Decline of the North American avifauna

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Science  04 Oct 2019:
Vol. 366, Issue 6461, pp. 120-124
DOI: 10.1126/science.aaw1313
  • 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 groupNo. of speciesNet abundance
    change (millions) and 95% CIs
    Percent change
    and 95% CIs
    Proportion species
    in decline
    Species summary
        All N. Am. species529–2,911.9–3,097.5–2,732.9–28.8%–30.2%–27.3%57.3%
        All native species519–2,521.0–2,698.5–2,347.6–26.5%–28.0%–24.9%57.4%
        Introduced species10–391.6–442.3–336.6–62.9%–66.5%–56.4%50.0%
        Native migratory species419–2,547.7–2,723.7–2,374.5–28.3%–29.8%–26.7%58.2%
        Native resident species10026.37.346.95.3%1.4%9.6%54.0%
        Aerial insectivores26–156.8–183.8–127.0–31.8%–36.4%–26.1%73.1%
    Breeding biome
        Boreal forest34–500.7–627.1–381.0–33.1%–38.9%–26.9%50.0%
        Forest generalist40–482.2–552.5–413.4–18.1%–20.4%–15.8%40.0%
        Habitat generalist38–417.3–462.1–371.3–23.1%–25.4%–20.7%60.5%
        Eastern forest63–166.7–185.8–147.7–17.4%–19.2%–15.6%63.5%
        Western forest67–139.7–163.8–116.1–29.5%–32.8%–26.0%64.2%
        Arctic tundra51–79.9–131.2–0.7–23.4%–37.5%–0.2%56.5%
    Nonbreeding biome
        Temperate N. America192–1,413.0–1,521.5–1,292.3–27.4%–29.3%–25.3%55.2%
        South America41–537.4–651.1–432.6–40.1%–45.2%–34.6%75.6%
        Southwestern aridlands50–238.1–261.2–215.6–41.9%–44.5%–39.2%74.0%
        Mexico–Central America76–155.3–187.8–122.0–15.5%–18.3%–12.6%52.6%
        Widespread neotropical22–126.0–171.2–86.1–26.8%–33.4%–19.3%45.5%

Supplementary Materials

  • 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

    Materials/Methods, Supplementary Text, Tables, Figures, and/or References

    Download Supplement
    • Materials and Methods
    • Figs. S1 to S7
    • Tables S1 to S5
    • References
    • Captions for Data S1 and S2
    Data S1
    Data S2

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