Northern Visitors

Last winter I spent hours in our Norway spruce grove watching red-breasted nuthatches. I first saw them on October 28 when one foraged on a Norway spruce tree trunk while another rushed around on the ground in search of Norway spruce nuts.

A red-breasted nuthatch on a Norway spruce in Pennsylvania

A red-breasted nuthatch on a Norway spruce in Pennsylvania (Photo by fishhawk on Flickr, Creative Commons license)

I had already learned from Doug Gross, Endangered and Non-game Bird Section Supervisor for the Pennsylvania Game Commission, writing in the October edition of PSO Pileated (the newsletter of the Pennsylvania Society for Ornithology), that 2016-17 was a big red-breasted nuthatch irruption year. Their conifer seed sources in the north had been sparse, and they were moving south in large numbers in search of native and non-native conifer seeds, including those of Norway spruce plantations.

Back in the 1990s, before the onslaught of hemlock woolly adelgids, I had often watched wintering red-breasted nuthatches in our eastern hemlocks along our stream, but those trees have been ravaged if not entirely killed by the adelgids. In this decade, wintering red-breasted nuthatches have relocated a mile and a half uphill to our one-acre Norway spruce grove.

After my first sighting of them, I rarely missed either hearing or seeing the red-breasted nuthatches in the grove, sometimes in the company of black-capped chickadees and dark-eyed juncos or sometimes on their own.

A portrait of a red-breasted nuthatch in Chester County, PA

A portrait of a red-breasted nuthatch in Chester County, PA (Photo by Kelly Colgan Azar on Flickr, Creative Commons license)

Then, on November 27, as I sat in the lower section of the spruce grove, my back against a black locust sapling, I spotted a red-breasted nuthatch flying frequently to the forest floor in what looked like nervous haste, poking about on the ground, and then flying up to a spruce trunk. I also heard another calling its nasal, tin-horn-sounding “yenk, yenk” from farther away. The one on the ground continued poking and prodding like a pepped-up robin. Suddenly, it landed on a spruce branch close to the ground, four feet away from me, called loudly, and flew back to where I had originally seen it.

Later, sitting on Alan’s Bench at the upper edge of the grove, I heard several red-breasted nuthatches calling from all directions.

Handsome, beguiling birds with bluish-gray backs and wings, rufous-cinnamon breasts and bellies, black heads, and a broad black line through their eyes with a white line above them, they were once known as Canada nuthatches (Sitta canadensis) or red-bellied nuthatches. They are closely related to the larger, deciduous-forest-dwelling white-breasted nuthatches (Sitta carolinensis). Both species climb up and head-first down tree trunks, probing bark crevices for insects, but white-breasted nuthatches are slower and less trusting than red-breasted nuthatches.

A red-breasted nuthatch probing a dead branch

A red-breasted nuthatch probing a dead branch (Photo by budgora on Flickr, Creative Commons license)

On December 1 I was decked out in orange because of rifle season, and I wondered if the red-breasted nuthatches would notice and shy away from me. As I neared my locust tree back rest in the spruce grove, a red-breasted nuthatch was busy probing in the low, dead branches of the large spruce in front of the locust and paid no attention to my flamboyant presence.

Instead, the bird flew to a nearby large dead spruce snag that had been topped in a storm and was joined by a second nuthatch that flew into the same tree. They kept their distance from one another as they ran along the dead, parallel branches as well as up the old trunk. Although highly aggressive and territorial during their breeding period, those that migrate south in the winter remain in small, stable groups with little or no aggression.

By then I was hooked on these quick, agile little birds, and almost every morning returned to the spruce grove to watch them. Sometimes there was one, sometimes two, and several times three birds. Usually they were scuttling around on the bare ground like gray mice, searching for spruce nuts detached from cone scales.

In Mercer County, PA, a red-breasted nuthatch in a November snow

In Mercer County, PA, a red-breasted nuthatch in a November snow (Photo by Dave Inman on Flickr, Creative Commons license)

But once I saw a pair running about on a thin, fresh layer of snow. Then one snatched a spruce nut, flew low on to a tree trunk, and ate it. Mostly though, on the few days with a snow cover, they were high in the spruce trees, hanging on dangling cones, and extracting the seeds.

