AUTUMN 1994/VOLUME 8, NUMBER 4

Project FeederWatch
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Project FeederWatch
Annual Report 1993-94
BY DIANE L. TESSAGLIA AND KENNETH V. ROSENBERG

Please cite this Page as:
Tessaglia, D.L. and Rosenberg, K.V. 1998.  Project FeederWatch Annual Report 1993-94.   Birdscope, Volume 8, Number 4.

A winter of "seeing red" in the North,
more purple and gold in the South

This report summarizes the observations of the roughly 8,700 FeederWatchers who collectively donated over 50,000 hours to counting birds this past season. In this
summary, we'll highlight several bird population trends that have continentwide
significance. We identified these trends from both our data analyses and from the many comments from Project FeederWatch participants.

    This year "red" was a predominant theme in comments from participants throughout the northern states and provinces. As we predicted in the last   Birdscope, many FeederWatchers will remember 1993-94 as "The Year of the
Redpoll." Common Redpolls and Red-breasted Nuthatches staged their largest
invasion since Project FeederWatch began, along with lesser numbers of Pine Grosbeaks and Bohemian Waxwings. In the southern and western regions, FeederWatching was less eventful, although resident bird populations appeared to be stable or increasing. How did your yard compare with others around North America? Read on and find out.

Seeing Redpolls-Invasions from the North

     Irruptive species-northern birds such as many finches, nuthatches, and waxwings that sometimes invade to the south-typically elicit the most comments from FeederWatch participants. In fact, many label their season as "good" or "bad" depending on the presence or absence of winter invaders at their feeders. Judging solely from your comments, we might sum up this past winter as "good" in the North and East and "bad" in the South and West.

    One of the great successes of Project FeederWatch, however, is its ability to
track the populations and movements of these irruptive species from year to year and region to region. To accomplish this, it is just as important to know where the birds are not, as where they are. Even your lowest counts, therefore, are extremely
valuable.

    This winter's "red invasion" was led by the Common Redpoll, a species that breeds in North America only in the arctic regions of Canada and Alaska. Last year,
only 8 percent of FeederWatchers across the continent reported Common Redpolls at their feeders. This year that number increased to 28 percent, and FeederWatchers reported seeing Common Redpolls in nearly every northern state and province. Figure 1 shows areas where redpolls increased their distribution compared with last winter, and areas where redpolls appeared this year but not at all last year.

    The center of the redpoll invasion, where the highest numbers were reported, was in southern Canada, especially the Maritime Provinces. Over 85 percent of FeederWatchers in Nova Scotia, New Brunswick, Newfoundland, Prince Edward Island, and southern Quebec reported Common Redpolls, in flocks of up to 350 birds.

    Two other redpoll hot spots were Alberta and Saskatchewan, where 95 percent
of FeederWatchers reported flocks of 12 birds on average. Perhaps more telling was that Common Redpoll was the most abundant species overall in Alberta,
Saskatchewan, Quebec, and Alaska (where this is not unusual).
Figure1

Figure 1. Distribution of Common Redpolls during the winter of 1993-94, compared with the previous winter (1992-93). Shading indicates changes in the percentage of feeders visited in each state or province.

Dynamic Changes in Redpoll Abundance

     This picture of overall distribution and abundance, however, fails to illustrate the
dynamic nature of redpoll movements throughout the season, which were carefully
documented by FeederWatchers on a weekly basis. When counting began in mid-
November, the species was already present in western Canada and around the Great Lakes; small numbers seen east and south of there presaged the large flights to come (Figure 2). By late December, redpolls were moving into new areas of New England, New York, and the other border states from Michigan to North Dakota. A few birds reached feeders in Nova Scotia, but numbers remained low in the Maritimes south to Maine. Until this time, only a few large flocks (more than 100 birds) had been reported, mostly from Ontario and Quebec (Figure 3).

