Bird Brains

Don’t call anyone a bird brain unless you are complimenting them. In the last couple decades, researchers worldwide have been discovering how amazing bird brains are. That should not be a surprise since feathered winged animals that fly have been evolving on earth for more than 150 million years, according to recent genetic analyses.

Neuroscientists Suzana Herculano-Houzel and Pavel Nemec recently published a paper entitled “Birds have Primate-like Numbers of Neurons in the Forebrain,” in which they write that the brains of birds are organized much like those of primates.

“We found that birds, especially songbirds and parrots, have surprisingly large neurons in their pallium: the part of the brain that corresponds to [our] cerebral cortex, which supports higher cognition functions such as planning for the future or finding patterns.”

To truly understand how intelligent birds are, researchers study how a species behaves in the wild, conduct experiments with captive birds, and compare what they see in the field with what they learn in the lab about a species’ genes and cells.

Some bird species seem to learn as little as possible to get along. Others are bird Einsteins. Most are in between. But relatively few of the more than 9000 species of birds worldwide have been studied in detail. And in much of the last century, even though people had been reporting anecdotally what appeared to be the intelligent actions of some birds such as crows and ravens, scientists had not begun any systematic studies of birds’ brains.

An American crow on a fence post

An American crow on a fence post (Photo by Joe McKenna on Flickr, Creative Commons license)

While some of us have watched parrots dance to music and New Caledonian crows solve problems on You Tube, many of our common birds are just as clever. American crows, for example, are adept at problem-solving. One researcher observed an American crow carrying water in a Frisbee to dampen its dried mash and another one using the end of a plastic slinky toy to scratch its head while it was perching.

According to research by John Marzluff in Washington State, American crows can recognize human faces, using the same parts of their brains to do this as we do. They plan ahead when they find and then leave a gift for a human who has been feeding them. In addition, they will delay gratification if they think they will be offered something better (usually food) at a later time.

Common ravens are socially adept, remembering other ravens they were friendly with before they paired for life, recalling those special friends even after they have been separated for three years.

A blue jay with an acorn

A blue jay with an acorn (Photo by Jeff Hart on Flickr, Creative Commons license)

Still another member of the Corvid family, our blue jays, can accurately select fertile acorns 88% of the time and can count to five. They also mimic red-shouldered and red-tailed hawks. Blue jays often mimic the latter on our mountain and fool us. Some scientists hypothesize that they do this to trick other blue jays into thinking that there’s a raptor in the area and they need to leave, giving the blue jay imitating the red-tail time to harvest acorns without competition.

Another scientist noticed that a blue jay was smart enough to rub red ants on its body to get rid of the ants’ formic acid before eating them.

Because more than 80% of bird species are socially monogamous, staying with one partner for a season or even, in some cases, for life, they have developed “relationship intelligence,” which is an ability to understand what their partners want or need and respond in order to successfully breed and raise their young.

But apparently 90% of both sexes also sneak off to copulate with others without getting caught by their partners. This results in more healthy offspring.

In autumn, birds that store food for the winter, such as black-capped chickadees, grow new cells in their brain center (the hippocampus) which deals with spatial memory. This allows them to remember where they hid seeds months later.

A brown-headed cowbird female in Codorus State Park

A brown-headed cowbird female in Codorus State Park, near Hanover, Pennsylvania (Photo by Henry T. McLin on Flickr, Creative Commons license)

Brood parasites such as brown-headed cowbirds, especially the females, have large hippocampuses, because they are the ones that must lay their eggs in other species’ nests. They must find, remember, and revisit the nests they parasitize.

And invasive bird species, such as house sparrows and European starlings, have larger brains, are innovative, and have more flexible behavior because they must adapt to a foreign environment.

But our brainiest birds may be hummingbirds, because their brain is the largest brain relative to its size, a whopping 4.2% of their total body weight. Their hippocampus is five times larger than that of songbirds, seabirds and woodpeckers. They can remember every flower in their territory and how long it takes them to refill with nectar after they feed from them.

A ruby-throated hummingbird at a feeder

A ruby-throated hummingbird at a feeder (Photo by likeaduck on Flickr, Creative Commons license)

From year to year at home and in migration they also remember where every feeder is. They even learn which feeder people are responsible or irresponsible and have huge episodic memories that allow them to plan when and where to feed on hundreds of flowers a day.

The females watch older females making nests to learn how to do this because female hummers are on their own once they have bred. They must build their nests, brood their eggs, and feed their young alone.

Hummingbirds have the ability to move backwards, forwards, and sideways because they have more complex brains. In the part of their brain that responds to visual stimuli, instead of the usual back-to-front preference most animals and humans have, hummingbirds have no preference and can move in any direction.

