1852  (1881)  The black squirrel, for a succession of years, was very rarely to be met with on the plains, while there were plenty of the red and grey in the "oak openings."
1939  The general results of the foregoing would seem at first sight to point to the " groves," "open woods," "oak openings," parklands, or whatever name one may give them, being more pronounced on the western borders of this huge territory than on the Atlantic slope.