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.

 

Superflight

red-breasted nuthatch

red-breasted nuthatch (photo by Matt MacGillivray, Creative Commons Attribution licence)

It began with red-breasted nuthatches. In early August 2012, one of the largest irruptions of this northern species in living memory started with reports from counties in eastern Pennsylvania. By the end of November unprecedented numbers were recorded in all 67 counties in the state.

In late September the first purple finches arrived in Pennsylvania and 63 counties had them by late November. Common redpolls and pine siskins began appearing in early October, evening grosbeaks by the last week in October, and both white-winged and red crossbills in early November. Even a few hoary redpolls and a couple pine grosbeaks made an appearance.

With so many northern finch species moving south, birders called it a superflight, which happens only once every decade or so when food sources fail in the north, forcing most conifer seed-eating species to fly south for food. I was especially excited that red and white-winged crossbills were in Pennsylvania, because our son, Steve, had had the only sighting of white-winged crossbills on our property eating hemlock seeds here in the winter of 1985 when I was in Peru. And I had never seen red crossbills.

Now that our hemlocks are dying from woolly adelgids, we could only hope to see crossbills in our 38-year-old Norway spruce grove at the top of First Field. By the first of October several red-breasted nuthatches had already arrived there.

white-winged crossbill

white-winged crossbill (OwenMartin12, CC BY-NC)

Then, on November 15, I hiked to the spruce grove. Black-capped chickadees and red-breasted nuthatches foraged in the spruces at the base of the grove. But I heard an unfamiliar bird call and wandered through the grove searching for the source of it. Finally, I gave up, walked out of the grove and glanced back at the spruces one last time. At the top of a spruce two white-winged crossbills perched. They remained long enough for me to admire white wing bars on black wings, rosy pink breasts, heads, and backs, and even the crossed bills of two beautiful males. At last I had seen crossbills on our property.

Previously, in early November, I had had a male and then a female purple finch at our feeder area for more than a week as well as pine siskins for three days and, as it later turned out, they were the only pine siskins and purple finches to visit us during fall and winter. But already I had seen four irruptive species, and it was only mid-November.

Then a bout with Lyme disease, followed by a nasty virus, kept me inside for several weeks. It took time for me to regain my strength, and I was grateful when our Christmas Bird Count arrived on December 15, that Kurt Engstrom and his keen birder son Carl, came once again to help me. They covered the much longer and more difficult section on Sapsucker Ridge and up our road while I walked a mile and a half on Laurel Ridge.

In the spruce grove I searched for red-breasted nuthatches and white-winged crossbills, but the grove was silent. I was tired and sank down on Alan’s Bench to rest. After a short wait, I heard the call of a red-breasted nuthatch.

red crossbills

red crossbills in Long Branch, NJ (John Beetham, CC BY licence)

However, I did not recognize the call of another bird coming from the upper edge of the grove. I turned my head in that direction and spotted what appeared to be a dull-colored bird at the top of a spruce tree, continually calling, looking around, and flicking its forked tail. It had clouded over, making it difficult to distinguish any color on the bird. I kept studying it through my binoculars, and finally noticed that it had a crossed bill. When I pished, in an attempt to bring it closer, it flew away still calling.

I had listened to it for so long that the call was seared in my brain. After studying my bird guides, I was almost certain the bird had been a female red crossbill. Still, when Kurt and Carl returned, I told them what I had seen and heard. Carl didn’t say anything. He just started playing a series of calls on an Audubon Birds app on his iPod.

“That’s it,” I said.

“Number 3 type of red crossbill,” he answered. “Exactly the type of red crossbill that should be here,” he replied.

I was ecstatic. A new species—number 171—for our property and, as it turned out, the only crossbill reported on our Juniata Valley Audubon Society’s Christmas Bird Count. My red-breasted nuthatch was also the only one on our count.

