Historical museum collections and contemporary population studies implicate roads and introduced predatory bullfrogs in the decline of western pond turtles.

The western pond turtle (WPT), recently separated into two paripatrically distributed species ( and ), is experiencing significant reductions in its range and population size. In addition to habitat loss, two potential causes of decline are female-biased road mortality and high juvenile mortality from non-native predatory bullfrogs (). However, quantitative analyses of these threats have never been conducted for either species of WPT.