Geographic Variation and Evolution in the California Gull (Larus californicus)

Abstract

[The California Gull (Larus californicus), currently regarded as a monotypic species, is separable into a small, dark-mantled race (L. c. californicus) that breeds primarily in the Great Basin of the United States, and a larger, paler race (L. c. albertaensis) from the Great Plains of the north-central U.S. and south-central Canada. The breeding ranges of these two races, previously disjunct, have expanded recently, and a zone of secondary contact seems to be forming east of the Rocky Mountains in the northern United States.]