If you have seen flocks of robins around the Quad-Cities this winter, you are not alone.
Lots of robins was a primary observation made by birdwatchers in December and earlier this month as they fanned out across the Quad-City region for the annual Christmas Bird Count.
The Christmas census of bird populations has been conducted nationally for 111 years under the auspices of the National Audubon Society. On designated days in December and January, volunteers count birds at feeders and in the field, taking note of numbers and species. Over time, the data reflect trends.
One of the trends Kelly McKay, a Hampton, Ill., field biologist who co-compiled the numbers, sees with this year's high population of robins is that the so-called semi-hardy species of birds are expanding their winter range farther north. These include robins, bluebirds, golden crowned kinglets, hermit thrushers and yellow rumped warblers.
While the bulk of those birds would have been in southern Illinois and points south during the winter 20 years ago, they are in the Quad-City region now, he said. McKay attributes that at least in part to climate change pushing warmer temperatures farther north.
In the winter, robins tend to flock together, so when they are found, they are in greater numbers than during the summer when they are in pairs and raising families. Occasionally, there were 50-60 in one location, McKay said.
"Twenty years ago, you hardly ever saw these birds during winter, let alone in multiples," he said.
Another trend McKay noted was a decrease in red-winged blackbirds and the common grackle, both birds that use marshes as night roosting sites. As marshes are filled for development, especially along the Rock River, the roosting sites disappear, he said.
Marshes in the Barstow, Ill., area have been fragmented into smaller units, which makes them less attractive to birds. One of the biggest areas remaining in that area has a "for sale" sign on it, he noted.
Overall, McKay was pleased with the total number of birds counted - about the same as previous years - as well as with the number of species, which was up a bit, partly because of the semi-hardies' increased numbers.
Steve Hager, an associate professor of biology at Augustana College in Rock Island and a co-compiler of the results, was especially happy with the diversity. He personally counted a peregrine falcon, trumpeter swan, cackling goose and northern goshawk, all birds that are fairly uncommon to see.
In photographing the peregrine falcon in Moline, Hager noted that the bird had a leg band with visible numbers. He consulted the website of the Midwest Peregrine Falcon Restoration Project and determined that the bird, named Blair, hatched in May at an electric power plant in Madison, Wis.
Given that Madison is 120 straight-line miles away and that female peregrines disperse an average of 245 miles, Blair may be using Moline as only a temporary resting/feeding spot before moving on to another location, he said.
In the mid-1900s, peregrine falcon populations were decimated by the use of the pesticide DDT, which caused egg shell thinning, and the birds once were considered endangered in both Iowa and Illinois. After a recovery effort that began in the early 1990s, the birds are listed now as "threatened" in Illinois and "of special concern" in Iowa.
The trumpeter swan, the largest bird native to North America, was hunted to the point of extinction at the beginning of the 20th century, but it has been reintroduced.
The trumpeter swan that Hager saw also was banded; he determined that the bird hatched in 2004 and that the banding was done in Long Grove, Iowa.