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Spatial Overlap and Dietary Selection of Native Rice Rats and Exotic Black Rats
Numi C. Goodyear
Journal of Mammalogy
Vol. 73, No. 1 (Feb., 1992), pp. 186-200
Published by: American Society of Mammalogists
Stable URL: http://www.jstor.org/stable/1381882
Page Count: 15
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The silver rice rat (Oryzomys argentatus), a rare endemic rodent, and the black rat (Rattus rattus), an exotic species, have coexisted for <500 years in the Florida Keys. Determination of fine-scale movements and behavior, by use of neck-attached fluorescent dust dispensers, revealed the degree of overlap in use of space, and some food resources, in free-ranging animals. Food selection tests were conducted in the laboratory. Significant differences in vegetation association, behavior, arboreality, and diet were found. From estimates of spatial niche overlap based on four indices I suggested the differences were biologically insignificant; the average value of four estimators on the habitat-choice resource axis was 89%, higher than reported for 47 of 48 pair-wise comparisons of native rodent species. I suggest that silver rice rat populations may be jeopardized by the presence of black rats whose invasion was reported to have caused oryzomine extinctions in the Galapagos and Antilles islands.
Journal of Mammalogy © 1992 American Society of Mammalogists