One January day it was seven degrees, the ground was bare, and I stood watching as one nuthatch rushed about in search of food. I marveled that its tiny feet and legs could move so quickly in the cold and that these little birds have feathers that kept them warmer than my five layers above and three below. Slowly, my upper body and feet froze as the nuthatch continued its rounds in wide circles about six feet away from my still figure.

Other folks in Pennsylvania were watching red-breasted nuthatches at their feeders. Of the 690 Project FeederWatch participants in our state, nearly half reported at least one red-breasted nuthatch at their feeders, but I never saw one come to our feeders.

A red-breasted nuthatch on a feeder in Montgomery County, PA

A red-breasted nuthatch on a feeder in Montgomery County, PA (Photo by Brian Henderson on Flickr, Creative Commons license)

I had hoped the nuthatches might stay to breed in our spruce grove, but I last heard them in mid-March calling from the spruce treetops. Here in Pennsylvania they are irregular, local breeders mostly in our northern tier, especially in the Poconos. But as the conifer plantations planted by the Civilian Conservation Corps in the 1930s during the Great Depression aged, in the 1960s, red-breasted nuthatches sometimes bred in plantations as far south in the commonwealth as York County on the Maryland border and west to Beaver County near Ohio.

Gene Wilhelm, in the Second Atlas of Breeding Birds in Pennsylvania, writes that “few counties had no records during the second Atlas period,” even though the species is still thinly distributed in the state. Most records are from the northern half of Pennsylvania in coniferous and mixed coniferous and deciduous forests and estimates of their numbers range from 18,000 to 28,000 birds.

According to a field note Wilhelm wrote for PSO Pileated, a pair of red-breasted nuthatches nested in their Butler County black spruce woodlot for three consecutive years (2011-13) and then disappeared until early last fall.

A close encounter with a red-breasted nuthatch

A close encounter with a red-breasted nuthatch (Photo by NechakoRiver on Flickr, Creative Commons license)

That’s when Wilhelm also had close encounters with a pair of red-breasted nuthatches. He was sitting outside writing when “the male bird landed two feet from my mobile TV tray, snatched a stinkbug from our porch screen door, carried it in his bill to a limb of a red maple less than ten feet above my head, ate the bug whole, then repeated the antic 10 times in the next 10 minutes. At that point, the female nuthatch dropped to the ground next to the screen door, and helped herself to the easy meal, too.”

That day they made 21 round trips in half an hour and ate 42 stinkbugs. And they returned for six more afternoons making “at least 89 round trips, ate at least 111 stink bugs, in three hours of hunting,” Wilhelm concluded.

Red-breasted nuthatches migrate through Pennsylvania from the second week in April to the third week in May, but those that stay to breed begin courting as early as March. The male sings his courtship song while turning his back to the female, swaying back and forth like a revolving fan and erecting his crest feathers. The pair also flies together with slowly fluttering wings or long glides.

The nest hole of a red-breasted nuthatch with orange colored resin visible around the entrance

The nest hole of a red-breasted nuthatch with orange colored resin visible around the entrance (Photo by Larry McGahey on Flickr, Creative Commons license)

Both sexes excavate a nest hole 2.5 to 8 inches deep in soft aspens, dead or dead parts of trees. They line their nest with fur, fine feathers, grass, hair and shredded bark. The female lays five to eight whitish, spectacled reddish-brown eggs in May.

The pair also applies sticky conifer resin at the outside and inner walls of the cavity entrance. They bring in resin globules from other conifers in the tips of their bills or on a small piece of bark which they use as a tool to apply the resin. Throughout the 12-day incubation and 18-day nestling periods, they do this as often as five to 10 times a day. It seems to be a deterrent for nest predators, such as house wrens, red squirrels, snakes, weasels and even ants, but the parents are able to avoid the resin by flying directly into and out of the nest hole.