Red crossbills live throughout the northern regions and high mountains in Europe, Asia, North America, and even the Atlas Mountains of North Africa. Here in North America ornithologists have teased out at least ten types of flight calls by red crossbills north of Mexico that some feel may be discrete species and others merely races or subspecies of red crossbills. Type 1, 2, and 10 calls were also heard in Pennsylvania, although type 3 was the most common. The calling of the lone red crossbill I saw may have been an effort to attract other red crossbills to a feeding source, according to some researchers.

Red crossbills prefer to feed on attached cones, using their feet and crossed bills like parrots to pry open the cones. Then they husk the seed coating by pressing a seed against the lateral groove opposite the side of the lower mandible tip with their tongue. Small seeds they swallow whole but crush large seeds in their bills before swallowing them.

white-winged crossbill (Jean-Guy Dallaire, CC BY-NC-ND)

Both white-winged and red crossbills have straight upper mandibles. Only the lower one curves, and while three-quarters of white-winged crossbills’ lower mandibles curve right and the other quarter left, red crossbills’ lower mandibles curve right half the time and left the other half.

Even though both crossbills eat conifer seeds, red crossbills prefer the cones of pines, including white, pitch, scrub, scotch, red, and even table mountain in our area, but they will also eat hemlock, spruce, tamarack, and occasionally the seeds of deciduous trees.

White-winged crossbills prefer the softer cones of hemlock, spruce, and tamarack, but they will also take seeds from pines with stiff cones and occasionally those of deciduous trees. Researchers claim they eat as many as 3,000 seeds a day.

While both species sometimes visit bird feeders, I never saw either one at our feeders. I had plenty of time to observe them because I no sooner had I gained my strength back in early January than I was diagnosed with a deep muscle tear in my left calf which kept me inside for nearly seven weeks. That’s when I began to refer to last winter as the winter of my discontent.

I did see at my feeders the sixth irruptive species—a male common redpoll that appeared on December 21. He or another male and a female showed up on January 3, and on January 6 and the two following days, a flock of more than 30 common redpolls blanketed the ground and feeders. The bright red forehead and black chins of both sexes and the pink breast of the male are the distinguishing features of these mostly brown-streaked birds. I never did see a hoary redpoll among them.

I similarly failed to see an evening grosbeak at our feeders, even though this species made its best showing in over a decade in Pennsylvania appearing in 33 counties.

Although most were gone from the state by mid-December, up to 150 at a time appeared at a feeder in Marienville, Forest County.

common redpolls in flight

common redpolls in flight (Jean-Guy Dallaire, CC BY-NC-ND)

Numbers of both crossbill species also diminished by mid-December. White-winged crossbills went from 43 counties in early November to 35 in the winter and red crossbills from 30 counties in early November to 20 in the winter.

During similar irruptive invasions of red crossbills in Pennsylvania, most appeared in mid-to-late October and left the state by the end of March. Although they remain paired through most of the year and may breed at any time an area suits them, there are very few verified sightings of breeding red crossbills in Pennsylvania.

White-winged crossbills arrive and leave on the same schedule as red crossbills, and there are no records of breeding here. During one of the largest crossbill invasions in Pennsylvania in 1997-98, over 1,000 white-winged crossbills spent the winter in Cook Forest State Park and were often joined by lesser numbers of red crossbills. But we never saw them on our mountain then, probably because our spruce grove was only 24 years old and not producing a good cone crop. So last winter will remain in my memory as our crossbill winter, my first ever in the 41 years I have lived on our central Pennsylvania mountaintop.

Superflight

Last winter was the kind of winter birders dream of. Not only did we have a classic “irruption” of winter birds from the north but a “superflight” in which all the highly irruptive finches–pine grosbeak, purple finch, common redpoll, hoary redpoll, pine siskin, evening grosbeak, red crossbill, and white-winged crossbill, as well as the red-breasted nuthatch–appeared somewhere in Pennsylvania.