    Late December is the time when Audubon Christmas Bird Counts take a
"snapshot" of winter bird distributions, but the redpolls continued to move. One of the unique strengths of Project FeederWatch is its ability to track bird movements long after Christmas-counters have sent in their data. In mid-January, the redpoll invasion really got exciting as flocks pushed south through Pennsylvania, New Jersey, and Maryland, and east into Maine, New Brunswick, and Nova Scotia. By the beginning of February, FeederWatchers across Ohio, northern Illinois, and Indiana, as well as Newfoundland, were enjoying redpolls. Flocks of over 100 birds were counted in New York, Connecticut, Pennsylvania, northern New England, New Brunswick, and Nova Scotia, and stragglers reached Virginia, South Carolina, Kentucky, and Missouri.

    Numbers continued to build throughout February and March, with the first large
flocks reported in Newfoundland, Massachusetts, Maryland, Michigan, and Minnesota. At the end of the FeederWatch season in April, redpolls were still common in many areas, but were showing signs of retreat. Overall, the redpoll invasion was the largest since 1977 and provided many FeederWatchers with a new bird for their feeder lists. These comments from FeederWatchers were typical of the many we received:
"Highlights of my fifth year of FeederWatch: Jan. 20, 1994, 2 Common Redpolls came and ate sunflower seeds-my first-ever sighting of this species here!" said Marilyn Wavering of Annandale, Virginia. "The Common Redpolls I had at my feeders this season were the first I've had since the winter of 1983-84," wrote David Wolfe of Ridgeway, Pennsylvania.

    A side benefit of the Common Redpoll invasion was that many people also were
treated to a glimpse of the much rarer Hoary Redpoll. This species is almost exclusively Arctic in its distribution and rarely invades areas where bird watchers live. This year we received reports of hoaries from nearly every region where Common Redpolls occurred-often in the same flocks. Identification of Hoary Redpolls can be extremely difficult, however-they look like lighter versions of Common Redpolls, but not all light-colored redpolls are hoaries. Therefore, some hoaries may have been missed, and some Common Redpolls misidentified.Figure 2

Figure 2. Changes in Common Redpoll distribution throughout the winter of 1993-94. Each dot represents a zip code or postal code where redpolls were reported. (a) The distribution at the start of the FeederWatch season; (b) during the week when most Christmas Bird Counts are conducted; (c) at the height of the redpoll invasion; (d) at the end of the FeederWatch season.  Figure 3.

More "Seeing Red"-Red-breasted Nuthatch

The second "red" species in last winter's invasion was the Red-breasted Nuthatch,
which increased in all regions except the West Coast and Southwest (Figure 4). The
areas that saw the largest changes compared with last year were the upper Midwest
and Great Lakes regions south to Oklahoma, Arkansas, and Tennessee. Red-breasted Nuthatches visited 62 percent of feeders in the North Central region, the highest percentage of feeders visited by this species in any region since Project FeederWatch began in 1987-88. This species was also numerous in the Canadian Maritime Provinces and New England, with a moderate invasion detected south along the Atlantic Coast to Virginia.

    Only Quebec saw a noticeable decrease in nuthatches compared with last year;
throughout the West and deep South, populations were essentially unchanged. In all
areas, Red-breasted Nuthatches usually visit feeders singly or in pairs, so the percentage of feeders visited not only shows distribution of this species, but also overall abundance. Unlike the slow-building redpoll invasion, the nuthatch invasion came early-in August or September in some areas. Thereafter, the birds' distribution
changed little throughout the FeederWatch season.
Figure 4

Grosbeaks and Waxwings Made the News

     Nearly overshadowed by the widespread irruptions of redpolls and nuthatches, several other species made notable movements out of the far North. Pine Grosbeaks made news in some areas, even though the numbers seen were generally small. Pine
Grosbeaks came to feeders most frequently across southern Canada from Alberta to Quebec, with the eastern provinces showing the largest increases from previous years. More unusual were small flocks crossing the border into northeastern states as far south as New Jersey, Pennsylvania, Indiana, Illinois, and Iowa. This species also occurred at 48 percent of all Alaskan feeders, but this was actually a decrease of 20 percent from last winter.

