Please cite this Page as:
Kammermeier, L. and Hochachka, W. 2000. Project FeederWatch Annual Report 1999-2000. Birdscope, Volume 14, Number 4:  1, 16.

This winter is warmest in 105 years records kept," read the newspaper headline. "Every state in the continental U.S. was warmer than its long-term average, with 21 states from California to the Midwest ranked as 'much above average.'" This news, which summarized a National Climatic Data Center report, was echoed by Feeder-Watchers across the United States. "Another mild winter, and consequently, a boring FeederWatch," sighed one FeederWatcher from Kansas. In addition to widespread warm temperatures, many southern states were gripped by a severe drought. For most FeederWatchers, the mild weather meant fewer birds, in number and variety, but for others it meant that some birds never left their summer homes, deciding instead to stay north and take their chances (you'll read about some of these gamblers in the rare birds section). Consider this view from Mrs. Carol Harrell, of Albuquerque, New Mexico: "We had a warm, dry winter. Many of the varieties I usually see at my feeders apparently never made it down from the mountainssharpies, flickers, towhees, woodpeckers, Curve-billed Thrashers, and Pine Siskins." For the birds that did migrate this past winter, some, such as the Red-winged Blackbird and the American Robin, returned early, according to FeederWatchers living in the northern states.

Common Redpolls flock to a feeder owned by a Connecticut FeederWatcher. FeederWatchers in many regions were treated to large flocks of this species at their feeders this past winter.

Despite last winter's relative paucity of birds, one FeederWatcher from Wisconsin remained optimistic: "At least this gives me a chance to get to know the birds personally!" quipped Sharon Ryther of Park Falls, Wisconsin.

Whether it was a boom or bust year at your feeder, with so many people counting their birds for FeederWatch, there are always interesting stories in the FeederWatch data.

The Big Picture

Among the patterns to emerge last winter were the "usual" biennial irruption of winter finches and Red-breasted Nuthatches in the East, unexpected increases in reports of a number of species, and declines in reports of several species that feed on the ground.

A few of these patterns are hinted at in Table 1, which shows the species that were reported most widely by FeederWatchers last winter. The last column in this table displays the FeederWatch Abundance Index for each species, which provides an overall estimate of how commonly a species visited FeederWatchers during the winter (for more specifics about how to interpret this index, see the sidebar "What do FeederWatch data tell us?") Table 1 also highlights the species with the largest percentage changes in their Feeder-Watch Abundance Index compared with the previous winter.

Looking at these percentage changes, you can see that FeederWatchers not only reported sighting more individuals of irruptive species such as Common Redpolls, Evening Grosbeaks, and Red-breasted Nuthatches, but also increases in the typically nonirruptive White-breasted Nuthatches and Brown Creepers. In addition, there were fewer and lower counts of ground-feeding species such as Dark-eyed Juncos and American Tree Sparrows. To find out where the greatest population changes for these species took place, see the Regional Scorecard.

Although Table 1 contains many bird species that are widespread across the continent, the data reflect a bias toward eastern species, because the majority of FeederWatchers live in the East. To find out which birds were reported in your FeederWatch region, see the Regional Top-10 List (Table 2).

If the Regional Top-10 List whets your appetite for more data, be sure to review the data retrieval and results section of the FeederWatch web site at <http://birds.cornell.edu/pfw>. Here you can see the 25 most common species seen by FeederWatchers in each state - along with additional FeederWatch summary statistics.

Winter finches irrupt in the East

Temperature isn't everything, at least not to birds when they are determining whether and where to move. Birds need to eat, and the biennial cycle of seed production in the northern forests of this continent seems to have been at a low phase, as we expected from past events. As a result, eastern North America experienced the "usual" biennial irruption of winter finches and Red-breasted Nuthatches (see the Regional Scorecard).

The excitement of this irruption was captured by Ruth White of New London, New Hampshire, who wrote, "We're in the midst of an irruption of Common Redpolls, Pine Siskins, and Bohemian Waxwings that arrived here yesterday in massive numbers. People who have not seen these species for years - or at all - are now watching them at their feeders!"

Each irruptive year is slightly different. Some species stage moderate irruptions during one year and major irruptions during the next. Among this year's irruptives, Common Redpolls appeared in larger-than-average numbers and were more common than in any winter since 1994. Redpolls were especially abundant in a band stretching from the Northern Rockieswhere sightings of the species increased by 129 percent to the North Atlantic regionwhere 40 times more redpolls were seen this year than last (Figure 1).