A ruby-throated hummingbird at a flower

A ruby-throated hummingbird at a flower (Photo by chrisdupe on Flickr, Creative Commons license)

During their mating flights, which we’ve watched with awe from our front porch, they make instantaneous course corrections much faster than a fighter jet. Thus, their brains can move efficiently in three dimensions, which some scientists believe makes their tiny brains the most complicated of any vertebrate species.

Hummingbirds have not been considered songbirds, but biologists Claudio Mello and Erich Jarvis have found that hummingbirds have the same areas in their brains that control song learning and production as songbirds and parrots. They do sing in a higher pitch than songbirds, but their songs are amazingly rich, and in some species, complex.

Neurobiologists have been comparing birdsong with human speech and language. Like human children, young birds listen to other birds of their species to learn songs. They imitate and practice, seemingly using the same brain structures and genes to learn songs as children use to learn language. Some birds even stutter.

There is incredible variety in birdsong, as various as the 4,000 songbirds on our planet. And if you listen as carefully as Donald Kroodsma, who has been studying birdsong, especially in the eastern United States, for more than 40 years, you might be able to hear the 30 to 40 songs of a Carolina wren, the 50 to 100 of an eastern bluebird, the song and mimicking calls of a white-eyed vireo, the 30 to 40 songs of the ethereal wood thrush, the 200 to 400 different mimicking songs and calls of a gray catbird, the 100 songs of a northern mockingbird, and the 2,000 of the mimic champion—the brown thrasher.

Then there is the hermit thrush whose song has been compared to human musical scales with trills and slides reminiscent of a woodwind instrument. Some ornithologists have claimed that hermit thrushes sing major, minor and pentatonic (five note) scales.

But composer Emily Doolittle and biologist Tecumseh Fitch didn’t believe it. Still, using recordings of 14 hermit thrushes from the Borror Laboratory at Ohio State University, they started analyzing the pitches of 114 song types. When they slowed them down, they could hear their harmonies.

A hermit thrush singing

A hermit thrush singing (Photo by Yankech gary on Flickr, Creative Commons license)

“They jumped out at us,” Doolittle said, adding that 70% of the hermit thrushes’ songs were harmonic.

And maybe most miraculous of all to us are our songbirds that migrate. Scientists have found that at first they rely on genetic information for both direction and distance until they gain experience. Then they use their own brain maps to find their way. They build up magnetic maps during migration and some may use odor to help guide them. Some researchers even think they may hear a landscape infrasonically, especially the ocean, to help navigate. But to do all that and more they must possess fantastic spatial memories.

Every day, it seems, more is being revealed about the brains of birds. It’s a hot topic. For instance, researchers have recently found that the bird that is closest to its dinosaur ancestors is our own wild turkey. That’s because, since the days of feathered dinosaurs, the wild turkey’s chromosomes have had fewer changes than those of other birds. And, as any hunter knows, wild turkeys are wily and smart.


Mindful Creatures

This column was rejected by the new editor of Game News because of what he considered to be controversial content. No doubt he knows his audience. But I would like to put this column out for my web readers who may find it useful and may, like me, wonder why so many people are willing to believe that their domestic pets have minds but not wild animals who, we must admit, have much harder lives to live. Surely we have all evolved from the same beginnings, and surely that means that other mammals, like us, as well as birds and other creatures, must have minds that resemble ours, even if they are not nearly as well-developed. On the other hand, many of these species have lived longer on this earth than we have.

North American porcupine close up

Up close and personal with a porcupine

For almost half my life, treating wild creatures as thinking beings was scorned as anthropomorphizing them. Most scientists considered them to be little more than thoughtless robots. They neglected the study of animal minds because they didn’t believe that they could tell the difference between automatic, unthinking responses on the part of animals from possible behavior that showed an ability to make choices in what they do.

In school, students learned that it was unscientific to ask what an animal thinks or feels. If they were so bold as to ask, they were “actively discouraged, ridiculed, and treated with open hostility” as Donald R. Griffin wrote in his ground-breaking book Animal Thinking back in 1984. A renowned bat biologist, his previous book, in 1981, The Question of Animal Awareness, had been the subject of widespread derision. Still, he was able to give many examples of seemingly thoughtful wild creatures who, when they were confronted with new problems, acted creatively to solve them.