    Another species that many FeederWatchers noticed was the Bohemian
Waxwing. The largest numbers were reported from western Canada, although the
percentage of feeders visited there was nearly identical to past years. Flocks that
appeared from southeastern Ontario to Nova Scotia were much more unusual, and a few stragglers were noted as far south as Cape Cod, Pennsylvania, and Illinois (Figure 5). Even though waxwings rarely visit bird feeders, we are pleased to see how FeederWatchers documented the movements of these interesting birds.
Figure 5

Another Winter of Purple and Gold in the South

     As northern FeederWatchers counted the red invaders, southern feeders didn't lack colorful visitors. Purple and gold, the colors of Mardi Gras and New Orleans, were also, appropriately, the colors of the winter finches recorded across the South. In fact, the distribution patterns shown by Purple Finch and American Goldfinch were remarkably similar across the entire continent.

    American Goldfinch is among the most widespread feeder visitors (see TABLE), and although not usually considered an irruptive species, its abundance may vary markedly from region to region. This year the center of goldfinch abundance was in the south-central states; it was the most numerous species at feeders in Oklahoma, Arkansas, Louisiana, and Mississippi, as well as North Carolina (Figure 6a). This is not necessarily unusual; goldfinch numbers were higher in Oklahoma and Louisiana, but actually lower in Arkansas and Mississippi, compared with last winter.

    Relatively high goldfinch abundance (more than two birds per feeder on average)
continued northward through the central states to Iowa and South Dakota, and most of this region saw an increase over last year. In contrast, goldfinch numbers were reduced in much of the Northeast, from New Brunswick and Maine west to Michigan and Minnesota. In Ontario and Quebec alone, the percentage of feeders visited dropped by over 30 percent and the number of birds per feeder crashed to only 15 percent of last winter's counts. Goldfinches were also less numerous than last year in South Carolina, Georgia, Alabama, and Tennessee.

    Overall, this pattern suggests that birds moving out of the Northeast and Great
Lakes regions traveled toward the West and avoided the extreme Southeast. Some
FeederWatchers speculated that the exodus of goldfinches in the North was due in part to the invading redpolls. Given that these species eat similar foods, both in the wild and at feeders, this scenario is at least possible. Western populations of American Goldfinch were more stable overall, with decreases noted in California, Utah, and Wyoming, and increases reported in British Columbia and Arizona.

    The relative abundance of Purple Finches essentially paralleled that of the goldfinch, with decreases of 50 percent overall in the Northeast and increases in the south-central and Midwestern states (Figure 6b). The largest reductions in numbers were seen in eastern Canada south to New England, New York, and Michigan. The largest increases over last winter's numbers were reported along the Gulf Coast from Alabama west to Louisiana, and from Oklahoma north to Nebraska. Relatively high Purple Finch numbers were seen in both winters in many of the remaining Midwestern and southern states. As with the goldfinch, western populations were relatively stable, with a small increase seen in British Columbia and a decrease in California.

The Most Widespread Species Are Also the Most Stable

     With just a few exceptions, this year's list of the most widespread feeder birds is nearly identical to last year's (see the table above). This year, 28 species were seen by at least 25 percent of FeederWatch participants across North America. All of the species reported last year made the list, and the two invading species-Common Redpoll and Red-breasted Nuthatch-were added. Among these common species, only minor changes were reported in either the percentage of feeders visited or the mean number of birds per feeder; eight species occurred at exactly the same percentage of feeders this year as last. Not surprisingly, Dark-eyed Junco retained its claim as Most Widespread Feeder Bird throughout the continental United States and Canada, occurring at 83 percent of all feeders. Readers may be surprised to learn that the largest number of juncos were counted at feeders in New Mexico, followed by Oregon, Washington, Iowa, and West Virginia.

