A strikingly large number of the world's reptile and amphibian species are in decline, primarily as a result of human activity. Major threats to both groups include habitat loss and fragmentation, road mortality, chemical contamination and other environmental pollution, infectious disease, invasive species, climate change, illegal collection and intentional persecution. In Canada, these threats tend to be most severe in southern portions of the country where human activity is concentrated; unfortunately, Canadian amphibian and reptile diversity is also highest in the southernmost parts of the country due to climatic restrictions, resulting in the widespread decline and extirpation of several Canadian amphibian and reptile species.