On the walls of the Grinnell College Museum of Art, anthropomorphic birds in period military garb, horse-riding guards and bell-toting fairies are scattered among surreal still-life works and portraits.  On Friday, Sept. 15, the Grinnell College Museum of Art opened “Correspondence,” an exhibition by London-based Canadian artist Stephen Appleby-Barr. At the opening reception, Appleby-Barr and…