  We study the ergodic properties of horospheres on rank 1 manifolds with
non-positive curvature. We prove that the horospheres are equidistributed under
the action of the geodesic flow towards the Bowen-Margulis measure, on a large
class of manifolds. In the case of surfaces, we define a parametrization of the
horocyclic flow on the set of horocycles containing a rank 1 vector that is
recurrent under the action of the geodesic flow. We prove that the horocyclic
flow in restriction to this set is uniquely ergodic. The results are valid for
large classes of manifolds, including the compact ones.
