Abstract
Freshwater and terrestrial ecosystems are linked by reciprocal flows of energy and nutrients, including the emergence of aquatic insects that provide abundant, high-quality prey for riparian birds. Local studies show that emergent aquatic insects can enhance bird reproduction and survival, yet it remains unclear whether such associations scale up across landscapes and persist under human disturbance. Here we show that the richness of mayflies, stoneflies and caddisflies (Ephemeroptera, Plecoptera and Trichoptera; EPT), an indicator of freshwater integrity and insect emergence, predicts the prevalence of 288 bird species across 14,177 rivers in the contiguous USA, even after accounting for human land use. Aerial insectivorous birds exhibit more than threefold higher prevalence at sites with high compared with low EPT richness. This linkage is consistent across river types describing hydrology (including intermittent systems), temperature and geomorphology, with the strongest gains occurring in rivers with low baseline bird prevalence. The associations are weaker in urbanized sites but persist in highly agricultural landscapes provided that EPT richness remains relatively high. Our findings provide continental-scale evidence that emergent aquatic insects sustain riparian birds, underscoring that freshwater conservation offers considerable co-benefits to terrestrial ecosystems.
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Fluctuation in the diversity of mayflies (Insecta, Ephemerida) as documented in the fossil record
The ecological benefits of more room for rivers
Standardized diversity estimation uncovers global distribution patterns and drivers of stream insects
Data availability
Bird survey data were obtained from the eBird Basic Dataset40 (via Cornell Lab of Ornithology at https://ebird.org/science/download-ebird-data-products) and are available under a data-use agreement from the Cornell Lab of Ornithology. Aquatic invertebrate data were compiled from US federal and state biomonitoring programmes and are subject to the data-sharing policies of the respective agencies. As these datasets are owned by the contributing agencies, the original raw data cannot be redistributed by the authors. Information on data sources, spatial coverage and contact details for access requests is provided in Supplementary Table 6. The minimum dataset with processed data required to reproduce the analyses and figures presented in this study, together with the analysis code, are publicly available via Zenodo at https://doi.org/10.5281/zenodo.17643668 (ref. 81).
Code availability
All code used for data processing, statistical analyses and figure generation is available via Zenodo at https://doi.org/10.5281/zenodo.17643668 (ref. 81).
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Acknowledgements
This work was supported by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) through a Walter Benjamin Fellowship (project number SCHU 3827/1-1 to C.S.) and by the Richard C. and Lois M. Worthington Endowed Professor in Fisheries Management (University of Washington) to J.D.O. We thank the US Environmental Protection Agency, US Geological Survey, Bureau of Land Management, US Forest Service, US Fish and Wildlife Service, National Park Service and numerous state agencies for conducting and providing macroinvertebrate monitoring data, and the Cornell Lab of Ornithology for access to eBird data. We thank D. Fink for discussions on the use of eBird data and acknowledge the many citizen scientists whose observations made this study possible. We thank G. Jacuzzi for constructive feedback.
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C.S. and J.D.O. conceptualized the study. C.S. carried out the analyses, and C.S. and J.D.O. wrote the paper.
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Extended data
Extended Data Fig. 1 Spatial distribution of all aquatic insect and bird survey locations prior to filtering.
(A) Red points show all aquatic insect survey sites that fall within the map extent (total dataset: 141,150 sites). (B) Blue points show all eBird survey locations within the displayed area (total dataset: 11,962,137 surveys).
Extended Data Fig. 2 Overview of data integration and analytical workflow.
Schematic representation of all processing steps linking aquatic insect surveys with riparian bird communities across the conterminous United States. Federal and state biomonitoring data were filtered for recent (≤ 25 years) spring–summer samples, and eBird surveys were standardized for effort and trait-annotated. Riparian interaction zones were delineated around rivers (50–550 m buffers) and intersected with bird surveys within 5 km of insect sites. Proximity weighting accounted for spatial and temporal correspondence, followed by 5-km rarefaction to ensure independence. Insect and bird metrics (EPT richness and weighted bird prevalence) were related to riparian land-cover variables using hierarchical hurdle models, with subsequent validation, diagnostics, and marginal-effects analyses.
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Schürings, C., Olden, J.D. Cross-ecosystem linkages between freshwater insects and riparian birds across the USA.
Nat Ecol Evol (2026). https://doi.org/10.1038/s41559-026-03041-1
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DOI: https://doi.org/10.1038/s41559-026-03041-1
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