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BIRDS DEFEND OIL PALMS FROM HERBIVOROUS INSECTS
Author(s) -
Koh Lian Pin
Publication year - 2008
Publication title -
ecological applications
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.864
H-Index - 213
eISSN - 1939-5582
pISSN - 1051-0761
DOI - 10.1890/07-1650.1
Subject(s) - herbivore , insectivore , biology , trophic level , predator , exclosure , ecology , biodiversity , elaeis guineensis , productivity , trophic cascade , agriculture , habitat , predation , palm oil , agroforestry , macroeconomics , economics
Top‐down forces are expected to be important in regulating herbivore populations in most agricultural systems where primary productivity is high and species diversity is low. Under such conditions, trophic cascades are predicted to occur when predator populations are reduced or removed. Studies on how predator removal indirectly affects herbivory rates in agricultural systems are lacking. Through a bird‐exclosure experiment, I test the hypothesis that insectivorous birds indirectly defend oil palms ( Elaeis guineensis ) from herbivorous insects. Results show that bird exclusion significantly increased herbivory damage to oil palms, and that the size of this exclusion effect increased with bird density, although the latter result was not statistically significant. These findings suggest that insectivorous birds deliver a natural pest control service for oil palm agriculture, which is important not only for the direct benefits it delivers for human welfare, but also in strengthening the economic justifications for conserving the remaining natural habitats and biodiversity in agricultural landscapes.