Updated Occupancy and Abundance for Northwestern Pond Turtle and Western Painted Turtle in the Lower and Middle Willamette Watersheds
Start Date
3-11-2024 4:00 PM
Abstract
Regional changes in land use and climate are anticipated to have profound effects on the ranges of native freshwater turtles in NW Oregon, so adequate baseline surveys are critical. The Lower and Middle Willamette watersheds are high priority for maintaining the current occupancy and abundance of native turtles as this region represents the only areas where the northern extent of the NW Pond Turtle (Actinemys marmorata) range and western extent of the Western Painted Turtle (Chrysemys picta bellii) range intersect. Both of Oregon’s two native freshwater turtle species are listed as “sensitive-critical” by the State of Oregon and one, A. marmorata, has been petitioned for listing under the federal Endangered Species Act. To date, information on the distribution of native freshwater turtles in Oregon has been gathered largely opportunistically through varied surveys ranging from ones at sites of high conservation value to those that are the focus of habitat modeling to predict occupancy based on key habitat variables. To address this deficiency, basking surveys were conducted at 334 aquatic sites throughout 7 counties in NW Oregon from 2021 through 2023 to provide that baseline, as well as a better understanding of the distribution of the widespread exotic turtle, the Red-eared Slider (Trachemys scripta elegans). Preliminary comparison to historical survey data was performed to identify changes in distribution both within and outside major urban areas. A current rate of occupancy was also developed for NW Oregon. Further study will focus on identifying key habitat variables that allow for sustainably reproducing populations.
Subjects
Animal ecology, Conservation biology, Habitat restoration
Persistent Identifier
https://archives.pdx.edu/ds/psu/41396
Creative Commons License
This work is licensed under a Creative Commons Attribution-Share Alike 4.0 License.
Updated Occupancy and Abundance for Northwestern Pond Turtle and Western Painted Turtle in the Lower and Middle Willamette Watersheds
Regional changes in land use and climate are anticipated to have profound effects on the ranges of native freshwater turtles in NW Oregon, so adequate baseline surveys are critical. The Lower and Middle Willamette watersheds are high priority for maintaining the current occupancy and abundance of native turtles as this region represents the only areas where the northern extent of the NW Pond Turtle (Actinemys marmorata) range and western extent of the Western Painted Turtle (Chrysemys picta bellii) range intersect. Both of Oregon’s two native freshwater turtle species are listed as “sensitive-critical” by the State of Oregon and one, A. marmorata, has been petitioned for listing under the federal Endangered Species Act. To date, information on the distribution of native freshwater turtles in Oregon has been gathered largely opportunistically through varied surveys ranging from ones at sites of high conservation value to those that are the focus of habitat modeling to predict occupancy based on key habitat variables. To address this deficiency, basking surveys were conducted at 334 aquatic sites throughout 7 counties in NW Oregon from 2021 through 2023 to provide that baseline, as well as a better understanding of the distribution of the widespread exotic turtle, the Red-eared Slider (Trachemys scripta elegans). Preliminary comparison to historical survey data was performed to identify changes in distribution both within and outside major urban areas. A current rate of occupancy was also developed for NW Oregon. Further study will focus on identifying key habitat variables that allow for sustainably reproducing populations.