The writings of Griffin and other scientists, interested in what Griffin called cognitive ethology, have encouraged some scientists to study learning in vertebrate and invertebrate animals. They have been bolstered by the work of neurobiologists, who study the brains of animals and have made some amazing discoveries, most notably the fact that an animal that has loops between its thalamus and its forebrain is a conscious thinker. Birds and mammals, including humans, have these loops. So too do reptiles, although their loops are minimal.

New Caledonian Crow painting by John Gerrard Keulemans

Corvus moneduloides, New Caledonian Crow (John Gerrard Keulemans, 1877)

If you call someone a “bird brain,” you are paying them a compliment. Birds, especially those in the Corvid family, have brains that weigh almost as much as ours do in relation to our total body weight. Our brain weighs three pounds or 1.9% on average of our body weight. Ravens and most crow species have brains that make up 1.4% of their body weight, although the super learners in the Corvid family—New Caledonian crows—possess brains that comprise a whopping 2.7% of their body weight. These percentages compare with those of similar-sized mammals such as small monkeys. Other bird species, even smaller songbirds like chickadees, also have amazing brains.

These discoveries and many more have been recently pulled together in Gifts of the Crow: How Perception, Emotion and Thought Allow Smart Birds to Behave Like Humans by Dr. John Marzluff and Tony Angell and Bird Sense: What It’s Like to Be a Bird by Dr. Tim Birkhead. Both of these books are written for a general audience but they make use of dozens of scientific papers with such titles as “Stress, Corticosterone Responses and Avian Personalities” (my italics) by J.F. Cockrem in the Journal of Ornithology and “An Intelligent Crow Beats a Lab” by A. Straub in Science.

All of this is an introduction, of sorts, to bird, mammal, and reptile behavior my husband, Bruce, our son, Dave, and I observed last June. None of it was particularly cutting-edge, but more than once I wished I had a better understanding of animals’ minds. Or, in the words of Griffin, “We like and admire other animals… because we enjoy trying to imagine what their lives are like to them…”

Dave exchanges threat displays with a porcupine

Dave communes with a porcupine (photo: Bruce Bonta)

That’s what I did wonder one June morning when a large porcupine waddled toward me on the Far Field Road. I stepped off the road and watched as it advanced. Because of its whitish quills, it looked as if it had a halo over its shoulders. Once it paused to scratch itself. When it was almost abreast of me, it turned and crossed the road, headed in my direction.

“Hello,” I said. It stopped and spread its tail to impress me with its quills. I continued talking quietly to it. Finally, it turned around and leisurely retraced its steps. Then it left the road and went into the woods where it slowly hitched its way up the largest chestnut oak tree beside the road. It flattened itself out on one of the highest branches overlooking the road directly above me, alert and watchful, until I moved on.

I’ve encountered numerous porcupines on our trails, and usually they hiss, spread their tails, and scramble up the nearest tree. But this porcupine, which looked like a grizzled old timer, didn’t seem fazed by me. Was it the animal’s age, experience, calmer temperament, or something else, I wondered, as I continued on my way.

Several nights later, Bruce was awakened by a bang on the back porch below the bedroom. He got up, grabbed his flashlight, and went downstairs to investigate, thinking that maybe a burglar was trying to get inside.

He tiptoed out to the kitchen, turned on the porch light, and saw not one but three masked bandits—a mother raccoon and her two kits. Since we had taken in our bird feeders two months before, he couldn’t figure out what they were doing as the little ones climbed up on the railing and the post that supported the porch roof. He shone his flashlight on first one kit, then the other, and finally on the mother but none of them seemed bothered by the light.

Raccoon family unit

Raccoon family unit (photo: Bruce Irschick, Creative Commons BY-NC-ND license)

He watched as they sniffed and explored. At last they climbed off the porch and trundled over to the outside cellar steps. Then one of the kits poked around in the grasses just below our sitting room bow window. That was when the mother raccoon noticed Bruce watching them. Or perhaps she smelled him through the screened window. She snarled loudly, but all three raccoons kept poking around in the underbrush as they made their way slowly toward the front of the house and out of sight.

This time it was Bruce who wondered about the mind of a raccoon, and the next morning Dave solved the mystery. He noticed that a bald-faced hornet nest (Dolichovespula maculate), which had been attached to the porch roof, lay in gray tatters on the porch floor. In that case, the mother raccoon had been teaching her kits about one of their favorite foods. I was reminded of a Nature show I had watched on PBS about how cleverly raccoons adjust to and find food and shelter even in busy cities. According to raccoon researcher, Stan Gehrt, raccoons are incredibly adaptive. Even their personalities change from shy and reclusive in the country to bold in the city as they use their hand-like paws and mammal-sized brains to defeat humans’ numerous attempts to design raccoon-proof garbage cans.

