Sometimes it’s better to be a city bird than a country bird
Bloomington-Normal is not a bad place to be if you are a bird. That's according to a study done by Illinois Wesleyan University biologist Given Harper.
In a two-year look at breeding birds within Bloomington-Normal, Harper said he and volunteers for the U.S. Geological Survey documented breeding species in town and compared the numbers with seven rural nearby areas. They found town numbers are a lot higher than in the countryside.
“In McLean County and surrounding counties, it's row crop agriculture — 75% to 90%, intensive row crop agriculture. And from a bird’s perspective, that's the equivalent for most of an ecological desert. These monocultures of corn, or soybeans provide no habitat for the vast majority of birds,” said Harper.
That flips the usual logic that cities are bad for wildlife. He said the context for the study was a paper published in 2019 that showed since 1970, the population of North American birds had dropped 29%.
“So, I think urban areas are going to be increasingly important to try to reverse some of these population declines,” said Harper.
Urban areas are not good for all kinds of birds, but there was a surprising diversity of species, including relatively rare birds.
“We had one species of Bell's Virio, and a field Sparrow, that were found in one location in Normal in a shrub land, in Maxwell Park," said Harper. "Those are what the Illinois Department of Natural Resources calls species of ‘greatest conservation needs.’ And we were actually quite surprised to find them there. I think they're rare out in the county because I think in large part there is very little shrub land available for them.”
Also spotted in the shrub land was a Blue Grosbeak, a vibrant colored seed eater.
Harper said he and others are now trying to compare Bloomington-Normal’s bird diversity to urban environments in similar-sized cities.
“There were surveys done in neighborhoods in Chicago, adjacent to forest preserves, and just for their neighborhoods alone, they documented 36 species. This is not reflective, I think, of the entire Chicago area. Those were strictly for neighborhoods. There was a survey done in Washington, D.C. Both of these cities are certainly larger than Bloomington-Normal. But Bloomington-Normal had a greater number of species than documented in the Greater Washington, D.C., area,” said Harper.
He said the Twin Cities have a lot of mature trees and even some grassland areas that are oases for birds.
“We were quite pleased and surprised by the relatively large number of species that we observed," said Harper.
He said the implication of the study is that if population declines of North American birds can be reversed, humans need to increase bird habitat in urban areas.
“Birds are absolutely vital parts of ecosystems. And humans were dependent upon those same ecosystems. Birds are pollinators. They disperse seeds. They help control insect pests. There was a study published a couple of years ago that indicated globally, birds consume, on the order of 500 million tons of insects per year,” said Harper.
And humans are dependent on that very same ecosystem.