Additional Information on a Nonnative Whiptail Population (Aspidoscelis flagellicauda/sonorae complex) in Suburban Orange County, California

Abstract

The lowlands of cismontane southern California have proven to be hospitable not only to humans but to many exotic plant and animal species (Cox 1999). In addition to 14 nonnative reptile species established in the area1 is a localized population of confusing whiptails in Orange County that was first reported by Winkleman and Backlin (2016). That report was based on observations in south Irvine in May 2014 and April-June 2015 and at least one similar whiptail seen in adjacent Lake Forest in July 2015. Four specimens collected in Irvine at that time were identified as belonging to the Aspidoscelis flagellicauda/sonorae complex. The Gila Spotted Whiptail (A. flagellicauda) and Sonoran Spotted Whiptail (A. sonorae) are morphologically similar all-female species native to Arizona, New Mexico, Sonora, and Chihuahua and previously not known to occur away from their native ranges. Gary Nafis2 provided an update on the status of these lizards, noting that they are not extirpated in Irvine, as suspected by Winkleman and Backlin (2016), and “as of 7/17, they have been found only in Orange County in Irvine, Lake Forest, and Aliso Viejo, but they appear to be spreading quickly.” The reference to Aliso Viejo was presumably based on the observations detailed here. Information displayed on iNaturalist3 under the name of Sonoran Spotted Whiptail includes the Irvine observations and others beginning in 2015, but the precise locality data is “obscured” according to the wishes of reporting individuals or institutions. All of the iNaturalist locations, obscured or otherwise, are within the general geographic boundaries described above (G.B. Pauly pers. comm.). Our observations come primarily from a church campus in suburban central Laguna Woods (33.609882 N, -117.733124 W; adjacent to the vast retirement community formerly known as Leisure World), approximately 4.8 km south-southwest of the locations reported by Winkleman and Backlin (2016). The manicured landscape with scattered ornamental shrubs provides suitable habitat for the whiptails, not unlike the situation described by Winkleman and Backlin (2016). Sandy substrates are especially favored by these lizards. Like Winkleman and Backlin, we initially struggled with their identification, generally trying to force the label of Orange-throated Whiptail (A. hyperythra) upon them. Our first observation was of a single individual on 13 June 2010. Infrequent observations continued through 2016, but in 2017 we increased our effort to document them. Spotted