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Shrub density effects on the presence of an endangered lizard of the Carrizo Plain National Monument, California

Published Article

California

Publication date: May 19, 2023

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This study shows that increasing shrub density significantly boosts the presence and above‑ground activity of the endangered blunt‑nosed leopard lizard (Gambelia sila) in the Carrizo Plain National Monument, California. Findings highlight how shrub structure supports thermoregulation, movement, and conservation planning for this imperiled species.

Subject Tags

  • Habitat restoration
  • Desert

Abstract

Positive associations between animals and foundational shrub species are frequent in desert ecosystems for shelter, resources, refuge, and other key ecological processes. Herein, we tested the impact of the density of the shrub species Ephedra californica on the presence and habitat use of the federally endangered lizard species, Gambelia sila. To do this, we used a 3-year radio telemetry dataset and satellite-based counts of shrub density across sites at the Carrizo Plain National Monument in San Luis Obispo County, CA. The effect of shrub density on lizard presence was contrasted with previous shrub cover analyses to determine whether measures of shrub density were superior to shrub cover in predicting lizard presence. Increasing shrub density increased lizard presence. As shrub density increased, lizards were located more frequently “above ground” versus “below ground” in burrows. Male lizards had significantly larger home ranges than females, but both sexes were similarly associated with increasing shrub densities. Shrub density and shrub cover models did not significantly differ in their prediction of lizard presence. These findings suggest that both habitat measures are effective analogs and that ecologically, both cover and the density of foundation shrub species are key factors for some desert lizards.

Citations

Zuliani, M., Ghazian, N., Owen, M., Westphal, M. F., Butterfield, H. S., & Lortie, C. J. (2023). Shrub density effects on the presence of an endangered lizard of the Carrizo Plain National Monument, California. Ecology and Evolution, 13(5), e10128.

https://doi.org/10.1002/ece3.10128

TNC Authors