An adult red-breasted nuthatch feeding its fledglings

An adult red-breasted nuthatch feeding its fledglings (Photo by Robin Horn on Flickr, Creative Commons license)

The male feeds the female during her incubation period, both on and off the nest and while she broods the hatchlings. Both parents feed their offspring in the nest and for two weeks or longer after they fledge in late June or early July. The young birds may join their parents in mixed species flocks of resident birds and stay together as a family since they have only one brood a year.

But if it is another irruption year, they may begin heading south as early as the first week in August, although their peak migration period is between the third week in September and third week in November.

Because they irrupt every two to three years, I doubt I will see any in our spruce grove this winter. But I will forever remember the year of 2016-17 as my winter with the red-breasted nuthatches.

 

Crow Blackbirds

On the last day of October, a flock of blackbirds lands on top of a tree behind me as I sit on Coyote Bench. Later, on the Vernal Pond Bench, I hear and then see an enormous blackbird flock as it alights on nearby oak trees and then erupts overhead in a wheeling flock of several hundred. Judging by the sounds I hear, I think it contains mostly European starlings, red-winged blackbirds and brown-headed cowbirds as well as common grackles, but I can’t get a close, long look at them before they fly off.

A mixed flock of red-winged blackbirds and common grackles

A mixed flock of red-winged blackbirds and common grackles (Photo by Nancy Magnusson on Flickr, Creative Commons license)

I remain still as a small flock appears and a few linger in the treetops while the others move on. I see bright yellow eyes and long tails. They are common grackles with a few smaller, bright-eyed birds that may be rusty blackbirds. Most blackbird flocks are mixed during migration, and common grackles are often part of red-winged blackbird, European starling and brown-headed cowbird flocks.

Later, I learned that common grackles, nicknamed “crow blackbirds,” use the hard keel of the inside of their upper mandibles to saw open acorns, scoring the outside of the acorns’ narrow ends and biting them open. Since we have had a bumper crop of acorns, I imagine they were feeding on their way south.

Common grackles (Quiscalus quiscula) breed in Canada from British Columbia in the west to Newfoundland in the east and south across the eastern and midwestern United States to the Rocky Mountains. They are partial migrants within North America, averaging 330 miles southward, and most spend their winters in the Mississippi Valley where grain fields are plentiful. Still, although they are abundant regular migrants in Pennsylvania, flocks may linger in the intensively farmed Piedmont region or at birdfeeders filled with grain.

A flock of common grackles on a communal winter roost

A flock of common grackles on a communal winter roost (Photo by Vilseskogen on Flickr, Creative Commons license)

Farther south and east they form a part of communal roosts during the winter that may contain as many as a million birds. They are partial to evergreen trees near agricultural areas and are notorious in farming circles for their love of grains, especially corn. They eat ripening corn as well as corn sprouts and are considered the number one threat to corn crops.

Common grackles are handsome birds, about the size of mourning doves, and only appear to be black. But seen closely in the sunlight, their heads are a glossy purple and their bodies a bronze-toned iridescent. They have long legs and long, keeled tails, flat heads, and bold yellow eyes. They waddle around on their legs and peck for food like chickens.

Because they sometimes eat other birds, eggs, and nestlings, many birdwatchers aren’t fond of them. These clever blackbirds have been known to steal worms from robins, follow plows to catch insects and rodents, pick leeches off the legs of turtles, wade into water to catch fish and even soak dry bread in water before eating it. Common grackles are omnivorous birds that thrive in our human-made environment and even pick through garbage.

A common grackle carrying a caterpillar for its nestlings

A common grackle carrying a caterpillar for its nestlings (Photo by Paul Hurtado on Flickr, Creative Commons license)

On the other hand, they also eat wild fruits, tree seeds, beetles, grasshoppers, caterpillars, spiders, and salamanders, with insects forming 25 to 30% of their animal diet. However, their year round diet does average 70 to 75% seeds and fruits, most of which are agricultural grains and seeds.

