It is shown analytically and by means of plasma numerical simulations that the large amplitude hydrogen cyclotron waves on auroral field lines near 1 RE altitude may be excited by upward flowing ion beams rather than by field-aligned currents. The large amplitude electric field near &ohgr;≈0 is identified as the ion gyro-harmonic waves on the beam ions observed in the frame of background ions and, therefore, such a wave exists only when the instability is excited by ion beams. Both the theory and numerical simulations support the conclusion.