  Particle number fluctuations are studied in the ideal pion gas approaching
Bose-Einstein condensation. Two different cases are considered: Bose
condensation of pions at large charge densities $\rho_Q$ and Bose condensation
at large total densities of pions $\rho_{\pi}$. Calculations are done in grand
canonical, canonical and microcanonical ensembles. At high collision energy, in
the samples of events with a fixed number of all pions, $N_{\pi}$, one may
observe a prominent signal. When $N_{\pi}$ increases the scaled variances for
particle number fluctuations of both neutral and charged pions increase
dramatically in the vicinity of the Bose-Einstein condensation line. As an
example, the estimates are presented for $p+p$ collisions at the beam energy of
70 GeV.