Occasionally, nestled among the Common Redpoll flocks, FeederWatchers detected the rarer Hoary Redpoll, a species that usually winters farther north than the Common. The Hoary looks like a paler and "frostier" version of the Common Redpoll. Last winter, it was seen three times more frequently in the Great Lakes region than during the 1998­99 FeederWatch season. The impression of bird watchers in the northeastern United States is that Hoary Redpolls were more abundant than is typical in an irruption, suggesting that both redpoll species moved farther south for the season last winter.

The redpolls' gregarious behavior makes for great feeder watching. Unfortunately, this also provides ideal conditions for the spread of disease. Large numbers of redpolls and, to a lesser extent, Pine Siskins, were afflicted with salmonellosis, a bacterial disease that periodically causes mass mortality in gregarious foraging flocks. Outbreaks of the disease are more frequent during irruption years. It is always important to maintain your feeders, but you should take extra precautions to keep your feeders clean and safe during irruption years, because the bird densities are higher.

A question that FeederWatchers are helping us answer is whether irruptive birds are passing through a region on their way south or settling in as their winter range expands southward. Last winter, Common Redpolls exemplified the latter case, whereas Red-breasted Nuthatches and Pine Siskins demonstrated the former. Some FeederWatchers commented that local invasions of nuthatches and siskins occurred early and the birds disappeared before the FeederWatch season started.

Nonetheless, many Feeder-Watchers were lucky enough to host these birds all season long. Red-breasted Nuthatches were reported by 40 percent of FeederWatchers (Table 1) and irrupted into parts of every region in the East (Figure 2). Pine Siskins were reported by 23 percent of FeederWatchers; their irruption was particularly noticeable in the New England, Allegheny, and Southeast regions, where their Feeder-Watch Abundance Index increased by an average of 973 percent (Figure 3). Looking back, however, last winter's siskin invasion was on par with previous invasions. You may recall that the winter of 1998­99 was a big irruption year for siskins in the West. We received fewer reports from the West, so it seems that the siskins are continuing their pattern of irrupting on opposite sides of the continent in alternate years.

Although some species roam large distances during irruptions, others simply go downhill, literally. Altitudinal shifts are especially common in the mountainous West. The Cassin's Finch, for example, occasionally descends from high-elevation open woodlands into low-elevation habitats, where more FeederWatchers live. According to FeederWatch reports, Cassin's Finches were four times more common in the Northern Rockies region last season than they were the previous winter (but falling far short of the banner 1993­94 and 1995­96 FeederWatch seasons).

Bohemian Waxwings also make elevational or relatively short-distance migrations in the mountainous West. "When they arrive, they arrive!" said Poo Wright-Pulliam of Sun Valley, Idaho, as she viewed a flock of more than 100 Bohemian Waxwings that had just touched down in her yard. On occasion, Bohemian Waxwings are long-distance irruptives as well, traveling across the continent to the North Atlantic region where the species' FeederWatch Abundance Index increased by 150 percent. The waxwings roamed in larger flocks than were seen in all but two previous winters.

Northern Shrikes make widespread movements

Many of our irruptive species move predictably southward every second year, but some species, such as the Northern Shrike, irrupt less predictably.

An invasion of Northern Shrikes made for some awesome feeder- watching last winter. Feeder-Watchers across the northern tier of the United States commented that they saw shrikes at their feeders, no doubt looking for the easy pickin's available there. The shrike's diet includes mice and other small rodents; but in years when small mammal populations are low, the species becomes a relatively common visitor at feeder areas, where it preys on songbirds. This past winter, FeederWatchers saw shrikes capturing redpolls, cardinals, Downy Woodpeckers, chickadees, and House Sparrows. A few participants even saw them harassing Blue Jays.

Although last winter's shrike invasion was noticed by many FeederWatchers, it was not as great as the influx that occurred in the 1995­96 winter.

Increased feeder visits by White-breasted Nuthatches and Brown Creepers

Other birds that were more common at feeder areas this past winter include White-breasted Nuthatches and Brown Creepers.

