  We establish a Poincar\'e-Dulac theorem for sequences (G_n)_n of holomorphic
contractions whose differentials d_0 G_n split regularly. The resonant
relations determining the normal forms hold on the moduli of the exponential
rates of contraction. Our results are actually stated in the framework of
bundle maps.
  Such sequences of holomorphic contractions appear naturally as iterated
inverse branches of endomorphisms of CP(k). In this context, our normalization
result allows to precisely estimate the distortions of ellipsoids along typical
orbits. As an application, we show how the Lyapunov exponents of the
equilibrium measure are approximated in terms of the multipliers of the
repulsive cycles.
