Hi Chris,
For plenty of reference, please also see my thread
http://www.vikingsword.com/vb/showthread.php?t=8630
Here is some more period artwork showing 15th and early 16th century bird's head pommels, plus a few others.
From top:
From the
Constitutio Criminalis Bambergensis (Bambergische Peinliche Halsgerichtsordnung), 1507: 2 woodcuts
From the
Wurzach altar by Hans Multscher, 1437: 1 detail
By Albrecht Dürer, Nuremberg, 1519: 1 image
From the
Arnstädter Auferstehungsaltar (the Arnstadt Resurrection altar), Thuringia, Germany, ca. 1430: 2 details
Detail from a woodcut, ca. 1505.
Best,
Michael