White-breasted Nuthatches are normally nonmigratory, but they occasionally stage large-scale movements. (The 1995­96 Feeder-Watch Annual Report covered one such movement and theorized that it was related to acorn-crop failures in the Northeast.) Overall, the abundance of this species increased 19 percent from the previous winter, sending it to the Top-10 List in three regions from which it was absent the year before: East Central, North Atlantic, and Mid-Atlantic.

The Brown Creeper is generally a solitary bird that feeds on insects. But sometimes creepers travel with winter flocks of tit-mice and nuthatches and visit suet feeders, which may make them more noticeable in people's backyards. Last winter, Brown Creepers increased in abundance in many regions across the continent (Table 3). The largest increases (and record-high reports) came from the New England and Southeast regions.

Ground-feeding juncos, towhees, and sparrows were scarce at feeders

Ground-feeding birds of all types were scarce this past winter, especially in the Mid- and South-Central regions (see Regional Scorecard). These regions experienced severe droughts last year, which may explain the low abundance of many of these species.

Food availability often determines why species move elsewhere. The food supplies of irruptive species vary because of the intrinsic schedules of their food plants, and generally they are little affected by year-to-year climate changes. The food supplies of other birds are more weather-dependent. The seed produced by smaller plants, such as grasses and forbs, is eaten by many ground-feeding sparrows and their relatives and can be easily affected by rainfall. This in turn affects the birds.

Harris's Sparrow showed an especially notable decrease in its FeederWatch Abundance Index. This species regularly winters in the Mid-Central and South-Central regions and was less common there than it was two winters ago. Because of their limited winter range, this suggests there were in fact either fewer Harris's Sparrows or that they stayed away from FeederWatchers' yards.

The "stayed away from yards" idea seems an especially plausible reason for the widespread decrease in the FeederWatch Abundance Index of species such as the Dark-eyed Junco and the American Tree Sparrow (Figure 4). These two species were particularly scarce in the East, where their visitation rates declined by an average of 18 percent and 31 percent respectively from the previous winter. As discussed in Birds at Your Feeder by Erica Dunn and Diane Tessaglia-Hymes, juncos and American Tree Sparrows prefer natural foods to commercial seed. A scarcity of birds at feeders may simply indicate that the species were "in the neighborhood" but didn't visit feeders because they had no trouble finding natural food supplies.

FeederWatchers spot rare birds

Each year, a handful of FeederWatchers are treated to glimpses of (or even extended stays by) rare birds. These FeederWatchers eagerly share their sightings by sending in a rare bird form. Last winter's rare bird reports that have been confirmed so far are listed in Table 4.

Many of the sightings on this list are somewhat "regular oddities," meaning that a few individuals of the species are regularly found wandering far from their usual winter haunts. Red-bellied Woodpeckers, for example, were reported by several FeederWatchers as far north as Maine, Minnesota, and Nova Scotia. These far-flung observations mirror reports of birders from last fall, which noted Red-bellied Woodpeckers moving into and through the same areas (including birds seen at sea in the Atlantic). This woodpecker has been expanding its range northward in recent decades, and northern sightings of these "pioneering" individuals are becoming increasingly common.

Several Baltimore Orioles were found lingering in the North during midwinter, foregoing their southerly migration to the American tropics. Like some bluebirds and robins, Baltimore Orioles are "half-hardy"a few often stay back to tough out the winter. Stray Dickcissels were found along the East Coast of the United States, south to Maryland and South Carolina, where occasional wintertime visits occur. Harris's Sparrows, another bird that regularly strays in small numbers, were seen in New York and Ontario.

We thank everyone who sent in rare bird reports this past season. As of this writing, we were still reviewing and confirming rare bird reports, and we'll post all confirmed records (including some photographs) on the FeederWatch rare bird archive at <birds.cornell. edu/pfw/> (in the data retrieval section).

Closing thoughts

Though to many FeederWatchers the winter that ushered in the new millennium seemed a bust for birds at feeders, the data in fact show that it was quite an exciting one, with short-term changes in a variety of species.
This demonstrates the importance of surveys such as this. Often what you find when you examine a population over its entire range is different from the view from your backyard or even a scientist's experimental woodlot. The Lab couldn't conduct this project or understand winter bird populations in such detail without the observations from your backyard "field stations." We sincerely appreciate your reports and thank you for making this project possible.

Where will North American feeder birds be in the winter of 2000­01? We look forward to finding out - from you!