Note: Though most of the other posts on this site are reprints of my columns in the Pennsylvania Game News, I wrote this one for Birdwatcher’s Digest, where it was the cover story for the January-February 2008 issue.
American robins remind me of old-fashioned, dignified businessmen of an earlier era. I almost expect them to pull out watches from their vest coat pockets. They also have a whiff of the sanctimonious about them, “tut-tuting” at everyone else’s foibles, as they run erratically over our lawns and golf courses. Then, in early November, on our central Pennsylvania mountaintop, the Hercules’ club berries, which hang in tempting purple clusters, ferment. Suddenly, our sober robins become drunkards. They sing as they gorge themselves and unlike their fellow drunks, the cedar waxwings, who manage to retain their staid, unruffled demeanor, the robins look more like bumbling, overgrown school boys on their first bar crawl. Fluttering like butterflies as they try to balance themselves on the tops of the bowed, berry heads, they also scratch in the leaf duff and poke in the ground, searching for earthworms and other insect food, loathe, perhaps, to imbibe on an empty stomach.
In the fall, robins are intoxicated by a variety of fermented fruit and, as L.A. Eiserer describes them in The American Robin: A Backyard Institution, robins “show all the signs of inebriation. They flap, flop, flutter, and stagger. Sometimes they even pass out…” When drunk they may fly in front of a car or into a window.
To see robins change from reliable, upright birds to tipsy, irrational alcoholics makes me mindful of their seemingly split personalities. In spring and summer, they boldly inhabit our yards and gardens and often raise their young in nests close to and even on our homes and garages. But in fall and winter, they retreat south into woods and swamps and shy away from humans.
Such changes, though, are understandable if you know the life history of these common but fascinating songbirds. For instance, male American robins fly to a roost every evening of the year. Females join them except during the breeding season. And as soon as their first batch of fledglings can fly well, the males escort their young to the roost. So inbred are their ties to roosting that even hand-reared fledglings, at 13 or 14 days of age, develop a restlessness toward dusk at the same time that wild robins are heading for their roosts. These roosting aggregations are not always composed solely of robins–kingbirds, brown thrashers, cedar waxwings, red-winged blackbirds, swallows, brown-headed cowbirds, common grackles, American crows or orioles may join them.
Unlike the fairly stable roost site during breeding season, those during migration and in the winter fluctuate. But the ideal roost site contains dense vegetation, saplings, and thick, berry-covered shrubs near a stream and field in either secluded woods and/or inaccessible swamps. Enormous numbers of robins have been recorded at some winter roosts — one million robins in Virginia’s Dismal Swamp, 50,000 in a Florida cypress swamp, 165,000 at Lakeside Park in Oakland, California, and 3,500,000 near Fertile, Missouri.
“At sunset the sky is black with Robins coming in to roost, and at daybreak when they are leaving the sound is like a train passing over a trestle,” one observer at an Alabama roost wrote back in 1931. Robins are not faithful to the same wintering grounds. They go where the food is and prefer temperatures between 40 and 60 degrees Fahrenheit. Most winter in the southern United States, but if the food supply is good and the winter, relatively warm, significant numbers of local robins may not migrate. Even on our cold mountaintop in January and February, many robins remain if the wild grape crop is plentiful.
One cold, February morning, I found the mother lode of robins–hundreds of them, some singing, as they gorged on wild grapes. During another grape-filled winter, I sat beneath wild grape-draped trees and watched as robins, accompanied by cedar waxwings, European starlings, and a couple northern flickers, harvested grapes on the vines and frozen ground. I dared not move as wild grapes plopped down around me. Sitting there in the warming sun, encircled by the birds of spring in a winter woods, the ground patched in white, I felt as if I was part of a winter mirage. But wherever I walked that February morning, more foraging robins swept over the landscape. During such fruit-filled winters, I don’t know when to record the first returning spring robin.
But then are robins truly harbingers of spring? Partly yes and partly no. Most do migrate south in the winter and, beginning in late February, fly north in fits and starts, depending on the temperature, which must be at least 37 degrees Fahrenheit, and the weather. If it suddenly turns cold or begins snowing or sleeting, they may head south again until the weather moderates.
Many robins follow the Mississippi River Valley north with western robins taking the Missouri River fork and eastern robins the Ohio River. Others prefer forested routes. The closer they come to their breeding grounds, the faster they travel, although robins on the Pacific coast migrate faster than those in the rest of the country.
Most return to or within ten miles of their birthplace, the males several days ahead of the females, looking fat and fit and arriving in a flock. Those robins that have not migrated are often alone or in pairs and are scrawny. So a single robin does not a spring make but a flock does. When our First Field fills up with robins one bright, warm day in mid-March, I know that spring is on its way.
And where else do these birds return to? These largest and most widespread of North American thrushes breed throughout most of North American from Alaska in the west to Quebec and Newfoundland in the east and south to Florida and Mexico. Robins have been extending their range since the beginning of the twentieth century, moving west into the Great Plains and south and west into Florida, Texas, Arizona, New Mexico and California, as we have moved into those areas with our well-watered lawns and pastures, which have introduced or brought to the surface earthworms, and have planted trees in prairies and deserts.
