Pond Turtles of the Sacramento Valley
In the years 2018 and 2019, a comprehensive survey spanning 124 sites across the Sacramento Valley was conducted by researchers seeking out two distinct species of pond turtles: the native Western Pond Turtle and the invasive Red-eared Slider. Once widespread throughout the Sacramento Valley and the Sacramento-San Joaquin River Delta, the native Northwestern Pond Turtle (Actinemys marmorata; WPT) has faced significant challenges due to extensive land conversion for agriculture, resulting in the alteration and reduction of aquatic habitats and surrounding uplands. Meanwhile, the introduced Red-eared Sliders (Trachemys scripta elegans; RES) have encroached upon much of the remaining WPT range, particularly in proximity to urban centers, potentially exacerbating competition for vital resources.
While previous surveys in central California tended to concentrate on rivers, lakes, and protected wetlands, this study focused on the distribution patterns of WPT and RES within the expansive agricultural landscapes across the Sacramento Valley and Sacramento-San Joaquin River Delta. Employing aquatic hoop nets, researchers surveyed 142 diverse locations, spanning irrigation canal sites, wetlands, and a tidally influenced slough, across eight counties during the summer seasons of 2018 and 2019. The findings were revelatory: both species were detected thriving within the agricultural milieu.
Utilizing occupancy modeling techniques, the researchers estimated that WPT were present at 44 of the surveyed trapping sites, while RES were identified at 51 sampled locations. The two species were found together in just six locations. RES exhibited a preference for restored wetlands near major roadways and urban areas, whereas WPT preferred wider canals situated further from urban centers.
This work sheds light on the intricate dynamics of how WPT and RES navigate the complex agricultural ecosystems of California. By providing a comprehensive portrayal of their habitat utilization patterns, this study offers invaluable insights that can inform targeted conservation strategies in the future. Authored by Alexandria M. Fulton, Jonathan P. Rose, and Brian J. Halstead, this article was published in Northwestern Naturalist, highlighting its importance in helping us better grasp the struggles native animals face in changing environments caused by human activities.
Alexandria M Fulton, Jonathan P Rose, Brian J Halstead "RURAL TURTLES: ESTIMATING THE OCCUPANCY OF NORTHWESTERN POND TURTLES AND NON-NATIVE RED-EARED SLIDERS IN AGRICULTURAL HABITATS IN CALIFORNIA'S SACRAMENTO VALLEY AND SACRAMENTO-SAN JOAQUIN RIVER DELTA," Northwestern Naturalist, 103(2), 97-109, (1 August 2022)
