This paper investigates how the various waves of the whistler resonance cone compete for the free energy available in field-aligned fluxes of precipitating electrons in the auroral ionosphere. A two-dimensional numerical simulation code, based on the coupled pair of quasi-linear equations, is used for the investigation. The description provided by these equations allows us to follow the nonlinear development of the instability and analyze the interplay between the modes as mediated by the changing distribution function. We present results for a parameter regime corresponding to altitudes probed by sounding rockets, around 103 km and &OHgr;e≳&ohgr;p. The presence of a halo of energetic electrons significantly affects the evolution of the turbulence. The spectrum is shown to shift with time toward increasingly oblique propagation angles including a substantial share of quasi-perpendicular, short-wavelength modes close to the lower hybrid frequency. ¿ 1997 American Geophysical Union