It’s mid-November and once again I‘m engaged in Project FeederWatch, keeping a record of the number and species of birds visiting my back porch feeder area. As a veteran of this citizen science project started by the Cornell Lab of Ornithology, both they and I are celebrating our 30th year engaged in this unique program.
The rewards have been enormous. Not only have I seen as many as 22 bird species at the feeders during the cold, snowy winter of 2014-15, but I have also observed interactions between small mammals and birds fighting for seeds on the ground. Although last winter, which was unusually warm, was not an exciting year for my feeder-watching, other wildlife observations while feeder watching added to my enjoyment.
This morning, for instance, shortly after 7:00, while glancing out at the feeder birds on the two tube feeders hanging from our back porch, I spot an eight-point buck walking to the edge of the woods and making or, more likely, freshening a scrape, pulling down a branch repeatedly with his mouth to leave his scent and then pawing the ground beneath.
Only a few yards from the buck, I see one, two, and finally three does foraging at the border between the woods and the flat area. I think I might see chasing and breeding, but he seems to sense that they are not yet in estrus.
When eight mourning doves feeding on the ground below the back porch steps suddenly take fright and fly, probably because they can see me standing at the kitchen door window staring out at the deer, the buck flees too. The does, though, continue eating placidly with no visible reaction to the buck’s retreat.
Week after week last winter I entered the same bird numbers and species, sometimes seeing as few as 11 species during my weekly, two-day count. But field work often consists of persistence with now and then a breakthrough. Mine came last February 16, when I recorded 18 American tree sparrows on the feeders and ground below, followed on March 3 by 21 tree sparrows. In previous winters my number of these sparrows hovered in the low single digits, and I couldn’t account for so many of these birds.
When the annual Project FeederWatch (PFW) report for the top 25 bird species from 6,498 sites in the northeast was issued, the American tree sparrow was 24th on the list, reported at 36% of sites, and the average flock size was three! All my other feeder birds—black-capped chickadee, dark-eyed junco, mourning dove, blue jay, northern cardinal, American goldfinch, downy and red-bellied woodpeckers, white-breasted nuthatch, tufted titmouse, song and white-throated sparrows and Carolina wren were much higher on the list.
Chickadee was first at 97% of sites, but that included both Carolina and black-capped chickadees, so dark-eyed junco, second on the list at 94% of sites, continued to be the most common feeder species. The flock size for juncos averaged four, but I’ve counted between 60 and 80 most years.
When I report those numbers, they are flagged during my online reporting as a result of a “smart filter” system the Cornell Lab has developed to root out mistaken observations. Species not usually seen in the area or high counts of a species are questioned. An error message pops up, and I am asked to confirm my number. Then when I do, my report is forwarded for review by PFW staff and regional biologists. Had I reported a rare bird, they would have required more validation, including a description of the site and bird and a photograph, if possible.
Because PFW data is being used by more and more researchers, they had to develop a reporting system that would increase both researchers’ and participants’ confidence in the resulting data. They tested their new “smart filter” system during the three winter seasons of November 2007-April 2010, flagging 50,104 PFW submissions out of a total of 3,924,088 or 1.3%, and reviewers approved 97.7% because a rare species had been confirmed in that region or, in my case, because large flocks of a species occasionally occur here. As researchers concluded in a paper about validating PFW reports, “Our methods ensure that unexpected reports are subjected to expert scrutiny, resulting in a more accurate and reliable data set regardless of the user.”
In contrast to last winter’s mild temperatures, the winter of 2014-15, which began late, was the coldest in decades. It was also a pine siskin invasion year. As they poured south from their boreal home grounds, we saw our first ones on November 9, 2014 when three dozen visited our feeder area. They must have headed farther south because our next siskin visitation happened on January 6, 2015. After that, it was every bird for itself and the mammals also, since pine siskins may be small, but they are feisty.
For example, on February 2, a cold, windy day, a sea of birds covered the ground when I threw out more birdseed in mid-afternoon. The siskins fought off all comers. Two on the large tube feeder fought with house finches and won. They scared off chickadees, tufted titmice, and each other as well as American goldfinches. The blizzard of birds, including siskins, continued through February and into a freezing March, with the siskins paying their last visit on March 30.
According to a paper about boreal bird irruption, pine siskin irruptions may happen every other year but also may occur in consecutive years or at longer intervals. Using more than two million PFW pine siskin observations from 1989-2012, researchers studied the patterns of pine siskin irruptions from their Canadian boreal homes where they eat conifer seeds to the high elevation Adirondack and Appalachian Mountains.
They concluded that a wet spring in the boreal region leads to a small seed crop, but a dry spring in the Appalachian region leads to a large seed crop. If the winter air temperature is also unusually cold in the boreal region, which even stresses these cold-adapted birds, they will irrupt south where the seed crop is plentiful. “This study,” they write, “is the first…to reveal how climate variability drives irruptions of North America boreal seed-eating birds.”
Using PFW data to track changes in winter bird communities has been useful in studying climate change in our backyards according to Karine Prince and Benjamin Zuckerberg. They maintain that since the 1970s, North America’s climate has been changing especially during the winter season with less and shorter snow cover and more variable and heavy precipitation.
Choosing 38 bird species that winter in eastern North America, they tested the influence of changes in winter minimum temperatures over 22 years and found that the winter bird communities became increasingly dominated by warm-adapted species such as mourning doves, Carolina wrens, red-bellied woodpeckers, eastern bluebirds and dark-eyed juncos, which moved northward about 4.2 miles a year.
Last winter PFW also received several reports of pine warblers as far north as Nova Scotia and growing numbers of hermit thrushes at northeastern feeders visiting two to four percent of sites.
The latest addition to PFW studies is a plea for us to report bird interactions at feeders. They began this project late last season and received 1,994 observations from 200 feeder watchers. Most were of one bird displacing another, 37 of one bird catching and eating another, and 23 of one bird mobbing another. Usually larger birds displaced smaller ones but sometimes smaller birds turned the tables with house finches displacing cardinals and downy woodpeckers displacing mourning doves.
I see many interactions a year, especially the winter of 2014-15. Some are harmonious such as the early January morning when a cottontail rabbit, a gray squirrel and juncos, white-throats, a tree sparrow, two song sparrows and a cardinal pair fed together on the porch and steps. Later they were joined by house finches, and goldfinches. Chickadees, titmice, and white-breasted nuthatches appeared and competed with goldfinches and house finches on the hanging feeders. Mourning doves flew in and out, as many as ten at a time, and a red-bellied woodpecker made several hurried appearances.
But our peaceable kingdom dissolved during a snowstorm two weeks later when four squirrels, the rabbit and 13 mourning doves pushed the small birds from the covered porch floor where I had spread birdseed. Then the birds that only eat from the feeders arrived—nine goldfinches, a couple chickadees and three house finches but goldfinches even displaced the house finches. A pair of cardinals sidled in and scared off as did a female red-bellied woodpecker.
Thus, instead of merely counting and recording my feeder birds I can contribute my observations of such interactions to PFW and help them learn more about what drives the interactions of feeder birds.
Happy 30th birthday Project FeederWatch, and may we celebrate many more birthdays together! A two-minute YouTube video provides an effective introduction to Project Feederwatch.
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