We used point counts to conduct systematic quantitative surveys of Darwin’s finches and other land birds on Santa Cruz Island in the Galápagos archipelago 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. Other factors including habitat alteration and introduced parasites or pathogens may be contributing to the observed declines.
Source:
Michael Dvorak, Birgit Fessl, Erwin Nemeth, Sonia Kleindorfer and Sabine Tebbich Distribution and abundance of Darwin’s finches and other land birds on Santa Cruz Island, Galápagos: evidence for declining populations. Oryx, Available on CJO 2011 doi:10.1017/S0030605311000597
http://www.esaim-m2an.org/10.1017/S0030605311000597
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