Robin, watercolor, c. 1895, by Louis Aggasiz Fuertes (public domain)
Open, grassy areas near trees and shrubs provide ideal breeding and feeding habitat for these most versatile of songbirds. In addition to earthworms, robins eat a wide variety of wild and cultivated fruits and both terrestrial and foliage-dwelling insects throughout their range, consuming primarily fruit in the fall and winter and insects and earthworms in the spring and summer.Once the males return, they reclaim their old territories, and when the females join them several days later, they too are more interested in returning to their former nesting area than in either courtship or loyalty to previous mates. A female robin will even help defend her mate’s territory or defend it if her mate dies. Often the territory encompasses only that area around a nest and territories sometimes overlap. Other robins will even help each other defend their nests from predators. Seemingly, excellent territory–wide stretches of short-cropped grasses–is frequently unclaimed and serves as a communal feeding ground.
To keep his territory and attract a mate, the male sings his familiar “cheerily” song. Robins begin singing very early in the morning and are one of the latest singers in the evening. They sing most during courtship and until the young hatch. Then they are silent until the young fledge when they resume singing. July and August, when robins molt, are silent times, but in late September, they sing during what one researcher calls their secondary song period. They also have a “whisper” or “hisselly-hisselly” song, described as similar to ethereal hermit thrush vocalizations. Donald Kroodsma, in his definitive The Singing Life of Birds, has studied robin song extensively and writes that “…each male robin has a largely unique repertoire of caroled phrases that I can use to identify him as an individual.”
Alarm calls are the familiar “chirp,” “yeep,” “cuck,” or “tut,” which are made when robins spot predators such as northern harriers, sharp-shinned, Cooper’s, red-tailed and red-shouldered hawks, American kestrels, merlins, and peregrine falcons, or to communicate with their young during nesting time.
Once a male attracts a mate, the relationship is monogamous during the season. According to John James Audubon, the male robin displays for the female by spreading and lifting his tail, shaking his wings, and inflating his throat. The male and female robins also approach each other with wide open bills in what researchers refer to as “ceremonial gaping.” Copulation usually occurs after day singing and is “brusque, businesslike, and to the point,” writes Eiserer.
The female selects the site and builds the nest, and he helps by bringing in nesting materials. The first nest in early spring is usually built in a low evergreen such as the 10-foot-tall juniper tree outside my bedroom window, but later nests are often constructed higher in a deciduous tree, where the thick leaves provide shelter from rain. Robins, though, are known for improvising where nest sites are concerned, and north of the tree limit they will build on cliffs. Even where there are plenty of trees and shrubs, they often nest on human-made structures such as fencepost tops, porch railings, outhouses, telephone booths, and roof gutters. Years ago, we took a six-week vacation in spring and returned to find a robin’s nest, crammed full of nestlings, on top of a garden hoe hanging in our garage. Needless to say, we waited until the robins fledged to hoe the weeds in our vegetable garden.The outer wall of the nest is made of dead grass and twigs, to which the female may add feathers, moss, white paper, cloth, wool, or mammal hair. Then she uses mud from worm castings to cement nesting materials in place. Finally, the female lines her nest with fine pieces of dried grass.
Unlike most songbirds, which lay their eggs at sunrise, she lays her 3 to 4 sky-blue eggs in late morning or early afternoon. She incubates her eggs from 12 to 14 days, and the eggs hatch in the order they were laid over a 2- to 3-day period.
Both parents feed the nestlings. For four days they are fed regurgitated soft parts of insects, earthworms, and plant material. After that, broken and then whole earthworms, as well as caterpillars, ants, flies, beetles, adult moths and butterflies, centipedes and millipedes are stuffed down their open beaks by their parents who work from dawn to dusk. Researchers estimate that each brood of robins eats 3.2 pounds of food and that on their last day in the nest each nestling may eat 14 feet of earthworms. They are fully feathered at 8 days of age, and by the time they fledge, at 13 days old, they have grown 1,000 percent–from 5.5 grams at hatching to 56 grams. Usually they leave the nest one at a time over a 24-hour period, but if something disturbs them, they leave, Eiserer writes, in a “flapping explosion of plump and chirping cannonballs that scatter in all directions.”
In addition to incubating eggs and feeding nestlings, robins must defend eggs and nestlings from a wide variety of predators — Steller’s, blue, western scrub, and gray jays, American crows, common ravens, common and great-tailed grackles, raccoons, bobcats, black bears, chipmunks, fox, gray and flying squirrels, and black snakes. Night predators on nestlings, fledglings and adults include eastern and western screech-owls, great horned, snowy, long-eared, barred, and northern saw-whet owls and northern pygmy-owls. But all the wild predators together do not kill nearly as many robins and their young as house cats do.
Yet these birds, which are “as American as apple pie, baseball, and the Stars and Stripes,” writes Roland Wauer in The American Robin, continue to thrive and even increase over much of their range, because unlike most of our songbirds, deforestation, urbanization, and increased agriculture have been a boon, not a bane, to them. American robins are indeed America’s backyard bird.
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,” 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.
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.
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.