One Wild Bird at a Time
Page 3
On the night of January 31, 2012, I walked through a foot of new snow. A northeaster was roaring through the woods, but I heard a barred owl nevertheless. At the cabin I built a fire in the woodstove to take the chill off before settling in for the night. The next morning at first light, as always, I heard a raven pair that roost in the pines close by call raucously before leaving on their daily errands. I walked down my hill to drag up the carcass of a stillborn fawn-brown Guernsey calf, brought from a dairy farm. I left it in the sugar maple grove about two hundred meters from the cabin, where it was soon rock-hard frozen and I chopped it open so the birds could feed on it.
An hour later a raven landed in the top of a pine tree, called briefly, and left. The next evening a pair of ravens flew over to the carcass, also cawed briefly, and flew on in silence. The ravens were apparently not interested in the calf, and I later found them feeding on a deer carcass in thick woods nearby. Then a few days later, to my surprise, a group of five common American crows arrived. When I was a boy we never saw a crow in this part of Maine in the winter, and the cawing of the just-arrived crows in April was the first sign of spring. To see them here in midwinter is a treat.
With pleasurable memories of tame crows I had known, I listened to the five crows’ calls as they perched in the tiptops of the pines at the edge of my clearing. Within moments they landed on the snow near the calf, and unlike Maine ravens, which usually hesitate sometimes for days before touching a carcass, the gang of five (as I would soon call them) walked up to it and started feeding without delay. In contrast to the squabbling that ravens are prone to, the crows showed no signs of status-posturing of dominance or submission.
By February 14, tracks showed that a coyote and ravens had also come near the carcass. But although both had inspected it from all sides, neither had touched it. They had walked up to it and then veered off. I erased their tracks from the snow to be able to detect new activity in either day or night. A red-tailed hawk also came, flushing the five crows as it landed in a nearby birch tree. The gang of five flew up and dive-bombed it, cawing all the while. After two minutes the hawk left, with the crows chasing it briefly.
The calf carcass was not again of interest to the hawk, but continued to be frequented by both the gang of five and sometimes a pair of crows, though not the two groups at once. Clearly the five were not just random birds that happened to be together at a given moment because of the food. They were a team, and their companionship and solidarity differed so profoundly from what I was used to seeing in ravens that I decided to watch the gang of five more closely to learn about what it is like to be a crow rather than a raven.
One of the questions routinely asked of ornithologists is: “What is the difference between a raven and a crow?” My flip initial answer, which relates to taxonomy, is that ravens are a type of crow. Confusion stems mostly from local nomenclature. All crows (including ravens) are corvids, of the genus Corvus, from a common stock originating in Australia. About a dozen species of Corvus are distributed, for example, over North America and Europe combined. The one we most often call a crow is Corvus brachyrhynchos, the American crow. A similar species over a large part of Europe, Corvus corone, is called the carrion or raven crow. The smallest crow is the Eurasian jackdaw, Corvus monedula, which weighs about two hundred grams, roughly half as much as the common American crow.
The largest corvid is the common raven, Corvus corax, which weighs up to about two thousand grams. Perhaps because of its large size and familiarity to people all over the northern hemisphere, it has garnered a special designation as “the” raven, legendarily known for its intelligence, having a brain capacity roughly double that of the common American crow. Crows can be impressively clever, but only the common raven will fly, at times apparently alone, over the forest emitting a continuous monologue of unendingly varying exclamations and murmurings, then casually tuck in one wing and do a half-roll, as a child might skip while running along. Only ravens will dance high in the sky in the moonlight, or pass snowballs back and forth from one to another in flight (as Andrea Lawrence and Alan Burger have observed), or bring golf balls to their nest.
Another major behavioral difference between ravens and crows is that crows form stable groups of individuals. Depending on context, they often allow their offspring to stay and become helpers at the parents’ subsequent nesting. With ravens, in contrast, the young are chased off and/or disperse a few months after fledging.
February 23, 2012. There is still some calf meat left. Sitting at my desk writing, at 2:10 p.m. I hear a crow making short staccato calls. The gang of five has arrived. Four feed while the fifth perches about six meters up in the birch tree near them. It continues cawing, with only short breaks, as those on the ground eat silently. At 2:26 p.m. one leaves the feeding crowd, but it returns in two minutes, so four are again together while a watcher still caws from the perch above them. With only slight variations this sequence, of one watching as the others eat, is repeated three more times until 3:37 p.m. But then, at 3:40 p.m., when three birds are feeding, the three suddenly leave all at once, the other two join them, and the five fly off together down the valley.
The first crow had watched for twenty-two minutes. Others who took over did so for short durations, and they waited for the rest to finish before leaving with them. My impression is in agreement with folklore: crows in cooperative flocks have individuals who voluntarily desist from feeding to keep watch.
The resident pair of crows continued coming to the carcass daily later that month, long after it was nearly depleted and the gang of five had left. Finishing the carcass, the couple then came to peanuts I had spread on the snow by the cabin. On their first visit one of them kept watch and cawed while the other silently grabbed peanuts and then cached them. After a while, presumably when they considered it to be safe, the birds sometimes collected the peanuts side by side.
