In San Diego County, California, anecdotal records of free-ranging Black-throated Magpie-Jays (Calocitta colliei) date back to the 1970s in the vicinity of the Solana Beach neighborhood of Eden Gardens (M. U. Evans pers. comm.). Of several locales within the county where the species has persisted, the oldest is the Tijuana River valley, where it has been documented continuously since ~1992 (G. McCaskie pers. comm.). These long-tailed corvids are endemic to the Pacific slope of mainland Mexico and reside in deciduous open woodlands and arid scrub forests between sea level and 1200 meters elevation. Their occurrence in San Diego County can almost certainly be attributed to the pet trade in adjacent northwestern Baja California (see Hamilton 2001) and escapees from aviaries north of the U.S.–Mexico border. Primary areas of their local occurrence and where I documented breeding include the Tijuana River valley as well as the Sweetwater River in the vicinity of the Plaza Bonita mall in the community of Bonita (Haas 2004). Magpie-jays seen in Jamul (e.g., 15 June 2000, M. U. Evans) were probably escapees from a local aviary. The origin of their occurrence on Point Loma (e.g., 17 May 1999, P. A. Ginsburg; 1 May 2000, S. E. Smith; 12 September 2004, K. Goldman) and within Mission Trails Regional Park and nearby residential communities (e.g., 20 April 2013, M. Beeve; 21 April 2013, B. Mulrooney) is less clear. They may have been escapees from local aviaries or individuals dispersing from Bonita or the Tijuana River valley.