The animals (both vertebrates and invertebrates) on Wisconsin's Natural Heritage Working List are species known or suspected to be rare in the state. It includes Species of Greatest Conservation Need that are legally designated as "endangered" or "threatened," as well as species in the advisory "special concern" category. Species become rare for a number of reasons, including habitat loss, habitat degradation, highly specialized habitat needs, disturbance sensitivity, genetic problems, exploitation, persecution, predation, competition and parasitism. Some species are rare here because Wisconsin is at the edge of their main ranges. Invasive species and climate change also have impacts on a species abundance and are expected to become even more significant factors in the future.
Animal species pages contain information about Wisconsin's rare animals, including preferred habitats, where they've been found in the state and their legal protection. See the Working List for rank and status definitions.