Most exciting was the invasion of both crossbill species, those birds with crossed bills which they use to wedge open cone scales and then lift seeds free with their tongues, eating as many as 3,000 conifer seeds a day. Previously, a red crossbill irruption had last occurred here in 1972-73 and a white-winged in 1981-82, but there had never been a year on record when both had appeared in large numbers. Add to that glimpses of such rarities as pine grosbeaks and hoary redpolls by a few lucky people, plus the added bonus of all the other finch species to most of us who feed birds, and the extraordinary winter took on all the trappings of a legend in the making. In years to come, birders will speak with awe and longing of the fabulous winter of 1997-98.

The first hint that something big was afoot occurred on September 22, 1997 when a single white-winged crossbill was spotted at Hawk Mountain Sanctuary. This was followed, on October 17, by a report of three white-winged crossbills at the DuBois reservoir. By November both red and white-winged crossbills were being reported in record numbers throughout much of Pennsylvania. Their numbers increased steadily in December and early January.

By the time the invasion was over the following April, crossbills had been seen at 120 individual locations in 55 of Pennsylvania’s 67 counties. Unfortunately, our county–Blair–was not one of them because we did not have the food crossbills prefer, the seeds of eastern hemlock cones.

Even though our hemlocks had only a few cones, I spent many hours in the hollow, watching and listening hopefully for glimpses of crossbills. But I never saw any despite the fact that the second highest numbers of crossbills in the state were found in the Ridge and Valley Province where I live. In the middle of January a sudden influx of crossbills occurred on Somerset County ridges, in Venango County, and, most notably, in Cook Forest State Park.

Cook Forest State Park, and Clarion County in general, recorded the highest counts of crossbills throughout the irruption. The park, with its large number of huge, old growth hemlocks, was a natural magnet for the crossbills. And luckily the hemlocks were loaded with cones. So were the old growth white pines, usually a secondary choice for crossbills when they irrupt. But, by and large, the crossbills ignored them and ate almost exclusively hemlock cones.

The red crossbills were first reported at the park on the 28th of November by Paul M. Brown of Pittsburgh who spotted them on the Longfellow Trail. Brown called Margaret Buckwalter, the chief bird compiler for Clarion County. Two days later, Margaret’s son, Ted, found at least 50 red crossbills high in the hemlocks on the same trail. A little more poking about produced red crossbills in Ridge Campground and near picnic tables along the Clarion River. As Margaret later wrote to me, “That was the beginning.”

White-winged crossbills were first sighted on January 12 at the park, and after that it was difficult to tell them apart from the red crossbills as they all fed high in the hemlocks in mixed flocks. It was easier to see them when they flew from place to place across open areas. Surprisingly, they even came to feeders in Clarion County. Friends of Margaret’s had seven white-winged crossbills eating sunflower seeds from their tube feeder. Other folks observed them eating white pine cone seeds, black birch catkins, and maple buds. Apparently, while the cone-laden hemlocks of Clarion County enticed the birds to stay, they did sample other food as well.

But why this incredible influx of birds that are quintessential north country birds? Because, across much of Canada, the seed crop had failed. According to a letter from Ian Thompson of the Canadian Forest Service quoted in Paul Hess, Michael R. Leahy, and Robert M. Ross’s excellent article “Pennsylvania’s Crossbill Winter of 1997-98” in Pennsylvania Birds (January-March 1998), “There are no seed on any trees this year over the entire area from Manitoba across Ontario and Quebec. I have never seen such a ‘bust’ year where all species were dormant simultaneously.” In Algonquin Provincial Park, Ontario, Christmas Bird Count participants reported no crossbills at all compared to normal years when several thousand of both species are reported.

Anyone with a computer hooked to the Internet could keep up with the unprecedented winter finch invasion that occurred throughout most of the United States. The Cornell Lab of Ornithology/National Audubon web site, BirdSource, started tracking it in mid-November, after learning that all the winter finch species except hoary redpolls had been reported by diligent Ithaca, New York birders by October 26. As it turned out, those finches were moving on through because the New York seed crops had failed too.

