Aspects of the Demography of a Relict Population of Southwestern Pond Turtles (Actinemys pallida) in a West Mojave Desert Stream in California

David Muth¹, Jeffrey E. Lovich^2,*, Rodrigo Macip-Rios³, Doug Gomez⁴, Kristy Cummings², Shellie Puffer², and Charles B. Yackulic²

¹LSA Associates, 157 Park Place, Point Richmond, CA 94801. ²US Geological Survey, Southwest Biological Science Center, 2255 North Gemini Drive, Flagstaff, AZ 86001. ³Escuela Nacional de Estudios Superiores, Unidad Morelia. Universidad Nacional Atónoma de México, Antigua Carretera a Páztcuaro, No. 8701, Col. Ex Hacienda San José la Huerta, Morelia, Michoacán 58190, México. ⁴Center for Environmental Management of Military Lands, Colorado State University, Fort Collins, CO 80523–1490. *Corresponding author.

Northeastern Naturalist, Volume 31, Special Issue 12: E109–E130

First published early online: 31 August 2024

Abstract
We studied Actinemys pallida (Southwestern Pond Turtle) in Amargosa Creek, near Palmdale, CA, from 1997 to 2023. The population in the upper creek was the focus of a mark–recapture study from 1997 to 2003 during monitoring required by a road-construction project. An estimated 193 (95% CI = 142–256) turtles were present in 1997 or recruited to the upper creek population between 1997 and 2003. Total abundance and recruitment declined after 2001, coincident with the onset of a multi-decadal megadrought. Turtles in upper Amargosa Creek are presumed to be extirpated because the creek dried up in the ensuing years. As part of a separate research project, we resurveyed the lower creek at Piute Ponds on Edwards Air Force Base from 2019 to 2023. As of 2023, there was a remnant breeding population of at least 22 turtles there. We did not find any marked turtles from the upper creek in the ponds. Only 2 populations of Southwestern Pond Turtles are known to survive in the Mojave Desert, one at Piute Ponds and another in the Mojave River.

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