Sorex maritimensis (Maritime Shrew) is endemic to New Brunswick and Nova Scotia. We suggest that post-glacial dispersal northward by this species from a coastal plain refugium located in the mid-Atlantic, rather than dispersal from a refugium off Nova Scotia as previously proposed, is more parsimonious with current understanding of the glacial history of the region. A range extension into northeastern New Brunswick shows that the species is distributed north—south in New Brunswick and suggests that wetlands in heavily forested regions meet the ecological requirements of the Maritime Shrew. Such wetlands may provide avenues for dispersal and ensure connectivity among populations. Habitat descriptions for the Maritime Shrew indicate a wetland-associated species adaptable enough to utilize disturbance-dominated and anthropogenic wetlands. Further investigations of the biology of the Maritime Shrew are required to inform future habitat and wetland protection policies that should consider the requirements of this poorly known Canadian mammal.