The male flicker at the nest hole

The male flicker at the nest hole (photo: Rachel Rawlins)

During last May and June Dave enjoyed sitting on his front porch and watching a yellow-shafted flicker family set up housekeeping in a dead elm tree at the edge of his yard. For more than a week in early May, the male and female took turns excavating the hole said to be 13 to 16 inches deep. Muffled knocks from inside the dead elm led to a flicker head popping out of the hole and flinging a bill full of wood chips into the air.

Eventually, by mid-May, their excavation work was over, and the female laid her 5 to 8 eggs. Then the parents attended the nest in shifts, each one doing its share of work. They were due to hatch in 11 to 13 days. In the meantime, they fought off a pileated woodpecker, downy woodpecker, and another flicker, all coveting the nest hole, and reminding me of the many times I have watched flickers over the years try to establish a nest in a black walnut tree hole beside our driveway. Never once have they been successful because of gray squirrels who consider it their home.

On June 12 Dave noticed that both parents were outside the hole at the same time for as long as 15 minutes, and he wondered if the eggs had hatched. The next afternoon he again saw both parents outside, and the male sounded agitated. The female sat on a dead elm branch a few feet above the nest hole.

The black rat snake after its meal of flicker young

The black rat snake after its meal of flicker young

That’s when Dave noticed something sticking out of the cavity. It was the head of a black rat snake. Somehow the reptile had realized a meal awaited it 25 feet up the nearly smooth trunk of the dead elm and managed to climb it.

It remained in the hole, digesting its meal until 10:30 a.m. the following day, and Dave watched as it spent 50 minutes slowly descending the tree trunk, seemingly studying all the alternatives each time before moving to a new knot, branch, or other protrusion where it could gain some purchase. It used a tall lilac shrub limb to move from the elm trunk to a dead branch that arched up from farther down the tree and then followed that branch to a lower spot on the lilac and on to the ground.

All of this reminded me of the most notorious article I ever wrote that was published in Bird Watcher’s Digest about watching a black rat snake get into and out of a house wren nest built inside one of our back porch posts. It took the snake one hour and forty minutes as it maneuvered up to our second floor, peered into windows, slowly lowered its body down the shingled porch roof and down the post into the nest. When it finally emerged, it worked even harder finding its way out by way of the drain pipe, down the post, and on to ground with many stops as it seemed to think its way past obstacles and over rough spots. As Griffin wrote, “mental events such as consciousness and awareness are indicated by surprising yet effective solutions to changing, unforeseen, and uncommon problems.” Both Dave’s snake and especially mine seemed to show such awareness.

Black rat snake in a black walnut tree

Black rat snake in a black walnut tree

It had been a scolding Carolina wren, not the silent flicker parents, who sounded the snake alarm. And it was a Carolina wren who sang along with a mezzo-soprano in Massenet’s opera Werther, which Bruce and I were watching during a hot June afternoon. The wren was busy putting twigs in the gap next to our living room window air conditioner. I checked the pitch of both the soprano and the wren and realized they were performing a kind of duet. Was the wren challenging what it thought was a wren intruder or did it enjoy the music? This time I was reminded of a white-tailed deer that stood still outside our kitchen window years ago when I was playing Mendelssohn’s Elijah. She looked as if she was listening to the music.

Carolina wren at the window

Carolina wren at the window

Our last bird observation went on for much of June when an eastern whip-poor-will chose our yard and Dave’s for his evening and dawn chorusing. A couple times he landed on the flat porch roof outside our bedroom window. Once when I was awakened by him at 5:00 a.m., I put my glasses on and snuck to the window where I had a view of him belting out his calls at deafening volume for about five minutes. He seemed so small to have such a loud mouth and reminded me of Dr. Seuss’s assertive Lorax in the way he stood.

The whip-poor-will was, of course, acting as male whip-poor-wills always do in spring and early summer. I only wondered about him because he started later and stopped earlier than whip-poor-wills are reported to do. But then the life style of these birds is still poorly understood because of their secretive, nocturnal lives. No doubt they too are able to solve unexpected problems with enterprising solutions, the strongest evidence, Griffin concludes, that suggest animal consciousness.

Photos by Dave Bonta except where indicated.

Flying Monkeys

Crows acting up, by Greg7
Crows acting up, by Greg7

“Why don’t you just shoot them?”

That’s the reaction of most homeowners when Grant Stokke asks permission to live trap American crows in their backyards. But he hastens to add that they do give him permission.

Stokke is a graduate student who is working with Dr. Margaret Brittingham, professor of wildlife resources at Penn State University, to try to understand the dynamics of winter crow roosts in Pennsylvania, specifically one in and around the city of Lancaster.

