  Let (\rho_\lambda)_{\lambda\in \Lambda} be a holomorphic family of
representations of a finitely generated group G into PSL(2,C), parameterized by
a complex manifold \Lambda . We define a notion of bifurcation current in this
context, that is, a positive closed current on \Lambda describing the
bifurcations of this family of representations in a quantitative sense. It is
the analogue of the bifurcation current introduced by DeMarco for holomorphic
families of rational mappings on the Riemann sphere. Our definition relies on
the theory of random products of matrices, so it depends on the choice of a
probability measure \mu on G.
  We show that under natural assumptions on \mu, the support of the bifurcation
current coincides with the bifurcation locus of the family. We also prove that
the bifurcation current describes the asymptotic distribution of several
codimension 1 phenomena in parameter space, like accidental parabolics or new
relations, or accidental collisions between fixed points.
