Volume 50 September-October, 1948 Number 5. Ecologic Races of Song Sparrows in the San Francisco Bay Region: Part 1. Habitat and Abundance, pp.193-215. Frontis of Cooper Hawk by Allan Brooks. Additional articles include: A Nesting Study of the Mountain Bluebird in Wyoming by Fred W. Haecker and Nestings of Some Shorebirds in Western Alaska by Lawrence H. Walkinshaw. Volume 50 November-December 1948, Number 6. Ecologic Races of Song Sparrows in the San Francisco Bay Region: Part 2. Geographic Variation, pp. 233-256. Frontis of Juvenal Saw-Whet Owl by Allan Brooks. Additional article: The Problematical Relationships of the Asiatic Shorebird by Frank A. Pitelka.