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Bite forces used by Japanese macaques ( Macaca fuscata yakui ) on Yakushima Island, Japan to open aphid‐induced galls on Distylium racemosum (Hamamelidaceae)
Author(s) -
Hill D. A.,
Lucas P. W.,
Cheng P. Y.
Publication year - 1995
Publication title -
journal of zoology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.915
H-Index - 96
eISSN - 1469-7998
pISSN - 0952-8369
DOI - 10.1111/j.1469-7998.1995.tb02746.x
Subject(s) - biology , gall , aphid , botany , homoptera , aphididae , horticulture , pest analysis
Japanese macaques on Yakushima Island have been seen attempting to open thick, woody plant galls in order to eat aphids contained within them. We analysed a sample of galls and gall fragments with toothmarks and found that 22% were still intact indicating a failure to open them. These marks were examined and measured. Ten pits had a mean indentational area of 1.44 mm 2 (S.D. 0.28 mm 2 ), while 15 elongated scratches had a mean width of 1.26mm (S.D. 0.27 mm). The gall resembled a light wood in its mechanical properties and had a microhardness of 80.4MPa. Assuming that at least two marks were formed in any given bite, indentational analysis gave a mean estimate of bite forces of 232N (maximum 291 N) to produce pits and 255 N (maximum 487N) to produce scratches. These forces are consistent with, but at the high end of, limits predicted by anatomical analysis.