eWestern Birds
The Quarterly Journal of Western Field Ornithologists
Geographic Variation in Cactus Wren Songs
Jonathan L. Atwood and Susannah B. Lerman
ABSTRACT: We compared Cactus Wren (Campylorhynchus brunneicapillus) songs recorded in three regions of coastal southern California (Ventura and Los Angeles counties, Orange County, and San Diego County), Baja California, and the Sonoran and Chihuahuan deserts. On the basis of four measures of the fine structure of individual notes, songs of wrens from Baja California south of 31° N latitude were most distinct; songs of birds from the three regions of coastal southern California were similar and most like songs given by birds in Baja California. Cactus Wrens in coastal southern California are geographically isolated, morphologically different, and differ in song behavior from those in Baja California. Compared with Sonoran and Chihuahuan desert populations, Cactus Wrens in coastal southern California are geographically isolated, differ in song behavior, and occur in a unique and unusual ecological setting. These characteristics suggest that the U.S. Fish and Wildlife Service should reconsider its 1994 decision denying coastal Cactus Wrens protection under the Endangered Species Act because the population was deemed to not meet the definition of a “distinct population segment.”