Fig. 1 Net population change in North American birds. (A) By integrating population size estimates and trajectories for 529 species (18), we show a net loss of 2.9 billion breeding birds across the continental avifauna since 1970. Gray shading represents the 95% credible interval (CI) around total estimated loss. Map shows color-coded breeding biomes based on Bird Conservation Regions and land cover classification (18). (B) Net loss of abundance occurred across all major breeding biomes except wetlands (see Table 1). (C) Proportional net population change relative to 1970, ±95% CI. (D) Proportion of species declining in each biome.
Fig. 2 NEXRAD radar monitoring of nocturnal bird migration across the contiguous United States. (A) Annual change in biomass passage for the full continental United States (black) and (B) the Pacific (green), Central (brown), Mississippi (yellow), and Atlantic (blue) flyways [borders indicated in (C)], with percentage of total biomass passage (migration traffic) for each flyway indicated; declines are significant only for the full United States and the Mississippi and Atlantic flyways (tables S3 to S5). (C) Single-site trends in seasonal biomass passage at 143 NEXRAD stations in spring (1 March to 1 July), estimated for the period 2007–2017. Darker red colors indicate higher declines and loss of biomass passage, whereas blue colors indicate biomass increase. Circle size indicates trend significance, with closed circles being significant at a 95% confidence level. Only areas outside gray shading have a spatially consistent trend signal separated from background variability. (D) Ten-year cumulative loss in biomass passage, estimated as the product of a spatially explicit (generalized additive model) trend, times the surface of average cumulative spring biomass passage.
Fig. 3 Gains and losses across the North American avifauna over the past half-century. (A) Bird families were categorized as having a net loss (red) or gain (blue). Total loss of 3.2 billion birds occurred across 38 families; each family with losses greater than 50 million individuals is shown as a proportion of total loss, including two introduced families (gray). Swallows, nightjars, and swifts together show loss within the aerial insectivore guild. (B) Twenty-nine families show a total gain of 250 million individual birds; the five families with gains greater than 15 million individuals are shown as a proportion of total gain. Four families of raptors are shown as a single group. Note that combining total gain and total loss yields a net loss of 2.9 billion birds across the entire avifauna. (C) For each individually represented family in (B) and (C), proportional population change within that family is shown. See table S2 for statistics on each individual family. (D) Percentage population change among introduced and each of four management groups (18). A representative species from each group is shown (top to bottom, house sparrow, Passer domesticus; sanderling, Calidris alba; western meadowlark, Sturnella neglecta; green heron, Butorides virescens; and snow goose, Anser caerulescens). (E) Proportion of species with declining trends.
- Table 1
Net change in abundance across the North American avifauna, 1970–2017. Species are grouped into native and introduced species, management groups (landbirds, shorebirds, waterbirds, waterfowl), major breeding biomes, and nonbreeding biomes [see data S1 in (18) for assignments and definitions of groups and biomes]. Net change in abundance is expressed in millions of breeding individuals, with upper and lower bounds of each 95% credible interval (CI) shown. Percentage of species in each group with negative trend trajectories is also noted. Values in bold indicate declines and loss; those in italics indicate gains.
Species group No. of species Net abundance
change (millions) and 95% CIsPercent change
and 95% CIsProportion species
in declineChange LC95 UC95 Change LC95 UC95 Species summary All N. Am. species 529 –2,911.9 –3,097.5 –2,732.9 –28.8% –30.2% –27.3% 57.3% All native species 519 –2,521.0 –2,698.5 –2,347.6 –26.5% –28.0% –24.9% 57.4% Introduced species 10 –391.6 –442.3 –336.6 –62.9% –66.5% –56.4% 50.0% Native migratory species 419 –2,547.7 –2,723.7 –2,374.5 –28.3% –29.8% –26.7% 58.2% Native resident species 100 26.3 7.3 46.9 5.3% 1.4% 9.6% 54.0% Landbirds 357 –2,516.5 –2,692.2 –2,346.0 –27.1% –28.6% –25.5% 58.8% Shorebirds 44 –17.1 –21.8 –12.6 –37.4% –45.0% –28.8% 68.2% Waterbirds 77 –22.5 –37.8 –6.3 –21.5% –33.1% –6.2% 51.9% Waterfowl 41 34.8 24.5 48.3 56.0% 37.9% 79.4% 43.9% Aerial insectivores 26 –156.8 –183.8 –127.0 –31.8% –36.4% –26.1% 73.1% Breeding biome Grassland 31 –717.5 –763.9 –673.3 –53.3% –55.1% –51.5% 74.2% Boreal forest 34 –500.7 –627.1 –381.0 –33.1% –38.9% –26.9% 50.0% Forest generalist 40 –482.2 –552.5 –413.4 –18.1% –20.4% –15.8% 40.0% Habitat generalist 38 –417.3 –462.1 –371.3 –23.1% –25.4% –20.7% 60.5% Eastern forest 63 –166.7 –185.8 –147.7 –17.4% –19.2% –15.6% 63.5% Western forest 67 –139.7 –163.8 –116.1 –29.5% –32.8% –26.0% 64.2% Arctic tundra 51 –79.9 –131.2 –0.7 –23.4% –37.5% –0.2% 56.5% Aridlands 62 –35.6 –49.7 –17.0 –17.0% –23.0% –8.1% 56.5% Coasts 38 –6.1 –18.9 8.5 –15.0% –39.4% 21.9% 50.0% Wetlands 95 20.6 8.3 35.3 13.0% 5.1% 23.0% 47.4% Nonbreeding biome Temperate N. America 192 –1,413.0 –1,521.5 –1,292.3 –27.4% –29.3% –25.3% 55.2% South America 41 –537.4 –651.1 –432.6 –40.1% –45.2% –34.6% 75.6% Southwestern aridlands 50 –238.1 –261.2 –215.6 –41.9% –44.5% –39.2% 74.0% Mexico–Central America 76 –155.3 –187.8 –122.0 –15.5% –18.3% –12.6% 52.6% Widespread neotropical 22 –126.0 –171.2 –86.1 –26.8% –33.4% –19.3% 45.5% Widespread 60 –31.6 –63.1 1.6 –3.7% –7.4% 0.2% 43.3% Marine 26 –16.3 –29.7 –1.2 –30.8% –49.1% –2.5% 61.5% Coastal 44 –11.0 –14.9 –6.7 –42.0% –51.8% –26.7% 68.2% Caribbean 8 –6.0 1.4 –15.7 12.1% –2.8% 31.7% 25.0%
Supplementary Materials
science.sciencemag.org/content/366/6461/120/suppl/DC1
Materials and Methods
Figs. S1 to S7
Tables S1 to S5
Databases S1 and S2
References (36–101)
Additional Files
- Decline of the North American avifauna
Kenneth V. Rosenberg, Adriaan M. Dokter, Peter J. Blancher, John R. Sauer, Adam C. Smith, Paul A. Smith, Jessica C. Stanton, Arvind Panjabi, Laura Helft, Michael Parr, Peter P. Marra
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