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!”