From the foregoing it may be seen that the wooded country represents a virtually fly-free haven for the Barren Ground Caribou during nearly ten months of the year. Is it any wonder, then, that they hasten throughout August toward or into the shelter of the woods, to gain freedom from the winged scourges of the Barrens? (See also _Retrograde autumnal movement_.) In the spring migration of 1947 the last of the Caribou passed the Windy River area on July 1, just before the mosquitoes and black flies had become seriously troublesome. It might be surmised that the animals keep marching northward in advance of the appearance of these flies, as long as that is feasible; and that when fairly overwhelmed by the winged hordes, they desist from further progress in that direction. The fawns are born at such a time (in late May or June) as to pass their first few tender weeks before becoming subject to serious insect attacks. (See also _Retrograde autumnal movement_; _Relations to flies_.) _References._--Richardson, “1825”: 328-329; Hoare, 1930: 33, 37-38; Jacobi, 1931: 193-195; Soper, 1936: 429; Hamilton, 1939: 247, 301; Clarke, 1940: 95-96; Porsild, 1943: 389; Banfield, 1951a: 27-29. _Effect of combined environmental factors on distribution_ The sum total of environmental factors apparently makes the Barren Grounds a distinctly more favorable summer habitat for the present species than the wooded country, since the latter region is virtually entirely deserted at that season. In general, the wooded country must be a more favorable winter habitat, since the bulk of the animals evidently resort to it at that time; yet its advantages are by no means clear-cut or overwhelming, since a very considerable proportion of the Caribou elect to spend the winter on the Barrens (Hanbury, 1904: 93, 120, 139; Hoare, 1930: 22; Clarke, 1940: 8-9, 11, fig. 4; Anonymous, 1952: 267). _Relations to man_ The Caribou dominates the thoughts, the speech, and the general human activities of the Barren Grounds. As the chief food resource of that region and the adjacent timbered country, it plays a highly important role in the economy of both primitive and civilized man. As long as those regions were occupied only by native Eskimos and Indians, employing such primitive weapons as bows and spears, the species was in no danger. Its vast numbers were maintained steadily from generation to generation, and were perhaps limited only by the grazing or browsing capacity of their range.