The crows at no time recruited strangers to share their food—a trait I tested again in mid-March 2014 by putting out a roadkill deer at the same place where I had put the calf two years earlier. A crow pair arrived within an hour, cawed briefly, and then one fed while the other perched silently nearby in a tree. After a while, the feeding crow flew up to perch. The other one started flicking its wings and tail—the signal for arousal or excitement that most reliably distinguishes crows from ravens from a distance—then flew down to feed. After that day the pair came regularly. A single crow also came. It was usually separate from the pair, though it sometimes joined them at the feast. But there was never a crowd; the same birds that had found the food returned to feed on it.
These observations might have seemed mundane to anyone else, but I compared them with those of ravens accumulated over the years at the same place. A deer carcass discovered by one raven was almost always soon shared by dozens of others, and often a cow or moose carcass soon accommodated more than a hundred. Most of the ravens came and went as individuals, rather than in cohesive groups as with crows. Ravens don’t recruit others to join in the feast from altruistic motives. Their sharing results from precisely the opposite impulse, a selfish motive not to share. Sharing happens because territorial pairs defend their food. For others to get access to the food, they need to recruit a gang and overpower the defenders. Once that goal is accomplished, a free-for-all ensues, with all the birds trying to grab as much as they can as quickly as they can. In this fracas, each raven hauls off one load of food after another and hides it, and when the source is exhausted each tries to steal caches made by others, a task that is not always easy because individuals defend even those bits of food if they can.
In the same period when the single crow, the pair, and the group of five were feeding peaceably one year on a calf and the next on a deer, a quite different scenario unfolded nearby. It occurred in an open snow-covered field by the house of Duane and Nancy Leavitt at the edge of the nearby town of Buckfield, Maine.
The Leavitts had seen a trio of crows around their property for years, and knew them we
ll enough to have named them (Dick, Donald, and George). The three had a group solidarity and were never seen to squabble. But between 7:35 and 7:45 a.m. on February 24, 2014, the Leavitts were alerted by a loud commotion in their backyard. They looked out and watched dumbfounded as two crows attacked a third while several others cawed in the trees near the field.
The three crows on the snow outside the window displayed a flurry of flapping wings and rolling about that the Leavitts described as “a bar-room brawl.” After ten to twelve minutes of this, the crows left—except for one that lay bloodied and dead. Ten minutes later a single crow arrived and pecked the dead crow. The carcass was then left in situ, and I retrieved it eleven days later when I heard about the incident.
The killed crow was lying on its back and frozen solidly into the crusted snow. Its head, buried in bloodied snow, was partially bare and the remaining feathers were matted with dried blood. Dried blood also marked its abdomen and the base of its right leg and tail. Its chest was dotted with puncture wounds. All traces of tracks from the fight had by then been obscured by a brief thaw followed by a dusting of new snow, but on the new snow there was a set of fresh crow tracks that came within a meter of the carcass.
After thawing the dead crow indoors for a day, I skinned it and was surprised to find bulging breast muscles, not the shrunken emaciated ones I had expected in a weakened bird. This crow had fat on its thighs, at the insertion of its neck, on its belly, and on feather tracts. It showed no signs of disease, prior injury, or starvation. No bones had been broken. The skull showed it to be an adult. It was a male with slightly enlarged gonads. It had sustained massive injury to the head, where skin, skull, and brain showed red from hemorrhage. Both eyes had been punctured. But not a speck of flesh had been removed from anywhere on the body.
The crow had succumbed to multiple pecks to the head in a deliberate and sustained attack. Numerous peck marks in one small area of the left breast muscles showed no evidence of bleeding; they had probably been inflicted when the victim was unable to move or after it was dead.
To my knowledge there is only one extended discussion in the literature of the rare and mostly unsubstantiated anecdotes suggesting that groups of crows gang up to attack individual crows. A commonly supposed reason for this behavior is to drive away or kill a weak or injured bird for “status enhancement.” I’m skeptical of this rationalization, because although the risk per individual participant is lower in a gang attack, the potential enhancement of status, if it were to accrue by killing, would be small, especially if it was unclear who among the crowd had done the damage.
However, there were some clues to the killing that bracketed the possibilities. First, the attack occurred near a feeder and not during a time of starvation; the crow was not killed for food. Second, the killed bird did not appear to have been weakend: it was of average to large size for a northern American crow in winter, and the autopsy indicated that it had been in excellent physical condition. These facts suggest that it may have been the aggressor, one able and willing to risk a fight, rather than a victim of a gang attack waged by individuals vying to score a kill to enhance their status.
The victim was a male strong enough to risk a fight, and he would have done so only when victory could have significant long-term benefits, such as reproductive ones. Had he tried to secure a mate by ingratiating himself with the trio of crows that had long resided in the area? The breeding male of the trio would have had more to lose than a challenger, because his mate was real, not potential. A scenario of two males’ cooperating against a would-be interloper presents an alternative hypothesis to the prevailing one of crows’ attacking a weakened individual simply because it is weak.
