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!”
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.