“It became apparent early on that the 1997-98 invasion was going to be extraordinary,” BirdSource project coordinator Steve Kelling, who developed the Winter Finch Survey, maintained. Fruit and berry-loving pine grosbeaks showed up in huge numbers in Minnesota and New England where wild fruit crops were abundant. In addition to Pennsylvania, large flocks of crossbills also found eastern hemlock and white pine cone seeds in parts of New Jersey, Maryland and Washington state.

When I last logged on to BirdSource in late February, I discovered that red crossbills had appeared in central Florida by mid-February, white-winged crossbills in central Alabama in January, pine siskins in coastal Louisiana in December and central Texas in February, common redpolls in North Carolina in January, and evening grosbeaks in central Florida and Texas in February. Most of these southern sightings broke records for both numbers and species of these usually far-north birds. For instance, a white-winged crossbill sighted in Tennessee was only the third ever seen in the state. Red-breasted nuthatches were equally surprising, appearing in unprecedented numbers as far south as central Texas.

Although we didn’t have the more glamorous species on our mountain–the crossbills, pine grosbeaks, or hoary redpolls–we certainly experienced the greatest winter finch diversity ever last winter, both at our feeders and in the woods. On November 12, 20 evening grosbeaks appeared at our feeders. The following day they were joined by pine siskins.

“it looks like it is going to be a finch winter,” I wrote happily in my journal. And indeed it was, even though the evening grosbeaks and pine siskins moved on by the end of the month, momentarily dampening my belief in a finch invasion.

But we did have and continued to have huge numbers of American goldfinches, far more than I could ever remember. There were 60 at a time at our feeders when five to 10 had previously been our highest count. And in the woods large flocks coursed back and forth overhead as I took my daily walk.

What were they eating and why were there so many? Our conifer cone crop might have failed, but our black birch catkin crop was mind-boggling. And that was what they were eating. American goldfinches, like their close relatives, pine siskins and common redpolls, are nomadic in winter, going where the food is. All three species prefer birch and alder catkin seeds to other foods, but they are not adverse to supplementing those seeds with black oil sunflower seeds at feeders.

Still unaware of the general excitement in the birding world by late December, I nevertheless held out the hope that those catkins would bring in common redpolls and more pine siskins. And on a less-than-auspicious Christmas Bird Count day in late December my hope became a reality. My husband Bruce and I plodded through light snow for three miles, combing empty ravines and seeing very few birds. But late in the morning, as we re-crossed the Far Field, we were halted in our tracks by a chorus of bird calls. A grove of black birches, loaded with catkins, was also loaded with at least 200 common redpolls.

We sat down on a fallen tree and watched for a long time as they wheeled back and forth over the treetops, then settled down to eat, first on one tree, then another, before the whole flock finally took off.

That was the real beginning of the finch invasion for me. Pine siskins also returned although not in high numbers like the common redpolls. Both siskins and redpolls visited the feeders most days in small numbers (five to 10), along with hordes of goldfinches, but if I wanted to see all three species in the hundreds I headed for black birch trees. Luckily they grow all over our mountain.

I spent many happy winter hours, on sunny days and overcast ones, sitting at the base of a nearby tree and watching them moving restlessly from catkin to catkin, chirping continually. One snowy day a mixed flock alternated eating catkins with eating snow from tree branches. Other days I encountered common redpoll flocks feeding alone as I had the day of the CBC.

The common redpolls and pine siskins remained on the mountain until mid-April and were joined for several days by more purple finches than usual. Then, just as the finches headed north, I found my first red-breasted nuthatch on April 17. They crescendoed on May 7 when literally dozens landed on trees around me as I sat on Dogwood Knoll surrounded by hundreds of foraging yellow-rumped warblers. Apparently the red-breasted nuthatches that had spent their winter in the south were heading back north to breed.

