Meeting Abstract
Traditionally, an eastern United States species, the barred owl, Strix varia, has been dispersing westward for the past seventy years, and arrived in northern California 30 years ago. S. varia is a large, aggressive, forest generalist and performs well in its new environment. It outcompetes its close relative, the threatened northern spotted owl (Strix occidentalis caurina) wherever the two species have overlapping ranges. Recent museum collections of western specimens of S. varia suggest that there may be morphological differences between western and eastern populations. These differences may be correlated to the advent of S. varia in California; the species could be adapting to new habitats, or receiving new genes through hybridization with S. occidentalis caurina. We investigated potential differences in size, coloration, and feather pattern between the several populations of barred owls in eastern and western USA and Mexico. For each individual, we measured wing chord, length of primaries, beak length and beak depth, and scored for color. The feather pattern of the stomach, which is subject to the most variation, was scored as well. Analyses showed that while there is no significant disparity of size between the east and west, the two populations do differ in color and belly pattern. The means of assessing color and pattern variance was by eye, but still yielded promising results. Future protocols using standardized means of color and pattern analysis, possibly through utilization of spectrophotometry and/or digital imaging, will add rigor to these analyses.