I joined Brittingham, Stokke, and field assistant David Burkett for a day of crow field work last January after reading about attempts the winter before to chase the birds from their winter roost in suburban Lancaster County. That winter three townships had called in the United States Department of Agriculture’s Wildlife Services to set out poison bait, which didn’t work very well and angered citizens who opposed using a toxic chemical to kill crows.

Lancaster isn’t the only mid-sized city adjacent to agricultural fields that supports winter crow roosts. Harrisburg, Bethlehem, Scranton, and most recently Lebanon, have a similar problem. So too do a host of other places from Auburn, New York to Riverton, Wyoming.

Most places have tried a combination of noisemakers, shooting, distress calls, and other harassment techniques such as hanging dead crows from trees at their roost site as Lancaster County did the previous winter to chase them away. Sometimes the crows leave, but usually they return.

After all, crows have always formed winter roosts. They used to be in the country, but now that we have provided well-lit malls and city streets that keep away crow predators, specifically their nemesis — the great horned owl — and which are close to agricultural areas that provide food during the day, crows spend the long, dark, winter nights close to humans. Unfortunately, they are not only noisy but incredibly messy, covering buildings, sidewalks, and cars with their excrement.

In the Lancaster area, the crows begin arriving the second week of November and build up their numbers in December. To find out where they are coming from, Stokke and Brittingham have collected stray feathers from American crows, which they subjected to hydrogen ion testing. The test indicated that those crows were in Canada when they grew their feathers, proving that winter roosts consist mostly of migrant crows.

Kevin McGowan, who has been studying American crows in and around Ithaca, New York, since 1988, writes that several of the birds he has tagged there, “have been shot or seen in Pennsylvania during the winter,” so at least a few of the crows come from New York state.

Furthermore, Stokke and Brittingham have discovered that about 25 to 35% of the local crows will occasionally join the roost.

“They will roost at the communal roost some nights and within their family home range the rest of the time. The other 70 to 75% roost within the family home range all the time,” Brittingham said. This finding directly contradicts McGowan’s research in Ithaca in which he found that winter roosts there are made up of migrants and locals and that all locals join the roost.

“I don’t know why there is a difference with Ithaca,” Brittingham said.

There Is A Light
“There Is A Light,” by CrowHand

But knowing where they come from doesn’t solve the problem. That’s why Stokke and Brittingham, in their crow behavior study — “Ecology and Management of Urban Crows in Pennsylvania” — are working with local citizens’ groups, local, state and federal government officials, and colleagues at Franklin and Marshall College “to develop a multifaceted approach to reducing the crow problem,” Brittingham said. “But,” she added, “there’s got to be some place for them to go.” Ultimately, Stokke said, they are “looking at whether we might create a place to attract these crows where they won’t be so much of a problem.”

Last winter, instead of poisoning crows, USDA Wildlife Services trained citizens in a variety of harassment techniques including shooting blanks at the birds. First, this harassment moved them from a suburban area northwest of Lancaster, which includes the Park City Mall, where the crows roosted on their 10-acre roof and pecked holes in it. They also made a mess of cars in the parking lot.

Then the crows congregated in center city Lancaster for two weeks. That, Stokke told us, was a rough neighborhood, but still the citizens continued their harassment.

The plan was to move the crows to a county park southwest of Lancaster. It was ideal crow habitat, they thought, but the crows didn’t agree. Instead, they circled and returned to the original northwest light industrial area near farm fields, and that’s where Brittingham and I met up with Stokke and Burkett.

They had already done their pre-dawn roost count, which they estimated to consist of 30 to 35,000 crows. Of those, ten to 20% are the smaller fish crows and the rest are American crows. So far they don’t know where the fish crows are coming from, although Brittingham said that, “Wildlife Services banded a lot of fish crows so we may eventually figure that out.”

Stokke and Burkett also drive a daily route to see where the 42 radio-tagged American crows, half of which are locals and half migrants, spend their days. They took us along for a portion of their route. At the edge of a field across from a housing development, the radio buzzed as we approached an American crow with a white antenna affixed to its back.

“That’s the first one I trapped,” Stokke said. He discovered that this local American crow family of nine or ten birds has less than a square mile of territory. They rarely leave it, although at least two crows did join the Lancaster roost for one night. Such information is hard won, because trapping American crows is not easy, as we found out.

