Shifting targets in the tundra: Protection of migratory caribou calving grounds must account for spatial changes over time

Industrial development, expansion of human populations and climate change increasingly affect habitats of migratory species. Effective protection of critical habitats is urgently required because several large migratory species have declined over the last decades. Protection of critical habitats, such as the calving grounds of migratory ungulates, may however require consideration of temporal shifts in spatial location. We assessed changes in the location of calving grounds used by migratory caribou over 35 years by the Rivière-George (RG) herd and 15 years by the Rivière-aux-Feuilles (RAF) herd, in Northern Québec and Labrador, Canada. We also evaluated the proportion of annual calving ground within protected Wildlife Habitats established to protect caribou calving grounds. The annual size and location of calving grounds changed substantially over time: calving ground size remained relatively stable for the RAF but it declined over 85% for the RG. Calving grounds moved 300 km northward in the Ungava peninsula for the RAF and shifted over 230 km back and forth to the Labrador coast for the RG. Despite recent modifications, legally designated Wildlife Habitats in Québec protected less than 20% of the RG and RAF calving grounds. Protection of calving grounds of migratory caribou must consider the dynamic use of space by adult females. We present recommendations on the use of available monitoring data to better protect calving grounds of migratory caribou and critical habitats of large migratory species.