Like other blackbirds, they are songbirds even though most descriptions of their songs use words such as “harsh,” “squeaky,” and “nasal”—songs ornithologists believe they learn from adults in winter roosts. But songbird expert Donald Kroodsma, in his Listening to a Continent Sing, writes, “I would sit quietly in a colony, savoring their ‘rusty hinge’ songs, the croaking, squawky, far-from-musical, third-of-a-second readle-eaks to my naked ears, knowing that they’re full of exquisite detail when slowed down. I hear each bird with its slightly different song, how females sing, too, how pairs in a flock are identifiable by how rapidly they respond to each other’s song, how intimate exchanges within the colony are mediated with all those harsh chack and chaa and jit calls.”

A male common grackle

A male common grackle (Photo by Vkulikov in Wikimedia, Creative Commons license)

The male common grackles arrive on their breeding grounds a week before the females. Here in Pennsylvania they may arrive as early as the last week in February during mild winters and as late as the second week in April.

Once the females arrive, pair formation begins with groups of males flying after a slow-flying female, a male chasing a female at high speed, and a male and female flying slowly next to each other. Eventually, they pair up and mate.

The female selects the nest site, but she may change her mind in the middle of nest-building and start all over in another place. Common grackles often nest in a colony as small as 10 pairs and as large as 200 or they may nest singly. Usually, they nest at the top of evergreen trees near agricultural fields, residential areas, or even woodlands. Almost always they locate near water.

Here on our mountain we have at least one pair nesting somewhere along our hollow stream, and I suspect they nest either atop a white pine or hemlock tree, although some grackles choose deciduous trees and even shrubs as nest sites. Occasionally, they will nest in tree cavities, birdhouses, barns, or in the massive, occupied nests of ospreys or great blue herons, feasting on the leftovers that fall from the larger birds’ nests.

A male common grackle gathering nesting material

A male common grackle gathering nesting material (Photo by OHFalcon72on Flickr, Creative Commons license)

Nest-building in Pennsylvania has been documented as early as March 16 and as late as June 30, but from April 18 to May 28 are the most common dates.

Female common grackles build their nests, sometimes aided by the males. The nests are bulky cups, six to nine inches across, of twigs, leaves, and grass with paper and string if they’re near human habitations, plastered with mud inside and lined with fine grasses. They can build their nests in as little as a week and as long as a month and a half in the case of one dawdling female.

They then lay one to seven eggs of variable colors from almost white to light blue, pearl gray, and even brown. Most have blackish brown scrawls and/or spots. Normally a female has only one brood. The females incubate on their own, spending most of their days and nights on their eggs, only getting off to eat, because most males desert their mates during this time.

A baby common grackle

A baby common grackle (Photo by Donna Dewhurst, U.S. Fish and Wildlife Service, in the public domain)

Incubation lasts 11 to 15 days. Once the eggs hatch, the males rejoin their mates and, while the females brood the nestlings, the males do much of the feeding for the first few days. Then both feed the nestlings during the 10 to 17 days they remain in their nests and afterwards as fledglings for several weeks until the first of July or thereafter when they join roosting flocks.

Of course, all does not always go well during this time, and they lose close to half their eggs, nestlings, and fledglings to predation or human impact. Fox squirrels eat eggs and nestlings, rat snakes eat nestlings and gray squirrels and raccoons eat eggs. Eastern chipmunks and free-roaming, domestic cats consume the young. Raptors, including Cooper’s hawks, northern harriers, and red-tailed hawks and short-eared owls and great horned owls also prey on common grackles at all stages of their lives.

Still, common grackles thrived during the first half of the 20th century, but from 1966 to 2014 they declined 58% according to the North American Breeding Bird Survey, and now their global population is estimated at 61 million birds. While they are still abundant and widespread, scientists from the North American Bird Conservation Initiative have drawn up a list of 33 United States common birds that have lost over half their global population during the last four decades, and in The State of the Birds 2014 report, common grackles made the Common Birds in Steep Decline list.

A male common grackle feeding its nestlings

A male common grackle feeding its nestlings (Photo by Larry McGahey on Flickr, Creative Commons license)

The Second Atlas of Breeding Birds in Pennsylvania estimated our population of common grackles at 1.5 million and one of the most abundant breeding bird species in the commonwealth. Still, our population has declined 1.9% per year from 1966 to 2009. Scientists don’t know why they are declining throughout their range since they are incredibly adaptable. But because they are a threat to agricultural crops, lethal methods have been used against them in some areas.

