Distribution and abundance of Darwin's finches and other land birds on Santa Cruz Island, Galápagos: evidence for declining populations

Michael Dvorak, Birgit Fessl, Erwin Nemeth, Sonia Kleindorfer, S Tebbich

    Research output: Contribution to journalArticle

    33 Citations (Scopus)

    Abstract

    Population monitoring is a vital tool for conservation management and for testing hypotheses about population trends in changing environments. Darwin's finches on Santa Cruz Island in the Galápagos archipelago have experienced habitat alteration because of human activity, introduced predators, parasites and disease. We used point counts to conduct systematic quantitative surveys of Darwin's finches and other land birds between 1997 and 2010. The temporal analysis revealed that six of the nine species investigated declined significantly and that this decline was most pronounced at higher elevations in humid native forest and agricultural areas; the highland areas have been most affected by introduced species or direct human impact. Five of the six declining species are insectivorous, which suggests that changes in insect abundance or insect availability are a critical factor in the declines. Further study is required to test this idea. Other factors including habitat alteration and introduced parasites or pathogens may be contributing to the observed declines.

    Original languageEnglish
    Pages (from-to)78-86
    Number of pages9
    JournalOryx
    Volume46
    Issue number1
    DOIs
    Publication statusPublished - Jan 2012

    Keywords

    • Camarhynchus
    • Certhidea
    • Darwin's finches
    • distance sampling
    • Galápagos
    • Geospiza
    • population estimate
    • Santa Cruz Island

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