company. In the winter, the beagle followed the raven when it cached food in the snow, predictably taking the hidden food. The raven responded by caching in high places that the beagle could not reach. He also cached food in vertical bolt holes that had been drilled into a sill. After caching meat in the drill holes, he capped them with pebbles that fit snugly so that the dog could not lick them or the meat out.

Terry McEneaney, who has been watching ravens for a long time, has many stories to tell. “I saw the pair of magpies near the house here
{in Gardine, Montana} become terribly excited, vehemently scolding a raven. I knew something was up so I continued to watch. Soon the raven approached the magpie nest in a juniper tree. Since a magpie’s nest has a nearly impenetrable dome of thick limbs, the raven couldn’t just tear into it. The raven proceeded to methodically pull out one stick at a time, until it had finally made a hole. Then he reached in and pulled out a pinfeathered young, flew by the house, and cached it nearby under a bush in the open sagebrush. He flew right back, got another young, and cached it in a different direction under another sagebrush. He then repeated this with a third and a fourth young. He kept the fifth one in his bill, and flew off with it and went right by his nest in the nearby cliff, as if to show his mate, who was brooding their own young. She left the nest and joined him as he cached this fifth one, then she followed him back to the magpie nest. She now took the sixth young magpie and brought it back to their nest to feed their three raven young. He took the seventh and cached it under another sagebrush, then came back to get the eighth, the final one. This one he did not cache. Instead, he took it into a dense juniper where he had some protection from the screaming magpies, who had in the meantime recruited helpers to harass the offending ravens. There, in the safety of the branches, he dismembered the young magpie and ate the whole thing.”

Lesly Woodroffe of Alna, Maine, told me a similar anecdote of a raven that raided a nestful of four young cottontail rabbits. It decapitated them, cached them one by one, and only then stopped to eat.

Ravens’ policy is: “Cache while it lasts and eat later.” At the calf, deer, and moose carcasses where I have watched ravens, most of the participants exhibit almost frenetic activity as they haul off meat, especially if the meat can be torn off in large chunks. On December 24, 1991, I stretched out under a spruce blind covered with snow to watch a crowd of about forty ravens disassembling a calf carcass. In one 135-minute stretch, my four individually marked birds made twenty-three, twenty-one, eleven, and nine trips, respectively. The birds worked steadily all day long, so the forty birds may have made more than four thousand caches that day. Knowing how much they
can eat per day and how much they carried, I presume they could each only have
eaten
the equivalent of one to two caches in that time.

The average time per caching trip in the incident I have just described was ten minutes. This seems long. When caching in soft snow, ravens merely thrust their bill with the meat into the snow, then release it with a push of the tongue. Loose snow from around the hole falls in and covers the meat as the bird retracts its bill. Usually, the raven makes a few more shoveling motions with its bill to draw more snow in from the sides. When the snow is crusted, the raven will lay the meat down onto the crust, peck a hole through the crust, then pick up the meat and push it down into the hole. It will cover the hole with pieces of crust or shove snow over it, as appropriate. Similarly, on bare ground, a raven will thrust food into crevices or holes, or dig holes with its bill if none exist, and then will pick up such debris as sticks, leaves, or grass from nearby to cover the food. Ravens also cache up in trees. Making the cache itself rarely requires more than half a minute, but it may take many minutes to tear off enough meat for any one cache. Just before flying off with the throat bulging full of meat, and with additional meat sometimes dangling from its bill, a raven usually stops a second or two, looking in all directions and blinking its eyes. Then it flies far off in one direction with vigor and resolve, as if having decided where to go before departing. Almost every trip is in a different direction. No two caches are ever in the same place. The big question posed by these observations is: Why do they go to all of this trouble to fly long distances, and to disperse all of their caches, when they could potentially cache nearby without flying, or flying only short distances? The key is, individuals or lone pairs cache much closer to the source than do birds from crowds.