Lately, research has been uncovering the dangers of neonicotinoids, widely used in insecticides, to birds and insects. According to the American Bird Conservancy, whose scientists have been researching these chemicals for years, neonics, as they are called, persist in the soil for months and even years and can affect entire food chains (Bird Conservation Winter 2016, p.7).

“A single seed coated with a neonic,” they write, “is enough to kill a songbird.”

So even though common grackles are still common, ornithologists haven’t forgotten that once billions of passenger pigeons roamed our continent. And then they were gone. They hope by acting now and figuring out what is causing the steep decline of common grackles and 32 other bird species, they can keep them common for future generations.

 

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.

 

Thistle-Birds

In August our weedy First Field is alive with singing American goldfinches. Although most songbirds are finishing their parental duties by then, American goldfinches have barely begun.

A male American goldfinch among thistles at the John Heinz National Wildlife Refuge at Tinicum, PA

A male American goldfinch among thistles at the John Heinz National Wildlife Refuge at Tinicum, PA (Photo by Jim, the Photographer, on Flickr, Creative Commons license)

Their preference for thistle and other seeds may be one reason they wait until midsummer when the seeds are mature, because they line their nests with thistle, milkweed or burdock down and feed their nestlings a slurry of those regurgitated seeds, instead of insects, which are favored by spring-breeding birds.

Another reason may be the length and intensity of goldfinches unique prenuptial body molt in early spring. The dramatic change of the olive-buff males to vibrant gold bodies and black caps, which set off their black-and-white wings, never fails to dazzle me every April.

But knowing they do not breed until midsummer, I am also surprised that they sing as lustily as other species beginning in early spring. Some researchers believe that they form pair bonds in late winter flocks or as soon as both sexes arrive on their breeding grounds.

A female American goldfinch

A female American goldfinch (Photo by Eric Bégin on Flickr, Creative Commons license)

On the other hand, males need to try harder for mates because for every 1.6 males, there is only one female, so first-year males have a difficult time acquiring a mate. Thus, while goldfinches are mostly monogamous, at least 15% of females mate with a second mate especially if they have a second brood.

Back in the years 1979 until 1985, Alex L. Middleton, of the University of Guelph in Ontario, was watching nests of goldfinches he had color-banded on the university grounds. That was when he made, for the first time in ornithological history, the observation that the goldfinch father of the first brood was not always the father of the second one, proving that regular and recurring classical polyandry was occurring in a passerine species.

A male American goldfinch at the John Heinz National Wildlife Refuge at Tinicum, PA

A male American goldfinch at the John Heinz National Wildlife Refuge at Tinicum, PA (Photo by Jim, the Photographer, on Flickr, Creative Commons license)

During his study, he found five cases of polyandry and concluded that even though only a few females practiced it, they had more than seven fledglings a season compared with slightly over three for “faithful” females. In addition, the polyandrous females were older, experienced birds that preferred to breed with older males because of their experience and their physiological fitness which enabled them to start breeding a week ahead of younger males.

But a younger male sometimes attached itself to the breeding pair and when the first male was still busy feeding his first brood and his mate was already building a second nest, the surplus male bred with the female. Since then, researchers have been finding that many so-called monogamous songbirds are not as faithful as they were once portrayed with both males and females sneaking extra-pair copulations.

A crowd of American goldfinches on a Nyjer thistle feeder in Danville, PA

A crowd of American goldfinches on a Nyjer thistle feeder in Danville, PA (Photo by fishhawk on Flickr, Creative Commons license)

Last April our feeders were crowded with males in the midst of molting and far fewer females. Whether they were migrant males and females or those that had been with us all winter was impossible to tell, because we had had on average 12 goldfinches at a time on our feeders throughout the colder months.

Here in Pennsylvania they migrate through the state from late March until late May, although their peak migration is from the fourth week in April to the second week in May. Many are coming from as far south as the Gulf states and Florida in the United States and central Mexico, but they do wander in large flocks wherever there is ample food, even in winter. They breed from southern Canada through most of the United States with the exception of the southwest and along the Gulf Coast.

