BLOOMINGTON — Illinois scientists can take a unique look at how changes in the state’s landscape have affected birds, thanks to three identical scientific studies spanning 100 years.
Jeff Walk, director of science for the Illinois Chapter of The Nature Conservancy and one of several scientists who collaborated on the book, “Illinois Birds: A Century of Change,” said the work actually started in the early 1900s when students from the University of Illinois walked three east-west routes across the state.
Their mission was to identify and count every bird they encountered. One path transected northern Illinois, one the midsection and a third southern Illinois. Whether they walked through forest, prairie, marshland, farmland or towns didn’t matter. They were to go straight and log every bird they saw. The research was the first-ever standardized bird survey in the United States.
The bird census was repeated on the same routes in the 1960s, and Walk and others repeated the effort in the early 2000s. Photos of landscape were taken in the same locations in 1906, 1956 and again in 2006.
The result is a bird’s-eye view of how particular bird species coped with changes caused by expansion of agriculture, urban development and other factors. Two-thirds of Illinois was once prairie and later converted in large part to farming. Grasslands and wetlands declined and cropland covered more acres over the years. Forests, which declined at first, are on the rise.
As a result, some birds thrived and some didn’t, depending on the kind of living space their species prefer.
“It is habitat, habitat, habitat,” Walk told a group in Bloomington not long ago at a presentation sponsored by the Illinois Wesleyan University departments of biology and environmental studies and the John Wesley Powell chapter of the Audubon Society.
Though some might predict gloomy results, the findings weren’t black and white. The number of bird species identified actually rose over time from about 90 in the earliest census to about 130 in the 1960s and about 140 in the latest work. The latest survey discovered 26 species that weren’t recorded at all in the early 1900s. The Bachman’s sparrow was the only species seen in the earliest survey that was gone from the state by the last one.
That’s not to say everything is fine. Better identification skills and even the time of day the researchers walked the route may account for some of the increase in species, according to Walk, and grassland ground-nesters, such as quail and pheasant, are among the long-term “losers.” Prairie chickens, which once populated about 80 counties in the early 1900s, were not seen in the latest census and only small protected pockets of the species remain.
About one-quarter of a million breeding pairs of Upland sandpipers were seen in the 1960s, compared to just about 250 pairs now, he said. Other losers include redheaded woodpeckers, which are no longer common in Illinois, he added.
But other bird species have made an appearance in the state, including the European starling and house finch. A total of eight species, including the cedar waxwing, mourning dove and red-bellied woodpecker arrived after expanding their previous ranges. Just as many species are moving northward into Illinois, others are moving south into the state due to climate change, which started in Illinois about 30 years ago, Walk said.
Hummingbirds were not counted in the earlier two surveys. But the latest survey found “a lot,” he said.
Among winners are wild turkeys, which were once numerous in Illinois and then gone in the 1960s, but now back, thanks to reintroduction. Raptors like bald eagles are recovering now that the chemical DDT was banned. Canada goose and blue heron numbers also have risen. Wood ducks, which some feared were on their way to extinction due to overhunting for their colorful plumage and loss of habitat, are Illinois’ most common nesting bird today. Other “winners” include what Walk referred to as “backyard birds,” such as cardinals and gold finches.
“The number of species is actually better than 100 years ago,” Walk said. “Right now is the best time to be a birder in Illinois as any time in the last century.”
Walk can only speculate on what the next 100 years will bring. Assuming urban development will continue, species that adapt to tolerate humans will fare better, he said. For example, crows that avoided towns 100 years ago routinely visit towns to feed on human food waste. Grasshopper sparrows nest in the shadow of Chicago’s skyline, he said.
“There is a lot of reason for hope,” he said.
On the other hand, the state doesn’t exist in a vacuum. “Illinois Birds: A Century of Change” contains a graphic showing Illinois’ climate by the end of this century will resemble today’s climate in Louisiana or Texas due to global warming. Birds that migrate over long distances will face serious challenges as temperature changes occur in the timing of the emergence of food sources, such as insects or seeds.
“By the end of the century our summers are going to look like Houston,” he said.
As Jean Graber, who did the survey in the 1960s with her husband, wrote in the book’s foreward: “Many of our problems arise because politicians who control the management of our resources have not had education grounded in biology and ecology and an appreciation of our natural world. We cannot increase indefinitely without destroying all other species, and, in the end, ourselves.”