    Among the species not already discussed, the House Finch is perhaps the most
significant. When Project FeederWatch began only seven years ago, House Finch
occurred at 48 percent of all feeders and was ranked ninth among widespread species. Having edged past the House Sparrow in 1992 with a fourth-place ranking and 61 percent of feeders visited last winter, the House Finch continues to expand its range steadily in the East as House Sparrows slowly decline. The expansion of this introduced eastern House Finch population was one topic of a poster that Project FeederWatch staff presented at the joint meeting of the Ornithological Societies of North America in Missoula, Montana, this past June (see item, below).

    Two species that declined this past winter are also worth mentioning. Pine Siskins have often been the focus of past FeederWatch reports because of their highly erratic movements. Indeed, one of the fun aspects of participating in Project FeederWatch has been seeing where the siskins go each year. This year, they were
virtually nonexistent in many regions, especially on the West Coast, where they were
particularly abundant last year. Was this part of a normal fluctuation in numbers, or did the Salmonella epidemic cause massive mortality in West Coast populations? Only continued counts in future winters will answer that question.

    Pine Siskins did stage a widespread invasion into the Southeast region, where numbers tripled overall compared with last winter. The largest increases were in North Carolina, Alabama, and Mississippi, although numbers in these areas were still lower than during previous invasions farther north. Siskin numbers remained relatively high in the Rocky Mountain states, and a second mini-invasion took place east of the mountains in North Dakota, South Dakota, and Nebraska.

    Interestingly, the general lack of siskins was not reflected in the overall percentage of feeders visited, which has remained remarkably stable over the years (see the table). Even in regions where siskins do not spend the winter, highly  mobile individuals may visit particular feeders on occasion, especially during return  flights in spring. The cumulative number of feeders visited, therefore, may give an exaggerated picture of siskin distribution in a given season.

    Another species showing a decline in 1993-94 was the Carolina Wren, which
elicited many concerned comments from FeederWatchers in the Northeast. The
northern states and provinces are clearly on the fringe of the Carolina Wren's range,   but this nonmigratory southern species has been gradually expanding its range northward. Because it is nonmigratory, however, this species may suffer high mortality during severe northern winters. Such an event was well documented in 1976-77, with northern populations crashing and then recovering completely in subsequent years.

    Did the bitter cold and frequent snowstorms this past winter take a similar toll on
wrens in the Northeast? We examined the weekly FeederWatch counts and noted that, in the Northeast Region, Carolina Wrens visited fewer and fewer feeders as the season progressed, although they didn't follow this pattern in the Southeast region (Figure 7). The Northeast decline came after a sharp peak in visitation during the week of January 8-14. This period corresponded with a severe storm that dropped at least three feet of snow over most of the Northeast and glazed much of the Southeast with ice.          Figure 7

    Carolina Wrens eat mostly insects year-round, and presumably only visit feeders
when natural foods are scarce. A large increase in numbers at feeders may signal
trouble for wren populations-for example, a similar peak in wren visits to feeders
occurred in the Northeast during the March 1993 blizzard. Although some FeederWatchers specifically stated that "their" wrens had died this year, we must await future surveys during the breeding season to indicate how Carolina Wren populations fared.

   Finally, we note that the majority of the remaining widespread species have been
quite stable since Project FeederWatch began. This includes many of the resident
chickadees, titmice, nuthatches, woodpeckers, and jays, as well as doves, starlings,
and some sparrows. The stability of the resident birds may be less exciting than the
massive irruptions noted above, but seeing such stability is heartening, for two reasons.

    First, when species that "should" remain stable actually do remain stable, then
we have greater confidence in FeederWatch's ability to detect changes that do occur. Also, as the population of FeederWatchers changes each year, the consistent numbers reported for resident species indicate that our sampling of winter bird populations is indeed adequate. This was a major theme of our presentation to the joint Ornithological Societies of North America meeting in June (see "Project FeederWatch Flies High in Montana," below). It is heartening also to report that in contrast to many populations of neotropical migrants and wetland and grassland birds, populations of most species that visit feeders in winter are either stable or increasing.

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