We humans find crows to be loveable because they have the mental capacity to bond (usually with kin). We notice this quality when we have one as a pet, to which we become a surrogate not only of the crow’s own kind but also of its family.
Social units evolve under selective pressure to garner help to gain an advantage in competition against other groups. Usually the stronger the ties to kin, the greater the intolerance of nonrelatives. So by its very nature, being loveable in bonding to members of the group implies discrimination that can lead to aggression toward others. The discrimination that results from favoring individuals for cooperation can scarcely exist without the discrimination against others, any more than light can exist without shadow.
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Getting to Know a Starling
I HAD GONE FOR A SWIM IN OUR FAMILY’S FAVORITE POOL BY a big rock in a bend of the Huntington River in Vermont. It was a hot day in August, and after a refreshing dip in the clear swirling current, as I strolled homeward along the hemlock-shaded path by the river bank, I felt a bird flutter over my head. Startled, I looked up and saw a lone starling perched in a honeysuckle bush next to the path. After a few more steps, I stopped short, thinking there had been something deliberate in this bird’s coming close to me. People routinely walked along the path to and from the swimming hole, but I had not heard of anyone else being accosted by a bird.
On impulse I picked a few berries from a nearby bush and held them out to the starling. It fidgeted. I talked to it, leaned forward, and talked some more, upon which it fluttered onto my outstretched hand, grabbed a berry, and flew back to the bush. I picked more berries, and we repeated the give-and-take maneuver.
Starlings routinely travel along the ground in flocks, turning over leaves when foraging for insects. Testing the bird further, I knelt and started scraping leaves from the ground, trying to mimic starling behavior. Amazingly, it flew down, landed beside me, and acted as though it was looking for food where I had scraped off the leaves. I had never before achieved such immediate empathy with a wild bird. I had to get to know this one better! I decided to try to catch it and take it home.
When I again held out berries, the starling landed on my hand. But as I slowly drew my other hand closer, “he” flew off (I was unable to determine the bird’s gender but will refer to it as a male). On his next landing I closed my fingers, trying to grab him by his legs, and managed to snag him by a toe. He screamed loudly until I cupped him securely in my hands. And I held him that way as I jogged the three kilometers home.
Put into an old parakeet cage after his ordeal in my hand, he seemed relieved: he shook himself and started to preen. He showed no fear of anyone in the family, and got himself adopted into a home where he would be housed and fed through the coming winter. “Pretty slick,” I thought. And so “Slick,” token of both his appearance and his behavior, became his name.
Slick, a common starling, Sturnus vulgaris, lived in his cage next to a window in our kitchen/living room. First thing in the morning when I turned on the light, he faced me and preened nonstop for about ten minutes. He reached for feathers from his back and pulled them through his bill, then did likewise for those on his breast, flanks, and throat. He angled one wing to the side and pulled shoulder feathers through the bill. He’d fluff himself, shake, go sleek, then puff out the feathers on his head and shake that. He’d stand on his right leg and stretch his left leg and wing, then stretch both wings over his head simultaneously, then raise his left foot over his left wing and vigorously scratch the back of his head with a toenail. After repeating these steps over and over, he’d lift his left foot to scratch his chin while closing his eyes, opening his bill, and uttering a tiny squeak. He might sneeze once or twice and wipe his bill on his perch. Then he’d lower his head down into his shoulders and look around.
Slick’s feather care seemed to be done for its own sake, for fun. And nowhere was the drive to have fun more evident than in his bathing routine. Bathing was his passion. Seeing water run from the tap in the kitchen sink sent him into a frenzy to be let out of the cage. I obliged him at least every three days and sometimes up to twice a day. I let the water run into a soup bowl. Whether the bowl was dirty or clean, he jumped in under the running water, squeaked as if in ecstasy, bent his legs to get deep
er, and whirred his wings like an egg beater in high gear. The spray flew several meters, soaking the floor and counters near the sink. Then he jumped out dripping wet and fluttered back into the cage to shake vigorously and preen until dry.
His grooming regimen seemed extravagant, but his appearance was worth the effort. From a distance he looked black, but from up close he glistened in sheens of metallic green, purple, and blue. The feathers on a starling’s breast, head, and neck are purple, and those on its back are green. Slick’s belly was blue with green, and just below the purple of his neck the feathers were tipped with light yellow, as if individually dipped in cream. As is typical of starlings in winter, his back feathers were fringed with light brown, so that he looked like a metallic rainbow with dots of cream and brown.
Starlings wear different garb in different seasons. Juveniles in their first summer are an undistinguished gray-brown color and their feet and legs are a dirty brown. When molting into adult plumage in late winter/early spring, they have whitish spots at the tips of their feathers, and by spring they lose the spots as the feather tips wear off. Their brilliant feather sheens then show, their bills become bright yellow, and their feet and legs turn orange.
After his morning grooming, when Slick saw me begin to prepare breakfast, he hopped around excitedly in his cage while emitting raspy, upward-inflected squeaks. I generally went to the cage and handed him a few tidbits to snack on, to get him to shut up.