I saw my last red-breasted nuthatch on May 13, effectively concluding my experience with the superflight of 1997-98. Of the nine official superflight bird species, I had seen five, a record for our mountain.

Although there is still some speculation in the ornithological world concerning the “why” of bird irruptions from the north, I am convinced that food supply controls irruptions. As I told my neighbor when he asked me where he could see redpolls and siskins, “Look for black birch trees, Charlie.” Or, as birder Douglas Gross said about the crossbill invasion, “They came, they saw, they conifered!”

Irrupting Birds

Every winter birdwatchers hope for an irruption of boreal birds from the northern forests. This “irruption” or irregular migratory movement southward of birds that ordinarily live and breed in Canada and Alaska include glamour species such as pine and evening grosbeaks, purple finches, red and white-winged crossbills, pine siskins, common and hoary redpolls, red-breasted nuthatches, snowy owls, northern shrikes, northern goshawks and rough-legged hawks.

The songbirds are dependent on the seeds of conifers and a few hardwood species, mainly alder and birch, and when the seed crop fails, as it does periodically, and bird numbers are high, they are forced to head south in search of food. The same is true of the birds of prey, including the meat-eating northern shrikes, all of which prey on lemmings, voles, or snowshoe hares or a combination of all three. When those populations crash, their predators must also migrate south in search of food.

Some of these movements have been absolutely stupendous. One flight of red-breasted nuthatches over Fire Island Beach, New York, as recorded by William Dutcher back in 1906, lasted from September 21 to 23. “At the height of the migration,” he wrote, “nuthatches were seen everywhere–on the buildings, on trees, bushes and weeds and even on the ground…Every tree had its nuthatch occupant, while many of them evidently found food even in the bushes and larger weeds. On a large abandoned fish factory at least 50 of these birds were seen at one time.”

In the 25 years we have lived on our central Pennsylvania mountaintop, we have had occasional visits from northern shrikes, evening grosbeaks, purple finches, white-winged crossbills, and northern goshawks, but we have only witnessed the irruption of three songbird species–pine siskins, common redpolls and red-breasted nuthatches–and all within the last nine years. The pine siskin irruption years were 1987-88, 1989-90, and 1995-96, common redpolls appeared in 1993-94 and 1995-96 and red-breasted nuthatches in 1995-96.

The pine siskin irruption in 1987-88 was one of the largest in living memory. At least 95 million siskins appeared at feeders all over North America.

I well remember my first sighting of the small, brown-streaked, sharp-billed birds. On October 26, 1987 at the Far Field I heard and then saw a flock of 20 pine siskins eating black birch seeds from a small tree at the edge of the field. Pine siskins (Carduelis pinus) both sound and fly like American goldfinches (Carduelis tristus) to whom they are closely related. But they are bolder than goldfinches and ignored me as I crept close and sat on the ground to watch them. After 15 minutes they whirled off.

A snowstorm in early November brought them to our feeders for the first time. I looked out almost in disbelief as more than 80 siskins descended, settling on saplings, the ground, back steps, porch floor and feeders. But they flew off in a few minutes.

Throughout the winter during stormy days the siskins came as a body to the feeders–up to 100 at a time–and gobbled up sunflower seeds. But since it was a mild winter, they spent most of their time in the forest eating black birch seeds. And I spent a lot of time watching them. On a sunny December day at the Far Field thicket, 60 of them twittered softly as they fed in a black birch tree. Then most of them flew down to a fallen tree trunk to eat snow. Fifteen of them lined up almost beak to beak. Others ate snow from tree branches and on the ground. After that they returned to birch seed eating.

At the end of February I found 80 siskins running over the snow-free ground at the base of Sapsucker Ridge. The golden wingbars of some of the males were prominent and in addition to their usual goldfinch-like calls, they also made buzzy sounds that resembled those of blackbirds. Occasionally they swooped up into saplings in response to warning calls, but I never did see what startled them. Mostly, though, they ran over the ground feeding on fallen tree seeds, sometimes coming within ten feet of where I was standing.

