  Spectral signatures of surface spots were recently discovered from high
cadence observations of the A star Vega. We aim at constraining the surface
distribution of these photospheric inhomogeneities, and investigating a
possible short term evolution of the spot pattern. Using data collected over
five consecutive nights, we employ the Doppler Imaging method to reconstruct
three different maps of the stellar surface, from three consecutive subsets of
the whole time-series. The surface maps display a complex distribution of dark
and bright spots, covering most of the visible fraction of the stellar surface.
A number of surface features are consistently recovered in all three maps, but
other features seem to evolve over the time span of observations, suggesting
that fast changes can affect the surface of Vega within a few days at most. The
short-term evolution is observed as emergence or disappearance of individual
spots, and may also show up as zonal flows, with low-latitude and high latitude
belts rotating faster than intermediate latitudes. It is tempting to relate the
surface brightness activity to the complex magnetic field topology previously
reconstructed for Vega, although strictly simultaneous brightness and magnetic
maps will be necessary to assess this potential link.