Large-mouth crows
Crows eating French fries, by Greg7

The bait that day was ground beef and peanuts in the shell, but usually it is hot dogs and Chitos, which are cheaper, Stokke told us. At the edge of a corn field, they spent many minutes setting up a portable trap designed by USDA’s Wildlife Services and then carefully camouflaging it with dried grasses. We retreated to their sport utility vehicle and waited for an hour.”All it takes is one brave crow and the rest are in,” Stokke said.

But not one crow came near the trap, not even a fish crow.

These smaller crows, Stokke explained, are easier to trap but they have to release them because the radio-tags are designed for the heavier American crows.

We moved on to a backyard across from a Barnes and Noble bookstore. Cars streamed past on nearby U.S. Route 30 and the Fruitville Pike. A line of tall trees divided the backyard from a corn field. Another copse of trees split the corn field, and it was there that the crows had congregated. We watched for an agonizingly long time as first one crow, then another, flew into the backyard trees for a look at the bait. Finally, one landed near the trap.

“One healthy bird, glossy feathers, lots of body fat,” Brittingham commented. She figured that it was too well-fed to be tempted by their bait. Usually it was a great place to trap crows, but the birds often outsmart them according to Stokke.

While we watched, the crows continued to fly over the bait, but no more birds stopped to look. I felt as frustrated as the researchers.

“They don’t look hungry,” Brittingham said.

By then the crows were engaged in what the scientists call PRA (pre-roosting aggregation) or staging in groups away from the roost, and everywhere we looked we could see flocks of crows calling and chasing.

“I think of them as flying monkeys,” Stokke said, “because they are so smart.” Other researchers agree that the crow family in general is incredibly intelligent. Carolee Caffrey, who studied American crows in Oklahoma, watched a male crow shape a piece of wood into a probe by pecking at its tapered end. He then stuck it into a fence post knot to extract a spider lurking just beyond the reach of his bill.

Caffrey also watched a female American crow defend her nest from a climbing researcher by breaking off pinecones and dropping them on the climber’s head. Altogether, she hit the researcher three out of four tries.

American crows are also the ultimate family-value birds. They mate for life, live in family groups, and older siblings often help feed and protect their younger brothers and sisters. Unlike most other wild creatures, adult American crows never chase away their offspring. When they do leave their family, they return frequently to visit. McGowan, in Ithaca, reported that “one individual (less than one year old) was seen at a compost pile in northern Pennsylvania with a flock of crows, and three weeks later it was back in Ithaca with its parents who were starting nesting. It helped the parents raise young that year, and remained in the area over subsequent winters.”

As the afternoon waned, crows flew more purposefully toward the roost area. In the distance we heard the “pop” of blanks being shot by citizens using nonlethal harassment techniques. The light industrial area hardly looked like a natural area. Under a single conifer surrounded by business buildings, Stokke spotted a banded dead crow. It was not one of their bands so he copied down the number and removed a tail feather for hydrogen ion testing. He also examined it for injuries and found none. The crow was stiff, covered with excrement, and had probably died on the roost the previous night.

The service manager for a nearby car dealer emerged from the back door, and when we told him what we were doing, he launched into his own crow woes. The crows had been using their roof for two weeks.

“We’re just not happy about it,” he said. “They hit a lot of new cars when they take off in the morning — “cars they have to wash before customers arrive.

Eventually, driving through a maze of linked roads behind business buildings, we reached the back of loading docks where we parked. On one side beyond the parking lot were a cattail-filled wetland, a line of tall trees, and the backs of substantial new homes. In front of us was a posted, chain link fence. Beyond that was a large grassy area and then a cement factory.

crow roost
A crow roost in State College, Pennsylvania, by mandy whale

Standing behind the fence, we watched in awe as a glorious sunset lit the thousands of crows flying in from all directions. Many alighted on the flat-roofed buildings, cawing loudly. Others landed in the line of trees along the wetland, disturbing a large flock of Canada geese that joined the general hubbub and flushing a great blue heron.

What a spectacular, yet ludicrous sight. Stokke, who had previously studied common ravens in a remote area of Washington state, could not imagine a more stark contrast to his present situation — malls and business buildings, housing developments, and crushing traffic.

Yet nature persisted and, in fact, preferred the city/suburban landscape. In our rush to expand and develop we had created ideal winter habitat for the gregarious, intelligent crows. Safe from predators and warmed by the “heat bubble,” rising from the buildings which can be five to ten degrees higher than the surrounding countryside, the crows slowly settled down for the night.

To learn how you can support local volunteers in Lancaster and protect the crows from lethal management, visit the website of the Lancaster County Crow Coalition.

All photos used by permission.

