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Historical redlining is associated with increasing geographical disparities in bird biodiversity sampling in the United States

Abstract

Historic segregation and inequality are critical to understanding modern environmental conditions. Race-based zoning policies, such as redlining in the United States during the 1930s, are associated with racial inequity and adverse multigenerational socioeconomic levels in income and education, and disparate environmental characteristics including tree canopy cover across urban neighbourhoods. Here we quantify the association between redlining and bird biodiversity sampling density and completeness—two critical metrics of biodiversity knowledge—across 195 cities in the United States. We show that historically redlined neighbourhoods remain the most undersampled urban areas for bird biodiversity today, potentially impacting conservation priorities and propagating urban environmental inequities. The disparity in sampling across redlined neighbourhood grades increased by 35.6% over the past 20 years. We identify specific urban areas in need of increased bird biodiversity sampling and discuss possible strategies for reducing uncertainty and increasing equity of sampling of biodiversity in urban areas. Our findings highlight how human behaviour and past social, economic and political conditions not just segregate our built environment but may also leave a lasting mark on the digital information we have about urban biodiversity.

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Fig. 1: Map of 195 selected cities included in the analyses, spanning a range of social and ecological conditions.
Fig. 2: Patterns of biodiversity across redlined areas.
Fig. 3: Predictions of sampling density and completeness.
Fig. 4: Temporal trends in cumulative sampling density of bird observations in km2 across HOLC grades from 2000 to 2020.

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Data availability

Data used in this analysis are publicly available on Zenodo (https://doi.org/10.5281/zenodo.8052525) and were queried from GBIF as a derived dataset (https://doi.org/10.15468/dd.ha9ksv). Climatic predictors used in our analysis are publicly available through the Chelsa Climatology platform (https://chelsa-climate.org/), remote-sensing data are available on the Google Earth Engine (https://earthengine.google.com) and the PAD-US dataset can be downloaded from the United States Geological Survey website (https://www.usgs.gov).

Code availability

The codes used to download biodiversity data and environmental data, as well as for necessary analysis and creation of figures to recreate our results are available on Zenodo (https://doi.org/10.5281/zenodo.8052525).

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Acknowledgements

We thank T. Engel, C. Schmidt, S. Yanco, R. Oliver and J. M. Grove for helpful feedback on this paper. D.E.-S. acknowledges support from the Yale Institute for Biospheric Studies, and the Yale Race, Indigeneity and Transnational Migration Institute. The findings and conclusions in this paper are those of the author(s) and should not be construed to represent any official USDA or US Government determination or policy. The funders had no role in study design, data collection and analysis, decision to publish or preparation of the manuscript.

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D.E.-S., M.C. and D.H.L. designed the study and performed research. D.E.-S. led the writing of the paper with substantial contributions from M.C. and D.H.L.

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Correspondence to Diego Ellis-Soto.

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Nature Human Behaviour thanks Ashley Dayer and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

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Supplementary Figs. 1 and 2 and Tables 1–4.

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Supplementary Data 1

Collection of bird biodiversity coldspots across 195 cities in the United States.

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Ellis-Soto, D., Chapman, M. & Locke, D.H. Historical redlining is associated with increasing geographical disparities in bird biodiversity sampling in the United States. Nat Hum Behav 7, 1869–1877 (2023). https://doi.org/10.1038/s41562-023-01688-5

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