Distribution and Habitat Associations of the Little Striped Whiptail (Cnemidophorus inornatus) at Wupatki National Monument

Persons, Trevor

Cnemidophorus inornatus has declined in parts of its range, likely due to the effects of overgrazing, expansion of woodlands, and competition with unisexual whiptail species. C. inornatus and the sympatric Plateau Striped Whiptail (C. velox) were surveyed in grassland and woodland habitats at Wupatki, as well as on grazed grasslands outside the monument, from 2001-2003. The Little Striped Whiptail (Cnemidophorus inornatus) is a Southwestern grassland lizardspecies that has declined in parts of its range, likely due to the effects of overgrazing, expansion of woodlands, and competition with unisexual whiptail species. The species has a highly disjunct distribution in Arizona, including on the southern Colorado Plateau. In northern Arizona it is known primarily from grasslands north and east of Flagstaff, including at Wupatki National Monument. I surveyed for C. inornatus (bisexual) and the sympatric Plateau Striped Whiptail (C. velox; unisexual) in grassland and woodland habitats at Wupatki, as well as on grazed grasslands outside the monument, from 2001-2003. Although a severe regional drought was likely responsible for low observation rates during the study, I was able to determine geographic distribution of whiptails and other lizards within the monument, as well as relative abundance within and between major habitat types. Both C. inornatus and C. velox occurred throughout the study area, and overall C. velox outnumbered C. inornatus by a ratio of 4.4:1. Cnemidophorus velox also outnumbered C. inornatus within each habitat, and was roughly equally common in all major habitats (grassland, juniper savanna, and juniper woodland) found in the study area within the monument. In contrast, C. inornatus was only common in grassland, and was rare in both savanna and woodland habitats. The relative abundance of the two whiptails in grazed grassland just outside the monument was similar to ungrazed grassland within, but the absolute abundance of both species was reduced by about one half, possibly related to the presence of large numbers of the Lesser Earless Lizard (Holbrookia maculata) in the more open habitat on the grazed sites. The relative rarity of C. inornatus in savanna and woodland habitats suggests that the increase of these habitats through juniper encroachment of grasslands has probably reduced populations of this species at Wupatki. Reduction of juniper in grassland habitats and transfer of adjacent ranch land to the monument would probably enhance conservation of C. inornatus at Wupatki. Longterm monitoring studies have the opportunity to address questions about the roles of drought,livestock grazing, and woodland expansion on the comparative abilities of bisexual andunisexual whiptail species to flourish in many areas of the Southwest.

Distribution and Habitat Associations of the Little Striped Whiptail (Cnemidophorus inornatus) at Wupatki National Monument

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