  We introduce a minimal model for a two-dimensional polar flock with
nonquenched rotators, and show that the rotators make the usual macroscopic
long-range order of the flock more robust than the clean system. The rotators
memorise the flock-information which helps in establishing the robustness.
Moreover, the memory of the rotators assists in probing the moving flock. We
also formulate a hydrodynamic framework for the microscopic model that makes
our study comprehensive. Using linearised hydrodynamics, it is shown that the
presence of such nonquenched heterogeneities increases the sound speeds of the
flock. The enhanced sound speeds lead to faster convection of information and
consequently the robust ordering in the system. We argue that similar
nonquenched heterogeneities may be useful in monitoring and controlling large
crowds.
