Spatial distribution and hotspots of mammals in Canada

Abstract

High-latitude countries often contain the polar range edge of species that are common farther south. The more peripherally a species occurs in a country, the smaller its national range will be and the more its national range will consist of range-edge populations, which are often predicted to be relatively small, isolated, and unproductive. Together, this may focus national conservation efforts toward peripheral species whose global conservation value is controversial. However, if range-edge taxa occur where overall diversity is also high, there would be fewer trade-offs in protecting them. Using 153 of the 158 terrestrial mammal species in Canada, we tested how species distributions relate to their national conservation status and total mammal richness. Half of Canadian mammals had <20% of their global range in Canada. Range area in Canada was strongly associated with national threat status; mammals considered at-risk in Canada had 42% smaller Canadian ranges than mammals considered secure. However, after accounting for range area, being more peripheral (smaller proportion of global range in Canada) did not increase the likelihood that a taxon was considered at-risk. We overlaid the 153 maps to calculate mammal diversity across Canada, divided into 100x100 km grid cells. We found that hotspots of at-risk mammals (cells with >4 at-risk taxa) and hotspots of range-edge mammals (cells with >12 taxa with [&le;]20% of their range in Canada) were about twice as species rich as non-hotspot cells, containing up to 44% of Canadian mammal diversity per grid-cell. Our results suggest that protecting areas with the most at-risk or range-edge mammals would simultaneously protect habitat for many species currently deemed secure.