The Northern Red-legged Frog occurs in some of the most developed regions in North America, and the conversion of wetland habitats into urban and agricultural areas has led to substantial and ongoing declines. The species appears to be declining in much of its range in North America including Oregon and California. In California, a subspecies (the California Red-legged Frog) has been listed as Threatened. In British Columbia, Northern Red-legged Frogs have declined on central Vancouver Island and in the Lower Mainland. Suspected drivers of decline include habitat loss, introduction of competitive Bullfrogs and Green Frogs, and the detrimental effects of forestry activities. Habitat loss appears to be the main threat to this species in British Columbia, where loss of wetlands has reduced habitat connectivity thereby increasing the risk of local extinction by reducing immigration and emigration between populations. As Northern Red-legged Frogs often disperse substantial distance from breeding ground, road mortality is a cause for concern especially in the Lower Mainland where road networks are particularly dense. Contaminated water run-off from roads and agricultural uses may also be an indirect threat to the health of Northern Red-legged Frog populations. In less developed parts of its range, forestry activities reduce and fragment the amount of available habitat for Northern Red-legged Frogs.