Owls of Winter

January is great horned owl month on our mountain. Not only are their hoots the quintessential signature of long, silent, moonlit, winter nights, but they are also more visible in the day time. During the rest of the year I may have an occasional glimpse of one as it flies from a roost, but my best sightings have occurred in January, most notably January 18, 1993 and January 19, 1998. In both instances the mobbing calls of American crows alerted me to their silent, motionless presence.

The 1993 sighting occurred on a windy, 20 degree, sunny morning. I tracked scolding crows to Margaret’s Woods, but I could not see any enemy they were mobbing. Still they persisted, so I finally walked toward them up the Steiner-Scott Trail (a recent logging road that leads to the top of Sapsucker Ridge).

Halfway along the trail, I spotted a large, beige-colored blob on the branch of a tree swathed in grapevines. To my delight that “blob” was a great horned owl, bathed in sunlight and not inclined to fly. I sat below it, my back against a tree, and watched as a pair of black-capped chickadees flew in close to scold the owl. Then a tufted titmouse joined the chickadees as they called a couple feet from the owl’s head. It blinked its eyes open to look and the birds flew off, so it closed its eyes again.

After a few moments, it again opened its eyes and slowly turned its head to the side. The eye toward me watched as I stood up. After I took a couple steps, it flew off.

I was amazed at how perfectly it had blended into the tree branch and grapevines. Without my binoculars I never would have distinguished the owl with its perfect camouflage. I thanked the crows, which for once had had something to crow about.

According to biologist Bernd Heinrich, who studied mobbing behavior while raising an orphaned great horned owl, birds that are permanent residents of an area, such as the tufted titmouse and chickadees I observed, use mobbing to encourage owls to move on. He further hypothesizes that “since crows have conspicuous roosts to which they return each night, the ‘move-on’ hypothesis should apply especially strongly to them. And, indeed, the vigor of the crows’ mobbing in winter is surpassed by few other birds, even in spring.” Furthermore, after analyzing owl pellets in his woods, he discovered that crows were the principal prey item of great horned owls there.

Whether or not our great horned owls prefer crows, mobbing crows again “showed” me great horned owls last January on an inclement morning. A light snow fell as I walked Greenbrier and Ten Springs trails through a forest that had been clearcut seven winters ago. But as I neared the end of Ten Springs Trail, five crows cawed loudly in the uncut forest ahead. I sat down in the heavily wooded hollow and, looking uphill, I quickly spotted the shape of a great horned owl sitting out on the end of a tree branch. It looked as if it were unbalanced, an extension of a branch that leaned but, in fact, the branch had a projection against which the owl was braced.

I sat and watched for fifteen minutes as two crows remained nearby, occasionally emitting low noises of approbation in their throats. Then I spotted a second, slightly larger owl sitting tightly against the tree trunk. No doubt it was a pair–the larger female against the trunk, the smaller male out on the branch. I’d never seen a pair before so I continued watching them until I was too stiff and cold to remain any longer.

As I stood up, stretched my cramped legs, and continued my walk, the male, which had had its head turned away from me the entire time, finally looked down at me. The female never moved. In both owls, it had been their ear tufts that had made it possible for me to first pick them out despite their frozen stances and excellent camouflage.

Heinrich also speculates on the use of ear tufts. Fifty of the world’s 131 species of owls have them, yet no one is sure what function they serve, if any. In the case of Heinrich’s captive great horned owl, Bubo, he says that “he has a fondness for perching on broken-off tree trunks, where he quite effectively impersonates the top of the stub” and wonders if the reasons for ear tufts could be that they mimic the ears of mammals which helps them in their threat displays, they serve as short-range species-recognition marks, and/or they provide added camouflage. Perhaps ear tufts helped to camouflage Bubo but not the wild owls I observed.

I assumed that the pair I saw was the same couple that hooted throughout the winter near our home since a breeding pair needs a square mile of good territory, which is exactly what we own. On February 13 and 14 a pair called from trees on top of Sapsucker Ridge in early evening, and we could easily see them with our binoculars. By February 18 they had moved to the small woods above our garage and hooted most evenings and early mornings until March 16. The female hoots are shorter and higher pitched than those of the male. Researcher John T. Emlen had sharp enough ears to detect grunting noises the male makes before he hoots and in between hooting to stimulate the female to hoot. The female hooting in turn stimulates the male to continue hooting. All of this is part of the annual courtship ritual between birds that mate for life.

Solitary hooting by males is done to advertise and defend their territories, which they hold on to throughout the year. Most great horned owls remain in the same area where they hatched unless food is scarce. Then the young may move on, as far as 837 miles in one case. But established pairs may choose not to breed if food is scarce because faithfulness to their territory is stronger than the urge to breed in most paired great horned owls.