American goldfinches rarely nest in Pennsylvania before July 5 and nests with eggs are found here through the end of August. However, the earliest confirmed breeding in the commonwealth, according to the Second Atlas of Breeding Birds in Pennsylvania, was that of a bird carrying nesting material on May 2 and the latest was of parents feeding young on October 14.

The female selects the nest site, often in a wet corner of a brushy pasture such as our First Field, and constructs it in the fork of a sapling or shrub, anywhere from one to 33 feet above the ground. Three dogwood species and numerous hawthorn and willow species are special favorites.

She takes at least four days to build her tightly constructed nest with walls so thick that the nest can hold water. Sometimes this leads to disaster during heavy rainstorms when unattended nestlings drown.

A male American goldfinch feeding a female on May 4, 2007

A male American goldfinch feeding a female on May 4, 2007 (Photo by Doug Greenberg on Flickr, Creative Commons license)

One unusual nest was found hanging from a broken cornstalk in a cornfield near Hamburg, Pennsylvania on September 24, 2008. It was turned on its side on the stalk and was attached by spider silk and plant fibers. Lined with thistle down, it contained a single egg. Even though American goldfinches have been known to nest in as many as 87 plant species, this was the first nesting on a cornstalk confirmed with a photograph. But after watching for a couple days and seeing no goldfinches nearby, the researchers concluded that the nest had been abandoned several weeks before, especially since the nest looked a bit tattered.

Once their nest is finished, the pair leaves the area for several days, maybe to deter predators such as eastern garter snakes, blue jays, and short-tailed weasels. Then the female lays four to six very pale bluish-white eggs and she sits on the nest 95% of the time incubating the eggs while her mate supplies almost all of her food.

The male often sings and flies high above the nest site, checking up on whether his mate needs food. When he hears her soft teeteeteetee hunger call, he drops down near the nest. Then she furtively hops through the underbrush to him to receive her meal.

After 12 to 14 days, the eggs hatch and she broods the young while the male continues feeding her on the nest. She in turn feeds the chicks, but after four days she leaves the nest. Then both parents feed their nestlings by regurgitating a sticky, half solid mass of seeds, including those of sunflower, thistle, burdock, dandelion, chicory, aster and goldenrod, all of which thrive in overgrown pastures.

The nestlings are quiet during their first week in the nest, but by the second week they are active and noisy and fledge anywhere from 12 to 17 days of age. They are dependent on their parents for three more weeks while they learn what to eat and where to find it.

Once they are independent, the young birds join flocks of adults that increase in size during late summer and early autumn. It is then that goldfinches, once they finish breeding, engage in their second molt of the season that lasts as long as 75 days.

They also wander the countryside in search of food. Their choices have led to a variety of nicknames such as “catnip-bird,” “beet-bird,” “lettuce-bird,” and “thistle-bird,” that attest to their liking of both garden and wild plant seeds. “Wild-canary” and “shiner” are tributes to the male’s golden plumage. In addition, their genus name, Carduelis, is Latin for “thistle” and their species name, tristis, means sad, referring to their plaintive calls. Their song, which is unusually long, is both rambling and warbling.

An American goldfinch in Chester County, PA

An American goldfinch in Chester County, PA (Photo by Kelly Colgan Azar on Flickr, Creative Commons license)

American goldfinch numbers are holding steady in the commonwealth, as they nested in 96% of the atlasing blocks with the highest numbers in suburban and rural developments, places that have both wild and garden foods as well as year around, amply stocked birdfeeders. In addition to weedy fields and suburban gardens, goldfinches also like river flood plains, early second growth forest, and orchards for nesting and food.

It is encouraging to learn that one of North America’s most attractive and appealing birds—“panoplied in jet and gold” as ornithologist Edward Howe Forbush once wrote, has benefited rather than suffered from humanity’s actions.

So, the next time your neighbors complain about the dandelions in your lawn or weeds in your garden, tell them you are growing food for American goldfinches.