I continued to see them in the woods until the end of April and then they were gone, off to nest in high altitude coniferous forests from Alaska east to Newfoundland and as far south in the eastern United States as northern Pennsylvania. Now siskins are one of Pennsylvania’s rarest breeding birds, but ornithologists think that they were more abundant here before our coniferous forests were cut.

During the 1989-90 siskin irruption, they spent more time at our feeders. Otherwise, I found them in the hollow eating hemlock seeds with American goldfinches. For sheer entertainment at the feeders that winter I couldn’t beat the antics of pine siskins. Although there were less of them (40) than in 1987-88, they totally dominated the feeders whenever they came in, even pushing aside the hoards of house finches. These littlest creatures on the feeders threatened every bird that came too close by running toward them, sharp beaks open. In addition, the males flashed their yellow wing patches like caution lights. House finches, goldfinches, dark-eyed juncos, American tree sparrows, black-capped chickadees and even tufted titmice fled.

The siskins gobbled pounds of sunflower seed every day. One of them even blundered inside the tube feeder when I forgot to close the top after refilling it. I found the bird flopping around, trapped by its own piggishness. When I reached in to lift it out, it seemed to understand what I was doing and did not struggle in my hand as most birds do nor did its heart beat any faster. Siskins, it seems, are too self-confident and scrappy to be scared of a mere human.

Other observers have found them to be downright tame. Back in 1925 Edwin Russell Davis of Leominster, Massachusetts had 100 pine siskins at his feeder throughout the fall and winter. “Their extreme tameness,” he wrote, “made them easy to photograph, the only adverse circumstance being their insatiable curiosity, for no sooner would I appear with my camera than they would perch on it…Whenever I would appear at the window, or step outside the door, down they would come and, settling upon my head, shoulders, and arms, would peer anxiously about for the food that they had learned to know I held concealed from them in a box, dish, or other receptacle.”

Common redpolls (Carduelis flammea), in the same genus as goldfinches and siskins, are similarly unafraid of humans. They also like birch seeds and breed even further north than siskins–from the southern edge of the Arctic tundra south into coniferous forests from Alaska to Newfoundland. They and their close relatives, hoary redpolls (Carduelis hornemanni), can survive colder temperatures than any other songbirds, probably, in part, because of a special storage pouch in their esophagus which they fill with food just before night falls and then digest over night.

So winter-hardy are they that Maurice Braun, when he was Curator of Hawk Mountain Sanctuary back in 1947, reported watching 300 common redpolls bathing and wading in icy brook water. “These are the only birds that I have ever seen bathing–really soaking–in mid-winter,” he wrote.

Both species have bright red caps on their foreheads (“redpoll” means “red cap”) and black chins and male common redpolls have pink breasts as well. While hoary redpolls’ rumps and breasts are frosty-white, common redpolls are brown-streaked as are the backs and wings of both species.

I have never seen a hoary redpoll and until the 93-94 irruption had seen only an occasional common redpoll in First Field over the previous 22 years. So, on January 10, 1994 I could hardly believe my eyes when, in the midst of the house finches, I spotted a nervous common redpoll on the outskirts. Within a couple hours it was joined by seven others. All through the bitter cold and snow of January and part of February I could expect to see as many as ten but their last day at the feeder was February 18.

Having waited so long for my first redpoll irruption, I was amazed to witness another one last winter. Four common redpolls first appeared at the feeders on December 9, 1995 when the thermometer stood at seven degrees. The pine siskins had already been in since November 12, but their numbers were low. Fourteen was the highest count we had all winter. Both species came and went irregularly until the middle of March with common redpoll numbers peaking on March 9 at 32.

