Abstract
Freshwater turtles are semiaquatic species that require upland habitats for nesting. This study characterizes the microhabitat of nesting site selection for turtles at Bushy Lake in Sacramento, California, which features a population dominated by red-eared sliders (slider) (Trachemys scripta elegans) and several individual native northwestern pond turtles (Actinemys marmorata). This study aims to fill knowledge gaps on the environmental factors potentially influencing nesting site selection for the red-eared slider in its non-native range.
Environmental data was collected at locations with observed turtle nesting activities and compared with randomized locations with no observed nesting activities. The variables included slope, elevation, litter depth, vegetation height, dominant vegetation, distance from water, canopy and relative ground cover, soil moisture, texture and density, and downward-facing cardinal direction.
Statistically significant variables identified turtle nests at Bushy Lake as occurring within shorter distances from water (x̄=77.03 m), on southward-facing slopes (42.62% frequency), and in medium-height vegetation (60.66% frequency). Observed nesting locations featured greater abundances of Bermuda grass (Cynodon dactylon), wild oat (Avena fatua), and rabbitsfoot grass (Polypogon monspeliensis). A comparison with northwestern pond turtle studies found variability in nesting habitat, however, additionally found similarities with the red-eared slider’s habitat. Researching sliders may hold benefits to informing pond turtle conservation measures. Conservation recommendations include managing low vegetation heights; planting native vegetation with reduced or soft aboveground biomass, such as grasses; conserving the maximum travel distance of turtles for nesting habitat; and focusing on slopes, particularly south-facing, for management implementation.