Bird sounds are an important component of field identification, and these days numerous compilations of recordings are available, usually for families of birds or for geographic regions. This pair of CDs (hereafter Bird Voices) includes the voices and other sounds of 190 species found in northern California, ranging from the Marbled Murrelet to the House Sparrow, from the Sandhill Crane to the Wrentit. The region covered is not defined but appears to be truly northern California (north of Sonoma county), rather than including central California. The species covered are listed on a simple insert (adorned with some nice color photos), which notes that the recordings were made primarily by LeValley, with help from the California Department of Fish and Game, Sean McAllister, Mark Higley, and Seth Bunnell. The insert also informs us that most recordings were made in Humboldt, Trinity, and Siskiyou counties, and that Fix wrote and spoke the accompanying narration."