Comparison of two methods to detect the northwestern pond turtle (Actinemys marmorata) and the invasive American bullfrog (Lithobates catesbeianus) in interior northern California

Chelonian Conservation and Biology
By: , and 

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Abstract

Knowledge about the distributions of species and the variables influencing their occurrence is important for their management and conservation, but factors affecting occurrence can vary across the range of a species. Northwestern pond turtles (Actinemys marmorata) are widespread generalist turtles, but are nonetheless of conservation concern throughout their range. To better understand the distribution of northwestern pond turtles and introduced American bullfrogs (Lithobates catesbeianus), we surveyed streams on private timberlands of the interior foothills of northern California using visual encounter surveys and collecting samples of environmental DNA. We found that northwestern pond turtle occurrence was negatively related to elevation in our sampling frame. Detection probabilities with environmental DNA were approximately twice those of visual encounter surveys, but both methods were effective for detecting turtles in streams. American bullfrogs were detected in a single sample at each of 2 sites (one by environmental DNA, one by visual encounter surveys). Management for northwestern pond turtles in forest streams within our sample area will likely have the largest effect at lower elevation sites where turtles are most likely to occur.

Publication type Article
Publication Subtype Journal Article
Title Comparison of two methods to detect the northwestern pond turtle (Actinemys marmorata) and the invasive American bullfrog (Lithobates catesbeianus) in interior northern California
Series title Chelonian Conservation and Biology
DOI 10.2744/CCB-1591.1
Edition Online First
Year Published 2024
Language English
Publisher Allen Press
Contributing office(s) Western Ecological Research Center
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