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Deforestation and Avian Extinction on Tropical Landbridge Islands

Authors

  • NAVJOT S. SODHI,

    Corresponding author
    1. Department of Biological Sciences, National University of Singapore, 14 Science Drive 4, Singapore 117543, Republic of Singapore
    2. Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA 02138, U.S.A.
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  • DAVID S. WILCOVE,

    1. Department of Ecology and Evolutionary Biology and Woodrow Wilson School of Public and International Affairs, Princeton University, Princeton, NJ 08544, U.S.A.
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  • TIEN MING LEE,

    1. Ecology, Behavior and Evolution Section, Division of Biological Sciences, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0116, U.S.A.
    2. Department of Ecology and Evolutionary Biology, Yale University, New Haven, CT 06520, U.S.A.
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  • CAGAN H. SEKERCIOGLU,

    1. Center for Conservation Biology, Department of Biology, Stanford University, Stanford, CA, U.S.A.
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  • R. SUBARAJ,

    1. Department of Biological Sciences, National University of Singapore, 14 Science Drive 4, Singapore 117543, Republic of Singapore
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  • HENRY BERNARD,

    1. Institute for Tropical Biology and Conservation, Universiti Malaysia Sabah, Locked Bag 2073, 88999 Kota Kinabalu, Sabah, Malaysia
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  • DING LI YONG,

    1. Department of Biological Sciences, National University of Singapore, 14 Science Drive 4, Singapore 117543, Republic of Singapore
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  • SUSAN L. H. LIM,

    1. Institute of Biological Sciences, University of Malaya, 50603 Kuala Lumpur, Malaysia
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  • DEWI M. PRAWIRADILAGA,

    1. Research Centre for Biology-LIPI, Division of Zoology, Jl. Raya Bogor Km 46, Cibinong 16911, Indonesia
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  • BARRY W. BROOK

    1. Environment Institute and School of Earth and Environmental Sciences, University of Adelaide, Adelaide, SA 5005, Australia
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email dbsns@nus.edu.sg

Abstract

Abstract: There are few empirical data, particularly collected simultaneously from multiple sites, on extinctions resulting from human-driven land-use change. Southeast Asia has the highest deforestation rate in the world, but the resulting losses of biological diversity remain poorly documented. Between November 2006 and March 2008, we conducted bird surveys on six landbridge islands in Malaysia and Indonesia. These islands were surveyed previously for birds in the early 1900s, when they were extensively forested. Our bird inventories of the islands were nearly complete, as indicated by sampling saturation curves and nonparametric true richness estimators. Fromzero (Pulau Malawali and Pulau Mantanani) to 15 (Pulau Bintan) diurnal resident landbird species were apparently extirpated since the early 1900s. Adding comparable but published extinction data from Singapore to our regression analyses, we found there were proportionally fewer forest bird extinctions in areas with greater remaining forest cover. Nevertheless, the statistical evidence to support this relationship was weak, owing to our unavoidably small sample size. Bird species that are restricted to the Indomalayan region, lay few eggs, are heavier, and occupy a narrower habitat breadth, were most vulnerable to extinction on Pulau Bintan. This was the only island where sufficient data existed to analyze the correlates of extinction. Forest preservation and restoration are needed on these islands to conserve the remaining forest avifauna. Our study of landbridge islands indicates that deforestation may increasingly threaten Southeast Asian biodiversity.

Abstract

Resumen: Existen escasos datos empíricos, particularmente los colectados simultáneamente en sitios múltiples, sobre extinciones resultantes del cambio de uso de suelo dirigido por humanos. El sureste de Asia tiene la mayor tasa de deforestación en el mundo, pero las pérdidas de diversidad biológica resultantes permanecen documentadas pobremente. Entre noviembre 2006 y marzo 2008, realizamos muestreos de aves en seis islas en Malasia e Indonesia. Las aves de estas islas fueron muestreadas previamente a principios del siglo XIX, cuando bosques eran extensos. Nuestros inventarios de aves de las islas fueron casi completos, como lo indicaron las curvas de saturación de muestreo y los estimadores no paramétricos de riqueza. Desde 0 (Pulau Malawali and Pulau Mantanani) hasta 15 (Pulau Bintan) especies de aves terrestres diurnas residentes fueron extirpadas desde los inicios del siglo XIX. Agregando datos de extinción de Singapur comparables pero publicados a nuestros análisis de regresión, encontramos proporcionalmente menos extinciones de aves forestales en áreas con mayor cobertura forestal remanente. Sin embargo, la evidencia estadística para soportar esta relación fue débil debido al tamaño de muestra inevitablemente pequeño. Las especies de aves que están restringidas a la región Indomalaya ponen menos huevos, son más pesados y ocupan una amplitud de nicho más angosta, fueron más vulnerables a la extinción en Pulau Bintan. Esta fue la única isla donde existieron datos suficientes para analizar las correlaciones de la extinción. Se requieren la preservación y restauración de bosques en estas islas para conservar la avifauna forestal remanente. Nuestro estudio de islas indica que la deforestación puede incrementar la amenaza sobre la biodiversidad del sureste de Asia.

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