When there is enough food, courtship takes place mostly in early January and February evenings and includes calling, displaying, mate-feeding and allo-preening. First the male approaches the female by hooting and landing on perches close to her. She may answer him if she is interested. He then performs such displays as fluffing his body feathers, partly spreading his wings and bowing, walking and hopping on the ground, and/or throwing his head back and repeatedly snapping his bill. If she doesn’t fluff her feathers or snap her bill at him–both signals that she is not interested–he sits on the same perch with her, gradually sidling closer, until they preen each other by pecking at the feathers around their mate’s bill and/or head and sometimes emitting a variety of barks, screams, whistles and hoots. Then both hop and bow, and occasionally a male brings in food for them before they mate. After mating, the pair often roosts together during the day like the pair I observed last January.

Great horned owls never build their own nests. Instead they occupy the used nests of red-tailed hawks, crows, ravens, herons or squirrels. Last winter I examined dozens of old squirrel nests in search of nesting great horned owls but never found any. Since they occupy their nests and lay their one to four white eggs from mid-February to early March in Pennsylvania, deserted nests are easy for the owls to preempt. The female, occasionally relieved by the male, incubates the eggs from 28 to 30 days, but once the eggs hatch, the female keeps the young warm while the male provides food for the family.

The young hatch over several days, according to the order in which the eggs were laid. if food is abundant, all of them survive and thrive. If it isn’t, the largest owlet is fed first and competition is fierce. Often the youngest (and weakest) die.

At two weeks of age their eyes are open, at three brooding stops, at four to five weeks they can move about the nest, and at six to eight weeks they leave the nest, perching on nearby branches where their parents continue to feed them. When they are nine to ten weeks old, they attempt to fly and gradually, after ten more weeks, they have learned to fly and been taught by their parents to hunt well enough to disperse, although half of all young do not survive their first year.

Humans have been their most implacable enemies. Because great horned owls eat popular game species such as ruffed grouse, eastern cottontails and ring-necked pheasants in Pennsylvania, persecution of great horned owls in the form of bounties were in place from 1937 to 1941 and from 1944 to 1966. The Federal Migratory Bird Treaty Act of 1972 forbade the taking of all raptors including great horned owls, and since that time their numbers have increased.

Great horned owls are opportunistic feeders and tend to eat whatever is available including rabbits, foxes, porcupines, skunks, other owls, hawks, crows, feral cats, mice and rats. They fish in water up to their stomachs for fish, turtles, crayfish and frogs, although Heinrich’s captive Bubo distinguished between wood frogs, which he relished, and bullfrogs, which he disliked.

One researcher in Wisconsin watched as a great horned owl perched on a tamarack tree, bobbed its head, flew off into a gradual climb, flipped back in midair, and grabbed large, chunky beetles, which it carried back to its perch to eat. Another owl was observed as it ripped a muskrat from a trap and still another tried to grab a raccoon from a hunter’s shoulder. Bubo dined happily on fresh kills made by Heinrich’s cat–mice, voles, shrews, and songbirds–and on fresh road kills collected by Heinrich. Heinrich also fed him red squirrels that he shot.

Years ago, when we raised Muscovy ducks, we arrived home after sunset and watched a great horned owl trying to fly off with our alpha male Muscovy named Big John. Big John flapped valiantly as the owl aborted a couple liftoffs before giving up. In the end, though, it was a raccoon that wiped out all 27 of our ducks as they roosted in the barn.

A food study done in Pennsylvania from 1965 until 1986 by biologists Wink, Senner and Goodrich analyzed owl pellets from 17 counties throughout the commonwealth and found that although eastern cottontail rabbits were a favorite prey item of great horned owls (15%), ruffed grouse prey ranged from 9% in northwestern Pennsylvania to 4% in southeast Pennsylvania and pheasants a mere 3%. The overwhelming favorite prey, however, were Norway rats (24%). But if the diet was based on the weight of the prey, opossums constituted 33%, rabbits 28% and Norway rats 12%.

The rats are an indication of how popular farm habitat is with great horned owls. According to a study carried out by Yahner and Morrell from 1986 to 1989 in south central Pennsylvania, great horned owls hunted most extensively in agricultural areas and adjoining woodlands. In fact, the more fragmented the landscape, the better the opportunities for great horned owls.

Because they will eat almost anything and live almost anywhere–from Arctic Canada and Alaska to the southern tip of South America–great horned owls will survive and thrive long after specialists have gone extinct. That’s good news for those of us who define our winter nights by the hooting of great horned owls.