Research ArticlePOPULATION BIOLOGY

Collapsing avian community on a Hawaiian island

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Science Advances  07 Sep 2016:
Vol. 2, no. 9, e1600029
DOI: 10.1126/sciadv.1600029
  • Fig. 1 Population estimates and distributions for native Kaua‘i forest birds.

    Population estimates (left panels) are from surveys conducted in 2000, 2005, 2007, 2008, and 2012 across both the interior and exterior portions of the Alaka‘i Plateau (with error bars representing the 95% CI of each estimate). Linear and exponential population change models fitted to the 2000–2012 data are projected from 2013 to 2050 or estimated year of extinction (when abundance is less than 30 individuals, which is a quasi-extinction level). The projections are just one possible outcome of many, assuming that the rate of change is accurate and does not change over the coming decades. Areas of distributional range (right panels) from 1968 through 2012 were determined from presence or absence at count stations and extrapolated across similar elevations and habitats. For ‘apapane, Kaua‘i ‘amakihi, and Kaua‘i ‘elepaio, estimated distributions from 2000 to 2012 were very similar, and only the 2012 range is shown.

  • Table 1 Estimates of 2012 population density and abundance and trend for seven native species of forest birds and the five most common non-native species on Kaua‘i.

    Trends (the average change in density over a 25-year period) are presented for both the interior (core area of most species’ range, 1981–2012 and 2000–2012) and exterior areas of the Alaka‘i Plateau (2000–2012). Trends were not calculated for species with few or no detections for one or more survey periods in a given area. Species abundances marked by an asterisk denote species that occur outside the survey area (<900 m), and abundance estimates do not include estimates from the unsurveyed area.

    Species2012 density
    (birds/ha)
    2012 abundanceTrend (25 years)
    Mean95% CIMean95% CIInterior (1981–2012)Interior (2000–2012)Exterior (2000–2012)
    Native
    ‘Akeke‘e0.212(0.201–0.223)945(460–1,547)−48%−98%
    ‘Akikiki0.088(0.082–0.096)468(231–916)−71%−7%
    ‘Anianiau1.657(1.584–1.733)10,787(8,396–13,434)−17%−57%−91%
    ‘I‘Iwi0.477(0.328–0.645)2,603(1,789–3,520)−63%−86%−97%
    ‘Apapane8.489(8.313–8.670)98,506*(62,863–117,435)−27%−67%−89%
    Kaua‘i ‘amakihi0.611(0.581–0.642)6,519*(4,844–8,495)−16%−91%−98%
    Kaua‘i ‘Elepaio7.141(6.716–7.592)82,437*(60,973–107,155)41%88%−64%
    Non-native
    Hwamei0.452(0.407–0.501)8,043*(5,715–10,920)46%−13%55%
    Japanese bush-warbler0.177(0.163–0.192)5,682*(3,987–8,011)311%13%508%
    Japanese white-eye5.863(5.719–6.011)106,327*(92,400–121,671)−27%−60%−83%
    Northern cardinal0.218(0.181–0.262)6,485*(3,550–11,456)−66%−63%
    White-rumped shama0.264(0.243–0.286)9,060*(6,422–12,272)273%

Supplementary Materials

  • Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/2/9/e1600029/DC1

    fig. S1. Spatial extent of interior and exterior survey areas used for the estimate of trends by region and period.

    table S1. Survey date and numbers of transects and stations sampled for forest birds on Kaua‘i from eight point-transect surveys.

    table S2. Density and population abundance estimates of Kaua‘i forest birds by elevation (900 to 1500 m) from the 2012 Kaua‘i surveys.

    table S3. Density of Kaua‘i forest birds by study area (interior and exterior) for each survey period (1981–2012).

    table S4. Trends in forest birds on Kaua‘i in the consistently sampled interior and exterior areas by survey period.

  • Supplementary Materials

    This PDF file includes:

    • fig. S1. Spatial extent of interior and exterior survey areas used for the estimate of trends by region and period.
    • table S1. Survey date and numbers of transects and stations sampled for forest birds on Kaua‘i from eight point-transect surveys.
    • table S2. Density and population abundance estimates of Kaua‘i forest birds by elevation (900 to 1500 m) from the 2012 Kaua‘i surveys.
    • table S3. Density of Kaua‘i forest birds by study area (interior and exterior) for each survey period (1981–2012).
    • table S4. Trends in forest birds on Kaua‘i in the consistently sampled interior and exterior areas by survey period.

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