A second route that joins the main artery on its eastern side is the one used by the blue goose (fig. 10), the migration route of which is probably more nearly due north and south than that of any other North American bird. The breeding grounds, which only recently have been discovered, are in the Fox Basin region of Baffin Island and on Southampton Island. In fall these geese work southward, chiefly along the eastern shore of Hudson Bay, and upon reaching the southern extremity of James Bay they take off for what is practically a nonstop flight to the great coastal marshes of Louisiana west of the delta of the Mississippi River (fig. 21). In some seasons the flocks make intermediate stops among the islands and sand bars of the Mississippi, as they are occasionally common in the general vicinity of Memphis, Tenn. Most of the birds push on, however, and during the period from the first of November to the last of March fully 90 percent of the species are concentrated in the area between the Sabine and the Mississippi Rivers. On the return trip northward there is sometimes a tendency for some of the blue geese to veer off toward the Northwest, as they are occasionally abundant in eastern South Dakota and southeastern Manitoba. It is of particular interest to note that while some other geese and many ducks start their northward journey at the first sign of awakening spring, the blue goose remains in its winter quarters until the season there is far advanced, seemingly aware that its own breeding grounds in the Arctic are still in the grip of winter. As shown by the route map (fig. 21) a great western highway also has its origin in the Mackenzie River delta area and in Alaska. This is used chiefly by the pintail and the baldpate (Mareca americana), which fly southward through eastern Alberta to western Montana. Some localities in this area, as for example, the National Bison Range, at Moiese, Mont., normally furnish food in such abundance as to induce these birds to pause in their migratory movement. Upon resuming travel, some flocks move almost directly west across Idaho to the valley of the Columbia River, from which they turn abruptly south to the interior valleys of California. Others leave the Montana feeding and resting areas and turn southeastward across Wyoming and Nebraska to join the flocks that either are moving southward through the Great Plains, or are to continue across Arkansas to the main Mississippi Valley fly way.