The redpolls proved to be as feisty as the siskins. One afternoon I watched a pugnacious redpoll hold the wooden bird feeder against all comers. In less than a minute it chased each interloper that landed by rushing at it and chittering loudly–downy woodpecker, tufted titmouse, black-capped chickadee, dark-eyed junco, and American tree sparrow, all of which fled in the face of its naked aggression.

Unlike the siskins and redpolls, the red-breasted nuthatches were peaceful in their close association with a huge flock of black-capped chickadees among the hemlocks along our hollow road. They also are not flocking birds during winter irruptions. Instead they live solitarily or in small stable groups on relatively small home ranges (about 15 acres). Even though home ranges may overlap during an irruption, they exhibit no aggression toward each other and, unlike resident red-breasted nuthatches, pair bonds are not important.

Smaller than white-breasted nuthatches, red-breasted nuthatches have a broad black line through their eyes with a white line above it and rusty-colored breasts. They live mostly in coniferous forests and eat pine and spruce seeds.

Here in Pennsylvania they will nest in Norway spruces and other ornamental conifers and were more common nesters before our Black Forest was cut. During the Pennsylvania Breeding Bird Survey one of the biggest surprises was the discovery of confirmed nesting in a wide range of coniferous tree plantations as far as the Maryland state line and west to Ohio.

Not only do they eat the seeds of conifers, they also use conifers’ pitch to smear around their nest hole entrances, probably as a defense against predators. According to William Brewster of Maine, “they brought it on the tips of their bills in little globules, alighted against the lower edge of the hole, and then tapped it on in various places as low as they could reach, but without shifting their foothold.”

Another behavioral pattern, one that they share with white-breasted nuthatches, is the ability to cache food. Usually they cache it under tree bark or in cracks and other interstices. But in Montana ornithologists watched a male red-breasted nuthatch flip through needle litter on the ground. Next he flew to the upper portion of a steep dirt cut bank carrying a pine seed. He probed in the dirt five or six times and he put the seed in the ground as deeply as the length of his bill. Then he picked up a small pebble and tamped it into the hole with a few beak jabs and repeated the same action with a similar-sized second pebble before flying to a nearby pine and foraging on the tree trunk.

My own observations of red-breasted nuthatches were not so dramatic. During the last week in December and first two weeks in January I found a red-breasted nuthatch every time I walked down the hollow. My first sighting occurred on a windy, cold December 21. It was silent in the hollow until I reached the hemlocks. They were filled with a merry band of chickadees eating hemlock seeds. As I stood watching them, I was thrilled to see a red-breasted nuthatch land on a hemlock trunk about six feet from me. After giving me the longest, closest view I had ever had of a red-breasted nuthatch, it flew to a fallen log spanning the stream and foraged beneath it. The red-breasted nuthatch was as quick and energetic as the chickadees, flitting from tree to tree, up, down and around at twice the speed of a white-breasted nuthatch.

During a red-breasted nuthatch irruption in the winter of 1972-73 in New Hampshire, ornithologist Lawrence Kilham also watched red-breasted nuthatches associate with chickadees in hemlock trees. Both ate hemlock seeds but only on dry, cold and windy days when hemlock cones opened. On warmer and more humid days the cones closed and the birds foraged on hemlock seeds that had previously fallen to the ground.

The hollow chickadee flock broke up by mid-January when the hemlock seed crop was exhausted, but we still had red-breasted nuthatches in the forest until May. I even watched a pair eating Norway spruce seeds in our own small plantation in late April and wondered if they would set up housekeeping there. So far, though, I have not discovered a nest.

I was not the only person in our area who watched red-breasted nuthatches. Most of the birdwatching members of our Juniata Valley Audubon Society similarly found them in their yards, woods, and even at their feeders. The same was true for common redpolls and pine siskins.

While last year’s irruption was weak in numbers it was the richest we have had in species’ diversity. To look out at my feeders and see both pine siskins and common redpolls and to walk down our hollow road on a cold, windy day and watch red-breasted nuthatches was a joy and a privilege that brightened what turned out to be the longest winter of our lives.