The Barren Ground Caribou is the outstanding migratory land mammal of North America at the present day. (Some of the bats, though extensively migratory, obviously belong in a category too distinct for comparison.) We know as yet extremely little concerning the movements of individual Caribou;[2] but it is fairly safe to assume that among those reaching the southern limits of the winter range in central Manitoba or northwestern Ontario, there must be many whose summer range is at least 500 or 600 miles to the northward. The latitudinal extent of such wanderings is comparable with, or equivalent to, an annual round trip between Philadelphia, Pennsylvania, and Charleston, South Carolina. There is perhaps less information available concerning the migrations of the wild Reindeer of the Old World than concerning the movements of the Barren Ground Caribou of North America (_cf._ Jacobi, 1931: 191-200). [Footnote 2: One means of gathering information on this subject would be to capture fawns as they swim across lakes or wide rivers on the autumn migration, then to affix numbered metal tags to their ears and to release them in time to rejoin their mothers. This would simply be a modification of the leg-banding method that has proved so highly successful in the study of bird migration. It would also be particularly useful in studies on age and growth.] _Southern limits of winter range_ In years long past the winter range extended at least occasionally as far south as Fort McMurray in Alberta and Cree Lake and the upper Mudjatick and Foster rivers in Saskatchewan, and rather regularly to Reindeer Lake (Preble, 1908: 137); and “on rare occasions as far south as Cumberland House on the Saskatchewan River” (Buchanan, 1920: 105). At an early date Richardson believed (1829: 243) that “none” of these Caribou “go to the southward of Churchill.” There are, however, records of long ago that deal with mass occurrences of Caribou on the lower courses of the Nelson, Hayes, and Severn rivers, emptying on the west coast of Hudson Bay. The records are very puzzling in several respects. Most of them do not definitely differentiate the species involved from the Barren Ground Caribou, but some of them (by Hearne, Richardson, and Preble) indicate that it is the Woodland Caribou. The direction of the migrations, as reported in some instances, is just the reverse of that taken at the present time by the Barren Ground species during its normal movements at corresponding seasons. Finally, it is all but impossible to reconcile the numbers reported with such knowledge as we have of the status of the Woodland Caribou at any other period or in any other region. Perhaps the earliest account is by Dobbs (1744: 22):