Spallation of copper by high-energy alpha particles

28 radionuclides produced by spallation of natural copper by 720 MeV $\alpha$ particles were investigated by direct $\gamma$ counting of irradiated targets. Although the isobaric yield distributions and mass yield curve are similar in many respects to those found in proton spallation, a suppression of yields of neutron deficient products is observed. Several interpretations of this latter phenomenon are critically discussed.