Discriminatory U.S. housing policies still affect bird sightings 90 years later

Citizen scientists are the main “collectors” of all recorded bird data, especially in the United States. More than 600,000 eBird experts and enthusiasts alike report on the colorful plumage and behaviors of species they spot in their American neighborhoods. Yet a recent study published in Nature Human Behavior unveils a disturbing scarcity of bird sightings within cities where the stain of racial segregation has lingered for nearly a century.

During the harsh economy of the Great Depression in the 1930s, the U.S. government enforced restrictive zoning policies for housing in cities. Certain neighborhoods were at the mercy of racist policymakers, who “redlined” areas they deemed risky and unsafe. In particular, redlining policies isolated Black residents in zones of high poverty.

The effects of redlining are still palpable today — not only through the racial segregation of neighborhoods, but also in the distribution of flora and fauna. Birds have always served as ideal indicators of the richness of nature in any area. So, ecologists sought to investigate the link by comparing the numbers of bird sightings in the last 90 years with neighborhood gradings across the U.S.

“We’re starting to untangle the environmental effects, because segregation did not just shape where highways and wastewater facilities were built,” said lead author Diego Ellis-Soto, an ecologist at Yale University, “but also where national parks and urban recreation areas were built.” Those green spaces, he noted, attract wildlife.

Ellis-Soto and his colleagues examined 195 cities where redlining policies were put in place in the 1930s. The team used data from the eBird and iNaturalist citizen-science digital platforms, as well as the Global Biodiversity Information Facility.

Their statistical analysis showed a clear pattern: a remarkable drop in bird sightings within redlined neighborhoods. Some of those zones had just one-quarter as many bird records as wealthier areas in the same cities. Americans living among these nature coldspots miss countless species of birds, the research suggests.

Those differences have gotten worse in recent years as well. Between 2000 and 2020, during the explosion of digital citizen science platforms, the information gap widened by more than 35%, the data shows.

“We find this consistent pattern across 200 cities that have experienced very different changes since the 1930s up to today,” Ellis-Soto told Mongabay. “Segregation is still measurable in our access of digital information in times of the biodiversity crisis.”

Indeed, birdwatching is dramatically different in areas surrounded by heavily redlined neighborhoods, something Ellis-Soto can observe just by walking outside. In the wealthy academic center of New Haven, Connecticut, where he lives, he can record 12 times as much bird data as in Dixwell, a historically redlined neighborhood a couple of blocks away.

The same patterns arise near California State University, Los Angeles, the home of wildlife biologist Eric Wood. His colleagues conducted a similar study focusing on the distribution of birds in the bustling city of Los Angeles. Wood, who was not part of Ellis-Soto’s team, coins the distinct change in wealth and natural environment between neighborhoods the “luxury effect.”

“You’ll just be in a neighborhood where there’s trees and gigantic houses everywhere,” Wood remarked. “And then you cross a certain street, and it becomes very poor very quickly.”

The luxury effect clearly influences which birds a citizen might spot in Los Angeles, and where, Wood said. For example, birdwatchers might see pigeons and sparrows in the urban landscape of Boyle Heights, compared to woodpeckers and hummingbirds around the lush greenery of San Marino.

In historically redlined areas with fewer parks and greenery, access to nature becomes difficult, Wood said. It’s an environmental justice issue, he told Mongabay: “You’re probably going to have less people doing things like going out and [birdwatching]. I think they showed that really clearly in their paper across cities all around the country.”

This strong digital human signature in biodiversity data is getting worse with time, Ellis-Soto emphasized. His team hopes their findings will contribute to the U.S. government’s Justice40 Initiative, which seeks to allocate federal funding toward communities impacted by environmental injustice.

“If we have biased data, we might be getting the wrong maps,” Ellis-Soto said, “and we might be making the wrong investments.”

Citation:

Ellis-Soto, D., Chapman, M. & Locke, D.H. Historical redlining is associated with increasing geographical disparities in bird biodiversity sampling in the United States. Nature Human Behavior (2023). https://doi.org/10.1038/s41562-023-01688-5

Chiara Villanueva (@chiiavilla) is a graduate student in the Science Communication M.S. Program at the University of California, Santa Cruz. Other Mongabay stories produced by UCSC students can be found here.