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Seasonal abundance and survival of North America’s migratory avifauna determined by weather radar


Avian migration is one of Earth’s largest processes of biomass transport, involving billions of birds. We estimated continental biomass flows of nocturnal avian migrants across the contiguous United States using a network of 143 weather radars. We show that, relative to biomass leaving in autumn, proportionally more biomass returned in spring across the southern United States than across the northern United States. Neotropical migrants apparently achieved higher survival during the combined migration and non-breeding period, despite an average three- to fourfold longer migration distance, compared with a more northern assemblage of mostly temperate-wintering migrants. Additional mortality expected with longer migration distances was probably offset by high survival in the (sub)tropics. Nearctic–Neotropical migrants relying on a ‘higher survivorship’ life-history strategy may be particularly sensitive to variations in survival on the overwintering grounds, highlighting the need to identify and conserve important non-breeding habitats.

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Fig. 1: Cumulative nocturnal migration traffic in spring and autumn.
Fig. 2: Southern and northern transects for quantifying seasonal biomass passage, migration traffic across these transects, and associated demographic indices.
Fig. 3: Annual cycle of avian biomass flow across the north and south transect.
Fig. 4: Angular definitions of transect direction and bird ground speed direction.

Data availability

NEXRAD weather radar data were accessed from the public ‘noaa-nexrad-level2’ Amazon S3 bucket20 (


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This work was supported through a Rose Postdoctoral Fellowship (to A.M.D.), AWS Cloud Credits for Research (to A.M.D.), NSF ABI innovation DBI-1661259 (to A.M.D. and F.A.L.S.), the Leon Levy Foundation (to A.F. and D.F.), National Fish and Wildlife Foundation 6001.16.052172 (to A.F. and S.K.), NSF IIS-1633206 (to A.F. and S.K.), NSF ABI sustaining DBI-1356308 (to F.A.L.S., D.F. and S.K.) and the Wolf Creek Charitable Foundation (F.A.L.S.).

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Authors and Affiliations



A.M.D., A.F. and S.K. conceived the study. A.M.D. performed the research and analysed the data. F.A.L.S. calculated species breeding and wintering distribution centroids. K.V.R. compiled transect species compositions from PIF population estimates. A.M.D. wrote the paper with input from all authors.

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Correspondence to Adriaan M. Dokter.

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Supplementary information

Supplementary Information

Supplementary text; Supplementary references; Supplementary Figures 1–5; Supplementary Tables 1–6; Captions to Supplementary Videos

Reporting Summary

Supplementary Video 1

Nightly migration traffic mt (accumulated per night, in blue-white linear colour scale) and average ground speed direction (orange arrows) during spring from 1 March 2016 to 30 June

Supplementary Video 2

Nightly migration traffic mt (accumulated per night, in blue-white linear colour scale) and average ground speed direction (orange arrows) during spring from 1 August 2016 to 30 November

Supplementary Video 3

Seasonally accumulating migration traffic mt (accumulated from 1 March 2016 until video frame time stamp, in blue-white logarithmic colour scale) up to 30 June 2016

Supplementary Video 4

Seasonally accumulating migration traffic mt (accumulated from 1 August 2016 until video frame time stamp, in blue-white logarithmic colour scale) up to 30 November 2016

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Dokter, A.M., Farnsworth, A., Fink, D. et al. Seasonal abundance and survival of North America’s migratory avifauna determined by weather radar. Nat Ecol Evol 2, 1603–1609 (2018).

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