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Parasite infestation and prédation in Darwin's small ground finch: contrasting two elevational habitats between islands
Jody A. O'Connor, Rachael Y. Dudaniec and Sonia Kleindorfer
Journal of Tropical Ecology
Vol. 26, No. 3 (MAY 2010), pp. 285-292
Published by: Cambridge University Press
Stable URL: http://www.jstor.org/stable/40665235
Page Count: 8
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Contrasting ecological conditions may affect the distribution, abundance and impact of parasites and predators throughout the ranges of hosts and prey. Such patterns are evident on the archipelagos of Hawaii and the Galapagos, which vary in their distribution and abundance of avian parasites within and across islands. Previous research has documented higher intensity of parasitic fly larvae (Philornis downsi) in nests of Darwin's finches on elevated islands of the Galapagos. Here we examine P. downsi intensity and prédation in 71 nests of Darwin's small ground finch (Geospiza fuliginosa) on Floreana Island. We found significant differences in parasite intensity, nest prédation and clutch size between the lowland (0-100 m) and highland (300-400 m) habitats. Lowland finch nests had few P. downsi parasites (mean of 8 per nest), high nest prédation (44% of nests) and large clutch size (3.4).Highland finch nests showed the opposite pattern, with many P. downsi parasites (40 per nest), low nest prédation (17%) and small clutch size (2.5). This study suggests that the impacts of an introduced parasite are limited by its niche requirements and resource availability within and across islands. Our findings also imply that the vulnerability of bird populations to introduced parasites and predators is linked with variation in life history strategies across habitats.
Journal of Tropical Ecology © 2010 Cambridge University Press